Data collected includes:


The NHFD has reported nationally annually since 2010


In addition, quarterly reports are generated to allow for  best practice tariff  payments against the following criteria:


The  American Academy of Orthopaedic Surgeons  ( AAOS ) is an  orthopedic  organization.   Founded at  Northwestern University  in 1933, as of 2015 AAOS had grown to include about 39,000 members. [ 1 ]  The group provides education and practice management services for orthopedic surgeons and allied  health professionals . It also lobbies and works on public education. It describes itself as "the world's largest medical association of  musculoskeletal  specialists." [ 2 ]  It is a provider of musculoskeletal education to orthopaedic surgeons and others. Its continuing medical education activities include an annual meeting, multiple  CME  courses held around the country and at the Orthopaedic Learning Center, and various medical and scientific publications and electronic media materials.


Monthly nonpeer-reviewed news magazine published by the AAOS.


The  American Orthopaedic Foot and Ankle Society  (AOFAS) is a professional medical society based in  Rosemont ,  Illinois . It was founded in 1969 and currently has a membership of around 2,400 foot and ankle orthopaedic surgeons. The society provides education, research, grants, and other services to the general public and orthopaedic doctors, allied health practitioners, and researchers specializing in orthopaedic foot and ankle medicine and surgery. The organization also operates its own peer-reviewed journal,  Foot & Ankle International .


The AOFAS was founded in 1969 as the American Orthopaedic Foot Society (AOFS) with around 150 members. Its founding members included doctors Nathaniel Gould, Robert Joplin, Nicholas Giannestras, Melvin Jahss, Hampar Kelikian, Paul Lapidus, and Joseph Milgram. Several of its founding members served as early presidents of the organization including Robert Joplin (1969–70), Nicholas Giannestras (1970–71), Nathaniel Gould (1971–72), and Melvin Jahss (1973–74). [ 1 ]  New presidents are elected by members of the society at an annual meeting each year. [ 2 ] [ 3 ]  The society held its first scientific meeting in  San Francisco  in 1971. In 1973, president Robert Samilson helped make the AOFS the first affiliate of the American Academy of Orthopaedic Surgeons (AAOS). [ 1 ]


Throughout its first decade, the society provided research grants, [ 4 ]  advised shoe manufacturers, [ 5 ]  analyzed and disseminated research, [ 6 ]  and provided education and resources to orthopaedic surgeons and the general public. [ 1 ] [ 7 ]  In 1981, Melvin Jahss helped establish and became the first editor of the society's official peer-reviewed journal, [ 3 ]   Foot & Ankle , which would eventually be renamed  Foot & Ankle International . In 1983, the members of the AOFS voted unanimously to change the name of the organization to the "American Orthopaedic Foot and Ankle Society". In the mid-1980s, the AAOS dissolved the affiliation agreements with the AOFAS and other organizations allowing them to congregate independently. This occurred under AOFAS president, John Gould (the son of founder, Nathaniel Gould). [ 1 ]


In the 1990s, the society researched and disseminated the results of several studies about footwear and its effects on feet and ankles. In particular, the studies often identified issues with women's footwear [ 8 ]  and, specifically, high heels. [ 9 ]  In a 1992 partnership with the National Shoe Retailers Association (NSRA), the AOFAS started a public awareness campaign with a pamphlet titled "10 Points of Proper Shoe Fit". [ 10 ]  In 1994, the AOFAS held a news conference to call on shoe manufacturers to create "women's shoes that do not deform the foot". [ 11 ]  Under president G. James Sammarco, in 1996, the society instituted a voluntary "seal of approval" program that allowed shoe manufacturers to send in their models to be inspected for comfort and design quality by AOFAS physicians and researchers. The organization also maintained offices in  Seattle  at that time. [ 12 ]


In 2001, AOFAS president Pierce Scranton established the Orthopaedic Foot and Ankle Outreach and Education Fund (OEF), a  501(c)(3) organization  that provides education and medical services to under-served communities throughout the world. [ 1 ]  In 2005, the organization established the website FootCareMD.com to provide education and resources to the general public. [ 13 ]  By 2010, the organization's headquarters were located in Rosemont, Illinois. [ 14 ]  In 2011, Judith Baumhauer became the organization's first female president. In 2014, OEF changed its name to the Orthopaedic Foot & Ankle Foundation. [ 15 ]


In July 2017, the AOFAS established a consumer awareness campaign called "Look for the 'O'", which urged individuals to seek the care of orthopaedic surgeons when experiencing foot or ankle pain. [ 16 ]  The current AOFAS president, Bruce E. Cohen, was elected in September 2020. The society maintained a membership of around 2,400 at that time. [ 17 ]


The AOFAS is composed of around 2,400 foot and ankle orthopaedic surgeons. [ 17 ]  Each member is a medical doctor specializing in the diagnosis and treatment of numerous foot and ankle injuries, diseases, and other ailments. The training required includes four years of medical school and five years of  medical residency  followed by a one- or two-year fellowship with a specialty focus in foot and ankle care. [ 18 ]


The American Orthopaedic Society for Sports Medicine (AOSSM)  promotes sports medicine education, research, communication, and fellowship and includes national and international  orthopaedic sports medicine  leaders. The Society works closely with many other sports medicine specialists, including  athletic trainers ,  physical therapists ,  family physicians , and others to improve the identification,  prevention ,  treatment , and rehabilitation of  sports injuries . Formed in 1972 as a forum for education and research with 100 members, the AOSSM today has to more than 2,000 members. [ 1 ]


The AOSSM developed out of the  American Academy of Orthopaedic Surgeons ’ (AAOS)  Committee  on  Sports Medicine . The committee was organized in 1964 with Jack Hughston as Chairman. Throughout the next seven years, interest in sports medicine among  orthopaedists  increased greatly. Don O’Donoghue, MD, approached the AAOS concerning the committee branching off and forming an affiliated, yet separate, society. [ 2 ]  On  January 30, 1972 , at the invitation of Dr. Donoghue, 58 orthopaedic surgeons involved in sports medicine gathered to discuss the creation of the new society. A total of 75 orthopaedists were invited, and these physicians make up the list of founding members of the society. [ 3 ]


The founding members developed the mission of AOSSM: to hold a scientific meeting that would serve as a forum for  presentation  and  publication  of new ideas; to provide opportunities for physicians to meet and exchange ideas concerning research and the future of sports medicine; as well as to develop a high-quality publication controlled by the Society. [ 3 ]


In 2013, Jo A. Hannafin, M.D., Ph.D., an orthopedic surgeon at Hospital for Special Surgery (HSS) in New York City, was named the first female president of AOSSM. [ 4 ]


AOSSM members are physicians and allied  health professionals  who demonstrate scientific leadership, involvement, and dedication in the daily practice of sports medicine. Members must demonstrate continuing active research and educational activities in the field of sports medicine. Such activities may include service as a  team physician  at any level of competition, involvement in the health of  athletes , service to local, regional, national, and international competitions, and the presentation of  scientific research papers  at sports medicine meetings. [ 1 ]


Members focus on the effects of exercise and the monitoring of its impact on active individuals of all ages, abilities, and levels of  fitness . While many members treat high-profile athletes who play on  professional teams , many also devote their practices to helping their  community  by treating players on the local high school or  junior college  team. Through research and advances in  surgical  and rehabilitation techniques, orthopaedic sports medicine specialists have been able to treat and rehabilitate athletes whose injuries were once  career-ending  and put them back in the game sooner.


Members are broken down into seven different groups: active members, associate members, candidate members, affiliate members, honorary members, emeritus members, and inactive members.


Active members are: U.S. or Canadian citizens who are orthopaedic surgeons specializing in sports medicine. They must:


Active members are eligible to vote, and unless specified otherwise, hold office in the Society.


Associate members are: international orthopaedic surgeons practicing outside of the United States or Canada who are certified in orthopaedic surgery and members of their country's national orthopaedic organization, or osteopathic physicians not qualified to be Active Members but certified by the  American Osteopathic Board of Orthopedic Surgery . They must:


Associate members are not eligible to vote, hold office, or serve on the Board of Directors. They may act in an  advisory  capacity and unless specified otherwise, may serve on committees with vote.


Candidate members are physicians who are enrolled in or have completed an  Accreditation Council for Graduate Medical Education  (ACGME) approved orthopaedic sports medicine  fellowship  in the United States or Canada. They must:


Candidate members are not eligible to vote, hold office, or serve on the Board of Directors. They may act in an advisory capacity and, unless specified otherwise, serve on committees with vote.


Affiliate members are physicians, surgeons, or allied health professionals not qualifying for other membership categories who are interested in or contributing to the knowledge of sports medicine. They must:


Affiliate members are not eligible to vote, hold office in the Society, or serve on the Board of Directors. They may act in an advisory capacity and unless specified otherwise may serve on committees with vote.


Honorary members are those who do not meet the qualifications of Active, Associate, or Affiliate membership, but who have made special contributions to sports medicine. They are not eligible to vote, hold office in the Society, or serve as a member of the Board of Directors, but may act in an advisory capacity and, unless specified otherwise, may serve on committees with vote.


Nominees for honorary membership are submitted to the Board of Directors for consideration. A limited number of honorary members is determined by the Board of Directors.


Emeritus members are an active member or affiliate member who has reached the age of 65 and is no longer engaged in active medical practice due to age or health. Emeritus Members are not eligible to vote, hold office, or serve as a member of the Board of Directors but may act in an advisory capacity and unless specified otherwise serve on committees with vote.


Inactive members are members or an allied health professional who have met the qualifications for any category of membership but are currently unable to practice medicine due to physical disability or such other reason acceptable to the Board of Directors. Inactive members are not eligible to vote, hold office, or serve as a member of the Board of Directors but may act in an advisory capacity and, unless specified otherwise, serve on committee with vote.


The  AOSSM Annual Meeting  and  AOSSM Specialty Day  are two of the AOSSM’s main meetings. The AOSSM Annual Meeting is held once a year (usually at the end of June or beginning of July) and is a place for the Society’s members and Board of Directors to meet, as well as for educational courses and research to be presented. [ 5 ]  AOSSM Specialty Day is held during the  American Academy of Orthopaedic Surgeons’ annual meeting . It is a one-day meeting that provides educational courses and presentations focused on sports medicine. The Society also hosts other meetings throughout the year focusing on particular injuries or sports specifics areas, such as  football  or  hockey .


The AOSSM Web site houses a full  Online Library  of scientific and patient education materials. The AOSSM also has five print publications.


