A novel technique for conduction studies of the infrapatellar nerve.

OBJECTIVE: To introduce a noninvasive method for electrodiagnostic evaluation of the infrapatellar nerve (IPN). DESIGN: A prospective cohort study. SETTING: Electrodiagnostic laboratory, rehabilitation department, Hadassah University Hospital. PARTICIPANTS: A total of 38 healthy adults; 57 asymptomatic limbs were studied. METHODS: Sensory nerve action potential of the IPN was recorded with surface electrodes placed 2.5 cm below the distal pole of the patella and 2 cm medially from the medial border of the patellar tendon. Transcutaneous antidromic electrical stimulation of IPN was applied above the medial femoral condyle and 8-10 cm proximally from the active surface electrode. RESULTS: The sensory nerve action potential mean (n = 38) onset latency was 1.69 ± 0.32 ms. Peak latency was 2.36 ± 0.47 ms, and amplitude was 6.96 ± 3.68 µV. CONCLUSIONS: This article describes a novel and simple technique for IPN conduction electrodiagnostic examination. The method used provides a new tool to evaluate IPN injury in reference to anterior or inferior knee pain with associated sensory deficit.