Pigmented villonodular synovitis (PVNS)
Pigmented villonodular synovitis (PVNS) is a disease affecting the synovial lining the tendon seath and the bursa and may present in the local (figure 1) or the diffuse type. Knee PVNS is usually diffuse. It is considered a benign disease. Repeated microtrauma and bleeding have been implicated as potential causes. In severe cases, the subchondral bone is also affected with cyst formation.
Clinical presentation – Diagnosis
Knee PVNS affects equally men and women aged between 20-45 years old. It presents with knee joint effusion and synovial thickening. Decreased knee range of motion and diffuse pain may also appear.
Clinical diagnosis requires high index of suspicious, while radiographs are usually normal. MRI is useful and definite diagnosis is accomplished after arthroscopy and synovial biopsy.
Conservative treatment with anti-inflammatory drugs offers temporary symptoms relief. Arthroscopic synovectomy is the recommended treatment (video 1 and 2). Total synovectomy is not feasible (part of the posterior synovium is not approached) and PVNS may recur.
Video 1. Arthroscopic treatment of localized PVNS.
Video 2. Arthroscopic treatment of diffused PVNS.