American Journal of Sports Medicine  is a monthly, peer-reviewed scientific journal, first published in 1974. It is the official publication of AOSSM, and is ranked 1st out of 63 journals in Orthopaedics  [ 6 ]  and 5th out of 84 journals in Sport Sciences  [ 7 ]  in Thomson Reuters’s 2012 Journal Citation Reports, with an Impact Factor of 4.439. [ 8 ]  The journal is published by SAGE Publishers.


Sports Health  (January 2009) is published  bimonthly  and is a collaborative publication from AOSSM, the  American Medical Society for Sports Medicine  (AMSSM), the  National Athletic Trainers' Association  (NATA), and the  Sports Physical Therapy Section  (SPTS). Sports Health is a resource for all medical professionals involved in the training and care of the competitive or  recreational  athlete. The journal is published by SAGE Publishers. [ 9 ]


Sports Medicine Update  is AOSSM's bimonthly publication and includes educational articles, Society news and research updates, resources, and new developments within the orthopaedic sports medicine community. [ 10 ]


Both  Sports Tips  and  In Motion  are patient education publications.  Sports Tips  are one-page fact sheets on athletic related conditions and injuries.  In Motion  is a quarterly newsletter and features short articles focusing on sports medicine, fitness, and musculoskeletal issues for people of all ages. [ 11 ]


AOSSM awards grants to researchers working on  break-through  treatments and investigations in sports medicine. [ 12 ]


The Young Investigator Grant provides awards aimed at providing "seed money," or start-up funds, for pilot projects. The principal investigator must be an early career orthopaedic surgeon, fellow, or resident with interests in sports medicine research. Any investigative team seeking such a grant must include at least one member of AOSSM in good standing.


Dr. Sandy Kirkley was an advocate for well-conducted,  randomized controlled trials  to evaluate the efficacy of interventions in orthopaedic sports medicine. She said that the field must "rise to the challenge of designing and implementing clinical trials that provide the same level of evidence in support of treatments as our nonsurgical colleagues demand." In honor and memory of Dr. Kirkley, AOSSM established a small grant that would provide start-up, "seed," or supplemental funding for an outcome research project or pilot study.


AOSSM offers a per year supplement grant to sports medicine orthopaedic surgeons who have an active Career Development Award (K Award) from the  National Institutes of Health  (NIH). The purpose of this grant is to facilitate the research careers of orthopaedic surgeons who have completed training in sports medicine and who have a faculty position at an academic institution. The award is open to individuals regardless of time since training.


AOSSM has initiated the AOSSM Multi-Center ACL Revision Study (MARS), utilizing a grant from the  Musculoskeletal Transplant Foundation  (MTF). The study will evaluate outcome for patients undergoing revision  ACL surgery  and examine the predictors of outcome. The MARS project has been approved by the  Institution Review Board (IRB) of the central coordinating site,  Vanderbilt University .


The Multi-Center Evaluation of the Responsiveness of the IKDC (MERI) Study is designed to evaluate and compare the responsiveness to change of several measures commonly used in patients undergoing knee surgery: the  International Knee Documentation Committee (IKDC) Subjective Knee Form , the  WOMAC , the Cincinnati Knee Rating System, and the  SF-36 . The specific patient population targeted for this study are those individuals who receive any form of surgical articular cartilage repair procedure for at least one symptomatic full thickness (Outerbridge Grade III or IV)  lesion  of the  femoral condyle  or  trochlea . These procedures can include  debridement ,  marrow  stimulation techniques such as  microfracture , drilling or abrasion  arthroplasty , osteochondral  autograft  or  allograft  transplantation, mosaicplasty or autologous  cartilage  implantation. Any surgeon who performs at least three of these procedures a year can be involved in the project.


Each year during the AOSSM Annual Meeting a variety of awards are presented for research and outstanding achievement in sports medicine. [ 13 ]


In 2001, AOSSM established the Hall of Fame to honor members of the orthopaedic sports medicine community who have contributed significantly to the specialty and set themselves apart. Being inducted into the Hall of Fame is one of the highest honors given to a Society member.


This award is given to an individual who has provided outstanding service in the orthopaedic community, and made numerous contributions to the specialty of sports medicine.


This lectureship is named in honor of John C. Kennedy, MD, FRCS(C) a past president of AOSSM. This lecture is supported by a Kennedy Family Endowment and AJSM and is named by the current AOSSM President.


This award is given to an orthopaedic surgeon who has been dedicated to excellence in sports medicine on a local level, with local athletes.


This award is given to the paper that best exemplifies clinically relevant  hypothesis -driven  basic science  research (hard or soft  tissue   biology ,  in vitro  research,  laboratory  or "bench-type" research, or  in vivo  animal).


This award is given to the best paper submitted in any category to the Awards Committee with a primary author under the age of 40 at the time of the Annual Meeting.


The award is given to the best paper submitted that pertains to the health, safety, and well-being of collegiate student-athletes.


This award is given to the best overall paper that deals with clinical based research or human  in vivo  research.


This award is given annually to an individual AOSSM member to recognize their contribution to sports medicine education throughout the years.


This award is given for the most outstanding paper that appeared in AJSM, the year prior to the award. It was named after the founder of AJSM, Jack C. Hughston, MD.


The Christian Koi Awards are given to the best paper in  clinical science  and the best paper in basic science submitted by a sports medicine fellow for the AOSSM Annual Meeting.


Given during the AOSSM Annual Meeting for an outstanding poster presented during the meeting.


AOSSM member physicians are listed in the  AOSSM Member Doctor Directory  for the public's use. Searches can be done by physician’s last name or by city/state or country.


The  American Osteopathic Board of Orthopedic Surgery  ( AOBOS ) is an organization that provides  board certification  to qualified  Doctors of Osteopathic Medicine  (DO) and non-osteopathic (MD and equivalent) physicians who specialize in the medical and surgical treatment of disorders of the  musculoskeletal system  ( orthopedic surgeons ). The board is one of 16  medical specialty  certifying boards of the  American Osteopathic Association Bureau of Osteopathic Specialists  approved by the  American Osteopathic Association  (AOA), [ 2 ]  and was originally a subdivision of the  American Osteopathic Board of Surgery [ 3 ]  until it became an independent board in 1978. Additionally, diplomates of the American Osteopathic Board of Orthopedic Surgery are eligible for membership in the  American Osteopathic Academy of Orthopedics [ 4 ]  and the  American Academy of Orthopaedic Surgeons . [ 5 ]


To become board certified in orthopedic surgery, candidates must have completed an ACGME-accredited  residency  in orthopedic surgery and one year of practice following the completion of residency. Additionally, candidates must have performed at least 100 major orthopedic surgeries in the six months preceding application for board certification, and successfully complete the required Written and Clinical exams. [ 6 ]  Since 2023, board certified osteopathic orthopedic surgeons complete the Osteopathic Continuous Certification (OCC) components, including annual Longitudinal Assessment, to maintain active board certification status. [ 7 ]


Board certified osteopathic orthopedic surgeons may also receive Certification of Added Qualifications (CAQ) in  Orthopedic Sports Medicine  and  Hand Surgery . [ 8 ] [ 9 ]  Orthopedic surgeons holding subspecialty certification in Hand Surgery complete the Osteopathic Continuous Certification (OCC) components, including a recertification examination completed every ten years. Orthopedic surgeons holding subspecialty certification in Orthopedic Sports Medicine must complete the Osteopathic Continuous Certification (OCC) components, including annual Longitudinal Assessment.


The  American Society for Surgery of the Hand  ( ASSH ) was founded in 1946 to facilitate the exchange of information related to problems of the  hand . [ 1 ] [ 2 ]   It is the oldest and largest medical specialty society in the United States devoted to the care of the hand.


Hand surgery  as a specialty grew out of the treatment of the hand injuries that occurred during World War II. Sterling Bunnell, MD, founder and first president of the ASSH, set up nine regional hand centers at U.S. Army bases throughout the United States during the 1940s. As  World War II  drew to a close, Bunnell suggested forming an organization to continue to foster interest in hand care. In January 1946, he and 34 hand surgeons, many of whom had worked in the Army hospitals, met immediately preceding the annual meeting of the  American Academy of Orthopaedic Surgeons  (AAOS). The group continued to meet in conjunction with the AAOS annual meeting until 1987, when it held its first stand-alone annual meeting.


ASSH offers four types of membership: Active, Candidate, International, and Affiliate.


Active members  are physicians who reside in the  United States  or  Canada , and are certified by the  American Board of Orthopaedic Surgery  (ABOS), the  American Osteopathic Board of Orthopedic Surgery  (AOBOS), the  American Board of Plastic Surgery  (ABPS), the  American Board of Surgery  (ABGS) or by the  Royal College of Physicians and Surgeons of Canada . [ 3 ]  All American-based hand surgeons seeking admission to Active Membership within ASSH are required to hold a  Certificate of Added Qualifications in Hand Surgery , which is jointly administered by the three American boards. To maintain membership within ASSH, Active Members must attend an ASSH annual meeting at least once every three years.


Candidate members  are qualified surgeons working in the United States who are interested in hand surgery and may eventually apply for full membership.


International members  are qualified hand surgeons practicing medicine outside of the United States.


Affiliate members  are allied healthcare professionals (e.g., hand therapists; occupational therapists; physical therapists; physician assistants; nurse practitioners; registered nurses) specializing in care of the hand and upper extremity.


The  British Orthopaedic Association  is a  professional association  in  Britain  for doctors who specialize in  orthopaedic surgery .


The British Orthopaedic Association was founded in 1918. [ 1 ]  One of the founders was  Harry Platt , who went on to serve as its president in 1934-1935. [ 2 ]


As of 2013 the organisation reports having 4,000 members with most based in the United Kingdom and  Ireland . [ 1 ]  The BOA represents 40% of the total surgical workforce in Britain. [ 1 ]


In 1919 the  Journal of Bone and Joint Surgery  became the official journal of the British Orthopaedic Association in addition to the American Orthopedic Association. [ 3 ]


In 2012  Royal College of Surgeons of England  and the British Orthopaedic Association called for increased regulation of implants to prevent implant failure. [ 4 ]


In association with the BGS, the BOA set up the  National hip fracture database  for England and Wales.


The  Brittle Bone Society [ 1 ]  is the only  UK  wide  charity  dedicated to providing support to people affected by  osteogenesis Imperfecta  (OI).


