THE PATELLAR CLUNK SYNDROME AFTER POSTERIOR STABILIZED TOTAL KNEE ARTHROPLASTY

In 20 patients with patellar ''clunks'' after posterior stabilized tot al knee arthroplasty, the average time to presentation was 10.7 months postarthroplasty. All patients demonstrated an audible and often pain ful ''clunk'' during extension. Fourteen procedures (11 arthroscopic d ebridements and three patellar component revisions) were performed in 12 patients. At reoperation, a suprapatellar fibrous nodule was seen t o wedge into the intercondylar notch during flexion and dislodge durin g extension, generating the symptoms. The disorder resolved after nodu le excision. Although four recurrences arose after arthroscopic debrid ements, none developed after arthrotomy and patellar button revision. Femoral component design, postsurgical inflammation, and altered exten sor mechanics are potential etiologic agents of this complication.