Association of Serratus Anterior and Pectoserratus Plane Blocks with Persistent Shoulder Dysfunction after Modified Radical Mastectomy in Older Breast Cancer Patients.

BACKGROUND:Postoperative shoulder dysfunction is a frequent and disabling complication following modified radical mastectomy (MRM), particularly in geriatric patients. Although pectoserratus plane block (PSPB) and serratus anterior plane blocks are well established for acute postoperative analgesia, their impact on long-term shoulder function remains unclear. METHODS:This retrospective cohort study included 147 women aged ≥65 years who underwent MRM for breast cancer. Patients who received PSPB combined with serratus anterior plane blocks formed the block group (n = 78), while those managed without regional anesthesia formed the control group (n = 69). Shoulder function at 6 months was assessed using Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) and Constant-Murley scores, and active range of motion. Secondary outcomes included persistent shoulder stiffness and chronic pain interference assessed by the Brief Pain Inventory (BPI) interference subscale. RESULTS:At 6 months, the block group demonstrated significantly better shoulder function with lower QuickDASH scores (7.8 ± 9.3 vs. 18.7 ± 8.8, p < 0.001) and flexion (138.9° ± 16.8 vs. 133.9° ± 17.1, p = 0.027), and abduction (131.1° ± 19.1 vs. 126.9° ± 18.1, p = 0.049) were also improved and persistent shoulder stiffness was significantly less frequent (42.3% vs. 69.6%, p = 0.002). Multivariable logistic regression analyses identified regional blockade as an independent protective factor against persistent stiffness (odds ratio 0.29, 95% CI 0.14-0.59, p = 0.001). Constant-Murley scores at 6 months did not differ significantly between groups (83.4 ± 6.9 vs. 84.0 ± 6.4, p = 0.682). CONCLUSION:Routine use of ultrasound-guided PSPB and serratus anterior plane blocks was associated with lower rates of long-term shoulder dysfunction after MRM in geriatric breast cancer patients. These findings suggest a potential association between regional anesthesia and improved postoperative functional recovery; however, causality cannot be established due to the retrospective design.