title: Metal on metal surface replacement of the hip. Experience of the McMinn prothesis.
abstract: The historical failure of surface replacement has been due to the production of wear debris with subsequent bone resorption, loosening, and failure. To avoid these problems, a surface replacement using a metal on metal bearing allowing thin components and femoral design and instrumentation to avoid varus alignment has been designed. Two hundred thirty-five joints have been resurfaced with this prosthesis in almost 5 years. There have been no femoral neck fractures and no dislocations. There have been 4 designs differing in the method of fixation. In the press fit group, 6 of 70 hips had to be revised for aseptic loosening. In the cemented group, debonding of the cup occurred in 3 of 43 cases. Six patients had hydroxyapatite coated components and have had excellent clinical outcomes. The current design uses a peripherally expanded hydroxyapatite coated cup and a cemented metal head; 116 of this design have been implanted during a 19-month period with excellent outcome. Despite short followup the authors are hopeful that the combination of a polar metal on metal bearing with appropriate fixation will yield a method of preserving bone stock in the younger patient requiring arthroplasty.
authors.affiliation: Midland International Orthopaedic Service, Birmingham Nuffield Hospital, United Kingdom.
authors.forename: D
authors.initials: D
authors.lastname: McMinn
authors.forename: R
authors.initials: R
authors.lastname: Treacy
authors.forename: K
authors.initials: K
authors.lastname: Lin
authors.forename: P
authors.initials: P
authors.lastname: Pynsent
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D005684:Gait; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000502:physiology; D006622:Hip Prosthesis / Q000379:methods; D006801:Humans; D008297:Male; D008670:Metals; D008875:Middle Aged; D009999:Ossification, Heterotopic / Q000209:etiology; D010146:Pain; D010865:Pilot Projects; D011474:Prosthesis Design; D011859:Radiography; D016059:Range of Motion, Articular; D012086:Reoperation
chemical_list: D008670:Metals