title: The focally constrained liner is a reasonable option for revision of unstable total hip arthroplasty.
abstract: Revision surgery for a patient with previous recurrent dislocations or abductor muscle dysfunction has been considered to be a complication-prone procedure regardless of the type of constrained implant used. We investigated the survivorship of a focally constrained acetabular liner used for revision total hip arthroplasty in patients with abductor insufficiency or previous recurrent dislocations.
  
  
  
  We retrospectively reviewed 98 patients in whom a focally constrained acetabular liner was used to treat abductor insufficiency or previous recurrent dislocations. The mean age was 69.4 years (37-92) and 64 of these were females. Previously, the patients had undergone a mean of two (1-5) revisions. The mean follow-up was 38 (12-66) months. Kaplan-Meier survival curves were calculated and Log-rank test was used to test the difference in survivorship between patients with abductor insufficiency and previous dislocations.
  
  
  
  Sixteen patients needed a further re-revision for any cause. Thus, the revision-free survivorship was 84.3 % at five years. Five patients suffered a dislocation with a mean of five months post-operatively and were managed with repeat revision. Five patients failed at the implant-host bone interface. Three of these failures occurred after cementing the constrained liner into a pre-existing shell.
  
  
  
  The focally constrained liner provided a reasonable option for revision total hip arthroplasty in patients with hip instability. Failures were observed in patients with acetabular osteolysis but seemingly well-fixed component and unrecognized impingement.
authors.affiliation: Division of Orthopaedic Surgery, Mount Sinai Hospital, University of Toronto, 600 University Avenue, Toronto, Ontario, M5G 1X5, Canada. tatu.makinen@hus.fi.
authors.forename: Tatu J
authors.initials: TJ
authors.lastname: Mäkinen
authors.affiliation: Division of Orthopaedic Surgery, Mount Sinai Hospital, University of Toronto, 600 University Avenue, Toronto, Ontario, M5G 1X5, Canada.
authors.forename: Simcha G
authors.initials: SG
authors.lastname: Fichman
authors.affiliation: Division of Orthopaedic Surgery, Mount Sinai Hospital, University of Toronto, 600 University Avenue, Toronto, Ontario, M5G 1X5, Canada.
authors.forename: Wael A
authors.initials: WA
authors.lastname: Rahman
authors.affiliation: Division of Orthopaedic Surgery, Mount Sinai Hospital, University of Toronto, 600 University Avenue, Toronto, Ontario, M5G 1X5, Canada.
authors.forename: Tomas
authors.initials: T
authors.lastname: Amenabar
authors.affiliation: Division of Orthopaedic Surgery, Mount Sinai Hospital, University of Toronto, 600 University Avenue, Toronto, Ontario, M5G 1X5, Canada.
authors.forename: Oleg
authors.initials: O
authors.lastname: Safir
authors.affiliation: Division of Orthopaedic Surgery, Mount Sinai Hospital, University of Toronto, 600 University Avenue, Toronto, Ontario, M5G 1X5, Canada.
authors.forename: Allan E
authors.initials: AE
authors.lastname: Gross
authors.affiliation: Division of Orthopaedic Surgery, Mount Sinai Hospital, University of Toronto, 600 University Avenue, Toronto, Ontario, M5G 1X5, Canada.
authors.forename: Paul R T
authors.initials: PR
authors.lastname: Kuzyk
mesh_terms: D000077:Acetabulum / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006617:Hip Dislocation / Q000601:surgery*; D006622:Hip Prosthesis / Q000009:adverse effects; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012086:Reoperation / Q000009:adverse effects / Q000379:methods*; D012189:Retrospective Studies
keywords: Abductor insufficiency; Constrained liner; Dislocation; Revision; Total hip arthroplasty