title: Simulation of surgical glenoid resurfacing using three-dimensional computed tomography of the arthritic glenohumeral joint: the amount of glenoid retroversion that can be corrected.
abstract: OBJECTIVE
  The magnitude of glenoid retroversion that can be surgically corrected in total shoulder arthroplasty and still enable implantation of a glenoid component has not been established. We hypothesized that increased retroversion will require smaller glenoid components for successful implantation when the glenoid is surgically corrected and that correction beyond 20 degrees of retroversion is not feasible without peg penetration.
  
  
  METHODS
  Using 3-dimensional models created from computed tomography of 19 patients with advanced shoulder osteoarthritis, we simulated glenoid resurfacing on varying degrees of retroverted, osteoarthritic glenoids using an in-line 3-peg glenoid component and asymmetric reaming to correct version.
  
  
  RESULTS
  Glenoids with preoperative retroversion of less than 12 degrees could always be implanted with 46-mm and 52-mm glenoid components at neutral version without vault violation. Conversely, glenoids with greater than 18 degrees of preoperative retroversion could not be implanted at neutral version due to vault violation from the pegs. The average preoperative glenoid retroversion of patients in which a 46-mm glenoid was implanted at neutral version was 8.9 degrees +/- 6.4 degrees compared with 19.0 degrees +/- 7.1 degrees for those that could not be implanted at neutral (P = .005).
  
  
  CONCLUSIONS
  Computer-aided surgical simulation shows that glenoid retroversion is a critical factor in determining successful glenoid implantation. Smaller sized glenoid components allow for greater version correction and less residual postsimulation retroversion when an in-line pegged component is used.
authors.affiliation: Center for Shoulder, Elbow and Sports Medicine, Columbia University, New York, NY, USA.
authors.forename: Douglas D
authors.initials: DD
authors.lastname: Nowak
authors.forename: Maher J
authors.initials: MJ
authors.lastname: Bahu
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Gardner
authors.forename: Marc D
authors.initials: MD
authors.lastname: Dyrszka
authors.forename: William N
authors.initials: WN
authors.lastname: Levine
authors.forename: Louis U
authors.initials: LU
authors.lastname: Bigliani
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Ahmad
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D019643:Arthroplasty, Replacement / Q000379:methods*; D015331:Cohort Studies; D003198:Computer Simulation; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional; D007595:Joint Prosthesis; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000000981:diagnostic imaging / Q000601:surgery; D011300:Preoperative Care / Q000379:methods; D011336:Probability; D011446:Prospective Studies; D011474:Prosthesis Design; D017755:Prosthesis Fitting; D011859:Radiography; D018570:Risk Assessment; D012540:Scapula / Q000033:anatomy & histology; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D016896:Treatment Outcome