Effects of Body Mass Index on Outcomes in Total Shoulder Arthroplasty

Body Mass Index (BMI) is one of the metrics used to assess overall health and has been implicated in having predictive value in many aspects of health, including outcomes after shoulder replacement surgery. Outcome data from a multi- institutional database with an average follow-up period of 39.8 months (minimum 24-months) demonstrated that all patients, regardless of BMI, improved significantly after treatment with anatomic total shoulder arthroplasty (aTSA) or reverse total shoulder arthroplasty (rTSA). Improvements in outcomes were stratified and compared based upon BMI in three groups: less than 25, 25 to 35, and greater than 35. Comparing these measures demonstrated that aTSA patients with higher BMI were generally associated with lower functional postoperative outcome metric scores than aTSA patients with lower BMI, though the preoperative to postoperative gains were generally equivalent regardless of BMI. Interestingly, postoperative outcome metric scores with rTSA patients were equivalent regardless of BMI as were the pre-to-postoperative gains. Additionally, differences in the magnitude of pre-to-postoperative improvement of range of motion (ROM) measurements between patients of BMI less than 25 and BMI greater than 35 were noted for forward flexion, internal rotation, and active and passive external rotation. The actual clinical significance of these differences is unknown. Finally, patients with lower BMI appeared to have a higher incidence of low-grade scapular notching.