title: Achieving fixation in glenoids with superior wear using reverse shoulder arthroplasty.
abstract: BACKGROUND
  Superior glenoid wear is a common challenge with reverse shoulder arthroplasty and, if left uncorrected, can result in superior glenoid tilt, which increases the risk of aseptic glenoid loosening. This study evaluates the impact of an E2 superior defect on reverse shoulder glenoid fixation in composite scapulae after correction of glenoid tilt by use of 2 different glenoid reaming techniques: eccentric reaming and off-axis reaming.
  
  
  METHODS
  A superior glenoid defect was created in 14 composite scapulae. The superior defect was corrected by 2 different glenoid reaming techniques: (1) eccentric reaming with implantation of a standard glenoid baseplate and (2) off-axis reaming with implantation of a superior-augment glenoid baseplate. Each corrected superior-defect scapula was then cyclically loaded (along with a control group consisting of 7 non-worn scapulae) for 10,000 cycles at 750 N; glenoid baseplate displacement was measured for each group to quantify fixation before and after cyclic loading.
  
  
  RESULTS
  Regardless of the glenoid reaming technique or the glenoid baseplate type, each standard and superior-augment glenoid baseplate remained well fixed in this superior-defect model scenario after cyclic loading. No differences in baseplate displacement were observed either before or after cyclic loading between groups.
  
  
  CONCLUSIONS
  Our results suggest that either glenoid reaming technique may be used to achieve fixation in the clinically challenging situation of superior wear with reverse shoulder arthroplasty.
  
  
  METHODS
  Basic science, biomechanical study.
authors.affiliation: Exactech, Gainesville, FL, USA.
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Roche
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Stroud
authors.forename: Brian L
authors.initials: BL
authors.lastname: Martin
authors.forename: Cindy A
authors.initials: CA
authors.lastname: Steiler
authors.forename: Pierre-Henri
authors.initials: PH
authors.lastname: Flurin
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Wright
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Zuckerman
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Dipaola
mesh_terms: D019643:Arthroplasty, Replacement / Q000379:methods*; D001696:Biomechanical Phenomena; D006801:Humans; D007595:Joint Prosthesis; D008954:Models, Biological; D011475:Prosthesis Failure; D012540:Scapula / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D012785:Shoulder Joint / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*
keywords: Basic Science; Biomechanical Study; Reverse shoulder arthroplasty; glenoid fixation