title: Gender Differences in Wear Rates for 28- vs 32-mm Ceramic Femoral Heads on Modern Highly Cross-linked Polyethylene at Midterm Follow-Up in Young Patients Undergoing Total Hip Arthroplasty.
abstract: BACKGROUND
  We report on the midterm linear and volumetric wear of highly cross-linked polyethylene (HXLPE) and survivorship of 2 prospective young total hip arthroplasty (THA) cohorts that differed by the size of ceramic femoral head used: 28 vs 32 mm.
  
  
  METHODS
  We prospectively analyzed 220 consecutive primary THAs in patients aged ≤50 years who received a cementless THA with a ceramic femoral head on HXLPE liner (C-HXLPE). There were 101 patients (46%) with 28-mm heads and 119 patients (54%) who received 32-mm heads at a mean follow-up of 5.5 years (range, 60-109 months). Wear was calculated using Martell Software.
  
  
  RESULTS
  The 28-mm C-HXLPE cohort demonstrated average linear and volumetric wear of 0.020 mm/y (standard deviation [SD], 0.074; 95% CI, 0.003-0.037) and 18.775 mm(3)/y (SD, 21.743; 95% CI, 13.773-23.778) compared with 0.032 mm/y (SD, 0.087; 95% CI, 0.013-0.050]) and 29.847 mm(3)/y (SD, 35.441; 95% CI, 22.294-37.401) in the 32-mm C-HXLPE group. Subgroup analysis by gender and head size discovered significantly greater wear in females with 32-mm heads compared with 28-mm heads in both linear (0.01, 95% CI = -0.014 to 0.033 vs 0.048, 95% CI = 0.022-0.074 mm/y, P = .004) and volumetric wear (14.11, 95% CI = 8.957-19.271] vs 29.71, 95% CI = 17.584-41.840] mm(3)/y, P = .009). We found a 96% (95% CI = 92.30%-97.94%]) survivorship by Kaplan-Meier analysis at minimum 5 years with no failures because of osteolysis.
  
  
  CONCLUSIONS
  Ceramic on HXLPE demonstrates extremely low wear properties in young patients at midterm follow-up. We identified a gender-dependent difference in wear based on head size, with 32-mm heads being associated with increased wear in females.
authors.affiliation: Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Stambough
authors.affiliation: Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Gail
authors.initials: G
authors.lastname: Pashos
authors.affiliation: Division of Biostatistics, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Ningying
authors.initials: N
authors.lastname: Wu
authors.affiliation: Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Jacob A
authors.initials: JA
authors.lastname: Haynes
authors.affiliation: Department of Orthopaedic Surgery and Rehabilitation Medicine, Orthopaedic Biomedical Institute, University of Chicago Medicine & Biological Sciences, Chicago, Illinois.
authors.forename: John M
authors.initials: JM
authors.lastname: Martell
authors.affiliation: Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: John C
authors.initials: JC
authors.lastname: Clohisy
mesh_terms: D000328:Adult; D019644:Arthroplasty, Replacement, Hip; D001672:Biocompatible Materials; D002516:Ceramics; D005260:Female; D005270:Femur Head / Q000601:surgery*; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D020959:Polyethylene; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012737:Sex Factors; D016896:Treatment Outcome
chemical_list: D001672:Biocompatible Materials; D020959:Polyethylene
keywords: Martell method; gender differences; highly cross-linked polyethylene; total hip arthroplasty outcomes; wear