PRIMARY TOTAL KNEE ARTHROPLASTY AFTER PATELLECTOMY

The results of twenty-two consecutive primary total knee replacements, performed an average of nine years (range, one to twenty-three years) after a patellectomy in twenty-two patients, were reviewed retrospect ively. The average duration of followup was seven years (range, three to fifteen years). The average age of the patients at the time of the arthroplasty was sixty-seven years (range, thirty-six to eighty-nine y ears). The average Hospital for Special Surgery knee score was 46 poin ts (range, 22 to 74 points) preoperatively and 76 points (range, 45 to 97 points) postoperatively. Thirteen patients had an excellent or goo d result and seven had a fair or poor result; in two patients, the ope ration was considered a failure. Except for one patient who had myasth enia gravis, all patients could climb stairs in a reciprocal manner. F our patients lacked 5 to 20 degrees of active extension compared with passive extension. With respect to the over-all results, there was no significant difference among the four types of prostheses that were us ed (p = 0.2). The patients who had received an Insall-Burstein posteri or stabilized prosthesis had better scores for pain and function than did the patients who had received a total condylar I prosthesis (p = 0 .005 and 0.01, respectively). There was a direct correlation between t he knee score and the number of years that had elapsed since the patel lectomy. The longer the interval between the patellectomy and the tota l knee replacement, the higher the postoperative knee score (r = 0.78, p < 0.001). While in general the results of a total knee arthroplasty done after a patellectomy are inferior to those reported in the liter ature for patients who have not had a patellectomy, notable decreases in pain and increases in function can be achieved.