Outcome of 17 pigmented villonodular synovitis (PVNS) of the knee at 6 years mean follow-up.

Between January 1950 and December 2000, 16 patients were identified from Scottish Bone Tumour Registry with 17 histologically proven pigmented villonodular synovitis (PVNS) of the knee. The mean follow-up was 6 years (range, 1-14 years). A knee swelling of chronic duration with dull ache was the common presenting symptom. The mean duration of symptoms prior to presentation was 25 months (1-108 months), however it was much less (mean, 7 months) in four patients with a history of trauma. The mean age was 33 years (range, 16-58 years) with a slight male predominance. The lesion was predominantly anterior in nine patients, posterior in four, anterolateral in two, and medial and lateral in one each. Three patients (four knees) had localised disease and 13 diffuse. Anteroposterior and lateral radiographs of the knee revealed normal findings in 11 patients, features of gonarthrosis in four and a large suprapatellar loose body in one patient (both knees). Open (incisional-eight, excisional-eight) biopsy was carried out in all and all were histologically confirmed as PVNS. Removal of a localised synovial mass or loose body with surrounding partial synovectomy (four) was carried out for the localised variety, whilst open partial (three) or total (radical) synovectomy (10) was performed in all cases of diffuse PVNS. Three of seventeen knees had a recurrence, noted at 4, 6 and 8 years postoperatively (0% - localised, 23% - diffuse variety). A total (radical) synovectomy should be considered in diffuse PVNS in order to obtain optimal outcome.