title: Accuracy of patient-specific guided glenoid baseplate positioning for reverse shoulder arthroplasty.
abstract: BACKGROUND
  The accuracy of reproducing a surgical plan during shoulder arthroplasty is improved by computer assistance. Intraoperative navigation, however, is challenged by increased surgical time and additional technically difficult steps. Patient-matched instrumentation has the potential to reproduce a similar degree of accuracy without the need for additional surgical steps. The purpose of this study was to examine the accuracy of patient-specific planning and a patient-specific drill guide for glenoid baseplate placement in reverse shoulder arthroplasty.
  
  
  METHODS
  A patient-specific glenoid baseplate drill guide for reverse shoulder arthroplasty was produced for 14 cadaveric shoulders based on a plan developed by a virtual preoperative 3-dimensional planning system using thin-cut computed tomography images. Using this patient-specific guide, high-volume shoulder surgeons exposed the glenoid through a deltopectoral approach and drilled the bicortical pathway defined by the guide. The trajectory of the drill path was compared with the virtual preoperative planned position using similar thin-cut computed tomography images to define accuracy.
  
  
  RESULTS
  The drill pathway defined by the patient-matched guide was found to be highly accurate when compared with the preoperative surgical plan. The translational accuracy was 1.2 ± 0.7 mm. The accuracy of inferior tilt was 1.2° ± 1.2°. The accuracy of glenoid version was 2.6° ± 1.7°.
  
  
  CONCLUSIONS
  The use of patient-specific glenoid baseplate guides is highly accurate in reproducing a virtual 3-dimensional preoperative plan. This technique delivers the accuracy observed using computerized navigation without any additional surgical steps or technical challenges.
authors.affiliation: Holy Cross Orthopedic Institute, Fort Lauderdale, FL, USA. Electronic address: jonlevy123@yahoo.com.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Levy
authors.affiliation: Holy Cross Orthopedic Institute, Fort Lauderdale, FL, USA.
authors.forename: Nathan G
authors.initials: NG
authors.lastname: Everding
authors.affiliation: Florida Orthopaedic Institute, Tampa, FL, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Frankle
authors.affiliation: Materialise, Leuven, Belgium.
authors.forename: Louis J
authors.initials: LJ
authors.lastname: Keppler
mesh_terms: D019643:Arthroplasty, Replacement / Q000379:methods*; D001860:Bone Plates; D002102:Cadaver; D006801:Humans; D021621:Imaging, Three-Dimensional; D012540:Scapula / Q000000981:diagnostic imaging / Q000601:surgery*; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D025321:Surgery, Computer-Assisted; D014057:Tomography, X-Ray Computed
keywords: 3D computed tomography; Reverse shoulder arthroplasty; glenoid baseplate; patient specific