Partial versus Intact Posterior Cruciate Ligament-retaining Total Knee Arthroplasty: A Comparative Study of Early Clinical Outcomes.

Objective: Whether the entire posterior cruciate ligament (PCL) should be retained during cruciate-retaining total knee arthroplasty (CR TKA) is controversial. The goal of this study was to compare the early clinical outcomes of partial versus intact PCL-retaining TKA.

Methods: Ninety-two patients who had undergone unilateral CR TKA from March 2012 to June 2013 were enrolled in this study. Forty-six of these patients were randomly selected to undergo intact PCL-retaining TKA (intact group), whereas the remaining 46 patients underwent tibial osteotomy together with anterolateral bundle and bone island resection (partial group). All operations were performed by a senior orthopedic surgeon and the PCL was released to some extent in both groups. After TKA, active and passive flexion and extension exercises of the knee and lower limb strength exercises were maintained until at least 3 months after surgery. Before surgery and 6, 12, and 24 months after surgery, range of motion, Knee Society Clinical Rating System scores (including clinical and functional scores of the knee) and maximum anteroposterior (AP) displacement of the knee at 30° and 90° of knee flexion were evaluated in both groups.

Results: Fourteen patients were rejected from the final analysis because of loss to follow-up or development of complications. Thus, 40 patients from the partial group and 38 from the intact group were followed up for 24-41 months (mean 32.8 months). Knee functional scores were significantly higher in the intact than in the partial group (88.1 vs. 84.8 points) 24 months after surgery There were no significant differences in range of motion or knee clinical scores between the two groups at any time point. However, 12 and 24 months after surgery, the mean maximum AP displacement of the knee in 90° knee flexion was significantly greater in the partial than in the intact group (12 months: 6.3 vs. 5.7 mm; 24 months: 7.0 vs. 6.2 mm).

Conclusion: Double-bundle PCL plays an important role in maintaining knee stability; the entire PCL should therefore be retained during CR TKA.