Effects of Obesity on Clinical and Functional Outcomes Following Anatomic and Reverse Total Shoulder Arthroplasty.

Abstract

BACKGROUND\nLimited data exists regarding the clinical and functional outcomes following primary total shoulder arthroplasty (TSA) in obese patients. The purpose of this study is to determine the effects of obesity on the clinical and functional outcomes following primary anatomic (aTSA) and reverse total shoulder arthroplasty (rTSA) in a large patient population with mid-term follow-up.\n\n\nMETHODS\nPatients in a multi-institutional shoulder registry receiving either a primary aTSA (n=1520) or rTSA (n=2054) from 2004 to 2018 with a minimum follow-up of 2 years were studied. All patients received the same platform shoulder prosthesis. Study groups were assigned based on implant type (anatomic or reverse), and further stratification was based on patient BMI, with obese patients having a BMI ≥ 30 kg/m2 and non-obese patients with a BMI <30 kg/m2. Patients were evaluated and scored preoperatively and at latest follow-up using five scoring metrics and range of motion (ROM).\n\n\nRESULTS\nMean follow-up was 5 years (range, 2-14 years). 41% of aTSA and 35% of rTSA were obese. Significant postoperative improvements in VAS pain scores, ROM, and all 5 scoring metrics occurred in both obese and non-obese patients (P<0.05). Obese patients in both groups reported higher preoperative and postoperative visual analog scale (VAS) pain scores and less preoperative and postoperative ROM compared to non-obese patients. Compared to non-obese patients, obese patients receiving an aTSA reported significantly worse postoperative SST, Constant, ASES, UCLA, and SPADI scores compared to non-obese patients, and those receiving rTSA reported significantly worse ASES and SPADI scores (all P<0.05). However, these differences did not exceed the minimal clinical important difference (MCID) or substantial clinical benefit (SCB) criteria. Radiographic analysis showed that in rTSA, obese patients had significantly less postoperative scapular notching and a lower scapular notching grade when compared to non-obese patients (P<0.05).\n\n\nDISCUSSION\nBoth non-obese and obese patients can expect clinically significant improvements in pain, motion and functional outcome scores following both aTSA and rTSA. Obese patients reported significantly more postoperative pain, lower outcome scores and less ROM compared to non-obese patients for both aTSA and rTSA at a mean follow-up of 5 years. However, statistically significant differences were not found to be clinically significant with respect to established MCID and SCB criteria. Therefore, obese and non-obese patients experience similar clinical outcomes following TSA, regardless of BMI. However, obese patients have more comorbidities, greater intraoperative blood loss and less scapular notching compared to non-obese patients.