A total of 9 studies with 38,728 patients were included. Overall, medical comorbidities were higher in the BS group compared with the control morbid obesity group before TJA. Our meta-analysis revealed that BS prior to TJA was associated with reduced short-term medical complications, length of stay, and operative time. However, BS did not reduce the short-term risks for superficial wound infection or venous thromboembolism, and the long-term risks for dislocation, periprosthetic infection, periprosthetic fracture, and revision. Subgroup analysis identified a significant reduction in the risk of short-term periprosthetic infection in the BS group after total knee arthroplasty, but not after total hip arthroplasty.