title: Wear rates of highly cross-linked polyethylene humeral liners subjected to alternating cycles of glenohumeral flexion and abduction.
abstract: BACKGROUND
  Although short-term outcomes of reverse total shoulder arthroplasty have been promising, long-term success may be limited due to device-specific complications, including scapular notching. Scapular notching has been explained primarily as mechanical erosion; however, the generation of wear debris may lead to further biologic changes contributing to the severity of scapular notching.
  
  
  METHODS
  A 12-station hip simulator was converted to a reverse total shoulder arthroplasty wear simulator subjecting conventional and highly cross-linked ultra-high-molecular-weight polyethylene humeral liners to 5 million cycles of alternating abduction-adduction and flexion-extension loading profiles.
  
  
  RESULTS
  Highly cross-linked polyethylene liners (36.5 ± 10.0 mm(3)/million cycle) exhibited significantly lower volumetric wear rates compared with conventional polyethylene liners (83.6 ± 20.6 mm(3)/million cycle; P < .001). The flexion-extension loading profile exhibited significantly higher wear rates for conventional (P < .001) and highly cross-linked polyethylene (P < .001) compared with the abduction-adduction loading profile. Highly cross-linked wear particles had an equivalent circle diameter significantly smaller than wear particles from conventional polyethylene (P < .001).
  
  
  CONCLUSIONS
  Highly cross-linked polyethylene liners significantly reduced polyethylene wear and subsequent particle generation. More favorable wear properties with the use of highly cross-linked polyethylene may lead to increased device longevity and fewer complications but must be weighed against the effect of reduced mechanical properties.
authors.affiliation: Department of Orthopaedic Surgery, Beaumont Health System, Royal Oak, MI, USA.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Peers
authors.affiliation: Department of Orthopaedic Surgery, Beaumont Health System, Royal Oak, MI, USA.
authors.forename: James E
authors.initials: JE
authors.lastname: Moravek
authors.affiliation: Department of Orthopaedic Surgery, Beaumont Health System, Royal Oak, MI, USA.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Budge
authors.affiliation: Department of Orthopaedic Research, Beaumont Health System, Royal Oak, MI, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Newton
authors.affiliation: Department of Orthopaedic Surgery, Beaumont Health System, Royal Oak, MI, USA; Department of Orthopaedic Research, Beaumont Health System, Royal Oak, MI, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Kurdziel
authors.affiliation: Department of Orthopaedic Research, Beaumont Health System, Royal Oak, MI, USA; Department of Surgery, Oakland University-William Beaumont School of Medicine, Rochester, MI, USA.
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Baker
authors.affiliation: Department of Orthopaedic Surgery, Beaumont Health System, Royal Oak, MI, USA; Department of Surgery, Oakland University-William Beaumont School of Medicine, Rochester, MI, USA. Electronic address: mwiater@beaumont.edu.
authors.forename: J Michael
authors.initials: JM
authors.lastname: Wiater
mesh_terms: D019643:Arthroplasty, Replacement / Q000009:adverse effects / Q000295:instrumentation*; D001672:Biocompatible Materials; D019544:Equipment Failure Analysis; D006801:Humans; D006811:Humerus; D007595:Joint Prosthesis / Q000009:adverse effects; D008422:Materials Testing; D020959:Polyethylene; D011475:Prosthesis Failure; D016059:Range of Motion, Articular; D012785:Shoulder Joint / Q000601:surgery*
chemical_list: D001672:Biocompatible Materials; D020959:Polyethylene
keywords: Reverse total shoulder arthroplasty; highly cross-linked polyethylene; in vitro wear simulation; scapular notching; wear particle analysis