Accuracy of obtaining optimal base plate declination in reverse shoulder arthroplasty
BACKGROUND: Reverse total shoulder arthroplasty has shown promising early and midterm results; however, complication rates remain a concern. Glenoid loosening and notching, for example, can be deleterious to the long-term success. A 15° inferior inclination angle has been shown to offer the most uniform compressive forces across the base plate and the least micromotion at the base plate-glenoid interface. The inferior inclination angle may also avoid scapular notching. The purpose of this study was to determine the accuracy of obtaining 15° of inferior inclination of the base plate. METHODS: The radiographs of 138 reverse total shoulder patients were included. Overall, glenoid inclination and change in inclination from preoperative radiographs were measured using a previously described standardized method. Measurements were obtained by 2 orthopedic surgeons, who repeated all measurements 3 weeks apart. The final angle and change in inclination were averaged. RESULTS: Seventy-two patients had pre- and postoperative radiographs of sufficient quality to accurately measure inclination. Average pre- and postoperative inclination measured -4.8° (-27.2° to 28.1°) and -13.3° (-22.8° to 43.6°), respectively. The average change in inclination was -8.5° (-53.7(o) to 34.6(o)). No scapular notching was observed, which may relate to the lateralized center of rotation of the implant used in this study. DISCUSSION: Overall, the average decrease in inclination was very close to the intended target value using the standard guide. However, patients with preoperative superior glenoid erosion from advanced rotator cuff tear arthropathy appeared to be consistently tilted superiorly, suggesting the standard guide may be inadequate in these patients.
Available from: Chris Roche
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ABSTRACT: BACKGROUND: Superior glenoid wear is a common challenge with reverse shoulder arthroplasty and, if left uncorrected, can result in superior glenoid tilt, which increases the risk of aseptic glenoid loosening. This study evaluates the impact of an E2 superior defect on reverse shoulder glenoid fixation in composite scapulae after correction of glenoid tilt by use of 2 different glenoid reaming techniques: eccentric reaming and off-axis reaming. MATERIALS AND METHODS: A superior glenoid defect was created in 14 composite scapulae. The superior defect was corrected by 2 different glenoid reaming techniques: (1) eccentric reaming with implantation of a standard glenoid baseplate and (2) off-axis reaming with implantation of a superior-augment glenoid baseplate. Each corrected superior-defect scapula was then cyclically loaded (along with a control group consisting of 7 non-worn scapulae) for 10,000 cycles at 750 N; glenoid baseplate displacement was measured for each group to quantify fixation before and after cyclic loading. RESULTS: Regardless of the glenoid reaming technique or the glenoid baseplate type, each standard and superior-augment glenoid baseplate remained well fixed in this superior-defect model scenario after cyclic loading. No differences in baseplate displacement were observed either before or after cyclic loading between groups. DISCUSSION: Our results suggest that either glenoid reaming technique may be used to achieve fixation in the clinically challenging situation of superior wear with reverse shoulder arthroplasty.
Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 05/2013; 22(12). DOI:10.1016/j.jse.2013.03.008 · 2.29 Impact Factor
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ABSTRACT: The reverse shoulder arthroplasty is considered to be one of the most significant technological advancements in shoulder reconstructive surgery over the past 30 years. It is able to successfully decrease pain and improve function for patients with rotator cuff-deficient shoulders. The glenoid is transformed into a sphere that articulates with a humeral socket. The current reverse prosthesis shifts the center of rotation more medial and distal, improving the deltoid's mechanical advantage. This design has resulted in successful improvement in both active shoulder elevation and in quality of life.
Orthopedic Clinics of North America 07/2013; 44(3):389-408. DOI:10.1016/j.ocl.2013.03.010 · 1.25 Impact Factor
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ABSTRACT: Reversed shoulder arthroplasty is an alternative to total shoulder arthroplasty for various indications. The long-term results depend on stable bone fixation, and correct positioning of the glenoid component. The potential contribution of image guidance for reversed shoulder arthroplasty procedures was tested in vitro.
27 positioning procedures (15 navigated, 12 non-navigated) of the glenoid baseplate in reverse shoulder arthroplasty were performed by a single experienced orthopaedic surgeon. A Kirschner wire was placed freehand or with the use of a navigated drill guide. For the navigated procedures, a flat detector 3D C-arm with navigation system was used. The Kirschner wire was to be inserted 12 mm from the inferior glenoid, with an inferior tilt of 10° and centrally in the axial scapular axis. The insertion point in the glenoid as well as the position of the K-wire in the axial and sagittal planes were measured. For statistical analysis, t-tests were performed with a significance level of 0.05.
The inferior glenoid drilling distance was 14.1 ± 3.4 mm for conventional placement and 15.1 ± 3.4 mm for the navigated procedure (P = 0.19). The inferior tilt showed no significant difference between the two methods (conventional 7.4 ± 5.2°, navigated 7.7 ± 4.9°, P = 0.63). The glenoid version in the axial plane showed significantly higher accuracy for the navigated procedure, with a mean deviation of 1.6 ±4.5° for the navigated procedure compared with 11.5 ± 6.5° for the conventional procedure(P = 0.004).
Accurate positioning of the glenoidal baseplate in the axial scapular plane can be improved using 3D C-arm navigation for reversed shoulder arthroplasty. However, computer navigation may not improve the inferior tilt of the component or the position in the inferior glenoid to avoid scapular notching. Nevertheless, further studies are required to confirm these findings in the clinical setup. Copyright © 2013 John Wiley & Sons, Ltd.
International Journal of Medical Robotics and Computer Assisted Surgery 12/2013; 9(4). DOI:10.1002/rcs.1519 · 1.53 Impact Factor
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