Instability, complications, and functional outcomes after reverse shoulder arthroplasty and anatomic shoulder arthroplasty for chronic neglected shoulder dislocation: a systematic review

BACKGROUND: Chronic shoulder dislocation has been treated by either anatomic shoulder arthroplasty (ASA) or reverse shoulder arthroplasty (RSA) with encouraging results. Although good results have been reported after both the procedures, several complications such as instability and glenoid failures have also been highlighted. The aim of this study was to aggregate the results that have been reported with the use of ASA or RSA in chronic shoulder dislocation and analyze the instability rates, complication rates, and functional outcomes. METHODS: A comprehensive search was performed in May 2020 using PubMed, EMBASE, and Cochrane Library databases. Studies that reported on the outcomes after either ASA or RSA for chronic anterior dislocation (CAD) or chronic posterior dislocation (CPD) were included in the systematic review. Methodologic quality was assessed using the Methodological Index for Nonrandomized Studies appraisal tool for observational studies. RESULTS: We aggregated 13 studies that included data on 128 patients with CAD and 51 patients with CPD. The combined weighted postoperative instability rate in the CAD group was significantly higher after ASA than after RSA (P = .04). There was no significant difference in the combined weighted instability rate between ASA in the CAD group and ASA in the CPD group (P = .37). The complications of RSA in CAD included glenoid base plate loosening, humeral shaft fractures, late infection, acromion fractures, and instability. The complications of the ASA in CAD and CPD included glenoid loosening and erosions, severe pain necessitating revision, severe superior migration of the head, redislocation with rupture of the cuff tendons, bone graft migration, instability, and 2 cases of neuropathies (median nerve and axillary nerve) that eventually resolved. CONCLUSION: Postoperative instability was significantly more common after ASA than after RSA for chronic shoulder dislocations, but both RSA and ASA had a high complication rate in CAD. Shoulder arthroplasty improved the range of motion, functional outcomes, and pain in patients with chronic shoulder dislocation.