To compare posterior cruciate ligament substituting (PCS) total knee arthroplasty (TKA) and posterior cruciate ligament retaining (PCR) total knee arthroplasty (TKA) to determine if greater overall flexion is obtained with the PCS TKA versus the PCR TKA at two year postoperative follow up. Secondarily, to determine whether there is a difference in the recovery of range of motion over time between the two groups from initial presentation, to discharge, and to follow up visits at three months, one year, and two years.

Prospective, randomised double-blind clinical trial consisting of one hundred male and female patients scheduled for primary TKA. Sample size allows detection of a difference of six degrees of knee range of motion using two-tailed tests, =0.05, and 0.20 (80% power). SCORPIO PCL substituting total knee system and the SCORPIO PCL retaining total knee system were implanted for evaluation in this study. Patients were assessed at initial presentation, at postoperative discharge from hospital, and at follow up visits at three months, one year and two years for flexion knee range of motion. Additional data were collected utilizing the WOMAC Osteoarthritis Index, the Knee Society Clinical Rating Scale, the SF-36, and the Knee Society Radiographic Evaluation as well as data on length of stay and surgical time.

Subjects were similar in demographic characteristics and all measurements at the baseline initial assessment. No differences were seen in knee flexion at two year follow up as measured using an independent t-test (p> 0.05). Recovery of knee range of motion over time was not different as measured using a two way repeated measures ANOVA (p=0.88 for group effect).

Postoperative flexion and recovery of kneww range of motion was not altered following TKA by using PCS or PCR prostheses.