The Brittle Bone Society was established in 1968 in  Dundee  by Margaret Grant, who has OI. When she was young, Grant was aware that there was virtually no support for people with OI and that many medical professionals knew little or nothing about the condition. When her daughter Yvonne was born some years later, very little had changed. For many years Grant was the driving force of the society, which was recognised when she was awarded an  MBE  in 1989 [ 2 ]  and in 2018 when she was awarded an honorary degree from the  University of Dundee . [ 3 ]


The society now has more than 1,000 members and works closely with specialist medical units and other professionals throughout the UK.


The CEO is Patricia Osborne who has been working with the charity since 2009 [ 4 ]


The society's archives, which include about thirty boxes of material, are held by the  University of Dundee . [ 5 ]


This article about a charitable organisation in the United Kingdom is a  stub . You can help Wikipedia by  expanding it .


The  Indian Orthopaedic Association  was founded in 1955 and as on 2013 had over 9,000 members. [ 1 ]


The first surgeons who focused on  orthopedic surgeries  in India were  Dr. R J Katrak , Dr. N S Narasimha Aiyar and Dr. S R Chandra. After World War II, Dr. Mukhopadhaya and Dr.  K S Grewal  suggested forming an association during the annual conference of ASI in Vellore in 1952. Many practicing surgeons met in  Agra  in 1953, most prominently Katrak, Dr. B N Sinha, Grewal, Mukopadhaya and Dr. A K Gupta. They agreed to form an orthopedic section of ASI. However, in 1954, the general body of the ASI at Hyderabad rejected the proposal.


The society was officially formed in Amritsar at an ASI meeting in December 1955. Dr. B N Sinha and Dr. Mukopadhaya were unanimously elected president and secretary.  Dr. A K Talwalkar started the Johnson & Johnson and the Smith & Nephew traveling fellowships on behalf of IOA. The annual Kini Memorial Oration started in 1958.  Sir Harry Platt  served as the first Orator in 1958. The members of the Association published the first issue of a journal in 1967 with Prakash Chandra as the Editor. A constitution prepared by a select committee was unanimously approved at the General Body meeting in 1967. This was later registered under the  Indian Societies Act .


At the 1986 Agra ASI conference, the IOA became independent of ASI. Sixteen regional chapters were formed.


The  International Fibrodysplasia Ossificans Progressiva Association  ( IFOPA ) is a US-based  501(c)(3)   non-profit organization  supporting medical research, education and communication for those afflicted by the rare genetic condition  Fibrodysplasia Ossificans Progressiva  (FOP). IFOPA's mission is to fund research to find a cure for FOP while supporting, connecting, and advocating for individuals with FOP and their families, and raising awareness worldwide. IFOPA is governed by a volunteer  board of directors  which may range in number from 9 to 15, at least one of whom must have FOP. The association's location is 1520 Clay St., Suite H2,  North Kansas City , MO, 64116,  part of the  Kansas City, Missouri  metropolitan area.


IFOPA was founded in 1988 by Jeannie L. Peeper. Diagnosed with FOP in 1962 at age four, Peeper graduated from college in 1985 with a bachelor of arts degree in social work.  Michael Zasloff , then at the  National Institutes of Health  (NIH), was studying FOP and put Peeper in contact with all FOP patients known to the NIH, eighteen in total, to whom Peeper mailed a questionnaire. Eleven responded. In early 1988, Peeper started a newsletter called  FOP Connection  in collaboration with Nancy Sando, one of the respondents. In June of that year, Peeper founded the IFOPA to facilitate fund raising for FOP research and generally create awareness of the disease. With an initial association membership of eleven, Peeper became the inaugural president and Sando was appointed vice president. In 1989, Peeper collaborated with the  University of Pennsylvania  to support establishment of the FOP Collaborative Research Project, and in 1992, the Center for Research in FOP and Related Disorders, efforts spearheaded by Drs.  Frederick Kaplan , Michael Zasloff, and  Eileen Shore .


Throughout the 1990s, IFOPA organized two international symposiums on FOP and several FOP family meetings. In the first decade of the 2000s, two more international symposiums were hosted by IFOPA, and other FOP scientific and family meetings were held in Argentina, Brazil, Canada, France, Germany, Italy, The Netherlands, Sweden, and the UK.  In April 2006, the Center for Research in FOP discovered the FOP gene. By 2020, the organization had over 500 members from 57 countries and had partnered with FOP organizations and communities on all continents except Antarctica.


In 2010, IFOPA implemented the first annual Jeannie L Peeper Awards to recognize philanthropy, community involvement, international leadership and youth leadership in support of the FOP cause. Also in 2010, the Central Florida Chapter of the Association of Fund Raising Professionals named Peeper as winner of the 2010 Lifetime Achievement Award for her work in founding and establishing the IFOPA. A gathering of FOP families, supporters, researchers, and pharmaceutical industry representatives was held in Orlando in late 2013 on the 25th anniversary of the Association.


IFOPA hosted FOP drug development forums in 2014 and 2016 in Boston, 2017 in Sardinia Italy, and 2019 in Orlando. The forums brought together FOP experts to discuss the latest research, solve drug development challenges and strengthen the global network of research collaborations. The 2019 Drug Development Forum attracted 154 attendees from 19 countries including researchers, clinicians, biotech and pharmaceutical company representatives, regulators, advocates and people living with FOP. [ 1 ]


Quoting the 27th Annual Report of the FOP Collaborative Research Project "As of January 1, 2018, there were 37 research universities and/or clinical centers actively engaged in FOP research; 18 in the United States & Canada, 12 in Europe, five in Asia, one in Africa and one in Australia. As of January 1, 2018, there were 12 pharmaceutical and biotechnology companies actively developing drugs for FOP based on a multitude of hard targets, and over 30 companies that have expressed interest." [ 2 ]


In early 2017, IFOPA closed its Orlando office and moved administrative operations to North Kansas City, Missouri.  A reorganization plan entailed creation of several new positions as follows: Director of Research Development and Partnerships, Family Services Manager, Donor Relations and Administrative Coordinator, Community Fundraising Manager, and FOP Registry Project Director.


Historically, IFOPA has allocated over 80% of its annual budget to medical research and programs, donating in the range of $350,000 to $650,000 annually to the FOP Laboratory.  IFOPA is a  GuideStar  Gold Participant by virtue of the public information IFOPA provides beyond that available from the IRS. [ 3 ]  General overhead, defined as a combination of fund raising and management expenses, has for the past decade averaged below the Association of Fundraising Professionals statement that the average American believes 23 cents on the dollar being spent on such costs is a reasonable figure. IFOPA's financial statements and 990s are posted on the IFOPA website.


IFOPA fund raising results principally from family-organized activities rather than large nationwide events. In addition to the association's own annual appeal, several grants, and traditional family/friends letter drives, the range of family fund raisers includes golf tournaments, barbecues, bingos, auctions, comedy shows, rock concerts, holiday card sales, raffles, suppers, athletic events, and a variety of other social events and receptions. Some of the more unusual fund raisers include an annual Burns Supper in Aberdeen Scotland, an ice fishing contest, and the auctioning of a quilt decorated with a double helical border symbolizing both the DNA double helix and the quest to find a cure. In 2010, the association established the Jeannie Peeper Heritage Society, a fund raising program that targets major donors and estate giving.


IFOPA's medical and scientific advisors are  Frederick S. Kaplan , Eileen M. Shore, and  Michael Zasloff .  The foregoing advise the association on issues such as family support and counseling, dissemination of medical documents and treatment guidelines, medical document translation, physician awareness strategies, research funding requests and initiatives, and other matters for which their expertise is required.


Kaplan is the Isaac and Rose Nassau Professor of Orthopaedic Molecular Medicine and Chief of the Division of Orthopaedic Molecular Medicine at the  Perelman School of Medicine at the University of Pennsylvania . Kaplan co-directs the Center for Research in FOP and Related Disorders and is recognized as the world's leading expert on genetic disorders of  heterotopic ossification  and skeletal metamorphosis. [ 4 ]  In 1997, Kaplan was awarded the first endowed chair in the USA for orthopaedic molecular medicine. In 2006,  Newsweek  named Kaplan as one of "15 people who make America great". [ 5 ]  In 2009, Kaplan was elected to the  Institute of Medicine , an organization established by the  United States National Academy of Sciences  to honor professional achievement in the health sciences.


Shore is the Cali and Weldon Research Professor in FOP, and Professor of Orthopaedic Surgery and Genetics in the Perelman School of Medicine at the University of Pennsylvania, Co-Director of the Center for Research in FOP and Related Disorders, and director of the FOP Molecular Biology Laboratory. She is a past-president of the Advances in Mineral Metabolism (AIMM) Board of Directors and served on the American Society of Bone and Mineral Research (ASBMR) Council. Shore was awarded a PhD from the University of Pennsylvania (Cell and Molecular Biology) followed by post-doctoral training in  cell biology  at the  Fox Chase Cancer Center  in Philadelphia. Shore's collaboration with Kaplan led to the discovery of the mutated genes in both FOP and POH  Progressive osseous heteroplasia . [ 6 ] [ 7 ]


Zasloff is Scientific Director, MedStar Georgetown Transplant Institute,  Georgetown University School of Medicine .  In the early 1980s, during his tenure at the National Institutes of Health as Chief of the Human Genetics Branch, he began clinical and basic studies of FOP and helped found the IFOPA with Jeannie Peeper.  In 1989, as the Upham Professor of Pediatrics and Genetics at the University of Pennsylvania and Chief of the Division of Human Genetics of the  Children's Hospital of Philadelphia , he began his collaboration with Fred Kaplan to find both the cause and cure of FOP.


As a result of the rareness of FOP, the condition is little known even among medical clinicians. Close to 90% of FOP patients worldwide are misdiagnosed. [ 8 ]  In such circumstances, the association directly supports research, makes information about FOP including symptoms and treatment guidelines available to both physicians and families, and supports afflicted families with mentoring, family meetings and an information network. Below are IFOPA's programs of research, education, family support, and advocacy. Additional information about these programs, including downloadable reports, articles and other materials, may be obtained from the IFOPA website.


The  International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine  ( ISAKOS ) is an international medical society with around 4,000 members. The membership comprises mostly orthopaedic surgeons along with sports scientists, sports physicians and sports physical therapists. The members are from some 92 different countries and are members of their local orthopaedic sports medicine societies or similar associations. Members may also be associated with their global regional orthopaedic sports medicine society such as the  Arthroscopy Association of North America , the  American Orthopaedic Society for Sports Medicine  (AOSSM), the Asia-Pacific Knee, Arthroscopy and Sports Medicine Society, the European Society for Sports Traumatology, Knee Surgery and Arthroscopy and the Sociedad Latinoamericana de Artroscopia, Rodilla y Deporte in particular.


