Anatomy of the Sural Nerve and Its Relation to the Achilles Tendon by Ultrasound Examination

Sural nerve injury is a relatively common complication after surgery on the Achilles tendon. Studies to determine the course of the sural nerve have been performed on cadaveric specimens. The purpose of this cross-sectional study was to use ultrasound to determine the relations of the sural nerve in a healthy population. The authors performed ultrasound examination of the posterior triangle of the ankle and Achilles tendon to determine the course of the sural nerve relative to the Achilles tendon in healthy participants. The mean distance between the nerve and the tendon was 21.48, 11.47, 5.8, and 0.81 mm lateral to the Achilles tendon as measured at the insertion and 4, 8, and 11 cm proximally, respectively. Male participants tended to have a nerve that was initially more lateral to the Achilles insertion compared with women. The distance between the sural nerve and the Achilles tendon was found to be lower in older participants, with the nerve passing significantly closer to the tendon at all levels (P<.01). Three anatomical variants were reported, with the nerve crossing the lateral border of the Achilles low or high or with multiple branches yet to converge. The course of the sural nerve can be visualized and plotted relative to the Achilles tendon using ultrasound examination in healthy participants. Older patients may be at an increased risk of iatrogenic nerve injury because the nerve courses closer to the Achilles tendon than that in young patients. Intraoperative ultrasound examination may be a useful modality to prevent sural nerve injury during Achilles tendon surgery.