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 a periarticular injection (PAI) analgesia for TKA.
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 (ACB); Group C (70 patients) obtained additional femoral nerve block (FNB); and Group D (73 patients) received additional ACB and intrathecal morphine (ITM). Propensity score matching was applied to compare visual analogue scale (VAS) for pain intensity, cumulative morphine use (CMU), knee flexion angle, straight leg raise (SLR), length of hospital stay (LHS), and postoperative nausea and vomiting (PONV).
There was no significant difference regarding VAS and morphine use, when either group B or C was compared to group A. Group D had significantly lower VAS than group A, B and C during the first 24 hours after surgery, and required significantly less CMU than group A and B. However, the pain score of group D increased afterward, with significantly longer LHS than group A and B. There was no difference in SLR among the groups.
Additional peripheral nerve block to PAI provides no benefit for TKA patients. Adjuvant ITM could significantly reduce the VAS and CMU in the acute postoperative period, however, rebound pain with prolonged hospital stays was observed.

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