Posterior cruciate ligament: Anatomy, femoral insertion and relationships with the anterior menisco-femoral ligament in 23 cadaver knees.

[BACKGROUND] Abundant anatomic descriptions exist of the posterior cruciate ligament (PCL) and menisco-femoral ligaments (MFLs). There is broad agreement that the PCL is composed of two bundles and inserts on the femur near the distal cartilage. However, a different configuration with a single bundle and a complex femoral insertion has been reported. The main objective of our cadaver study was to determine the number of anatomical bundles forming the PCL. We also described the insertion of the PCL and its relationships with the anterior menisco-femoral ligament (AMFL).

[HYPOTHESIS] The PCL consists of a single ribbon-like bundle and inserts on the femur separately from the AMFL.

[MATERIAL AND METHODS] We used 23 knees of fresh unembalmed cadavers, which we dissected under a microsurgery loupe. Inclusion criteria for the knees were freedom from trauma and scars. No age limits were set. The features of the PCL were studied using the clock method. Measurements were taken using callipers with a precision of 0.01mm.

[RESULTS] No knees were excluded from the final analysis. Macroscopically, the PCL appeared as a single bundle forming a slender flat ribbon. With the knee flexed at 90°, the ligament footprint extended from 58min to 25min on the right and from 48min to 2min on the left. The femoral insertion of the AMFL started 2.07mm from the distal cartilage and masked the distal insertion of the PCL. After removal of the AMFL, the middle of the femoral insertion of the PCL started on average 5.99mm from the distal cartilaginous rim when the knee was flexed at 90°.

[DISCUSSION] Our study confirms descriptions of the PCL as a single bundle shaped as a flat ribbon. The presence of the AMFL gives the appearance of a double bundle and partially masks the femoral insertion of the PCL, which is located further back relative to the distal joint cartilage.

[LEVEL OF EVIDENCE IV] Experimental cadaver study.