Retrospective Cohort Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Orthop. Nov 18, 2016; 7(11): 738-745
Published online Nov 18, 2016. doi: 10.5312/wjo.v7.i11.738
Prosthetic design of reverse shoulder arthroplasty contributes to scapular notching and instability
Gazi Huri, Filippo Familiari, Nima Salari, Steve A Petersen, Mahmut Nedim Doral, Edward G McFarland
Gazi Huri, Mahmut Nedim Doral, Department of Orthopaedic and Traumatology Surgery, Hacettepe University Medical School, Ankara 06100, Turkey
Filippo Familiari, Nima Salari, Steve A Petersen, Edward G McFarland, Division of Shoulder Surgery, Department of Orthopaedic Surgery, the Johns Hopkins University, Baltimore, MD 21093, United States
Author contributions: Salari N and McFarland EG designed the research; Huri G, Familiari F and McFarland EG performed the research and analyzed the data; Huri G, Doral MN, Petersen SA and McFarland EG wrote the paper and critically revised the manuscript for important intellectual content.
Institutional review board statement: Institutional review board approval was obtained for this retrospective study.
Informed consent statement: Patients were not required to give the informed consent for the study.
Conflict-of-interest statement: The authors declare that they have no conflicts of interest concerning this article.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Edward G McFarland, MD, Division of Shoulder Surgery, Department of Orthopaedic Surgery, The Johns Hopkins University, 10753 Falls Rd, Suite 215, Baltimore, MD 21093, United States. editorialservices@jhmi.edu
Telephone: +1-410-5832850 Fax: +1-410-5832855
Received: April 5, 2016
Peer-review started: April 13, 2016
First decision: May 19, 2016
Revised: July 14, 2016
Accepted: August 17, 2016
Article in press: August 18, 2016
Published online: November 18, 2016
Processing time: 223 Days and 9.5 Hours
Abstract
AIM

To evaluate whether implant design, glenoid positioning, and other factors influenced instability and scapular notching in reverse total shoulder arthroplasty.

METHODS

We retrospectively reviewed records of patients who had undergone reverse total shoulder arthroplasty by the senior author from July 2004 through October 2011 and who had at least 24 mo of follow-up. The 58 patients who met the criteria had 65 arthroplasties: 18 with a Grammont-type prosthesis (Grammont group) and 47 with a lateral-based prosthesis (lateral-design group). We compared the groups by rates of scapular notching and instability and by radiographic markers of glenoid position and tilt. We also compared glenoid sphere sizes and the number of subscapularis tendon repairs between the groups. Rates were compared using the Fisher exact test. Notching severity distribution was compared using the χ2 test of association. Significance was set at P < 0.05.

RESULTS

The Grammont group had a higher incidence of scapular notching (13 of 18; 72%) than the lateral-design group (11 of 47; 23%) (P < 0.001) and a higher incidence of instability (3 of 18; 17%) than the lateral-design group (0 of 47; 0%) (P = 0.019). Glenoid position, glenoid sphere size, and subscapularis tendon repair were not predictive of scapular notching or instability, independent of implant design. With the lateral-based prosthesis, each degree of inferior tilt of the baseplate was associated with a 7.3% reduction in the odds of developing notching (odds ratio 0.937, 95%CI: 0.894-0.983).

CONCLUSION

The lateral-based prosthesis was associated with less instability and notching compared with the Grammont-type prosthesis. Prosthesis design appears to be more important than glenoid positioning.

Keywords: Arthroplasty; Reverse; Instability; Scapular notching; Shoulder

Core tip: In reverse total shoulder arthroplasty (RTSA), we found that a Grammont-type prosthesis was associated with higher rates of instability and scapular notching and more severe notching compared with a prosthesis with a lateralized center of rotation. This study also suggests that some inferior tilt of the baseplate may decrease the notching rate. For the 2 prosthesis designs studied, neither glenoid sphere size nor repair of the subscapularis tendon was associated with rates of instability, rates of scapular notching, or severity of scapular notching. These findings are important to surgeons considering whether to use a Grammont-type prosthesis or a lateral-based implant when performing RTSA.