Case Report Arthroscopic Treatment of Soft-Tissue Impingement Under the Patella After Total Knee Arthroplasty

There has been an increased number of reports of complicated diseases of the patellofemo- ral joints after total knee arthroplasty (TKA). We treated soft-tissue impingement under the patella after TKA by arthroscopic surgery and investigated the findings and efficacy of the treatment. Six patients and 8 knees that showed soft-tissue impingement of patellofemoral joints after TKA were treated by arthroscopic surgery. We classified the patients with soft-tissue impingement under the patella into 3 groups: (I) patellar clunk syndrome, the isolated fibrous nodule located in the suprapatellar lesion without the other fibrous tissues causing the impingement (n 2); (II) impinging hypertrophic synovitis, generalized hypertrophic synovitis with no fibrous nodule (n 4); and (III) the combination of types I and II, the suprapatellar fibrous nodule with generalized hypertrophic synovitis (n 2). Therapeutic efficacy was in type I, 2 were good to excellent; in type II, 3 were fair and 1 was poor; and in type III, 2 were fair. Better results were obtained in type I (a patellar clunk syndrome) than in type II (impingement synovitis). Key Words: Arthroscopic surgery—TKA— Patellar clunk syndrome—Soft-tissue impingement—Synovitis.