Mid- to long-term clinical outcomes after press-fit short stem reverse shoulder arthroplasty

Background: To date, a limited number of studies report mid- to long-term outcomes of press-fit short stem shoulder arthroplasty. The purpose of this study was to report and analyze mid- to long-term outcomes in a series of patients that received press-fit short stem reverse shoulder arthroplasty (RSA). The hypothesis was that press-fit short stem RSA would be a safe and effective treatment with satisfactory mid- to long-term outcomes. Methods: The authors retrospectively reviewed the records of 60 patients that received RSA using press-fit uncemented short humeral stems by two surgeons between March 2014 and December 2015. The absolute Constant Score (CS), age-/sex-adjusted CS, and the American Shoulder and Elbow Surgeons (ASES) score were recorded preoperatively and postoperatively at a minimum follow-up of 6 years. The proportions of patients that achieved a satisfactory outcome after RSA were based on the substantial clinical benefit, as proposed for the absolute CS (net improvement ≥19.1). Results: Of the initial cohort of 60 patients, 9 (15%) died of causes unrelated to RSA, 5 (8%) were revised with partial implant removal, and 4 (7%) were lost to follow-up. This left a final cohort of 42 patients (70%) with complete postoperative CS (absolute and age-/sex-adjusted) and ASES scores at a mean follow-up of 6.7 ± 0.5 years (range, 6.1-7.8). Of the final cohort, 11 (18%) had complications, of which 9 (15%) were treated conservatively, and 2 (3%) required reoperations without implant removal. Net improvements in functional outcomes were 34.7 ± 21.2 for the absolute CS, 54% ± 32% for the age-/sex-adjusted CS, and postoperative ASES scores were 87.9 ± 13.7. Of the 29 patients who had complete records for absolute CS, 22 (76%) received a substantial clinical benefit (net improvement ≥19.1). Conclusions: Mean net improvements of absolute CS exceeded the substantial clinical benefit after press-fit short stem RSA at a follow-up of 6.1 to 8.6 years. While 5 patients (8%) experienced postoperative instability, none had fracture sequelae, which indicates that offset or angular adjustments may be required even in patients with normal bony anatomy. Press-fit short stem RSA is a safe and effective treatment with satisfactory mid- to long-term outcomes, with no stem revisions for aseptic reasons, which compares favorably to the literature that reports high rates of osteolysis and subsequent stem loosening.