THE PRESS-FIT CONDYLAR MODULAR TOTAL KNEE SYSTEM - 4-TO-6-YEAR RESULTS WITH A POSTERIOR-CRUCIATE-SUBSTITUTING DESIGN

One hundred and eighteen patients who had had 150 consecutive primary total knee replacements (sixteen bilateral procedures) between Februar y 1988 and February 1990, with insertion of the press-fit condylar mod ular total knee system with cement, were enrolled in a prospective stu dy. Ninety-six patients (125 knees) were followed for an adequate inte rval (mean, 4.8 years; range, 3.8 to 6.2 years). Thirteen patients (fi fteen knees) died, and nine patients (ten knees) were lost to follow-u p. The mean age of the patients at the time of the index arthroplasty was seventy years (range, twenty-nine to eighty-five years). The patie nts were evaluated clinically and radiographically, according to the s coring system of the Knee Society, and the results on a self-administe red questionnaire were used to evaluate pain, function, satisfaction, and patellofemoral symptoms. A Kaplan-Meier survivorship analysis was performed with a revision operation as the end point. The mean functio nal and clinical scores, according to the system of the Knee Society, were 78 and 93 points, respectively, at the most recent follow-up exam ination. The result was excellent for 103 knees, good for thirteen, fa ir for three, and poor for six. Three revision operations were necessa ry: two because of infection and one because of instability. The over- all rate of patellofemoral symptoms was 8 per cent (ten knees). Three knees had tibiofemoral instability; subsequent modification of the des ign of the tibial cam decreased the prevalence of this problem. Non-pr ogressive radiolucent lines were present at the cement-bone interface in 39 per cent (thirty-nine) of the ninety-nine knees that had complet e radiographic follow-up. No prosthesis had loosened by the time of th e most recent follow-up examination. The rate of survival of the impla nt was 97 per cent at six years, and the standard error of the mean wa s 1.6 per cent. In the present series, total knee arthroplasties with the press-fit condylar modular knee system resulted in excellent relie f of pain, an excellent range of motion, and restoration of function. They were also associated with a low prevalence of patellofemoral prob lems.