|Beitragstitel||Patient-specific guides to help position augmented glenoid components for biconcave glenoids in total shoulder arthroplasty|
Preoperative planning softwares and patient-specific guides have become available to help improve the positioning of the glenoid component in anatomical total shoulder arthroplasty (aTSA). In addition, for biconcave glenoids with a substantial wear, augmented glenoid implants are proposed to better adapt to the remaining glenoid cavity. The objective of this study was to compare the glenoid implant position and humeral head subluxation between preoperative planning software and postoperative CT.
A total of 7 patients (4 women) with a mean age of 68 years (50-78) were prospectively included in this study. All patients underwent aTSA with an augmented glenoid implant (PerForm+, Tornier) to compensate for substantial biconcave wear. Blueprint software was used for preoperative planning. The keeled glenoid implants were positioned using patient-specific guides. Patients underwent standardized preoperative and postoperative shoulder CT scans. Reduced-dose postoperative CTs were performed using iterative reconstructions and dual-energy CT with a metal artifact reduction algorithm. Preoperative and postoperative CTs were registered with Amira software, using six bony landmarks. The two metallic cylinders within the implant were segmented on the postoperative CT, and the implant computer-aided design file was registered to these cylinders. The registrations were assessed visually with Amira. Postoperative implant position and orientation was measured using the same preoperative coordinate system used by planning software. Preoperative and postoperative subluxation was measured in 3D as the ratio of the humeral head offset from the scapular axis and humeral head radius.
The difference between planned preoperative and measured postoperative version (inclination respectively) of the glenoid component was 0.9° ± 6.1° (3.0° ± 3.9° respectively). Humeral head subluxation was reduced from 54% ± 7% to 26% ± 12%), and remain postero-superior.
This initial study shows that the planned positioning of the augmented glenoid implant was obtained, within the error of the measurement method. Although the measurement error was actually not calculated, we estimate that it could be 5°. We conclude that augmented glenoid implants positioned with preoperative software and patient-specific guides can efficiently correct the worn glenoid cavity and reduce the humeral head static subluxation.