Cutaneous anaesthesia of hip surgery incisions with iliohypogastric and subcostal nerve blockade: A randomised trial

Background Cutaneous nerve blockade may improve analgesia after hip surgery. Anaesthesia after the lateral femoral cutaneous (LFC) nerve block is too distal for complete coverage of most hip surgery incisions, which requires additional anaesthesia of the adjacent, proximal area. The transversalis fascia plane (TFP) block potentially anaesthetises the iliohypogastric and subcostal nerves. The primary aim of the present study was to investigate, if the TFP block provides cutaneous anaesthesia adjacent to the LFC nerve block. Methods Active vs placebo TFP blocks were compared in a paired randomised controlled trial (RCT) in 20 volunteers, who all had bilateral LFC nerve blocks. The day preceding the RCT, the area anaesthetised by a novel selective ultrasound guided subcostal nerve block was identified bilaterally in order to assess the contribution of the subcostal nerve to the area anaesthesia by the TFP block. Results Anaesthesia of the lateral hip region after TFP block was 80%. The cutaneous anaesthesia after active TFP block was in continuity with the LFC nerve block in 65%. Combined TFP and LFC nerve blockade significantly increased the coverage of hip surgery incisions compared to LFC nerve block alone. The success rate of blocking the subcostal nerve was 50% with the TFP block. Conclusion The TFP block anaesthetises the skin proximal to the LFC nerve block by anaesthetising the iliohypogastric and subcostal nerves. TFP block as a supplement to LFC nerve block improves the coverage of the proximal surgical incisions used for hip surgery.