The purpose of ISAKOS is to act as an umbrella association for these regional societies to provide a means for exchange of knowledge between them and, most importantly, to promote education in the fields of knee surgery and orthopaedic sports medicine to those areas of the world where such educational opportunities are lacking. ISAKOS achieves these goals by the involvement of members in educational meetings, sponsoring of visitations by surgeons from poorer countries to centres of excellence along with other awards, scholarships and endorsements of regional meetings.


Arthroscopy  (also called arthroscopic surgery) is a  minimally invasive   surgical procedure  on a  joint  in which a treatment or just an examination is performed using an arthroscope, an  endoscope  that is inserted into the joint through a small incision.


Sports medicine , also known as sport and exercise medicine (SEM), is a part of  medicine  that deals with the prevention and treatment of  injuries  related to  sports  and  exercise .


ISAKOS was formed in 1995, in Hong Kong, at the combined congress of the International Arthroscopy Association (IAA) and the International Society of the Knee (ISK). These two societies previously held meetings 'back to back' and as most delegates attended both it became a logical step to combine them. ISAKOS is the union of these International societies (IAA and ISK). ISAKOS holds an international Congress every two years. Since the founding in 1995, these Congress meetings have been held throughout the world. The first president of ISAKOS was Dr. Peter J. Fowler of Canada, in the years 1995 to 1997.


For the 2015–17 term, the society was chaired by Dr. Philippe Neyret of France, followed by Dr. Marc Safran of the USA from 2017–19. [ 1 ]  The society is currently chaired by  Dr. Willem van der Merwe  of South Africa, who will hold the post until 2021. [ 2 ]


ISAKOS is an international society of individuals interested in Sports Orthopaedics and the fields of medicine and science related to that. These include knee surgery, arthroscopic surgery of all joints and orthopaedic sports medicine. It is very common for those applying for membership to also be a member of one of the major regional Associations. These are the Arthroscopy Association of North America (AANA), the American Orthopaedic Society for Sports Medicine (AOSSM), the Asia-Pacific Knee, Arthroscopy and Sports Medicine Society (APKASS), the European Society for Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA) and the Sociedad Latinoamericana de Artroscopia, Rodilla y Deporte (SLARD). Members are also members of their regional or National orthopaedic sports medicine society (or equivalent). Indeed, members of these Associations may gain Associate Membership of ISAKOS immediately on application.


There are two primary membership categories:


Associate members


Those with an interest or ability in the fields of medicine or science with an interest in arthroscopy, knee surgery, and orthopaedic sports medicine shall be eligible. These members are not entitled to vote and are not eligible to hold office.


Active members


Individuals qualified as orthopaedic surgeons, musculoskeletal surgeons, rheumatologists or the equivalent in their home countries and who are in good medical standing in their national or regional association as determined by the membership committee of the ISAKOS. Active members are entitled to vote at all meetings of the membership and are eligible to hold office in the society. Active Membership is awarded pending an application review at a meeting of the Membership Committee. The Membership Committee meets at all annual AAOS meetings and at ISAKOS congresses.


ISAKOS offers a number of awards. These awards are for original papers in the various categories which are submitted for the biennial Congress. The awards are presented at the Congress and notified in the Society Newsletter and on the ISAKOS website.


Many of the Awards honour prominent present and past ISAKOS members and past notable doyens of sports surgery while others offer financial support for research, Fellowships and attendance at various ISAKOS sponsored meetings.


In keeping with the fundamental mission of ISAKOS some preference is given to supporting research and scholarships to individuals from countries where such opportunities may not have otherwise been available.


These awards include;


Awards


Fellowships and Scholarships


Applications for these Awards and Scholarships are usually invited a year before the Biennial Congress.


The primary focus of ISAKOS is education in the fields of Orthopaedic Sports Medicine, Arthroscopy and Knee Surgery. It achieves this goal by 4 means; the Biennial ISAKOS Congress, focussed expert consensus meetings resulting in a publication, instructional courses and surgical techniques available on the ISAKOS website and involvement with approval of many other courses with similar educational intent throughout the world. ISAKOS also allows branding of Fellowship programs and financially supports specific educational Travelling Fellowships.


The Biennial Congress


This is the most important event in the ISAKOS calendar and much activity centres on the planning and organisation of this International Congress. Many of the ISAKOS Committees have input into the structure, format and content of the Congress with the oversight of the Program Committee and the Program Chair. The Congress is a forum for free papers and abstracts are required usually 12 months in advance.


In addition, the Congress also includes Instructional Courses on specific topics led by International experts along with Symposia on topics of current interest. In recent years the Congress has expanded to include live surgical demonstrations and 'Hands on Workshops'.


Poster presentations are now presented electronically and delegates receive an electronic copy of these with their registration. More recently the Congress has also made available a dedicated app which allows delegates to preview abstracts and plan their involvement at the Congress.


The Congress also includes sessions for debates on current issues, technical exhibits and time for networking which is so important in developing International professional contacts and acquaintances.


The biennial ISAKOS Congress is usually held for a total of five days, during the months of May or June. Several ISAKOS Awards for outstanding clinical or laboratory research are presented during this meeting. The most recent ISAKOS meeting was held in 2017 in Shanghai, China, and involved over 4000 attendees from 84 countries presenting 256 papers and 753 E-posters.


ISAKOS also supports and collaborates on several other meetings throughout the year focusing on knee injuries or other sports related areas of interest. In addition, the Society provides accreditation for numerous other educational courses all over the world.


Focussed Expert Consensus Meetings


The Clinical Committees of ISAKOS are made up of multinational members with common interests. This provides a forum for discussion and often resolution of many issues relevant to that speciality. Often the Committee will convene a meeting to resolve a specific issue or discuss a specific topic. Experts from around the world, whether ISAKOS members or not, are invited to these meetings and a consensus is usually developed.


These consensus meetings usually result in a publication on the topic. Such international consensus on a controversial topic is a much more considered resolution of an issue than the opinions of a single expert.


A number of ISAKOS derived publications of the outcomes of consensus meetings are available to members, many of which have been published in respected orthopaedic literature.


Instructional Course Lectures and Surgical Technique Videos


Through the ISAKOS website and the Global link members are able to view many Instructional videos on current topics. Surgical technique videos are also available. Many of these have been recorded during previous Congress sessions and others have been supplied by individual surgeons for the benefit of ISAKOS members.


ISAKOS Approved Meetings


Regional societies have their local meetings attracting their members and other delegates from locally or from other countries. These local societies can apply to ISAKOS for approval of their program. This is determined by the Scientific Committee and if approval is granted then this can be advertised by the regional society. The expectation is that such approval offers a degree of enhanced credibility to the scientific nature of the approved meeting.


The  Major Extremity Trauma Research Consortium  (METRC) is a network of clinical centers centered at the  Johns Hopkins Bloomberg School of Public Health  conducting multicenter  clinical research studies  on the treatment and outcomes of traumatic  orthopedic injuries .


In 2024, the PREVENT CLOT study was awarded the Distinguished Clinical Research Achievement Award by the Clinical Research Forum. [ 1 ]


In 2023, the American Academy of Orthopaedic Surgeons (AAOS) awarded METRC the Kappa Delta Elizabeth Winston Lanier Award. [ 2 ]


In 2023, Dr. Michael J. Bosse and Dr. Ellen J. MacKenzie of METRC were awarded Lifetime Achievement Awards by the Orthopaedic Trauma Association. [ 3 ]


The  National Association of Orthopaedic Nurses   (NAON) is an American non-profit volunteer-run  professional association  that aims to advance  orthopaedic nursing . Formed in 1980, NAON was designed to promote the highest standards of  nursing practice  by educating its practitioners, promoting research, and encouraging effective communication between orthopaedic nurses and other groups with similar interests.


NAON membership consists of more than 6,000  registered nurses ,  licensed practical nurses , student nurses, and associate members from across the United States and around the world who share an interest in  musculoskeletal  health care. [ 1 ]


NAON is accredited as a provider of continuing nursing education by the  American Nurses Credentialing Center 's Commission on Accreditation. Starting in 1981, NAON has organized an annual congress at different locations in the United States.


One of the main goals of the founders of NAON was to form a stronger and firmer foundation for the development of an orthopaedic nursing organization. Recovering from the unexpected dissolution of the previous organization, Orthopaedic Nurses Association (ONA), members from across the United States met on March 8, 1980, in  Atlanta, Georgia , under the leadership of Nancy Hesselbach and Barbara Fiehler. This meeting was convened during the annual meeting of the  American Academy of Orthopaedic Surgeons . Subsequently, NAON was established and incorporated in  Missouri  on April 14, 1980.


NAON publishes:


The NAON Foundation supports the goals and mission of NAON by providing grants, scholarships, and awards to nurses pursuing careers in orthopaedic nursing practice, education,  administration , and research. [ citation needed ]


The  National Institute of Traumatology & Orthopaedic Rehabilitation (NITOR)  is an orthopedic hospital and undergraduate & post-graduate institute in  Sher-e-Bangla Nagar ,  Dhaka ,  Bangladesh . It was established in 1972 by the  Government of Bangladesh  as the Shaheed Suhrawardy Hospital. In October 2002 the name of the institute was changed to National Institute of Traumatology & Orthopaedic Rehabilitation (NITOR). [ 1 ]  NITOR is affiliated previously  to       Dhaka University  and now to  Bangabandhu Sheikh Mujib Medical University .


Master of Surgery (MS) (Orthopedics) and D. Ortho. awarded by NITOR, a post-graduate institute, are recognized by the  Bangladesh Medical and Dental Council .


23°43′32″N   90°23′53″E  /  23.72556°N 90.39806°E  /  23.72556; 90.39806


This article about a hospital in Bangladesh is a  stub . You can help Wikipedia by  expanding it .


New England Baptist Hospital (NEBH)  is a 141-bed adult  medical - surgical   hospital  in  Boston, Massachusetts  specializing in  orthopedic  care and complex orthopedic procedures. NEBH is an international leader in the treatment of all forms of  musculoskeletal  disorders and diseases. [ 1 ]


NEBH is located atop Parker Hill in the  Mission Hill  neighborhood within walking distance of the  Longwood Medical and Academic Area .


The hospital is a teaching affiliate of both the  University of Massachusetts Medical School  and  Tufts University School of Medicine . It also conducts teaching programs in collaboration with the  Harvard T.H. Chan School of Public Health  and  Harvard Medical School .


