[Is a blockade of the lateral cutaneous nerve of the thigh an alternative to the classical femoral nerve blockade for knee joint arthroscopy? A randomised controlled study].

Background. Gaps in the distribution area of the lateral femoral cutaneous nerve (LF-CN) are assumed to be the reason for pain caused by a thigh tourniquet when perforing a fermoral nerve (FN) block according to Winnie. The aim of the study was to evaluate of a direct single blockade of the LFCN in patients undergoing knee surgery resulted in a better tolerance to the tourniquet with equally good analgesic quality during surgery. Methods. A total of 40 patients undergoing knee arthroscopy received a proximal blockade of the sciatic nerve and randomly either an FN or an LFCN block. Practicability, onset time, quality of sensory and motor block, and clinical effectiveness during tourniqued and surgery were assessed. Results. Stimulation time was significantly longer in the LFCN than in the FN group. Quality of sensory and motor block was worse in the LFCN than the NF group. Of the LFCN patients 65% indicated trouble-some paraesthesia or pain when a tourniquet was placed, compared to 35% of the FN patients. Of the LFCN patients 50% had pain during cutaneous incision, compared to none of the FN group. During the course of surgery, 70% of the LFCN patients needed supplemental systemic analgesia, but this was required by only 30% of the FN group. Conclusion. An LFCN block is not a suitable alternative to an FN block for regional anaesthesia. For patients with contraindications for an FN block according to Winnie (e.g. vessel surgery in the groin) other more effective methods are available.