Accuracy of placement of the glenoid component in reversed shoulder arthroplasty with and without navigation.
OBJECTIVE
Navigation can improve accuracy of placement of the glenoid component in reversed shoulder arthroplasty.


METHODS
A glenoid component of a reversed shoulder prosthesis was implanted in 14 paired scapulohumeral cadaver specimens. Seven procedures with standard instrumentation were compared with 7 procedures using navigation. The intraoperative goal was to place the component centrally in the glenoid in the axial plane and 10° inferiorly tilted in the frontal plane. Glenoid component version and tilt and screw placement were studied using CT scan and macroscopic dissection.


RESULTS
The mean version of the glenoid component in the standard instrumentation group was 8.7° of anteversion, compared with 3.1° of anteversion in the navigated group. The mean tilt of the glenoid component was 0.9° in the standard group and 5.4° of inferior tilt in the navigated group. Using navigation, the range of error for version was 8° (SD 3.3°) compared to 12° (SD 4.1°) in controls. For tilt, the range of error was 8° (SD 3.6°) in navigated specimens and 16° (SD 6.0°) for controls. In the control group, there were no perforations of the central peg, but 1 inferior screw and 4 superior screws were malpositioned. In the navigation group, no central peg perforated, all inferior screws were correctly positioned, and 2 superior screws were malpositioned.


CONCLUSIONS
Computer navigation was more accurate and more precise than standard instrumentation in its placement of the glenoid component in reversed shoulder arthroplasty.
Department of Orthopaedic Surgery, AZ Sint Lucas, Brugge, Belgium. olivier.verborgt@telenet.be
Olivier
O
Verborgt
Thomas
T
De Smedt
Matthias
M
Vanhees
Stefan
S
Clockaerts
Paul M
PM
Parizel
Francis
F
Van Glabbeek
D000368:Aged; D019643:Arthroplasty, Replacement; D001863:Bone Screws; D006801:Humans; D066298:In Vitro Techniques; D008875:Middle Aged; D015641:Radiography, Interventional; D012540:Scapula / Q000000981:diagnostic imaging / Q000601:surgery*; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D025321:Surgery, Computer-Assisted; D014057:Tomography, X-Ray Computed