Beth Israel Lahey Health  is the parent  non-profit  holding company for New England Baptist,  Beth Israel Deaconess Medical Center , the  Lahey Hospital & Medical Center ,  Mount Auburn Hospital  and others. [ 2 ]


New England Baptist Hospital was established in 1893 by  American Baptist Churches USA , a  Baptist   Christian denomination  with a long history in  New England .


When the hospital was created in 1893, Parker Hill was a  streetcar suburb  considered far enough away from  downtown Boston  to provide fresh air and an escape from the noise and congestion of the city for patients who might benefit from long term rest and relaxation. Parker Hill offers panoramic views of the city,  Boston Harbor , and the  Blue Hills . Even today, it is a remarkably peaceful site considering its location near the center of one of the largest metropolitan areas in  North America . In April 2017, New England Baptist Hospital agreed to join with Lahey Health and Beth Israel Deaconess Medical Center. [ 3 ] [ 4 ]


Through the associated New England Baptist Bone & Joint Institute, the hospital offers a full range of services in orthopedics and  rheumatology ,  occupational medicine  and  sports medicine , foot and ankle care,  joint replacement ,  spine  care, and  hand surgery . The institute offers such services as preventive, educational, diagnostic, treatment, and rehabilitation services.


NEBH has a long association with sports medicine and has provided services to U.S.  Olympic teams  and multiple  professional athletes .


Boston Red Sox  legend  Ted Williams  came to the Baptist for treatment of a cervical disk disorder in the 1950s. In 1999, esteemed  PGA Tour  player  Jack Nicklaus  came to the Baptist for a new hip.


NEBH is the official hospital of the eighteen-time world champion  Boston Celtics  and has a long association with the  Boston Athletic Association  which hosts the  Boston Marathon .


Novosibirsk Research Institute of Traumatology and Orthopedics named after Y. L. Tsivyan  ( Russian :  Новосибирский научно-исследовательский институт травматологии и ортопедии имени Я. Л. Цивьяна ) is a medical organization in  Novosibirsk , Russia, that specializes in  orthopedic surgery , the treatment of  rheumatologic  conditions and scientific research of diseases of the  musculoskeletal system . It was founded in 1946.


The medical organization was created in 1946 on the basis of evacuation hospital No. 1239, which was located in the building of the Bookselling Technical School on  Frunze Street . Initially, the institute specialized in the surgical treatment of people who received injuries during the Second World War.


In 2015, for the first time in Russia, the institute's doctors implanted nanoceramic hip joint implant made in Russia. A hip joint prosthesis was implanted free of charge to a resident of  Birobidzhan . [ 1 ]


The  International Osteoporosis Foundation  ( IOF ), headquartered in  Nyon ,  Switzerland , is a  non-governmental organization  (NGO) founded in 1998. It was formed from the merger of the European Foundation for Osteoporosis, founded in 1987, and the International Federation of Societies on Skeletal Diseases. [ 1 ]  The foundation functions as a global alliance of individuals and organizations concerned with the prevention, diagnosis and treatment of  osteoporosis  and musculoskeletal  bone disease . The goal of the Foundation is to increase the early detection of osteoporosis and related musculoskeletal diseases, as well as to improve the treatment of these conditions through international collaboration among national healthcare systems and governments. [ 2 ]  The Foundation is the largest global NGO dedicated to osteoporosis and musculoskeletal diseases.


Members of IOF are divided into a committee of 323 National Societies, a committee of 163 Scientific Advisors, and a committee of Corporate Advisors. The current president of IOF is Professor Cyrus Cooper. [ 3 ] [ 4 ]


IOF is a member of the Non Communicable Disease (NCD) Alliance as of 2015. [ 5 ]


IOF publishes the following journals:


The International Osteoporosis Foundation organises the annual  World Osteoporosis Day , observed internationally on October 20. [ 10 ]  The day is dedicated to raising global awareness of the prevention, diagnosis and treatment of osteoporosis and related diseases of bones, muscles and joints. [ 11 ] [ 12 ]


The Capture the Fracture (CTF) [ 13 ]  program was created by IOF in 2012 to promote secondary fracture prevention through best practice framework guidance and recognition of Fracture Liaison Services [ 14 ]  around the World. 856 Fracture Liaisons Services (FLS) have been established in 54 countries as part of the CTF program. The Map of Best Practice, [ 15 ]  established as part of the CTF program, gives recognition to FLS by grading their level of service. The excellence obtained by the FLS is designated as gold, silver or bronze. [ citation needed ]


Members of the IOF Committee of Scientific Advisors address key subjects in 13 Scientific Working Groups, [ 16 ]  and publish consensus statements, position papers, [ 17 ]  reviews and guidelines. Topics currently being studied include adherence, bone and cancer, bone and diabetes, epidemiology/quality of life, fracture care and secondary fracture prevention, therapeutic targets, HR-pQCT High Resolution Peripheral Quantitative Computer Tomography, bone marker standards, chronic inflammation and bone structure, Menopausal Hormone Therapy (MHT),  sarcopenia  and impaired mobility, and skeletal rare diseases. [ citation needed ]


Calcium  is essential for building and maintaining healthy bones at all ages. The IOF Calcium Calculator [ 18 ]  is a simple calculator to enable individuals to assess whether they are consuming enough calcium as part of a regular diet.


The IOF Osteoporosis Risk Check [ 19 ]  enables people to understand the status of bone health through a series of simple questions on family history and personal clinical risk factors.


Launched in March 2017 with a call for ‘ No more broken bones ’, the IOF Global Patient Charter [ 20 ]  was developed in cooperation with osteoporosis patient societies worldwide. It seeks to drive global action for improved osteoporosis prevention and fracture patient care. The Charter calls on healthcare authorities to address the needs of millions of osteoporosis patients worldwide, who should have the right to diagnosis, care, involvement, and support. [ citation needed ]


The International Osteoporosis Foundation was established in 1998 with the merger of the European Foundation for Osteoporosis (EFFO) and the International Federation of Societies on Skeletal Diseases (IFSSD). [ 21 ]  In 2008 IOF was granted Roster  Consultative Status  with the  United Nations Economic and Social Council . [ 22 ]


Since 2010, IOF and the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) [ 23 ]  jointly organize the annual World Congress on Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (WCO). [ 24 ]  The first WCO was held in 2000 in Chicago, Illinois and was formerly run by the IOF secretariat. Since 2010, there have been 13 WCO congresses organized in collaboration with ESCEO.


In addition to the annual WCO congress, IOF also hosts regional meetings and has organized 9 regional meetings since 2010 across Latin America, Middle East & Africa, and Asia Pacific. [ 25 ]


The  Société Internationale de Chirurgie Orthopédique et de Traumatologie (SICOT)  is an international non-profit organization in the field of orthopaedics and traumatology.


The foundations of the Society were laid during its first Congress in  Paris  at the  Hotel Crillon  on October 10, 1929. [ 1 ]


The group of founders who attended included: from Austria,  Erlacher  and  Spitzy ; from Belgium, Lorthioir, Delchef [ 2 ]  and Maffei; from Spain, San Ricart; from the United States, Albee, Baer and Meyerding; [ 3 ]  from France,  Ombrédanne ,  Rocher ,  Sorrel  and  Nové-Josserand ; from Great Britain, Fairbank; [ 4 ]  from Germany, Bielsalski; from Italy,  Galeazzi  and Putti; from Holland, Murk Jansen; from Romania, Frans Jiano; from Sweden,  Haglund  and  Waldenström ; from Switzerland, Machard; and from Czechoslovakia,  Zahradníček .


International Orthopaedics is an official journal of SICOT. The Journal is published monthly by  Springer Verlag , and is distributed to 50,000 surgeons in electronic format and in 3,200 printed issues for libraries and special subscribers. It has an impact factor of 2.7 (2022). [ 22 ]


SICOT-J is an official journal of SICOT founded in 2014. It is a peer-reviewed open access journal. Its focus is on clinical, basic and transnational research in the field of orthopaedics surgery and traumatology. [ 23 ] [ 24 ] [ 25 ]


The  Valdoltra Orthopedic Hospital  ( Slovene :  Ortopedska bolnišnica Valdoltra ) is one of  Slovenia 's most important treatment facilities. It is located in  Ankaran  on the coast of the  Adriatic Sea  in southwestern Slovenia. Its beginnings go back to 1909, when it began receiving patients with skeletal  tuberculosis . [ 1 ]


The  muscular system  is an  organ system  consisting of  skeletal ,  smooth , and  cardiac  muscle. It permits movement of the body, maintains posture, and circulates blood throughout the body. [ 1 ]  The muscular systems in  vertebrates  are controlled through the  nervous system  although some muscles (such as the  cardiac muscle ) can be completely autonomous. Together with the  skeletal system  in the human, it forms the  musculoskeletal system , which is responsible for the movement of the  body . [ 2 ]


There are three distinct types of muscle:  skeletal muscle ,  cardiac or heart muscle , and  smooth (non-striated) muscle .  Muscles  provide strength, balance, posture, movement, and heat for the body to keep warm. [ 3 ]


There are more than 600 muscles in an adult male human body. [ 4 ]  A kind of elastic tissue makes up each muscle, which consists of thousands, or tens of thousands, of small muscle fibers. Each fiber comprises many tiny strands called fibrils, impulses from nerve cells control the contraction of each muscle fiber.


Skeletal muscle, is a type of  striated muscle , composed of  muscle cells , called  muscle fibers , which are in turn composed of  myofibrils . Myofibrils are composed of  sarcomeres , the basic building blocks of striated muscle tissue. Upon stimulation by an  action potential , skeletal muscles perform a coordinated contraction by shortening each sarcomere. The best proposed model for understanding contraction is the  sliding filament model  of muscle contraction. Within the sarcomere,  actin  and  myosin  fibers overlap in a contractile motion towards each other. Myosin filaments have club-shaped  myosin heads  that project toward the actin filaments, [ 1 ] [ 3 ] [ 5 ]  and provide attachment points on binding sites for the actin filaments. The myosin heads move in a coordinated style; they swivel toward the center of the sarcomere, detach and then reattach to the nearest active site of the actin filament. This is called a ratchet type drive system. [ 5 ]


This process consumes large amounts of  adenosine triphosphate  (ATP), the energy source of the cell. ATP binds to the cross-bridges between myosin heads and actin filaments. The release of energy powers the swiveling of the myosin head. When ATP is used, it becomes  adenosine diphosphate  (ADP), and since muscles store little ATP, they must continuously replace the discharged ADP with ATP. Muscle tissue also contains a stored supply of a fast-acting recharge chemical,  creatine phosphate , which when necessary can assist with the rapid regeneration of ADP into ATP. [ 6 ]


Calcium ions  are required for each cycle of the sarcomere. Calcium is released from the  sarcoplasmic reticulum  into the  sarcomere  when a muscle is stimulated to contract. This calcium uncovers the actin-binding sites. When the muscle no longer needs to contract, the calcium ions are pumped from the sarcomere and back into storage in the  sarcoplasmic reticulum . [ 5 ]


There are approximately 639 skeletal muscles in the human body.


