title: Ceramic-on-ceramic total hip arthroplasty: incidence of instability and noise.
abstract: BACKGROUND
  Alternative bearing materials in THA have been developed to reduce the incidence of osteolysis. Alumina-on-alumina bearings exhibit extremely low wear rates in vitro, but concerns exist regarding component impingement with the potential for dislocation and the occurrence of noise.
  
  
  OBJECTIVE
  We determined generation of squeaking and the relationship between squeaking and component position.
  
  
  METHODS
  We prospectively entered 436 alumina-on-alumina, cementless, primary THAs in 364 patients into our institutional database. All procedures were performed with the same surgical technique and the same implant. We obtained Harris Hip scores and a noise questionnaire and assessed radiographic component position and loosening. We determined the difference in abduction angle between squeakers and nonsqueakers. Minimum followup was 2 years (average, 3.5 years; range, 2.0-6.2 years).
  
  
  RESULTS
  The mean Harris hip score increased from 51.9 preoperatively to 94.4 at latest followup. Six hips underwent reoperation: four hips (1.1%) for dislocation and two (0.53%) for periprosthetic fracture after trauma. The incidence of noise of any type was 11%, with the most common type of noise being clicking or snapping. Squeaking was reported by 1.9% of patients, with no patient being revised for this phenomenon. We found no association between component position and squeaking.
  
  
  CONCLUSIONS
  At average 3 years followup, 98% of ceramic-on-ceramic THAs did not require a revision, with 1.1% of hips having been revised for dislocation. Fewer than 2% of patients reported hearing an audible squeak, with no association found between component position and squeaking.
  
  
  METHODS
  Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedic Surgery, Hospital for Special Surgery, New York, NY10021, USA.
authors.forename: David
authors.initials: D
authors.lastname: Schroder
authors.forename: Lindsey
authors.initials: L
authors.lastname: Bornstein
authors.forename: Mathias P G
authors.initials: MP
authors.lastname: Bostrom
authors.forename: Bryan J
authors.initials: BJ
authors.lastname: Nestor
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Padgett
authors.forename: Geoffrey H
authors.initials: GH
authors.lastname: Westrich
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D002516:Ceramics; D005260:Female; D006621:Hip Joint / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D007592:Joint Diseases / Q000601:surgery; D008297:Male; D009518:New York / Q000453:epidemiology; D009622:Noise; D011183:Postoperative Complications / Q000453:epidemiology; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure / Q000209:etiology*; D011795:Surveys and Questionnaires