Background: Lesion of the lateral femoral cutaneous nerve (LFCN) represents the main complication during minimally invasive anterior approach dissection to the hip joint. The aim of this anatomical study was to describe the different presentation features of the LFCN at the thigh and particularly to determine the potential location of damage during minimally invasive anterior approach for total hip replacement.
Methods: The LFCN was dissected bilaterally at the thigh under the inguinal ligament in 17 formalin-preserved cadavers. Branching patterns of the nerve were recorded and distances from the LFCN to the anterior superior iliac spine (ASIS) and the anterior margin of the tensor fascia lata (TFL) were measured to clarify skin incision positioning during minimally invasive anterior approach for total hip replacement.
Results: The LFCN divided proximal to the inguinal ligament in 13 cases and distal to it in 21 cases. In the distal group the mean distance from the ASIS to the nerve division was 34.5 mm (10-72 mm). The gluteal branch crossed the anterior margin of the TFL 44.5 mm (24-92 mm) distally to the ASIS. In 18 cases the femoral branch did not cross the TFL and was located in the intermuscular space between TFL and sartorius. In the remaining 16 cases, this branch crossed the anterior margin of the TFL 46 mm (27-92 mm) distally to the ASIS. During minimally invasive anterior approach along the anterior border of the TFL, the LFCN was found to be potentially at risk between 27 and 92 mm below the ASIS. We used those informations to describe a map of "danger zones" for the LFCN or its two main branches.
Conclusion: According to this study, numerous anatomical variations of the LFCN at the thigh should be considered when performing anterior approach to the hip joint. Different mechanisms of injury during surgery should be considered especially during minimally invasive total hip replacement, such as section of the gluteal or the femoral branch where it crosses the anterior margin of the TFL or stretching of the femoral branch due to retractors positioned into the intermuscular space between sartorius and TFL. According to the map of "danger zones" reported, the author policy consists of positioning the skin incision as lateral and distal to the ASIS as possible.