title: Use of a custom alignment guide to improve glenoid component position in total shoulder arthroplasty.
abstract: OBJECTIVE
  Total and reverse total shoulder arthroplasty (TSA) are used to treat patients with glenohumeral joint osteoarthritis. The revision rate remains high compared with hip and knee arthroplasty. Glenoid component loosening is an important complication and may be caused by poor positioning of the component. We aimed to evaluate the safety and accuracy of a custom glenoid jig created using preoperative computed tomography (CT) imaging with 3D modelling for glenoid component implantation.
  
  
  METHODS
  Preoperative CT scans of each shoulder (N = 7) were obtained. Implants were virtually aligned and custom templates were created for intraoperative use. A two-part custom jig was manufactured for alignment of the central peg and the peripheral screws. Three-dimensional orientation of the component and screws was evaluated in postoperative CT scans. The difference between the preoperative plan and the result was then calculated.
  
  
  RESULTS
  No technical difficulties or complications occurred. The mean absolute difference between the planned alignment and the postoperative placement of the glenoid component in the three-dimensional space was 3.4 mm (SD = 1 mm). The total average difference for all screws (N = 10) was 6.3° (SD = 3.2°).
  
  
  CONCLUSIONS
  A CT-based custom glenoid component alignment can reliably guide the placement of the glenoid component during conventional and reverse TSA. This custom jig may be useful for optimizing glenoid component position in the setting of reverse and TSA.
authors.affiliation: Department of Orthopaedic Surgery, Sports Medicine and Shoulder Service, Hospital for Special Surgery, 535 E 70th St., New York, NY, 10021, USA, eduardosuero@gmail.com.
authors.forename: Eduardo M
authors.initials: EM
authors.lastname: Suero
authors.forename: Musa
authors.initials: M
authors.lastname: Citak
authors.forename: Darrick
authors.initials: D
authors.lastname: Lo
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Krych
authors.forename: Edward V
authors.initials: EV
authors.lastname: Craig
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Pearle
mesh_terms: D000368:Aged; D019643:Arthroplasty, Replacement / Q000379:methods*; D001863:Bone Screws; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D010003:Osteoarthritis / Q000000981:diagnostic imaging / Q000601:surgery; D056888:Patient Positioning; D012785:Shoulder Joint / Q000000981:diagnostic imaging* / Q000601:surgery*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome