title: Sonographic evaluation of the abductor mechanism after total hip arthroplasty.
abstract: OBJECTIVE
  The purpose of this series was to determine the frequency of abductor mechanism avulsion by sonography after total hip arthroplasty with the Hardinge approach (J Bone Joint Surg Br 1982; 64:17-19) and its relationship to the presence of insufficiency of this musculature in the postoperative period.
  
  
  METHODS
  Thirty-four consecutive patients were prospectively accessed in the postoperative period of hip arthroplasty by the Trendelenburg test, hip sonography, and abductor muscle electromyography. In patients who were found to have clinical insufficiency of the abductor musculature, we also measured the femoral offset in the preoperative and postoperative radiographs. Hip sonography was performed by an experienced musculoskeletal radiologist blinded to the other tests, and the tendons of the gluteus medius and gluteus minimus were visualized on longitudinal and transverse sections with a 7- to 10-MHz linear transducer.
  
  
  RESULTS
  Eight patients presented clinical insufficiency of the abductor musculature as detected by the Trendelenburg test. Four of these 8 patients with abductor insufficiency presented tendinous avulsion detected by sonography. One of the 4 patients with abductor insufficiency and normal sonographic findings had a decrease in the femoral offset caused by the arthroplasty itself. Two patients presented electromyographic changes of the abductor musculature, with no tendinous avulsion detected by sonography and no abductor insufficiency.
  
  
  CONCLUSIONS
  We concluded that in patients undergoing total hip arthroplasty by the Hardinge approach in whom insufficiency of the abductor musculature develops, sonography is an interesting method of investigation because it identified the cause of this problem in most of our patients.
authors.affiliation: Department of Biomechanics, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Flávio Luís
authors.initials: FL
authors.lastname: Garcia
authors.forename: Celso Hermínio Ferraz
authors.initials: CH
authors.lastname: Picado
authors.forename: Marcello Henrique
authors.initials: MH
authors.lastname: Nogueira-Barbosa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000000981:diagnostic imaging* / Q000209:etiology*; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging*; D014463:Ultrasonography / Q000379:methods*