抄録
Objective: Patellar clunk syndrome is a complication of posterior-stabilized total knee arthroplasty and is related to the intercondylar box of the femoral component. The etiology of this syndrome is multifactorial. We investigated the incidence of patellar clunk syndrome after mobile-bearing posterior-stabilized total knee arthroplasty and considered the causative factors of this syndrome.
Methods: A total of 243 patients (192 women, 51 men; average age, 74.1 years) in whom 330 consecutive mobile-bearing total knee arthroplasties were performed using the Vanguard RP prosthesis (Biomet, Warsaw, IN, USA) were examined postoperatively to check for the presence of patellar clunk during knee extension. The patella had been resurfaced in 252 knees and had not been resurfaced in 78 knees. Radiographic analysis was performed in patients with patellar clunk.
Results: Six knees were diagnosed with patellar clunk syndrome (incidence, 1.8%). The patella had been resurfaced in all of these patients. The mean period of onset of symptoms was 4.5 months (range, 3-6 months), and the mean postoperative flexion angle was 120.8 (range, 110-125). No specific joint line changes were observed, and the patellar height was within the normal range. The mean tilting angle of the patella in patients with patellar clunk was 0.3 (range, -1 to +2).
Conclusion: The Vanguard RP prosthesis allows hyperextension of 12 and prevents the post from impinging against the anterior margin of the intercondylar box. However, the position of the box seemed to be one of the factors affecting patellar clunk syndrome. Further, an excellent range of motion is another important factor.
