Summary

The clinical results of RSA for DA treated with eccentric reaming are comparable to the results of a matched cohort of OA patients with similar treatment.

Abstract

Background

Dislocation arthropathy (DA) of the shoulder is due to glenohumeral dislocations with or without previous stabilization surgery. Reverse shoulder arthroplasty (RSA) has emerged as a favorable treatment option in patients with DA but the literature of clinical results is limited to few studies with small sample size. The goal of this study was to compare the clinical results of RSA in patients with DA with patients having glenohumeral osteoarthritis (OA) with intact cuff and severe bone loss.

Methods

This is a retrospective matched cohort study of 13 patients with DA who were treated with RSA by one surgeon between 2011 and 2019 and a 3 to 1 matched control group of 39 patients with osteoarthritis according to age, follow-up length, sex, and BMI. All patients in both groups had a minimum of two years of follow-up and were treated with the same RSA system: a lateralized glenosphere, a 135° neck shaft angle, and an uncemented humeral stem. Glenoids were reamed eccentrically until there was at least 90% coverage of the baseplate [1]. No bone grafting or augmented glenoid components were utilized. The primary outcomes were patient reported outcomes (PROs) and ranges of motion (ROM). Secondary outcomes included complications such as dislocations, baseplate loosening, nerve palsies, infection, revisions, and periprosthetic fractures.

Results

At final follow-up, the DA and OA groups each showed statistically significant improvements in PROs (SST, ASES, WOOS, SANE, satisfaction) and ROM following RSA procedure. Furthermore, there was there was no statistically significant difference between the groups in PROs and ROM. There were no complications in the DA group but there were 5/39 (13%) in the OA group (P=0.41). In the OA cohort, the complications included an iatrogenic greater tuberosity fracture, one median and one ulnar neuropathy which resolved by 4 months postoperatively and 1 ulnar neuropathy that required surgical release at the elbow at 9 months post-op, The fifth complication in the OA group was a baseplate failure secondary to scapular notching that required revision. The revision rate at final follow-up was 0/13 (0%) in the DA group and 1/39 (2%) OA group. In the DA group there were no signs of baseplate loosening nor notching in any patient.

Conclusion

This study found that the clinical results of RSA for DA treated with eccentric reaming are comparable to the results of a matched cohort of OA patients with similar treatment. At the short term follow up, RSA with eccentric glenoid reaming is a valid treatment strategy in patients with DA but studies with larger sample size and longer follow up are warranted.

References
1. McFarland EG, Meshram P, Rojas J, Joseph J, Srikumaran U. Reverse Total Shoulder Arthroplasty without Bone-Grafting for Severe Glenoid Bone Loss in Patients with Osteoarthritis and Intact Rotator Cuff: A Concise 5-Year Follow-up of a Previous Report. J Bone Joint Surg Am. 2021 Apr 7;103(7):581-585.