Anatomic proximity of the peroneal nerve to the posterolateral corner of the knee determined by MR imaging.

Abstract

The pie crusting technique has been extensively used to release the lateral soft tissue in total knee arthroplasty. However, it may place the peroneal nerve at direct injury risk when performed in a valgus knee. The aim of this study was to determine the anatomic proximity of the peroneal nerve to the posterolateral corner of the knee. One hundred knees were measured on axial MR images for the proximity of peroneal nerve to the closest edge of the inner surface of joint capsule or the posterolateral corner of proximal tibia at the level of the joint line and the level of the tibial cut respectively. The distance between the peroneal nerve and the closest edge of the inner surface of joint capsule at the level of the joint line was 15.0 ± 2.6mm (range, 8.5-22.3mm), and the distance between the peroneal nerve and the posterolateral corner of proximal tibia was 14.0 ± 2.7 mm (range, 8.0-23.2mm). These distances were correlated with the anteroposterior diameter of the soft tissue of the knee, but not correlated with the size of the tibia. These results suggest that it is safe enough providing that the scalpel blade does not pierce more than 8mm deep. However, patients with smaller legs are at greater risk of direct peroneal nerve injury.