To evaluate the efficacy of arthroscopic synovectomy through the direct posterior-posterior approach in pigmented villonodular synovitis (PVNS) of the knee.

Between January 1997 and May 2004, twenty-one patients underwent an arthroscopic synovectomy for PVNS of knee. The mean follow-up period was 35 months. The arthroscopic and MRI findings revealed the localized form of PVNS in six patients and the diffuse form in fifteen patients. All patients underwent an arthroscopic examination and synovectomy through the direct posterior-posterior approach. The clinical results were evaluated by the range of motion, Lysholm knee score, and the knee pain score using the visual analogue scale (minimum 0-maximum 10).

Among the fifteen cases with the diffuse form, three cases (14%) recurred and had secondary arthroscopic total synovectomy. One cases recurred again. Therefore, radiation therapy was performed. The Lysholm knee score improved from 62.5 to 87.3, and the VAS score improved from 5.9 to 1.8. Three patients had a mild limitation in knee motion. However, the others had full range of motion of the knee at the last follow-up.

Arthroscopic synovectomy through the direct posterior-posterior approach could be a useful method for the treatment of PVNS of the knee, and can be used as an effective therapeutic tool particularly in posteromedial or posterolateral lesions.