Hypobaric unilateral spinal anesthesia with multimodal analgesia enhances recovery in total knee arthroplasty

BACKGROUND: Total knee arthroplasty (TKA) is an effective treatment for end‐stage knee osteoarthritis, but postoperative pain and delayed recovery remain challenges. This study aimed to evaluate the effects of hypobaric unilateral fine‐needle spinal anesthesia combined with multimodal analgesia (MMA) on postoperative recovery in TKA patients. METHODS: A randomized controlled triple‐blind trial enrolled 118 patients scheduled for TKA between January 2022 and June 2023. Patients were divided into three groups: hypobaric fine‐needle spinal anesthesia (Group A, n=40), isobaric fine‐needle spinal anesthesia (Group B, n=39), and hypobaric spinal‐epidural combined anesthesia (Group C, n=39). Outcomes included puncture success rates, puncture time, maximum active knee flexion angle, breakthrough analgesia frequency, statistical test and complications. RESULTS: No significant differences were observed in puncture success rates. However, Group C had a significantly longer puncture time than Groups A and B. Group B showed a lower maximum active knee flexion angle on postoperative day 1 compared to Groups A and C. Group C had a higher incidence of low back pain and headache within 7 days. Postoperative pain scores (NRS) were significantly lower in Group A at all time points. CONCLUSIONS: Hypobaric fine‐needle spinal anesthesia (Group A) demonstrated superior performance in puncture time, postoperative mobility, and complication rates, making it a preferred anesthetic strategy for TKA. TRIAL REGISTRATION: Chinese Clinical Trial Registry (ChiCTR2500100428). Registered on 9 April 2025. Retrospectively registered.