title: Glenoid articular conformity affects stress distributions in total shoulder arthroplasty.
abstract: BACKGROUND
  The stress applied to the glenoid component in total shoulder arthroplasty (TSA) remains an important concern because of the risk of wear and loosening. The purpose of this study was to determine the stress pattern in the glenoid component with 3 different surface designs.
  
  
  METHODS
  Computer models of 9 scapulae of patients scheduled for TSA were created from computerized tomography images. Each glenoid was virtually reamed, and 3 different glenoid component designs (conforming, nonconforming, and hybrid) were placed. Using finite element analysis, superior translation of the humeral head was modeled. Maximum stress and shear stress were measured at 3 different locations in the glenoid component: center, transition, and superior regions.
  
  
  RESULTS
  All 3 designs showed a similar level of maximum stress at the center and transition regions, while the maximum stress at the superior periphery was significantly higher in the conforming design than in the other 2 designs (P = .0017). The conforming design showed significantly higher shear stress at the superior periphery (P < .0001).
  
  
  CONCLUSIONS
  Stress from periphery loading is higher than from the center and transition region regardless of component design and is highest in the conforming design. The stress at the transition region of the hybrid design was not higher than the other 2 designs. The hybrid design has favorable characteristics based on its low stress at the periphery and greater contact area with the humeral head at the center.
  
  
  METHODS
  Basic Science Study, Biomechanical Computer Simulation Study.
authors.affiliation: Department of Orthopaedic Surgery, Columbia University Centers for Orthopaedic Research and Shoulder, Elbow and Sports Medicine, New York, NY 10032, USA.
authors.forename: Jingzhou
authors.initials: J
authors.lastname: Zhang
authors.forename: Charlie
authors.initials: C
authors.lastname: Yongpravat
authors.forename: H Mike
authors.initials: HM
authors.lastname: Kim
authors.forename: William N
authors.initials: WN
authors.lastname: Levine
authors.forename: Louis U
authors.initials: LU
authors.lastname: Bigliani
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Gardner
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Ahmad
mesh_terms: D000368:Aged; D019643:Arthroplasty, Replacement; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D007595:Joint Prosthesis; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000601:surgery*; D011474:Prosthesis Design; D012540:Scapula / Q000000981:diagnostic imaging*; D012785:Shoulder Joint / Q000601:surgery; D013314:Stress, Mechanical; D014057:Tomography, X-Ray Computed