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Navigation may lead to better component positioning in reverse shoulder procedures
Study finds a 16° range of error for component tilt in controls compared to 8° for the navigated group.
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Using computer navigation may be more accurate and consistent than using standard instrumentation for glenoid component placement during reverse shoulder arthroplasty, according to research conducted by Belgian investigators.
“Navigation improved the accuracy of placement of the glenoid component,” Olivier Verborgt, MD, PhD, said during his presentation at the American Academy of Orthopaedic Surgeons annual meeting. “The range of error for version was reduced by one third and for tilt by half. Navigation improved positioning of the locking screws.”
Deltopectoral approach
To compare the accuracy of glenoid component placement in reverse shoulder arthroplasty performed with and without the use of navigation, Verborgt and his colleagues implanted the glenoid component of a reverse total shoulder prosthesis system through a deltopectoral approach using either navigation or standard instrumentation in 14 scapulohumeral cadaveric specimens. The investigators assessed the glenoid component version, tilt and screw placement using multiple-slice CT and macroscopic dissection.
Version, screw placement
They found that the mean version of the glenoid component in the control group was 8.7° anteversion compared to 3.1° anteversion in the navigated group. They also discovered that the mean inferior tilt of the glenoid component was 0.9° in the control group and 5.4° of inferior tilt in the navigated group.
Compared to the ideal glenoid component position of 0· version, the investigators discovered a 12° range of error for the control group compared to an 8° range of error for the navigated group. Regarding glenoid component tilt, where the ideal position is 10° of inferior tilt, the control group had a 16° range of error and the navigation group showed an 8° range.
Macroscopic dissection revealed no perforations of the central peg in either group. In the control group, the investigators found that four superior screws and one inferior screw perforated anteriorly or posteriorly. In the navigated group, two superior screws perforated posteriorly, he said.
“We observed an image-based navigation system so there is a need for preoperative CT,” Verborgt said. “It will be less accurate or impossible, if preoperative hardware is in place.”
He also noted that navigation systems have yet to be perfected. “Real-time tracking remains vulnerable to inconsistency and reaming was not taken into account,” Verborgt said.
Guido Marra, MD, a moderator for the session, asked Verborgt if the investigators studied the difference in set-up time between the navigated and traditional procedures.
“We did not really measure it,” Verborgt said. “Of course, as we gain more experience in the procedure, we got faster [with navigation]. I think, at the end, it would be 20 minutes extra.”
For more information:
- Guido Marra, MD, can be reached at Loyola University Medical Center, 2160 S 1st. Ave. Ste. 1700, Maywood, IL 60153; 708-216-6718; e-mail: gmarra@lumc.edu. He is a paid consultant, is in the Speakers Bureau and has received research support from Zimmer.
- Olivier Verborgt, MD, PhD, can be reached at Department of Orthopaedic Surgery, AZ St. Lucas 29, 8310 Bruges, Belgium; 050 36 90 80; e-mail: olivier.verborgt@stlucas.be. He is a paid consultant for Zimmer; however no benefits were received for the study mentioned in this article.
Reference:
- Verborgt O, Desmedt T, van Glabbeek F, et al. Accuracy of glenoid component placement in reverse shoulder arthroplasty with and without navigation. Paper #569. Presented at the American Academy of Orthopaedic Surgeons 76th Annual Meeting. Feb. 25-28, 2009. Las Vegas.