Anatomical and reverse shoulder arthroplasty utilizing a single implant system with a platform stem: A prospective observational study with midterm follow-up

Background: No studies compare outcomes of anatomic total shoulder arthroplasty to reverse total shoulder arthroplasty with more than five-year follow-up.

Methods: A multicenter prospectively collected shoulder registry was utilized to review all patients undergoing primary anatomic total shoulder arthroplasty or primary reverse total shoulder arthroplasty with a minimum five-year follow-up utilizing a single platform stem implant system. One-hundred-ninety-one patients received an anatomic total shoulder arthroplasty and 139 patients received a reverse total shoulder arthroplasty. Patients were scored preoperatively and at latest follow-up using the simple shoulder test (SST), University of California Los Angeles (UCLA), American shoulder and elbow surgeons (ASES), Constant, and shoulder pain and disability index (SADI) scores as well as range of motion. Radiographs were evaluated for implant loosening or notching. Complications were reviewed. A Student's two-tailed, unpaired t-test identified differences in preoperative, postoperative, and pre-to-postoperative improvements.

Results: Reverse total shoulder arthroplasty patients were significantly older than anatomic total shoulder arthroplasty patients. All patients demonstrated significant improvement in functional metric scores and range of motion following anatomic total shoulder arthroplasty or reverse total shoulder arthroplasty. There was no difference in final outcome scores between anatomic total shoulder arthroplasty and reverse total shoulder arthroplasty patients at midterm follow-up; however, reverse total shoulder arthroplasty patients demonstrated significantly less motion.

Discussion: We demonstrate equivalent outcomes with five scoring metrics at mean follow-up of 71.3 ± 14.1 months. Although postoperative scores were significantly greater than preoperative scores for both anatomic total shoulder arthroplasty and reverse total shoulder arthroplasty patients, significant differences in outcome scores between cohorts were not observed.