Metformin is associated with 90-day decreased risk of death and AKI after shoulder arthroplasty in diabetic patients.

Abstract

Metformin is a widely used antidiabetic medication with emerging evidence suggesting anti-inflammatory effects, reduced musculoskeletal pain, and lower complication rates following joint arthroplasty. However, its impact on outcomes after shoulder arthroplasty remains unclear. The purpose of this study was to evaluate the association between metformin use and postoperative complications in diabetic patients undergoing shoulder arthroplasty, with the hypothesis that metformin users would experience fewer perioperative complications and reduced postoperative analgesic requirements. Using the TriNetX database, diabetic patients undergoing shoulder arthroplasty were identified and stratified into two cohorts based on metformin prescription within one year prior to surgery. 1:1 propensity score matching was performed to balance relevant baseline comorbidities. Ninety-day postoperative medical and surgical complications and 2-year implant-related outcomes were then compared between cohorts, with statistical significance set at p < 0.05. After matching, each cohort consisted of 5,181 patients. Patients prescribed metformin had a significantly decreased 90-day risk of death (0.31% vs 0.66%, p = 0.011) and acute kidney injury (3.05% vs 3.69%, p = 0.027) compared to the control cohort. No significant difference was observed in 90-day infectious complications including prosthetic joint infection (PJI), revision surgery and number of opioid prescriptions. Similarly, at 2 years postoperatively, rates of PJI, loosening, periprosthetic fracture and revision were all comparable between both cohorts. Metformin use was associated with lower 90-day risks of mortality and acute kidney injury in diabetic patients undergoing shoulder arthroplasty, without an increased risk of implant-related complications. These findings support the perioperative safety of metformin and may help inform surgical decision-making and patient counseling. III; retrospective study.