Reference Value for Infrapatellar Branch of Saphenous Nerve Conduction Study: Cadaveric and Clinical Study

OBJECTIVE: To determine the optimal stimulation and recording site for infrapatellar branch of saphenous nerve (IPBSN) conduction studies by a cadaveric study, and to confirm that obtained location is practically applicable to healthy adults. METHODS: Twelve lower limbs from six cadavers were studied. We defined the optimal stimulation site as the point IPBSN exits the sartorius muscle and the distance or ratio were measured on the X- and Y-axis based on the line connecting the medial and lateral poles of the patella. We defined the optimal recording site as the point where the terminal branch met the line connecting inferior pole of patella and tibial tuberosity, and measured the distance from the inferior pole. Also, nerve conduction studies were performed with obtained location in healthy adults. RESULTS: In optimal stimulation site, the mean value of X-coordinate was 55.50±6.10 mm, and the ratio of the Y-coordinate to the thigh length was 25.53%±5.40%. The optimal recording site was located 15.92±1.83 mm below the inferior pole of patella. In our sensory nerve conduction studies through this location, mean peak latency was 4.11±0.30 ms and mean amplitude was 4.16±1.49 µV. CONCLUSION: The optimal stimulation site was located 5.0–6.0 cm medial to medial pole of the patella and 25% of thigh length proximal to the X-axis. The optimal recording site was located 1.5–2.0 cm below inferior pole of patella. We have also confirmed that this location is clinically applicable.