title: Distal Insertions of the Biceps Femoris: A Quantitative Analysis.
abstract: BACKGROUND
  Avulsion of the biceps femoris from the fibula and proximal tibia is encountered in clinical practice. While the anatomy of the primary posterolateral corner structures has been qualitatively and quantitatively described, a quantitative analysis regarding the insertions of the biceps femoris on the fibula and proximal tibia is lacking.
  
  
  OBJECTIVE
  To quantitatively assess the insertions of the biceps femoris, fibular collateral ligament (FCL), and anterolateral ligament (ALL) on the fibula and proximal tibia as well as establish relationships among these structures and to pertinent surgical anatomy.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  Dissections were performed on 12 nonpaired, fresh-frozen cadaveric specimens identifying the biceps femoris, FCL, and ALL, and their insertions on the proximal tibia and fibula. The footprint areas, orientations, and distances from relevant osseous landmarks were measured using a 3-dimensional coordinate measurement device.
  
  
  RESULTS
  Dissection produced 6 easily identifiable and reproducible anatomic footprints. Tibial footprints included the insertion of the ALL and an insertion of the biceps femoris (TBF). Fibular footprints included the insertion of the FCL, a distal insertion of the biceps femoris (DBF), a medial footprint of the biceps femoris (MBF), and a proximal footprint of the biceps femoris (PBF). The mean area of these footprints (95% CI) was as follows: ALL, 53.0 mm(2) (38.4-67.6); TBF, 93.9 mm(2) (72.0-115.8); FCL, 86.8 mm(2) (72.3-101.2); DBF, 119 mm(2) (91.1-146.9); MBF, 46.8 mm(2) (29.0-64.5); and PBF, 215 mm(2) (192.4-237.5). The mean distance (95% CI) from the Gerdy tubercle to the center of the ALL footprint was 24.3 mm (21.6-27.0) and to the center of the TBF was 22.5 mm (21.0-24.0). The center of the DBF was 8.68 mm (7.0-10.3) from the anterior border of the fibula, the center of the FCL was 14.6 mm (12.5-16.7) from the anterior border of the fibula and 20.7 mm (19.0-22.4) from the tip of the fibular styloid, and the center of the PBF was 8.96 mm (8.2-9.7) from the tip of the fibular styloid.
  
  
  CONCLUSIONS
  A tibial footprint, distal fibular footprint, medial fibular footprint, and proximal fibular footprint were all consistent components of the insertion of the biceps femoris. Consistent relationships existed between the biceps femoris and insertions of the ALL and FCL.
  
  
  CONCLUSIONS
  The size of these footprints and distances from pertinent surgical landmarks will guide repairs of biceps femoris avulsion injuries.
authors.affiliation: Florida State University College of Medicine, Tallahassee, Florida, USA.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Branch
authors.affiliation: Andrews Orthopaedic and Sports Medicine Center, Gulf Breeze, Florida, USA. ; Andrews Research and Education Foundation, Gulf Breeze, Florida, USA.
authors.forename: Adam W
authors.initials: AW
authors.lastname: Anz
keywords: anterolateral ligament; avulsion; biceps femoris; fibular collateral ligament; repair