Forty-six patients undergoing bilateral THA were randomized to receive spinal anesthesia (SA) with monitored anesthesia care (n=23) or general anesthesia (GA) (n=23). The primary outcome was change in handgrip strength on postoperative day 1 relative to baseline. Secondary outcomes included maximal inspiratory pressure (MIP), EQ-5D-5L health status, and biomarkers of the stress response (ACTH, cortisol, IL-6), measured up to 28 days. Overall, the results revealed smaller day-1 handgrip decline with SA versus GA and better respiratory muscle performance, alongside lower immediate postoperative Adrenocorticotropic hormone (ACTH), cortisol, and IL-6 with SA. In short, SA preserved early peripheral and respiratory muscle strength and blunted early stress signaling without long-term between-group differences at 28 days.