Fifty-four consecutive patients underwent total knee arthroplasty utilizing a posterior-stabilized prosthesis, and another group of fifty-three consecutive patients received a cruciate-retaining implant. All patients who had osteoarthritis, osteonecrosis, or rheumatoid arthritis and who were indicated for a total knee arthroplasty were invited to take part in a prospective study to follow their outcomes, and none of the patients declined. In the cruciate-retaining cohort, 1 patient passed away and 6 patients changed their addresses prior to the five-year follow-up visit, so their results were not included in the study. At the latest follow-up visit (mean follow-up time 17 months; range, 3 to 48 months), the patients who were lost to follow-up had mean Knee Society knee and function scores of 85 points (range, 52 to 100 points) and 78 points (range, 50 to 100 points), respectively. In the posterior-stabilized group, 3 patients passed away and 6 patients could not be reached at the five-year follow-up visit, so they were also excluded. At their last follow-up (mean follow-up time 29 months; range, 7 to 49 months), the mean Knee Society knee and function scores of the patients who were lost to follow-up were 85 points (range, 34 to 100 points) and 63 points (range, 45 to 100 points), respectively. No other patients were excluded. The patients were evaluated in the office one month after the procedure and annually thereafter. The ranges of motion, Knee Society scores,18
radiographic outcomes, and complications were assessed at each follow-up visit, and these were compared at the five year follow-up. This study received full institutional review board approval.
The patients who received cruciate-retaining arthroplasties consisted of 20 men and 26 women who had a mean age of 64 years (range, 40 to 77 years), a mean body mass index of 32 kilograms per meter squared (range, 26 to 43 kilograms per meter squared), a mean preoperative Knee Society knee score of 42 points (range, 20 to 73 points), and a mean preoperative Knee Society functional score of 36 points (range, 10 to 60 points). The patients who received posterior-stabilized arthroplasties consisted of 17 men and 28 women who had a mean age of 66 years (range, 45 to 81 years), a mean body mass index of 32 kilograms per meter squared (range, 23 to 47 kilograms per meter squared), a mean preoperative Knee Society knee score of 38 points (range, 20 to 70 points) and a mean preoperative Knee Society functional score of 32 points (range, 10 to 70 points).
All procedures were performed by two of the authors, who both used a standard median parapatellar approach. All surgeries utilized the Scorpio CR cruciate-retaining system or the Scorpio PS posterior-stabilized system (Stryker, Mahwah, New Jersey). Each author performed approximately half of the CR procedures and half of the PS procedures.
The patients were evaluated in the office one month, one year, and annually after the surgery. Knee Society scores,18
ranges of motion, and radiographs (weight-bearing anteroposterior and lateral views) were assessed at each follow-up visit. Radiolucencies were evaluated using the system of zonal analysis developed by the Knee Society.19
The Knee Society scores and ranges of motion of the two groups were compared with Student t-tests. All statistical analyses were performed using SigmaStat version 3.0 (SPSS, Chicago, Illinois).