title: Five-year comparison of wear using oxidised zirconium and cobalt-chrome femoral heads in total hip arthroplasty: a multicentre randomised controlled trial.
abstract: Oxidised zirconium (OxZi) has been developed as an alternative bearing surface for femoral heads in total hip arthroplasty (THA). This study has investigated polyethylene wear, functional outcomes and complications, comparing OxZi and cobalt-chrome (CoCr) as part of a three-arm, multicentre randomised controlled trial. Patients undergoing THA from four institutions were prospectively randomised into three groups. Group A received a CoCr femoral head and highly cross-linked polyethylene (XLPE) liner; Group B received an OxZi femoral head and XLPE liner; Group C received an OxZi femoral head and ultra-high molecular weight polyethylene (UHMWPE) liner. At five years, 368 patients had no statistically significant differences in short-form-36 (p = 0.176 mental, p = 0.756 physical), Western Ontario and McMaster Universities Osteoarthritis Index (p = 0.847), pain scores (p = 0.458) or complications. The mean rate of linear wear was 0.028 mm/year (standard deviation (SD) 0.010) for Group A, 0.023 mm/year (SD 0.010) for Group B, and 0.09 mm/year (SD 0.045) for Group C. Penetration was significantly higher in the UHMWPE liner group compared with both XLPE liner groups (p < 0.001) but no significant difference was noted between CoCr and OxZi when articulating with XLPE (p = 0.153). In this, the largest randomised study of this bearing surface, it appears that using a XLPE acetabular liner is more important in reducing THA component wear than the choice of femoral head bearing, at mid-term follow-up. There is a non-significant trend towards lower wear, coupling OxZi rather than CoCr with XLPE but long-term analysis is required to see if this observation changes with time and becomes significant.
authors.affiliation: Royal National Orthopaedic Hospital, Brockley Hill, Stanmore HA7 4LP, UK.
authors.forename: S S
authors.initials: SS
authors.lastname: Jassim
authors.affiliation: University College London Hospitals, 235 Euston Road, London NW1 2BU, UK.
authors.forename: S
authors.initials: S
authors.lastname: Patel
authors.affiliation: Colchester Hospital University Foundation Trust, Turner Road, Colchester CO4 5JL, UK.
authors.forename: N
authors.initials: N
authors.lastname: Wardle
authors.affiliation: Trauma and Orthopaedics , Ground Floor Central, 250 Euston Road, London NW1 2PG, UK.
authors.forename: J
authors.initials: J
authors.lastname: Tahmassebi
authors.affiliation: Bournemouth University, Bournemouth, UK.
authors.forename: R
authors.initials: R
authors.lastname: Middleton
authors.affiliation: Yeovil District Hospital NHSFT, Higher Kingston, Yeovil BA21 4AT, UK.
authors.forename: D L
authors.initials: DL
authors.lastname: Shardlow
authors.affiliation: Royal Derby Hospital, Uttoxeter New Road, Derby DE22 3NE, UK.
authors.forename: A
authors.initials: A
authors.lastname: Stephen
authors.affiliation: Royal Derby Hospital, Uttoxeter New Road, Derby DE22 3NE, UK.
authors.forename: J
authors.initials: J
authors.lastname: Hutchinson
authors.affiliation: University College London Hospitals, 235 Euston Road, London NW1 2BU, UK.
authors.forename: F S
authors.initials: FS
authors.lastname: Haddad
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D002858:Chromium Alloys; D005260:Female; D005270:Femur Head; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008422:Materials Testing; D008875:Middle Aged; D020959:Polyethylene; D011095:Polyethylenes; D011446:Prospective Studies; D011474:Prosthesis Design; D013997:Time Factors; D015040:Zirconium
chemical_list: D002858:Chromium Alloys; D011095:Polyethylenes; C111601:ultra-high molecular weight polyethylene; D020959:Polyethylene; D015040:Zirconium
keywords: Hip arthroplasty alternative bearing surfaces; highly cross-linked polyethyelene; oxidized zirconium; total hip arthroplasty; ultra-high molecular weight polyethylene