Heart muscle is striated muscle but is distinct from skeletal muscle because the  muscle fibers  are laterally connected. Furthermore, just as with smooth muscles, their movement is involuntary. Heart muscle is controlled by the  sinus node  influenced by the  autonomic nervous system . [ 1 ] [ 3 ]


Smooth muscle contraction is regulated by the autonomic  nervous system ,  hormones , and local chemical signals, allowing for gradual and sustained contractions. This type of  muscle tissue  is also capable of adapting to different levels of stretch and tension, which is important for maintaining proper blood flow and the movement of materials through the  digestive system .


Neuromuscular junctions  are the focal point where a  motor neuron  attaches to a muscle.  Acetylcholine , (a  neurotransmitter  used in skeletal muscle contraction) is released from the axon terminal of the nerve cell when an action potential reaches the microscopic junction called a  synapse . A group of chemical messengers across the synapse and stimulate the formation of electrical changes, which are produced in the muscle cell when the acetylcholine binds to receptors on its surface. Calcium is released from its storage area in the cell's sarcoplasmic reticulum. An impulse from a nerve cell causes calcium release and brings about a single, short  muscle contraction  called a  muscle twitch . If there is a problem at the neuromuscular junction, a very prolonged contraction may occur, such as the muscle contractions that result from  tetanus . Also, a loss of function at the junction can produce  paralysis . [ 5 ]


Skeletal muscles are organized into hundreds of  motor units , each of which involves a motor neuron, attached by a series of thin finger-like structures called  axon terminals . These attach to and control discrete bundles of muscle fibers. A coordinated and fine-tuned response to a specific circumstance will involve controlling the precise number of motor units used. While individual muscle units' contract as a unit, the entire muscle can contract on a predetermined basis due to the structure of the motor unit. Motor unit coordination, balance, and control frequently come under the direction of the  cerebellum  of the brain. This allows for complex muscular coordination with little conscious effort, such as when one drives a car without thinking about the process. [ 5 ] [ 7 ]


A tendon is a piece of connective tissue that connects a muscle to a bone. [ 8 ]  When a muscle intercepts, it pulls against the skeleton to create movement. A tendon connects this muscle to a bone, making this function possible.


At rest, the body produces the majority of its  ATP  aerobically in the  mitochondria [ 9 ]  without producing  lactic acid  or other fatiguing byproducts. During exercise, the method of ATP production varies depending on the fitness of the individual as well as the duration and intensity of exercise. At lower activity levels, when exercise continues for a long duration (several minutes or longer), energy is produced aerobically by combining oxygen with  carbohydrates  and  fats  stored in the body. [ 6 ] [ 10 ]


During activity that is higher in intensity, with possible duration decreasing as intensity increases, ATP production can switch to anaerobic pathways, such as the use of the  creatine phosphate  and the phosphagen system or anaerobic  glycolysis . Aerobic ATP production is biochemically much slower and can only be used for long-duration, low-intensity exercise, but produces no fatiguing waste products that cannot be removed immediately from the  sarcomere  and the body, and it results in a much greater number of ATP molecules per fat or carbohydrate molecule. Aerobic training allows the oxygen delivery system to be more efficient, allowing aerobic metabolism to begin quicker. Anaerobic ATP production produces ATP much faster and allows near-maximal intensity exercise, but also produces significant amounts of  lactic acid  which render high-intensity exercise unsustainable for more than several minutes. The phosphagen system is also anaerobic. It allows for the highest levels of exercise intensity, but intramuscular stores of  phosphocreatine  are very limited and can only provide energy for exercises lasting up to ten seconds. Recovery is very quick, with full creatine stores regenerated within five minutes. [ 6 ] [ 11 ]


Multiple diseases can affect the muscular system.


Muscular dystrophy  is a group of disorders associated with progressive muscle weakness and loss of muscle mass. These disorders are caused by mutations in a person's genes. [ 12 ]  The disease affects between 19.8 and 25.1 per 100,000 person-years globally. [ 13 ]


There are more than 30 types of muscular dystrophy. Depending on the type, muscular dystrophy can affect the patient's heart and lungs, and/or their ability to move, walk, and perform daily activities. The most common types include:


An  acceleromyograph  is a  piezoelectric   myograph , used to measure the force produced by a  muscle  after it has undergone nerve stimulation. Acceleromyographs may be used, during anaesthesia when muscle relaxants are administered, to measure the depth of neuromuscular blockade and to assess adequacy of  recovery from these agents at the end of surgery. Acceleromyography is classified as quantitative  neuromuscular monitoring . [ citation needed ]


Patients who undergo anesthesia may receive a drug that  paralyzes  muscles, facilitating endotracheal intubation and improving operating conditions for the surgeon. Longer-acting drugs have higher prevalence of residual blockade in the  PACU  or  ICU  than shorter acting drugs. Different clinical tests to measure or exclude evidence of residual  muscle weakness  have been described but cannot exclude  postoperative residual curarization . [ 1 ]  Small degrees of muscle blockade can only accurately be measured by the use of quantitative neuromuscular monitoring. Specifically, the observer cannot reliably measure muscular fade when  train-of-four  ratios are between 0.4 and 0.9. [ 2 ]


Acceleromyographs measure muscle activity using a miniature  piezoelectric transducer  that is attached to the stimulated muscle. A voltage is created when the muscle accelerates and that acceleration is proportion to force of contraction. The mass of the piezoelectric transducer is known and the acceleration is measured therefore the force can be calculated, ( Force  =  mass  ×  acceleration ). Acceleromyographs are more costly than the more common twitch monitors, but have been shown to better alleviate residual blockade and associated symptoms of muscle weakness, and to improve overall quality of recovery. [ citation needed ]


An  accessory muscle  is a relatively rare  anatomical variation  where duplication of a  muscle  may appear anywhere in the  muscular system . Treatment is not indicated unless the accessory muscle interferes with normal function. [ 1 ]


Examples are the  accessory soleus muscle  in the calf or ankle, the  extensor digitorum brevis manus  in the hand and  epitrochleoanconeus muscle  of the upper arm.


Additional examples in the hand include Flexor carpi radialis brevis which can compress the anterior interosseous nerve. [ 2 ]  Also see  palmaris profundus muscle .


On the extensor side:
 extensor digitorum brevis manus ,
 extensor carpi radialis intermedius ,
 extensor medii proprius muscle


Accessory muscles of the anterior thoracic wall include the  sternalis muscle , the  axillary arch  (Langer's), variations of  pectoralis major  such as the  pectoralis minimus ,  pectoralis quartus , and  pectoralis intermedius , the  chondrocoracoideus  and  chondrofascialis . [ 3 ]  The whole pectoral region is subject to a high degree of variability. The pectoralis major or pectoralis minor may be absent, or in some cases the pectoralis major may be doubled. Other variants noted in this region are the  chondroepitrochleas  originating in one or more ribs, or directly from the pectoralis major; the  costocoracoideus  from the 6th to 8th ribs, and a  chondrocoracoideus  and another variant of this waiting to be named. Most of these accessory muscles are implicated in neurovascular compression. Of clinical use the newly described  chondrocoracoideus  has potential for use in reconstructive surgery. [ 4 ]


Axillary accessory muscles may be encountered in axillary lymph node removal, the awareness of which could avoid complications. [ 5 ]


An accessory muscle can also refer to a muscle that is not primarily responsible for movement but does provide assistance. [ 1 ]  Examples of such muscles are the  accessory muscles of respiration  where the  sternocleidomastoid  and the  scalene muscles  ( anterior ,  middle  and  posterior scalene ) are typically considered accessory muscles of respiration. [ 6 ]


Airway tone , short for  airway smooth muscle tone , is the degree of sustained  contractile  activation of  airway   smooth muscle . [ 1 ]  The airways have a tone baseline, and consequently a baseline level of contraction of their smooth musculature. Airway tone is a key determinant of  lung function  and the presence of  respiratory symptoms  in  obstructive lung diseases  such as  asthma , where baseline airway tone is elevated. [ 2 ]  The upper extreme of the spectrum of airway tone represents  bronchoconstriction , wherein the airway smooth muscles are significantly contracted, while the lower extreme represents  bronchodilatation , wherein the muscles are relatively relaxed.


While airway tone is related to respiratory  airflow  and airway caliber insofar as an increase in airway tone decreases airflow due to the airway smooth muscle contraction, the two are not synonymous as airflow is determined by the structural and functional properties of the airways as well as the  lung parenchyma  in addition to airway tone. [ 1 ] [ 3 ]


Airway tone and  airway resistance  are mostly correlated, [ 4 ]  but adequate  upper airway  tone is necessary for airflow and  airway patency ; [ 5 ]  insufficient upper airway tone during  sleep  can, for instance, result in  obstructive sleep apnea . [ 6 ]


Autonomic nervous system  signalling plays a pivotal role in determining airway tone. The  innervation  of airway smooth musculature varies between the upper and  lower airways . [ 7 ]


The  pharynx  is innervated by  cranial nerves   VII ,  IX ,  XII , while both the pharynx and the  larynx  are innervated by the vagus nerve. [ 7 ]


Lower airway, bronchial, or bronchus tone is mediated both by the innervation of airway smooth musculature and, possibly, also by the innervation of airway  mucosal   vasculature . Lower airway smooth muscles are mostly only innervated by the vagus nerve. [ 8 ] [ 9 ]


Airway smooth muscle is primarily innervated by  cholinergic   parasympathetic  nerves, while its  adrenergic   sympathetic  innervation is sparse to non-existent. Specifically, cholinergic parasympathetic signalling increases the airway tone, meaning the airway tone is proportional to the  vagal tone . [ 8 ] [ 10 ]


Despite this overall airway tone-increasing effect, the individual effects of  muscarinic acetylcholine receptors  expressed by airway muscle cells, of which there are 5 subtypes, M 1  through M 5 , are ambivalent.  M 3  receptors  directly lead to airway smooth muscle contraction, i.e., an increase in airway tone, while  M 2  receptors  (also) expressed by airway  neurons  suppress the further release of  acetylcholine  in a  negative feedback loop , wherein cholinergic parasympathetic signalling reduces further cholinergic parasympathetic signalling, which may explain the unexpectedly low effectivity of certain non-selective  muscarinic receptor antagonists  such as  ipratropium bromide . [ 10 ]


M 2  receptors are less functional in asthma, disrupting the negative feedback which normally reduces airway tone, which may play a role in asthmatic airway hyperresponsiveness. [ 10 ]


As mentioned, adrenergic sympathetic innervation of airway smooth muscle is likely insignificant; however, the sympathetic innervation of the airway mucosal vasculature is significant. Airway muscular vasculature controls the flow of  nutrients  to the airways, the temperature of the airways, as well as the clearance of insoluble particles in the airways, which may play an important role in the  activity  of  inhaled bronchodilators , thus affecting  airway reactivity  and airway tone changes in obstructive lung diseases. [ 9 ]


There is conflicting evidence regarding  dopamine's  effect on airway tone  in vivo , with some studies reporting bronchoconstriction and others bronchodilatation following dopamine inhalation. In one study, dopamine attenuated the increase in airway tone caused by cholinergic signalling, but exacerbated  histaminergic  bronchoconstriction, while both signals were attenuated in the present study following the administration of intravenous dopamine. [ 11 ]  Thus, no conclusion can be drawn at this time.


