title: Metal-Backed Glenoid Components Have a Higher Rate of Failure and Fail by Different Modes in Comparison with All-Polyethylene Components: A Systematic Review.
abstract: BACKGROUND
  Glenoid component failure is a common and serious complication of total shoulder arthroplasty. The purpose of this study was to evaluate published evidence on whether metal backing lessens the rate of glenoid component failure.
  
  
  METHODS
  A comprehensive systematic review yielded twenty-one studies on radiolucency, radiographic failure, and revision after arthroplasty with metal-backed glenoid components and twenty-three studies with all-polyethylene components. Our analysis included data on 1571 metal-backed and 3035 all-polyethylene components. The mean duration of follow-up was 5.8 years in the studies with metal-backed components and 7.3 years with all-polyethylene components.
  
  
  RESULTS
  All-polyethylene components had a 42.5% rate of radiolucency compared with 34.9% for metal-backed components (p = 0.0026) and a 21.1% rate of radiographic loosening or failure compared with 16.8% for metal-backed components (p = 0.0005). However, the rate of revision was more than three times higher with metal-backed components (14.0%) than with all-polyethylene components (3.8%, p < 0.0001). Although 77% of the revisions of all-polyethylene components were for loosening, 62% of the revisions of metal-backed components were for other reasons, such as component fracture, screw breakage, component dissociation, polyethylene wear, metal wear, and rotator cuff tear (p < 0.0001).
  
  
  CONCLUSIONS
  The published evidence indicates that metal-backed glenoid components require revision at a significantly higher rate and for different reasons in comparison with all-polyethylene components.
  
  
  METHODS
  Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: Southeastern Orthopedics, 730 Oakridge Boulevard, Suite B, Lumberton, NC 28358. E-mail address: papadonik@hotmail.com.
authors.forename: Anastasios
authors.initials: A
authors.lastname: Papadonikolakis
authors.affiliation: Department of Orthopaedics and Sports Medicine, University of Washington Medical Center, Box 356500, 1959 N.E. Pacific Street, Seattle, WA 98195. E-mail address: matsen@u.washington.edu.
authors.forename: Frederick A
authors.initials: FA
authors.lastname: Matsen
mesh_terms: D000072228:Arthroplasty, Replacement, Shoulder / Q000295:instrumentation*; D006801:Humans; D008670:Metals / Q000737:chemistry*; D020959:Polyethylene / Q000737:chemistry*; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012086:Reoperation
chemical_list: D008670:Metals; D020959:Polyethylene