Arthrofibrosis associated with total knee arthroplasty: gray-scale and power Doppler sonographic findings

OBJECTIVE: The objective of this study was to determine gray-scale and power Doppler sonographic findings in patients with arthrofibrosis associated with total knee arthroplasty. SUBJECTS AND METHODS. From a consecutive cohort of more than 3000 mobilebearing total knee arthroplasties, 44 cases (1.5%) with arthrofibrosis were identified, of which 38 were recruited for a clinical and sonographic investigation. A control group of 38 patients with a well-functioning total knee arthroplasty was matched. Synovial hypertrophy, presence of neovascularity, patellar tendon thickness, and extent of effusion were assessed. RESULTS: Synovial membrane thickness was significantly (p < 0.001) increased in the arthrofibrosis group (medial, 3.4 mm; lateral, 3.0 mm; suprapatellar, 3.1 mm) when compared with the control group (medial, 2.0 mm; lateral, 2.0 mm; suprapatellar, 1.9 mm). When a cutoff of 3.0 mm was used, sonography had a sensitivity of 84% and a specificity of 82% for detecting arthrofibrosis. Neovascularity (rated as grades 0-3) of the synovial membrane and Hoffa's fat pad was significantly (p