title: Outcome of the Stryker® Trident 'All-Poly' constraint acetabular insert: a district general hospital experience.
abstract: BACKGROUND
  Constrained acetabular inserts are designed as revision solutions for unstable total hip arthroplasties to prevent dislocation and as a possible primary option for elderly patients at risk of recurrent dislocation.
  
  
  OBJECTIVE
  Our aim was to establish clinical and radiological outcomes of an 'all-poly' constrained acetabular device and to highlight reasons for component failure.
  
  
  METHODS
  We retrospectively reviewed our use of the Stryker® Trident 'all-poly' constrained acetabular insert between 2008 and 2013. All inserts were cemented directly into the acetabulum. Demographic data was collated. The indication for use of a constrained insert and postoperative complications were determined. Patients were reviewed clinically and underwent radiographic follow-up.
  
  
  RESULTS
  A total of 56 constrained inserts were utilised during the study period. Follow-up was for a minimum of 2 years (mean 4.0 years and range 2.0-6.8 years). The mean latest follow-up Oxford hip score was 34.6 (11-48). One postoperative superficial wound infection, 1 breakage of the constraining ring without clinical consequence and 1 recognised complication of liner failure at the bipolar interface were noted.
  
  
  CONCLUSIONS
  In the short to medium term, acetabular constraint offers a useful primary or revision option in patients at risk or with recurrent dislocation.
authors.affiliation: Department of Trauma and Orthopaedics, Huddersfield Royal Infirmary, Huddersfield - UK.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Harrison
authors.affiliation: Department of Trauma and Orthopaedics, Huddersfield Royal Infirmary, Huddersfield - UK.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Leeder
authors.affiliation: Department of Trauma and Orthopaedics, Huddersfield Royal Infirmary, Huddersfield - UK.
authors.forename: Timothy G
authors.initials: TG
authors.lastname: McWilliams
authors.affiliation: Department of Trauma and Orthopaedics, Huddersfield Royal Infirmary, Huddersfield - UK.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Metcalf
authors.affiliation: Department of Trauma and Orthopaedics, Huddersfield Royal Infirmary, Huddersfield - UK.
authors.forename: Sameh A
authors.initials: SA
authors.lastname: Sidhom
mesh_terms: D000077:Acetabulum; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000295:instrumentation*; D005260:Female; D005500:Follow-Up Studies; D006617:Hip Dislocation / Q000000981:diagnostic imaging / Q000209:etiology / Q000517:prevention & control*; D006622:Hip Prosthesis / Q000009:adverse effects*; D006767:Hospitals, District; D006769:Hospitals, General; D006801:Humans; D008297:Male; D008875:Middle Aged; D011475:Prosthesis Failure / Q000009:adverse effects*; D011859:Radiography; D012189:Retrospective Studies; D016896:Treatment Outcome