title: Assessment of the medial head of the gastrocnemius muscle in functional compression of the popliteal artery.
abstract: OBJECTIVE
  Nonfunctional popliteal entrapment is due to embryologic maldevelopment within the popliteal fossa. Functional entrapment occurs in the apparent absence of an anatomic abnormality. Gastrocnemius hypertrophy has been associated with the latter. Both forms of entrapment may cause arterial injury and lower limb ischemia. This study assessed the attachment of the medial head of the gastrocnemius muscle in healthy occluders and healthy nonoccluders.
  
  
  METHODS
  Provocative tests were used to identify 58 nonoccluders and 16 occluders. Ten subjects from each group underwent magnetic resonance imaging evaluation of the popliteal fossa. The medial head of the gastrocnemius muscle attachment was assessed in the supracondylar, pericondylar, and intercondylar areas.
  
  
  RESULTS
  In the occluder group, significantly more muscle was attached towards the femoral midline (supracondylar), around the lateral border of the medial condyle (pericondylar), and within the intercondylar fossa.
  
  
  CONCLUSIONS
  The more extensive midline position of the medial head of the gastrocnemius in occluders is likely to be a normal embryological variation. Forceful contraction results in compression and occlusion of the adjacent popliteal artery. The clinical significance of these anatomic variations remains unclear. However, these new observations may provide insight for future analysis of the causes and natural history of functional compression and the potential progression to clinical entrapment.
authors.affiliation: Division of Vascular Surgery, Department of Surgery, University of the Witwatersrand. vascular@telkomsa.net
authors.forename: Jayandiran
authors.initials: J
authors.lastname: Pillai
authors.forename: Lewis J
authors.initials: LJ
authors.lastname: Levien
authors.forename: Mark
authors.initials: M
authors.lastname: Haagensen
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Candy
authors.forename: Michelle D V
authors.initials: MD
authors.lastname: Cluver
authors.forename: Martin G
authors.initials: MG
authors.lastname: Veller
mesh_terms: D000328:Adult; D001157:Arterial Occlusive Diseases / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000473:pathology* / Q000503:physiopathology; D011150:Popliteal Artery / Q000473:pathology*; D011237:Predictive Value of Tests; D013577:Syndrome