title: Nine year follow-up of a ceramic-on-ceramic bearing total hip arthroplasty utilizing a layered monoblock acetabular component.
abstract: BACKGROUND
  Early ceramic bearing systems in total hip arthoplasty (THA) sought to provide long term wear improvement over traditional metal on polyethylene systems. However, previous designs exhibited fractures of the ceramic acetabular liner, leading to the development of the Implex Hedrocel ceramic bearing THA system where the ceramic liner was supported on a layer of polyethylene intended to transition liner loads to the metal shell, a so-called "sandwich" design. Unfortunately, the device trial was stopped to further enrollment when liner fractures were reported. The current study examines nearly 10-year follow-up on 28 devices implanted by two surgeons at one institution in order to document ceramic bearing system performance over a longer time period.
  
  
  METHODS
  Radiographic and patient reported outcomes, in the form of Harris Hip Scores (HHS) and 12-Item Short Form Health Survey (sF-12), were collected.
  
  
  RESULTS
  During the study period two cups were replaced, one at three years and a second at seven years. At the five year follow-up HHS were similar to those reported in the literature for devices with traditional metal-on-polyethylene bearing surfaces and for other sandwich ceramic bearing designs. At the nine year follow-up, the HHS had not changed significantly and SF-12 scores measuring overall physical and mental health were higher than age matched national norms (p<0.001). There were no signs of cup migration, stem subsidence, osteolysis or cup loosening at any time up to the last follow-up in this patient cohort. The 89% survivorship rate and device revisions due to delamination of the liner observed in this group were similar to those reported earlier for this device and for other "sandwich design" ceramic bearing systems.
  
  
  CONCLUSIONS
  This cohort did not exhibit new failure modes and HHS and SF-12 scores indicated high functionality for the majority of patients. These data suggest that a focus on preventing ceramic liner fracture through design and/or materials improvements may result in a device with long-term functionality.
authors.affiliation: McLaren Regional Medical Center 401 S. Ballenger Hwy, Flint, MI 48532.
authors.forename: David
authors.initials: D
authors.lastname: Mayor
authors.affiliation: McLaren Regional Medical Center 401 S. Ballenger Hwy, Flint, MI 48532.
authors.forename: Savan
authors.initials: S
authors.lastname: Patel
authors.affiliation: McLaren Regional Medical Center 401 S. Ballenger Hwy, Flint, MI 48532.
authors.forename: Clayton
authors.initials: C
authors.lastname: Perry
authors.affiliation: McLaren Regional Medical Center 401 S. Ballenger Hwy, Flint, MI 48532.
authors.forename: Norman
authors.initials: N
authors.lastname: Walter
authors.affiliation: McLaren Regional Medical Center 401 S. Ballenger Hwy, Flint, MI 48532.
authors.forename: Stephen
authors.initials: S
authors.lastname: Burton
authors.affiliation: Kettering University 1700 University Ave, Flint, MI 48504.
authors.forename: Theresa
authors.initials: T
authors.lastname: Atkinson
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D002516:Ceramics; D005260:Female; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D012086:Reoperation; D016896:Treatment Outcome