Is regional ankle block needed in conjunction with general anaesthesia for first ray surgery? A randomised controlled trial of ultrasound guided ankle block versus "blind" local infiltration.

BACKGROUND: Regional anaesthesia is commonly utilised for foot and ankle surgery. Debate remains at to the level of regional anaesthesia that is required. The objective of this study was to evaluate whether surgeon-delivered "blind" local anaesthetic infiltration around the first ray (metatarsal block without ultrasound guidance) was as effective as an ultrasound guided ankle block in providing post-operative analgesia after osseous first ray surgery performed under general anaesthetic.

METHODS: 50 patients were recruited to a single surgeon and anaesthetist double-blinded randomised controlled trial at a single-centre. 20mls of 0.5% levobupivacaine was used to perform either an ankle or metatarsal nerve block.

RESULTS: Forty-eight patients completed the study: 25 in the ankle block treatment arm and 23 in the metatarsal block arm. The demographics were comparable between groups. There was no statistical difference in visual analogue pain scores at two (21.3 vs 15.2), six (23.6 vs 20.8) and 24 (42.2 vs 50.4) hours following the procedure between the two groups (metatarsal block vs ankle block). Metatarsal block groups had a faster return of normal sensation (2.3 vs 2.8h) but there was no difference in time to safe mobilisation (2.6 vs 2.8h).

CONCLUSION: This study demonstrates the efficacy and safety of surgeon delivered "blind" metatarsal block is comparable to an ultrasound guided ankle block for first ray surgery performed under general anaesthetic.

LEVEL OF EVIDENCE: 1.