title: Improved accuracy of computer assisted glenoid implantation in total shoulder arthroplasty: an in-vitro randomized controlled trial.
abstract: BACKGROUND
  Glenoid replacement is challenging due to the difficult joint exposure and visualization of anatomical reference landmarks. Improper positioning of the glenoid component or inadequate correction of the retroversion using currently available instrumentation may lead to early failure. The objective of this study was to evaluate a computer-assisted technique to achieve a more accurate placement of the glenoid component compared to traditional techniques.
  
  
  METHODS
  Sixteen paired cadaveric shoulders were randomized to either traditional or computer-assisted glenoid implantation. Preoperative planning consisting of CT scanning with 3-dimensional image modeling of the shoulder specimens and intraoperative tracking with real-time feedback provided to the surgeon was employed in the computer-assisted group. A validated, previously published, standardized protocol for tracking the orientation of the glenoid in space using 3 glenoid surface landmarks was employed. All phases of glenoid implantation (initial guide pin insertion, reaming, drilling of the peg holes, and final component implantation) were tracked and recorded by the computer. A post-implantation CT scan was performed in both groups to compare how accurately the implants were placed.
  
  
  RESULTS
  The computer-assisted technique was more accurate in achieving the correct version during all phases of glenoid implantation and as measured on the post-implantation CT scan (P < .05). The largest errors with traditional glenoid implantation were observed during drilling and, more so, during reaming. The trend was to overly retrovert the glenoid.
  
  
  CONCLUSIONS
  Computer assisted navigation results in a more accurate glenoid component placement relative to traditional techniques.
  
  
  METHODS
  Basic Science Study.
authors.affiliation: Department of Surgery Faculty of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada. dnkoas@hotmail.com
authors.forename: Duong
authors.initials: D
authors.lastname: Nguyen
authors.forename: Louis M
authors.initials: LM
authors.lastname: Ferreira
authors.forename: James R
authors.initials: JR
authors.lastname: Brownhill
authors.forename: Graham J W
authors.initials: GJ
authors.lastname: King
authors.forename: Darren S
authors.initials: DS
authors.lastname: Drosdowech
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Faber
authors.forename: James A
authors.initials: JA
authors.lastname: Johnson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019643:Arthroplasty, Replacement / Q000379:methods* / Q000592:standards*; D002102:Cadaver; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012540:Scapula; D012785:Shoulder Joint / Q000601:surgery*; D025321:Surgery, Computer-Assisted