title: The rate of wear of second-generation highly crosslinked polyethylene liners five years post-operatively does not increase if large femoral heads are used.
abstract: OBJECTIVE
  The increased in vivo resistance to wear of highly crosslinked polyethylene (HXLPE) in total hip arthroplasty (THA) has led to an increased use of larger articulations which have been shown to reduce the incidence of early dislocation. To date, there are few reports of the wear of larger articulations using second generation HXLPE liners. Our prospective cohort study measured the bedding-in and early wear of large (36 mm and 40 mm diameter) articulations involving a second generation X3 HXLPE liner and compared our findings with previous clinical and in vitro studies of the same material.
  
  
  METHODS
  The proximal penetration of the femoral head five years post-operatively was measured for 15 patients using radiostereometric analysis (RSA).
  
  
  RESULTS
  The median proximal bedding-in within the first post-operative year was 0.022 mm (interquartile range (IQR) -0.050 to 0.091). The median proximal rate of wear between one and five years was -0.004 mm/year (IQR -0.021 to 0.022). The rates of proximal, medial, 2D or 3D wear between one and five years post-operatively of the X3 HXLPE liner did not increase with larger articulations compared with our previous study of 32 mm articulations.
  
  
  CONCLUSIONS
  Although reassuring, the use of larger articulations requires continued monitoring to determine whether the low wear observed in the short-term continues to the mid- to long-term. Cite this article: Bone Joint J 2016;98-B:1604-10.
authors.affiliation: Royal Adelaide Hospital, Orthopaedics and Trauma, Level 4, Bice Building, North Terrace, Adelaide, South Australia, 5000, Australia.
authors.forename: S A
authors.initials: SA
authors.lastname: Callary
authors.affiliation: University of Adelaide, Adelaide 5000, South Australia, Australia.
authors.forename: J R
authors.initials: JR
authors.lastname: Field
authors.affiliation: Wakefield Orthopaedic Clinic, Wakefield Street, Adelaide 5000, South Australia, Australia.
authors.forename: D G
authors.initials: DG
authors.lastname: Campbell
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation* / Q000379:methods; D020099:Coated Materials, Biocompatible; D003432:Cross-Linking Reagents; D005260:Female; D005270:Femur Head / Q000000981:diagnostic imaging; D005500:Follow-Up Studies; D006622:Hip Prosthesis / Q000009:adverse effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery; D020959:Polyethylene; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure / Q000209:etiology*; D059869:Radiostereometric Analysis / Q000379:methods
chemical_list: D020099:Coated Materials, Biocompatible; D003432:Cross-Linking Reagents; D020959:Polyethylene
keywords: Highly crosslinked polyethylene; Large articulations; Radiostereometric analysis; Total hip arthroplasty; Wear