title: Arthrofibrosis associated with total knee arthroplasty: gray-scale and power Doppler sonographic findings.
abstract: 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 <or= 0.003) more pronounced in the arthrofibrosis group (medial, 1.1; lateral, 1.2; suprapatellar, 1.0; Hoffa's fat pad, 1.1) than in the control group (medial, 0.1; lateral, 0.3; suprapatellar, 0.2; Hoffa's fat pad, 0.1). No significant difference was seen between study groups with regard to the amount of joint effusion at three locations and with regard to patellar tendon thickness.
  
  
  CONCLUSIONS
  Synovial membrane thickening and neovascularity are characteristic sonographic findings for the diagnosis of arthrofibrosis associated with total knee arthroplasty.
authors.affiliation: Department of Orthopedic Surgery, Schulthess Clinic, Lenggstrasse 2, Zurich CH-8008, Switzerland.
authors.forename: Jens G
authors.initials: JG
authors.lastname: Boldt
authors.forename: Urs K
authors.initials: UK
authors.lastname: Munzinger
authors.forename: Marco
authors.initials: M
authors.lastname: Zanetti
authors.forename: Juerg
authors.initials: J
authors.lastname: Hodler
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee; D005260:Female; D005355:Fibrosis; D005500:Follow-Up Studies; D006801:Humans; D006984:Hypertrophy / Q000000981:diagnostic imaging / Q000209:etiology; D017746:Joint Capsule / Q000000981:diagnostic imaging / Q000473:pathology*; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000000981:diagnostic imaging* / Q000473:pathology; D016059:Range of Motion, Articular; D013585:Synovitis / Q000000981:diagnostic imaging* / Q000209:etiology; D016896:Treatment Outcome; D018615:Ultrasonography, Doppler, Color