Additional Peripheral Nerve Block to Periarticular Injection Has No Benefit for Patients Undergoing TKA: A Factorial Propensity Score-Matched Analysis Comparing Four Multimodal Analgesic Techniques.

Background: Controversy remains over what and how many analgesic techniques are required as the most effective multimodal pain regimen in total knee arthroplasty (TKA). This study aimed to evaluate the effect of additional analgesic methods combined with periarticular injection (PAI) analgesia for TKA.

Methods: Using retrospective cohort data, patients undergoing TKA with spinal anesthesia and PAI were divided into 4 groups. Group A (control) comprised 66 patients; group B (73 patients) had additional adductor canal block; group C (70 patients) obtained additional femoral nerve block, and group D (73 patients) received additional adductor canal block and intrathecal morphine. Propensity score matching was applied to compare visual analog scale (VAS) for pain intensity, cumulative morphine use (CMU), knee flexion angle, straight leg raise, length of hospital stay, and postoperative nausea and vomiting.

Results: There was no significant difference regarding VAS and morphine use, when either group B or C was compared with group A. Group D had significantly lower VAS than groups A, B, and C during the first 24 hours after surgery and required significantly less CMU than groups A and B. However, the pain score of group D increased afterward, with significantly longer length of hospital stay than groups A and B. There was no difference in straight leg raise among the groups.

Conclusion: Additional peripheral nerve block to PAI provides no benefit for patients undergoing TKA. Adjuvant intrathecal morphine could significantly reduce the VAS and CMU in the acute postoperative period; however, rebound pain with prolonged hospital stays was observed.