Acute activation of  D 2  receptors  expressed by airway smooth muscle cells inhibits the  adenylyl cyclase , lowering  cAMP  levels, leading to an increase in airway tone. However, their prolonged activation by  quinpirole , a D 2  and D 3  receptor  agonist , paradoxically enhances adenylyl cyclase activity, raising cAMP levels, leading to bronchodilatation via  phospholipase C  and  protein kinase C . [ 12 ]


Histamine  is a direct bronchoconstrictor that increases airway tone by activating  H 1  receptors  expressed by airway smooth muscle cells. [ 3 ]


Six  type 2 (bitter) taste receptors  (TAS2Rs) are expressed by airway smooth muscle cells. In the tongue, bitter taste receptors have probably evolved for avoiding the ingestion of plant toxins. In the lungs, bitter taste receptors serve a paradoxically reversed function, causing the relaxation of airway smooth muscle, i.e., a lowering of airway tone. Thus, bitter taste receptor agonists represent promising potential novel bronchodilators. [ 12 ] [ 13 ]


Theophylline 's non-selective  phosphodiesterase inhibition  has been proposed as the mechanism behind its bronchodilatating action. Phosphodiesterases degrade intracellular  cAMP , which leads to muscle contraction. Inhibiting phosphodiesterases increases cAMP concentrations in airway smooth muscle cells, lowering airway tone. Adenosine receptor agonism probably does not play a major role in theophylline-induced lowering of airway tone, as inhalation of adenosine actually increases airway tone, though it is probably the cause of theophylline's  arrhythmogenicity . [ 12 ] [ 14 ] [ 15 ]


Like histamine, some  cysteinyl leukotrienes , such as  leukotriene D 4 , are direct bronchoconstrictors and increase airway tone by binding to receptors on airway smooth muscle cells. Bronchoconstrictive leukotrienes act via a common  cys-LT 1  receptor . [ 3 ]


Thromboxane  is a direct bronchoconstrictor that acts via the  thromboxane receptor  on airway smooth muscle cells. [ 3 ]


Anatomical terminology  is used to uniquely describe aspects of  skeletal muscle ,  cardiac muscle , and  smooth muscle  such as their actions, structure, size, and location.


There are three types of  muscle tissue  in the body: skeletal, smooth, and cardiac.


Skeletal muscle , or "voluntary muscle", is a  striated muscle tissue  that primarily joins to  bone  with  tendons . Skeletal muscle enables movement of bones, and  maintains posture . [ 1 ]  The widest part of a muscle that pulls on the tendons is known as the  belly .


A  muscle slip  is a slip of muscle that can either be an  anatomical variant , [ 2 ]  or a branching of a muscle as in  rib  connections of the  serratus anterior muscle .


Smooth muscle  is involuntary and found in parts of the body where it conveys action without conscious intent. The majority of this type of muscle tissue is found in the  digestive  and  urinary systems  where it acts by propelling forward food,  chyme , and  feces  in the former and  urine  in the latter. Other places smooth muscle can be found are within the  uterus , where it helps facilitate  birth , and the  eye , where the  pupillary sphincter  controls  pupil  size. [ 3 ]


Cardiac muscle  is specific to the  heart . It is also involuntary in its movement, and is additionally self-excitatory, contracting without outside stimuli. [ 4 ]


As well as  anatomical terms of motion , which describe the motion made by a muscle, unique terminology is used to describe the action of a set of muscles.


Agonist muscles and antagonist muscles are muscles that cause or inhibit a movement. [ 5 ]


Agonist muscles  are also called  prime movers  since they produce most of the force, and control of an action. [ 6 ]  Agonists cause a movement to occur through their own activation. [ 7 ]  For example, the  triceps brachii  contracts, producing a  shortening (concentric) contraction , during the up phase of a push-up ( elbow extension ). During the down phase of a push-up, the same triceps brachii actively controls elbow flexion while producing a  lengthening (eccentric) contraction . It is still the agonist, because while resisting gravity during relaxing, the triceps brachii continues to be the prime mover, or controller, of the joint action.


Another example is the dumb-bell curl at the elbow. The  elbow flexor group  is the agonist, shortening during the lifting phase ( elbow flexion ). During the lowering phase the elbow flexor muscles lengthen, remaining the agonists because they are controlling the load and the movement (elbow extension). For both the lifting and lowering phase, the "elbow extensor" muscles are the antagonists (see below). They lengthen during the dumbbell lifting phase and shorten during the dumbbell lowering phase. Here it is important to understand that it is common practice to give a name to a muscle group (e.g. elbow flexors) based on the joint action they produce during a shortening contraction. However, this naming convention does not mean they are only agonists during shortening. This term typically describes the function of  skeletal muscles . [ 8 ]


Antagonist muscles  are simply the muscles that produce an opposing joint torque to the agonist muscles. [ 9 ]  This torque can aid in controlling a motion. The opposing torque can slow movement down - especially in the case of a  ballistic movement . For example, during a very rapid (ballistic) discrete movement of the elbow, such as throwing a dart, the triceps muscles will be activated very briefly and strongly (in a "burst") to rapidly accelerate the extension movement at the elbow, followed almost immediately by a "burst" of activation to the elbow flexor muscles that decelerates the elbow movement to arrive at a quick stop. To use an automotive analogy, this would be similar to pressing the accelerator pedal rapidly and then immediately pressing the brake. Antagonism is not an intrinsic property of a particular muscle or muscle group; it is a role that a muscle plays depending on which muscle is currently the agonist. During slower joint actions that involve gravity, just as with the agonist muscle, the antagonist muscle can shorten and lengthen. Using the example of the triceps brachii during a push-up, the elbow flexor muscles are the antagonists at the elbow during both the up phase and down phase of the movement. During the dumbbell curl, the elbow extensors are the antagonists for both the lifting and lowering phases. [ 10 ]


Antagonist and agonist muscles often occur in pairs, called  antagonistic pairs . As one muscle contracts, the other  relaxes . An example of an antagonistic pair is the  biceps  and  triceps ; to contract, the triceps relaxes while the biceps contracts to lift the arm. "Reverse motions" need antagonistic pairs located in opposite sides of a joint or bone, including  abductor-adductor  pairs and flexor-extensor pairs. These consist of an  extensor muscle , which "opens" the joint (by increasing the angle between the two bones) and a  flexor muscle , which does the opposite by decreasing the angle between two bones.


However, muscles do not always work this way; sometimes agonists and antagonists contract at the same time to produce force, as per  Lombard's paradox . Also, sometimes during a joint action controlled by an agonist muscle, the antagonist will be slightly activated, naturally. This occurs normally and is not considered to be a problem unless it is excessive or uncontrolled and disturbs the control of the joint action. This is called agonist/antagonist co-activation and serves to mechanically stiffen the joint.


Not all muscles are paired in this way. An example of an exception is the  deltoid . [ 11 ]


Synergist muscles  also called  fixators , act around a joint to help the action of an  agonist muscle . Synergist muscles can also act to counter or neutralize the force of an agonist and are also known as  neutralizers  when they do this. [ 12 ]  As neutralizers they help to cancel out or neutralize extra motion produced from the agonists to ensure that the force generated works within the desired plane of motion.


Muscle fibers can only contract up to 40% of their fully stretched length.  [ citation needed ]  Thus the short fibers of  pennate muscles  are more suitable where power rather than range of contraction is required. This limitation in the range of contraction affects all muscles, and those that act over several joints may be unable to shorten sufficiently to produce the full range of movement at all of them simultaneously (active insufficiency, e.g., the fingers cannot be fully flexed when the wrist is also flexed). Likewise, the opposing muscles may be unable to stretch sufficiently to allow such movement to take place (passive insufficiency). For both these reasons, it is often essential to use other synergists, in this type of action to fix certain of the joints so that others can be moved effectively, e.g., fixation of the wrist during full flexion of the fingers in clenching the fist. Synergists are muscles that facilitate the fixation action.


There is an important difference between a  helping synergist  muscle and a  true synergist  muscle. A true synergist muscle is one that only neutralizes an undesired joint action, whereas a helping synergist is one that neutralizes an undesired action but also assists with the desired action.  [ citation needed ]


A muscle that fixes or holds a bone so that the agonist can carry out the intended movement is said to have a neutralizing action. A good famous example of this are the  hamstrings ; the  semitendinosus  and  semimembranosus muscles  perform knee flexion and knee  internal rotation  whereas the  biceps femoris  carries out knee flexion and knee  external rotation . For the knee to flex while not rotating in either direction, all three muscles contract to stabilize the knee while it moves in the desired way.


Composite  or  hybrid  muscles have more than one set of fibers that perform the same function, and are usually supplied by different nerves for different set of fibers. For example, the tongue itself is a composite muscle made up of various components like longitudinal, transverse, horizontal muscles with different parts innervated from a different nerve supply.


There are a number of terms used in the naming of muscles including those relating to size, shape, action, location, their orientation, and their number of heads.


The insertion and origin of a muscle are the two places where it is anchored, one at each end. The connective tissue of the attachment is called an  enthesis .


