title: Congenital absence of the semimembranosus muscle: case report.
abstract: Congenital anomalies of the muscles of the lower extremity are rare. A case of complete absence of the semimembranosus muscle incidentally found with magnetic resonance imaging is reported. The patient was a 55-year-old female presenting with knee pain and no previous history of trauma. Clinical and imaging findings were consistent with meniscal tears. Two cases of uncommon distal insertion of the semimembranosus tendon are also described to illustrate the anatomical variations in this area. The anatomical and biomechanical relations between the semimembranosus muscle and the posteromedial corner of the knee are examined in this case report.
authors.affiliation: Musculoskeletal Division, Radiology Department, The Emory Orthopedics and Spine Center, Emory University School of Medicine, 59 Executive Park South, 4th floor, Suite 4009, Atlanta, GA, 30329, USA. vmoncay@emory.edu
authors.forename: Valeria M
authors.initials: VM
authors.lastname: Moncayo
authors.forename: Walter A
authors.initials: WA
authors.lastname: Carpenter
authors.forename: Claude
authors.initials: C
authors.lastname: Pierre-Jerome
authors.forename: Robert D
authors.initials: RD
authors.lastname: Smitson
authors.forename: Michael R
authors.initials: MR
authors.lastname: Terk
mesh_terms: D001182:Arthroscopy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D033162:Incidental Findings; D007719:Knee Joint / Q000002:abnormalities* / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000002:abnormalities* / Q000601:surgery; D009135:Muscular Diseases / Q000151:congenital* / Q000601:surgery