Relation of the Sural Nerve and Medial Neurovascular Bundle With the Achilles Tendon in Children With Cerebral Palsy Treated by Percutaneous Achilles Tendon Lengthening

Background: One of the most common treatment options for a short Achilles tendon (AT) in cerebral palsy is percutaneous AT lengthening using 3 hemisections. Because of proximity of neurovascular structures around the tendon, iatrogenic injury to them have been a concern about this technique. The sural nerve (SN) is under risk of injury at the site of the lateral incomplete cut, especially if it is done proximally. The medial neurovascular bundle is under injury risk at medial cuts. The aim of the article was to study the anatomical relations of the SN and medial neurovascular bundle to the AT, and define dangerous levels for injury with the help of magnetic resonance imaging (MRI). Methods: Patients operated for percutaneous Achilles lengthening were called for MRI investigation of the SN and medial neruvascular bundle integrity and their anatomical relation with the AT. The distance of 5 mm was taken as the threshold for increased risk of injury. Measurements were done on MRI at each cm from the insertion of the tendon on both medial and lateral sides, and at the level of the middle cut. Results: Thirty ankles operated and followed at least 1 year were included to the study. On the medial side, the tibial nerve, and the posterior tibial artery lied more than 5 mm away from the tendon at all levels in all patient. On the lateral side, the first 4 cm were relatively safe for the middle lateral cut, while increased risk of SN damage was detected in more proximal levels. Overall, 6 of 30 ankles had radiographically detectable SN injury. Conclusions: The first 4 cm of the AT on the lateral side was detected to be safe for the middle lateral directed cut, while whole tendon length were found to be safe for the first and the third cuts of the percutaneous Achilles lengthening surgery using 3 hemisections in children with cerebral palsy.