RESURFACING OF THE PATELLA IN TOTAL KNEE ARTHROPLASTY - A PROSPECTIVE, RANDOMIZED, DOUBLE-BLIND-STUDY

During a two-year period, eighty-nine patients who were scheduled to h ave a total knee arthroplasty for the treatment of degenerative osteoa rthrosis were randomly assigned to one of two groups: resurfacing of t he patella or retention of the patella, All patients received the same posterior cruciate-sparing prosthesis, and all operations were perfor med by, or under the direct supervision of, one of us. Three patients died in the early postoperative period, The remaining eighty-six patie nts (118 knees; fifty-eight that had had resurfacing of the patella an d sixty that had not) formed the study group, They were followed for a mean of thirty months (range, twenty-four to forty-four months). Eval uation was performed with use of the clinical scoring system of The Kn ee Society, a patient-satisfaction questionnaire, specific questions r egarding patellofemoral symptoms and function, and radiographs, All cl inical evaluations were performed by the same research nurse, without the involvement of a physician, in a blinded manner (neither the nurse nor the patient had knowledge of whether the patella had been resurfa ced). Preoperatively, the mean Knee Society score, ion a scale ranging from 0 to 200 points, was 89.7 points (range, 33 to 132 points); post operatively, this score wimproved to a mean of 172.7 points (range, 98 to 200 points), With the numbers available for study we could detect no significant difference between the knees that had had patellar resu rfacing and those that had not with regard to the over-all score (p = 0.63), the subscore for pain (p = 0.56), or the subscore for function (p = 0.77). We also could detect no difference between the treatment g roups, with the numbers available, with regard to patient satisfaction or the responses to questions involving the function of the patellofe moral joint, including the ability to exit from an automobile, to rise from a chair, and to climb stairs. Thirty-two patients had bilateral total knee replacement with resurfacing of the patella in one knee and retention of the patella in the other, These patients expressed no cl ear preference for either knee. Eight (13 per cent) of the sixty knees that had not had resurfacing were painful anteriorly compared with fo ur (7 per cent) of the fifty-eight that had; this was not a significan t difference (p = 0.38), with the numbers available, The anterior pain that was noted postoperatively was predominantly of new onset; it had not been observed preoperatively in three of the four knees that had had resurfacing or in four of the eight that had not. No additional tr eatment options were offered to the patients who had anterior pain in the knee after resurfacing, However, six (10 per cent) of the sixty kn ees that had not had resurfacing had it subsequently, because of anter ior pain in the knee, after the twelfth postoperative month (range, fi fteen to thirty-nine months), The pain decreased in four of these knee s. Thus, total knee arthroplasty with retention of the patella yielded clinical results that were comparable with those after total knee art hroplasty with patellar resurfacing, but it was associated with a 10 p er cent prevalence of the need for subsequent resurfacing, The prevale nce of anterior pain after total knee arthroplasty was not influenced by whether or not the patella had been resurfaced. The postoperative c linical scores, the postoperative development of anterior pain, and th e need for subsequent resurfacing were not predicted by the presence o f preoperative anterior pain, obesity, or the grade of chondromalacia observed intraoperatively Because of the short duration of follow-up, these results should be considered preliminary. Additional follow-up i s planned.