Long-term follow-up of surgically treated localized pigmented villonodular synovitis of the knee.

PURPOSE: The purpose of this study was to review a single institution's large consecutive series of localized pigmented villonodular synovitis (PVNS) of the knee.

METHODS: Cases for review were identified by a search of our institution's pathology records for definitive diagnoses of monoarticular localized PVNS (LPVNS) of the knee between 1970 and 1996. Patients' presenting symptoms and examination were recorded, as were the preoperative diagnosis and documentation of the PVNS nodule's location in the knee at surgery. Eighty-four patients were diagnosed with localized PVNS of the knee during the study period. Twenty-nine of these cases were incidental findings associated with planned total knee replacement and were excluded from the study. Of the remaining 55 patients constituting the study subgroup, 26 have been reviewed in detail.

RESULTS: There were 15 males and 11 females, and the mean age at presentation was 36.7 years. Patients presented for evaluation at an average of 15 months after the onset of symptoms. Pain was the most common complaint, reported by 24 of the 26. Locking and giving way were reported by 10 and 5 patients, respectively. On examination, 13 patients had an effusion, 11 had joint line tenderness, and 10 had a palpable mass. The most common preoperative diagnosis was a meniscus tear (10 of the 26), followed by PVNS (4), "mass" (4), and anterior cruciate ligament injury (3). At surgery, the nodule of PVNS was found most frequently in the suprapatellar pouch (6 cases), followed by the femoral notch (4), lateral synovium/gutter (4), popliteal fossa (3), lateral compartment (3), and medial compartment (2). Fourteen of the procedures performed were open, and 12 were performed by arthroscopy. Ten of the 26 patients participated in a long-term follow-up via the Lysholm Knee Scoring Scale questionnaire (average, 65.8 months postoperatively; average score, 95.4/100). Of these 10, 7 returned for follow-up clinical examinations (6 excellent results and 1 good). All 10 patients were operated on arthroscopically, and none required repeat surgery.

CONCLUSIONS: This review represents the largest series of localized PVNS of the knee to date. Echoing the findings of other PVNS studies, patients presented, on average, in their fourth decade. The common preoperative diagnosis of a meniscal tear is not surprising given the frequent presentation of a painful and, typically, locking knee with joint line tenderness and effusion. Interestingly, what is perhaps the most diagnostic finding on examination, a palpable mass, was present in only 1 of the 6 patients who had PVNS in the most common location, the suprapatellar pouch. With the ease and utility of modern arthroscopy, however, PVNS is an easily treatable condition that can be diagnosed at the time of surgery.

LEVEL OF EVIDENCE: Level IV, therapeutic case series.