ShoulderDoes bony increased-offset reverse shoulder arthroplasty decrease scapular notching?
Section snippets
Methods
A retrospective comparative cohort study was designed after a sample size calculation indicated that a total of 36 patients (18 in each cohort) would be required to show a 50% reduction in notching rates (α = .05, λ = 7.99). This sample size would also allow detection of a minimal clinically important difference of 6.4 American Shoulder and Elbow Surgeons (ASES) points between cohorts5 (TB Edwards et al unpublished data March 2013). For enhancement, the total study group was increased to 40
Results
For the entire cohort of 40 patients, the mean age at surgery was 74 ± 6 years and there were 17 male and 23 female patients. At a mean follow-up of 34 ± 13 months (all patients had >24 months' follow-up), the mean DASH score was 20 ± 16, the mean ASES score was 69 ± 11, the mean SST score was 9.6 ± 2.4, the mean Constant score was 61 ± 10, and the mean GRC scale rating was +4.5 ± 0.5. The mean range of motion at final follow-up was as follows: active forward elevation, 141° ± 14°; active
Discussion
Scapular notching has been described as a problem, rather than a complication, after RSA.9 The reported incidence of notching in the literature varies and has been associated with implant design characteristics. A recent systematic review reported an overall notching rate of 35%, with a 50% notching rate with use of a Grammont-style implant.9 Several methods may be used to decrease the potential for impingement between the medial aspect of the humeral implant and the lateral scapular pillar,
Conclusion
This comparative cohort study showed no substantial differences between standard RSA and BIO-RSA with respect to range of motion, strength, or validated outcome scores at a minimum of 2 years' follow-up, whereas the rate of scapular notching was significantly lower in the BIO-RSA cohort than in the standard Grammont-style arthroplasty cohort. However, at short-term follow-up, the presence of scapular notching did not have a substantial effect on patient outcomes.
Acknowledgments
We thank Dr T. Bradley Edwards for assistance with this research project.
Disclaimer
A research foundation with which George S. Athwal, Kenneth J. Faber, and Darren Drosdowech are affiliated received research support from Tornier, which manufactures the implant used in this study. Tornier had no input into this research project in any manner.
The authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.
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Institutional review board approval was obtained from Western University/St. Joseph's Health Care (file No. 103218).