title: Modular component exchange for treatment of recurrent dislocation of a total hip replacement in selected patients.
abstract: BACKGROUND
  Exchange of modular components is a treatment option for the correction of recurrent dislocation of a total hip replacement. In this study, we reviewed our experience with this technique in order to define patient selection criteria and to report the outcome of treatment.
  
  
  METHODS
  Of 2935 hips treated with primary porous-coated total hip arthroplasty, fourteen (in fourteen patients) that met certain preoperative and intraoperative criteria were treated with modular component exchange because of recurrent hip instability. The primary arthroplasties in these fourteen patients had been performed through a posterior approach. At the revisions, we removed any sources of osseous or soft-tissue impingement that contributed to dislocation. Acceptable stability at the completion of component exchange was defined as stability in maximum flexion, in full extension with external rotation, and in at least 45 degrees of internal rotation with the hip in 90 degrees of flexion and maximum adduction.
  
  
  RESULTS
  One patient was lost to follow-up. At a mean of 5.8 years (range, 2.8 to 11.8 years) after the revision, ten of the remaining thirteen patients had not had a dislocation. Of the three patients in whom the hip dislocated after the modular component exchange, only one had recurrent dislocation; thus, recurrent dislocation was eliminated in twelve of thirteen patients.
  
  
  CONCLUSIONS
  In selected cases, modular component exchange for the treatment of recurrent hip dislocation has a success rate comparable with that of more extensive operations. This method should be considered because it avoids the morbidity associated with revision of well-fixed components. However, to ensure the appropriateness of this surgical option, each patient must be thoroughly evaluated to identify all factors that contribute to instability and adequate intraoperative stability must be achieved.
authors.affiliation: Anderson Orthopaedic Research Institute, Alexandria, VA 22307, USA.
authors.forename: S D
authors.initials: SD
authors.lastname: Toomey
authors.forename: R H
authors.initials: RH
authors.lastname: Hopper
authors.forename: J P
authors.initials: JP
authors.lastname: McAuley
authors.forename: C A
authors.initials: CA
authors.lastname: Engh
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D005260:Female; D006617:Hip Dislocation / Q000209:etiology* / Q000601:surgery*; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D011474:Prosthesis Design; D012008:Recurrence; D016896:Treatment Outcome