Pigmented villonodular synovitis diagnosed during revision total knee arthroplasty for flexion instability and patellar fracture

• Pigmented villonodular synovitis (PVNS) can arise in the knee following TKA.
• Diffuse PVNS in the setting of TKA can be treated with complete synovectomy.
• Treated patients can obtain durable pain relief.
• By histology, PVNS can be distinguished from general synovitis with hemarthrosis.
• This distinction is critical as it guides treatment.

Occurring in either a localized or diffuse form, pigmented villonodular synovitis (PVNS) is a disease of unknown etiology that typically presents with insidious onset of pain, swelling, stiffness, or mechanical symptoms as a result of synovial tissue proliferation. PVNS preferentially affects large joints, most commonly the knee. Currently there is no known association with PVNS and total knee arthroplasty (TKA), and to date, there are only a few cases reported in the orthopedic literature in which PVNS was diagnosed after primary TKA. To our knowledge, this is the first case of diffuse PVNS that was discovered at the time of revision TKA for flexion instability and patellar fracture. In this patient, with no known history of PVNS, the diagnosis of diffuse PVNS was made at the time of surgery. She underwent revision TKA, partial patellectomy, and extensive synovectomy.Level of EvidenceV, Case Report.