title: A patient-specific guide for optimizing custom-made glenoid implantation in cases of severe glenoid defects: an in vitro study.
abstract: BACKGROUND
  Glenoid component and screw malpositioning in cases of severe glenoid defects might result in complications. We examined the efficacy of a surgical method to treat severe glenoid defects, including a custom-made glenoid component and accurate screw positioning, using a patient-specific positioning guide.
  
  
  METHODS
  Glenoid defects were created in 10 cadaveric shoulders. Computed tomography images were used to plan reversed shoulder arthroplasty and design patient-specific glenoid components. A patient-specific positioning guide was designed for 5 specimens. The remaining 5 specimens were implanted without the guide. Computed tomography images were used to determine the postoperative glenoid component and screw positions. Differences from the preoperatively planned implant and screw positions were calculated.
  
  
  RESULTS
  The patient-specific positioning guide significantly reduced the angular deviations from the planned glenoid implant positioning (P < .05) and also significantly improved the positioning of the screws (P < .001). In the group without the guide, the average total intraosseous screw length was 52% of the ideal preoperatively planned length compared with 89% for the group with the guide. A strong correlation (r = -0.85) was found between the orientation of the implant and the postoperative total intraosseous screw length.
  
  
  CONCLUSIONS
  A patient-specific positioning guide significantly improves the position and fixation of a custom-made glenoid component in cases of severe glenoid defects.
authors.affiliation: Department of Mechanical Engineering, Katholieke Universiteit Leuven, Heverlee, Belgium; R&D Department, Mobelife, Heverlee, Belgium.
authors.forename: Koen
authors.initials: K
authors.lastname: Eraly
authors.affiliation: Orthopaedics, GasthuisZusters Antwerpen (GZA) St Augustinus Hospital, Wilrijk, Belgium.
authors.forename: Danny
authors.initials: D
authors.lastname: Stoffelen
authors.affiliation: Department of Mechanical Engineering, Katholieke Universiteit Leuven, Heverlee, Belgium.
authors.forename: Jos
authors.initials: J
authors.lastname: Vander Sloten
authors.affiliation: Department of Kinesiology, Katholieke Universiteit Leuven, Heverlee, Belgium.
authors.forename: Ilse
authors.initials: I
authors.lastname: Jonkers
authors.affiliation: Orthopaedics, University Hospitals Leuven and Department of Development and Regeneration, Katholieke Universiteit Leuven, Pellenberg, Belgium. Electronic address: philippe.debeer@uzleuven.be.
authors.forename: Philippe
authors.initials: P
authors.lastname: Debeer
mesh_terms: D000368:Aged; D000072228:Arthroplasty, Replacement, Shoulder / Q000295:instrumentation* / Q000379:methods; D001863:Bone Screws; D002102:Cadaver; D061165:Glenoid Cavity / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D011474:Prosthesis Design; D019919:Prosthesis Implantation / Q000379:methods*; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D000072227:Shoulder Prosthesis; D014057:Tomography, X-Ray Computed
keywords: Glenoid defects; custom-made implant; patient-specific guides; reverse shoulder arthroplasty