Continuous adductor-canal-blockade for adjuvant post-operative analgesia after major knee surgery: preliminary results

TLDR

The authors aimed to assess whether a continuous adductor‑canal block could provide effective postoperative analgesia after total knee arthroplasty. They performed a systematic literature review, evaluated pain and opioid use in eight patients receiving continuous adductor‑canal blockade, and used cross‑sectional MR imaging to confirm local anaesthetic spread. The pilot study showed that 48 h of continuous blockade after TKA was associated with low pain scores, reduced morphine consumption, and MR imaging confirmed the anesthetic reached the distal canal, suggesting it may be a valuable adjunct analgesic strategy.

Abstract

Because both the saphenous nerve and in part the obturator nerve are traversing the adductor canal of the thigh, we hypothesised that repeated administration of a local anaesthetic (LA) into this aponeurotic space could be a useful option for post-operative analgesia after knee replacement surgery. A systematic search of the literature pertinent to the blockade of the saphenous and/or obturator nerves for pain relief after knee surgery was conducted. Further, pain and opioid requirements were evaluated in eight patients receiving a continuous blockade of the saphenous and obturator nerve (adductor-canal-blockade) after total knee arthroplasty (TKA). Finally, we performed cross-sectional MR scans of the adductor canal after injection of ropivacaine 30ml in one patient. The systematic literature search revealed only one controlled study, where selective blockade of the saphenous nerve was investigated for the purpose of clinical pain relief after knee arthroscopy. We located no studies reporting on saphenous and/or obturator nerve block for pain relief after TKA. Preliminary findings in eight patients demonstrated that a continuous adductor-canal-blockade for 48h after TKA was associated with low mean pain scores at rest and low mean requirements for supplemental morphine. MR scans in one patient demonstrated that 30ml of LA filled the adductor canal, including the distal part, where the posterior branch of the obturator nerve joins the vessels and the saphenous nerve. Continuous adductor-canal-blockade may be a valuable adjunct for post-operative analgesia after major knee surgery. These preliminary results should be confirmed in randomised, controlled trials.