持続大腿三角ブロックに併施したIPACKブロックと選択的脛骨神経ブロックの人工膝関節全置換術における鎮痛効果：ランダム化比較試験

Comparison of IPACK Block and Selective Tibial Nerve Block Combined with Continuous Femoral Triangle Block for Analgesia after Total Knee Arthroplasty：A Randomized Control Trial

要旨

　人工膝関節全置換術を施行した60名に対し，鎮痛手段として持続大腿神経ブロックに加えて，IPACK（infiltration between the popliteal artery and capsule of the knee）ブロックまたは選択的脛骨神経ブロックを施行した2群に分けて鎮痛効果を比較検討した。

　両群とも，患者自己調節鎮痛（patient-controlled analgesia：PCA）使用回数や補助鎮痛使用回数に有意差を認めなかったが，術後1日目の視覚アナログスケール（visual analogue scale：VAS）スコアがIPACK群で有意に低値であった。また，選択的脛骨神経ブロックを受けた2症例で術直後に腓骨神経麻痺を認めた。

　人工膝関節全置換術における坐骨神経領域の鎮痛手段としては，IPACKブロックがより適している可能性が示された。

　Background：This study aimed to evaluate the analgesic efficacy of infiltration between the popliteal artery and capsule of the knee（IPACK）block and selective tibial nerve block（STNB）, combined with continuous femoral triangle block（FTB）in patients undergoing total knee arthroplasty（TKA）.

　Methods：The study was conducted from October 20, 2018 to May 31, 2021 including a total of 60 patients undergoing unilateral TKA. Of these 60 patients, 30 received continuous FTB＋IPACK block（Group I）, whereas the other 30 received continuous FTB＋STNB（Group S）. All patients were evaluated using the visual analogue scale（VAS）score for pain recorded at 6 h and 12 h after surgery, postoperative day（POD）1, and POD 2. The second outcome measures assessed were ankle dorsiflexion after surgery, use of patient-controlled analgesia or adjuvant analgesics, and the range of movement.

　Results：VAS score showed lower values（P＜0.05）in group I than in group S on POD 1. Two patients（6.7％）could not do ankle dorsiflexion in group S, while all patients could do it in group I. There were no significant differences between the two groups regarding other outcomes.

　Conclusions：IPACK block is effective as postoperative analgesia for TKA compared to STNB.