CT Analysis of the Posteromedial Neurovascular Bundle in Patients with End Stage Ankle Arthritis for Planning of Total Ankle Replacement Surgery

Abstract

Category: Ankle Arthritis; Ankle Introduction/Purpose: Aim of this study is to identify reliable anatomical landmarks of the posterior tibial neurovascular bundle during Total Ankle Replacement (TAR) to minimise the risk of iatrogenic injury. Secondary aim is to identify if there is associated translation of the bundle when anterior translation of the talus is present. Methods: A radiological landmark protocol was devised to create a consistent method for measuring the relations of the bundle to the tibia, talus and medial gutter line when measured at levels mimicking those of resection undertaken in TAR. Analysis between patients with and without anterior subluxation was undertaken. Results: Total of 42 ankles were reviewed with 38% patient having anterior translation of the talus. At the tibiotalar joint, the bundle lies less than 5mm lateral to the medial gutter line and less than 8mm posterior to the posterior tibia. The same measurements at 10mm superior to the tibiotalar joint are less than 8mm and less than 6.5mm respectively. At 5mm distal to the dome of the talus, the bundle is less than 4mm lateral to the medial gutter line and between 8.4-16.0mm posterior to the posterior talus. The bundle to posterior tibia distance does not increase in the sagittal plane for patients with anterior subluxation of the talus. Conclusion: This study provides relevant guidance for surgeons to use intraoperatively when undertaking tibial and talus resections in TAR to identify their relations to the vulnerable neurovascular structures. The measurements of this study indicate for the first time that there is not an increased risk of iatrogenic injury during bone resection at the tibia in patients with anterior subluxation of the talus.