Intra-Articular Magnesium Sulfate and Bupivacaine Versus Saline After Arthroscopic Rotator Cuff Repair: A Prospective Comparative Study

Background: Postoperative pain following arthroscopic rotator cuff repair can delay rehabilitation and impair function-al recovery. Intra-articular injections of magnesium sulfate, an N-methyl-D- aspartate (NMDA) receptor antagonist, in com-bination with bupivacaine may provide prolonged analgesia compared with placebo. Aim of Study: To compare the analgesic duration, func-tional outcome, and pain control provided by intra-articular magnesium sulfate plus bupivacaine versus saline following arthroscopic rotator cuff repair. Patients and Methods: This prospective comparative study included 52 patients who underwent arthroscopic rotator cuff repair between October 1, 2023, and October 1, 2024, at Helwan University Hospital. Patients were equally allocated into two groups: - Group A: At wound closure, patients received an intra-ar-ticular glenohumeral injection of 10mL 0.25% bupivacaine combined with magnesium sulfate 1,000mg (100mg/mL; 10mL), for a total volume of 20mL, administered under ar-throscopic visualization. - Group B: Intra-articular saline (volume matched). The primary outcome was the time to the first postopera-tive analgesic request, categorized as <12 hours, 12–24 hours, or >24 hours. Secondary outcomes included pain intensity measured by visual analog scale (VAS) and functional out-come assessed by the University of California, Los Angeles (UCLA) shoulder score. VAS and UCLA were recorded pre-operatively and at 6-month follow-up. Statistical analysis was performed using paired t-test, Mann-Whitney test, and the Chi-square test, with p<0.05 considered statistically significant. Results: The distribution of analgesia duration differed significantly between groups (p=0.000245), with a higher pro-portion of patients in the magnesium sulfate + bupivacaine group experiencing analgesia lasting >24 hours compared with the saline group. At 6 months, VAS scores and UCLA scores significantly higher in both groups than preoperative. The magnesium sulfate + bupivacaine group compared with the saline group showed faster recovery and return to work. Conclusion: Intra-articular magnesium sulfate combined with bupivacaine significantly prolongs postoperative analge-sia and improves early pain control and functional outcome compared with saline after arthroscopic rotator cuff repair.