Posterior cruciate ligament effects on the flexion space in total knee arthroplasty

Twelve fresh frozen anatomic specimen knees were used in this study to meas ure changes in the tibiofemoral joint gaps after sacrificing the posterior cruciate ligament. Joint gap changes were measured using a motion tracking device in full extension and at 45 degrees and 90 degrees flexion, Tibiofem oral gaps were measured with no external compressive loads and under tensio n to define the flexion gap, the space available to be filled by components . After initial anterior cruciate ligament removal, meniscectomy, and a l-c m tibial plateau cut, sacrifice of the posterior cruciate ligament caused s ignificant differences in the flexion gap. At 90 degrees flexion the tibia distracted from the femur 5.26 +/- 1.9 mm (range, 3.2-9.1 mm) at rest and 6 .4 +/- 2.5 mm under tension, No differences in the joint space were calcula ted in full extension under either loading case. The authors conclude that a major result of posterior cruciate ligament sacrifice is the creation of a larger flexion gap. This result provides insight into relative joint line changes that can occur after posterior cruciate ligament sacrifice. It als o suggests the need for greater attention to flexion stability when sacrifi cing the posterior cruciate ligament and rethinking the role of posterior c ruciate ligament release in the management of pure, primary flexion contrac ture.