title: An evaluation of the relationships between reverse shoulder design parameters and range of motion, impingement, and stability.
abstract: BACKGROUND
  The purpose of this study was to evaluate the role of reverse shoulder design parameters on performance.
  
  
  METHODS
  A computer analysis was conducted on the Grammont reverse shoulder to quantify the effect of varying design parameters on functional measurements during humeral abduction/adduction. To demonstrate the application of these relationships, a novel prosthesis was designed.
  
  
  RESULTS
  The Grammont reverse shoulder impinged inferiorly and superiorly on the glenoid at 31 degrees and 95 degrees of humeral abduction with an average jump distance of 10 mm. Several linear relationships were identified. The proposed 38 mm, 42 mm, and 46 mm reverse shoulder designs impinged inferiorly and superiorly on the glenoid at 7.3 degrees/87.5 degrees, 1 degrees/87.5 degrees, and 0 degrees/89.3 degrees of humeral abduction with an average jump distance of 11.7 mm, 13.5 mm, and 14.1 mm, respectively.
  
  
  CONCLUSIONS
  The results of this study demonstrate that subtle changes in design parameters can minimize inferior glenoid impingement and offer potential for dramatic functional improvements in ROM (39%) and jump distance (36%).
authors.affiliation: Exactech Inc, Gainesville, FL, USA.
authors.forename: Chris
authors.initials: C
authors.lastname: Roche
authors.forename: Pierre-Henri
authors.initials: PH
authors.lastname: Flurin
authors.forename: Thomas
authors.initials: T
authors.lastname: Wright
authors.forename: Lynn A
authors.initials: LA
authors.lastname: Crosby
authors.forename: Michael
authors.initials: M
authors.lastname: Mauldin
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Zuckerman
mesh_terms: D019643:Arthroplasty, Replacement / Q000379:methods*; D003198:Computer Simulation; D006801:Humans; D021621:Imaging, Three-Dimensional; D007593:Joint Instability / Q000517:prevention & control; D007595:Joint Prosthesis; D011474:Prosthesis Design; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology*; D012307:Risk Factors; D019534:Shoulder Impingement Syndrome / Q000517:prevention & control; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000601:surgery*