The  origin  of a muscle is the  bone , typically proximal, which has greater mass and is more stable during a  contraction  than a muscle's insertion.  [ 14 ]  For example, with the  latissimus dorsi muscle , the origin site is the torso, and the insertion is the arm. When this muscle contracts, normally the arm moves due to having less mass than the torso. This is the case when grabbing objects lighter than the body, as in the typical use of a  lat pull down  machine. This can be reversed however, such as in a  chin up  where the torso moves up to meet the arm.


The  head  of a muscle, also called  caput musculi  is the part at the end of a muscle at its origin, where it attaches to a fixed bone. Some muscles such as the  biceps  have more than one head.


The  insertion  of a muscle is the structure that it attaches to and tends to be moved by the  contraction  of the muscle.  [ 15 ]  This may be a  bone , a  tendon  or the subcutaneous dermal  connective tissue . Insertions are usually connections of muscle via  tendon  to bone. [ 16 ]  The insertion is a bone that tends to be distal, have less mass, and greater motion than the origin during a contraction.


Intrinsic muscles  have their origin in the part of the body that they act on, and are contained within that part. [ 17 ]   Extrinsic muscles
have their origin outside of the part of the body that they act on. [ 18 ]  Examples are the  intrinsic and extrinsic muscles of the tongue , and  those of the hand .


Muscles may also be described by the direction that the  muscle fibres  run, in their  muscle architecture .


Hypertrophy  is increase in muscle size from an increase in size of individual muscle cells. This usually occurs as a result of exercise.


This article incorporates text in the  public domain  from the 20th edition of   Gray's Anatomy   (1918)


The  anterior chain , which comprises the  antagonists  of the  posterior chain , refers to the group of  skeletal muscles  that lies on the front of the human body. This includes the  biceps , the  pectoralis major  and  pectoralis minor  (chest) muscles, the  abdominals , the  obliques , the  serratus anterior , and the  quadriceps . [ 1 ]


Beach muscles  are muscles developed for the purpose of looking good and largely consist of the muscles of the anterior chain.  This is because it is these muscles that are seen from the front (or in a mirror) and are thus the most noticeable to an observer. [ 2 ]


Often, these muscles are not emphasized by  power lifters  who aim exclusively to increase their maximal strength in the  squat ,  deadlift , and  bench press , or by athletes who seek to increase physical performance. [ dubious  –  discuss ]   They are overall not as important for pure physical performance as the posterior chain. [ citation needed ]   It is however, necessary to train both the anterior chain and the posterior chain.


Architectural gear ratio , also called  anatomical gear ratio  (AGR) is a feature of  pennate muscle  defined by the ratio between the longitudinal strain of the muscle and  muscle fiber  strain.
It is sometimes also defined as the ratio between muscle- shortening  velocity and fiber-shortening velocity. [ 1 ]


AGR = ε x /ε f


where ε x  = longitudinal strain (or muscle-shortening velocity) and ε f  is fiber strain (or fiber-shortening velocity)
In  fusiform  muscle, the fibers are longitudinal, so longitudinal strain is equal to fiber strain, and AGR is always 1.


As the pennate muscle is activated, the fibers rotate as they shorten and pull at an angle. In pennate muscles, fibers are oriented at an angle to the muscle's  line of action  and rotate as they shorten, becoming more  oblique  such that the fraction of force directed along the muscle's line of action decreases throughout a contraction. Force output is dependent upon the angle of fiber rotation, so changes in muscle thickness and the vector of change in thickness vary; based upon the force being produced. Due to the rotational motion; pennate muscles operate at low velocities (low shortening distance). The shortening velocity of the pennate muscle as a whole is greater than that of the individual fibers. This gives rise to the property of AGR. Fiber rotation decreases a muscle's output force but increases output velocity by allowing the muscle to function at a higher gear ratio (muscle velocity/fiber velocity). Azizi and Brainerd demonstrated that the gear ratio of pennate muscle can vary; dependent on external load. [ 2 ]


Segmented musculature, like pennate muscle, has fibers aligned at an angle and due to this feature of design, when muscle fibers increase in angle with respect to the  medial axis , along with the direction and amount of muscle bulging, the Architectural gear ratio increases. [ 1 ] [ 3 ]  A variable gear ratio, based upon different  anatomical position , loading and movement conditions, has since been dubbed spatially varying gear ratio. The occurrence of spatially varying gear ratio gives rise to a new insight of muscle biology; “inhomogenous muscle mechanics. [ 4 ] ”


One feature of the ratio is that there is an optimal gear ratio for each muscle; as the  length-tension  and force-velocity relationships describe. Length-tension refers to the max tension that can be created over the muscle fiber strain range and force-velocity refers to the power that is possible of the fiber compared to the shortening velocity. These two features of musculature help to define an optimal AGR for a muscle. [ 1 ]


The Architectural gear ratio is explained through the segmented muscle model 3 proposed by Emanuel Azizi, where a muscle segment is shown as a single muscle fiber attached to the myosepta of a  Siren lacertina  an aquatic salamander at a certain acute, pennation angle. The model allows segments to bulge out differently in the horizontal, and vertical direction and was used to calculate the Architectural gear ratio of each segment. Preliminary models results show that with muscle bulging, the Architectural gear ratio will increase. Different bulging conditions were studied, and shown in Fig. 2 The model results show the more a muscle bulges in dorsoventral height, the further the muscle fibers shorten, therefore providing a higher Architectural gear ratio. [ 3 ]


In pennate muscles, segments with higher pennation angles put out less force per shortening muscle fiber. Therefore, the architectural gear ratio of a pennate muscle is higher than the architectural gear ratio of spindle like muscles (e.g. fusiform). A smaller fiber length neutralizes this higher architectural gear ratio if the muscle fibers must be squeezed into the same space. [ 3 ]


The  rotator cuff  comprises four pennate muscles, the  supraspinatus ,  infraspinatus ,  subscapularis  and  teres minor , and their accompanying tendons. These muscles form a cuff around the  glenohumeral joint  and function to stabilize and manipulate the shoulder. [ 5 ]


The  pennation angle  of the rotator cuff myofibers, the angle at which fibers connect to the associated tendon, affects the contractile properties and function of the whole pennate muscle. For example, the pennation angle determines the architectural gear ratio at which a pennate muscle operates. A large initial pennation angle results in a large AGR and velocity amplification. [ 2 ]


A 2011 study on human cadaveric shoulders suggests tendon tears may affect the pennation angle of the rotator cuff muscles. Researchers compared pennation angle between a control group and tear groups comprising either partial or complete-thickness tendon tears. Via dissection of ten injured and ten non-injured cadeveric shoulders, the study discovered a correlation between tendon tear size and an increase in pennation angle among two of the rotator cuff muscles. Pennation angle remained unaffected across all rotator cuff muscles in the partial tendon tear group, suggesting a threshold tear size must be exceeded to produce any changes in pennation angle. Full-thickness tendon tears did not affect the pennation angle of the subscapularis or teres minor muscles. However, a correlation between full-thickness rotator cuff tear size and the pennation angle of the supraspnatus and infraspinatus muscles was evident. The length of the full-thickness tendon tear strongly correlated with an increase in the pennation angle of the supraspinatus muscle. In addition, a moderately strong association between the area of the full-thickness tear and the resulting increase in pennation angle of the infraspinatus was visible. [ 5 ]


The increase in pennation angle may lead to changes in muscle structure. In a study utilizing sheep subjects, a chronic rotator cuff tear resulted in an increase in both the pennation angle and separation between myofibers of the rotator cuff muscles. Fat cells then populated the rearranged muscle. This phenomenon was also evident in the aforementioned human experiment. [ 5 ]


The increase in pennation angle following full-thickness tendon tears will result in a change to the PCSA of the supraspinatus and infraspinutus muscles. This would reduce the force producing capacity of these muscles. However, partial tendon tears, which did not result in a change to pennation in any of the rotator cuff muscles, may not impair the force producing properties of the muscles. [ 5 ]  Azizi's observations on variable gearing in pennate muscles further suggests tendon tears will affect the AGR of the supraspinatus and infraspinutus. The greater pennation angle could result in an increased AGR. [ 2 ]


Some scientists suggest patch grafts ought to be applied to irreparable rotator cuff tears. Though this practice lessens pain, muscle strength is not fully recovered. The abovementioned human rotator cuff study correlates pennation angle with tear length in the supraspinatus muscle. Therefore, a patch graft may not resolve the length change necessary to restore pennation angle; retraction of the torn tendon may lessen the post-tear pennation angle and restore muscle strength to a greater extent. [ 5 ]


Intrafasciular strain showed that the muscle was nonuniform, and that the architectural gear ratio is the highest at the proximal region of the muscle but then decreases towards the distal region. “ It is currently not possible to determine the precise distribution of stress throughout a muscle, but it seems reasonable to assume that the total (integrated) force at any cross section of the muscle and tendon remains fairly constant along the proximodistal axis. The smaller cross-sectional areas as the muscle thins and becomes tendon will thus result in a higher stress concentration to accommodate the same stress over a smaller area and therefore potentially higher strains if material properties remained constant." [ 6 ]


The  muscle architecture  of pennate muscles, such as the human  quadriceps , is highly plastic and strongly influences contractile properties. [ 6 ]  Changes to pennate muscle architectural properties, such as pennation angle and thereby the PCSA, can alter the muscle's force-producing capabilities as well as the AGR at which the muscle operates. Parallelogram models predict that total PCSA of bipennate muscles increases in proportion to sin(θpennation) while total force exerted on the associated aponeurosis decreases with cos(θpennation). This theorizes that pennate muscle force generation increases until a 45 degree pennation angle is achieved. [ 7 ]


A 2001 study, conducted by Aagaard  et al. , utilized MRI, ultrasonography and muscle biopsy techniques to examine the relationship between muscle architecture, contractile strength and pennation angle in the human quadriceps muscle after 14 weeks of resistance training. Upon completion of the training program, Aagaard  et al.  noticed a symmetrical increase in quadriceps CSA and volume, as each increased 10.2 and 10.3 percent respectively; however, these parameters increased disproportionately to quadriceps PCSA, which grew 16 percent. The rapid increase in PCSA was accompanied by a 35.5% increase in the fascicle pennation angle of the vastus lateris, one of the major quadriceps muscles, as well as a 16% increase in myofiber CSA. The increase in pennation angle in the vastus lateris resulted in an increase to the muscle's PCSA, a measure proportional to the contractile force a pennate muscle is capable of producing. [ 7 ]  Work by Azizi  et al.  suggests this increase in pennation angle of the vastus lateris following resistance training generates an increase in the muscle's AGR, a property which allows the whole muscle to contract with a higher velocity. [ 2 ]