Knee Swelling

Abstract

HISTORY A 17-year-old female seen in consultation for a painless chronic left knee effusion for 3 years. There was an insidious onset to the swelling and she denies any trauma. The swelling has remained relatively unchanged during this time period. She denies any nighttime pain, mechanical symptoms of locking or giving out. She denies any other joint complaints or a family history of collagen-vascular diseases. She does not participate in any sports and is most concerned about the cosmetic appearance of the swelling. She has had serosanguinous fluid aspirated from her knee on 3 separate occasions and has had 2 previous MRIs which were reported to be normal. PHYSICAL EXAMINATION She was in no distress and walking with a normal gait. Examination of her right knee was normal. Her left knee revealed a good VMO tone and bulk. She had a significant effusion localized to the suprapatellar lateral, infrapatellar lateral and medial aspects. There was no peripatellar pain. Negative McMurray, Lachman and anterior drawer. DIFFERENTIAL DIAGNOSIS Juvenile Rheumatoid Arthritis Pigmented Villonodular Synovitis Synovial Osteochondromatosis Synovial Hemangioma Synovial Sarcoma TEST AND RESULTS Previous knee aspirates: Negative gram stain and no growth. Laboratory Studies: CBC and CMP: normal ESR 9 ANA 1:40 speckled pattern RF: Negative Radiological Studies: Knee radiograph: Large effusion. No joint erosion. Chest radiograph: Normal Knee MRI: Ligaments and menisci intact. Fluid and hypertrophy of synovium in suprapatellar pouch. Multiple loculations of synovial fluid in posterior aspect. Hemosiderin deposition. No erosions. FINAL DIAGNOSIS Pigmented Villonodular Synovitis (PVNS) TREATMENT AND OUTCOMES Arthroscopic synovial biopsy and synovectomy. Operatively the knee had frondular synovium with hemosiderin pigmentation in all compartments. The biopsy was consistent with pigmented villonodular synovitis. Patient was started on physical therapy to help with range of motion postoperatively. Two months postoperatively the patient has full ROM with decreased knee swelling.