Controlling Femoral Extension and Derotation Osteotomy In Cerebral Palsy With Electromagnetic Tracking

Overview

The study is designed to evaluate the use of electromagnetic tracking in multi plane femoral osteotomies, namely extension derotation osteotomies. The goal is to raise the precision of the surgical procedure in order to improve the outcome in short- and long term. All patients are examined with an instrumented 3D gait analysis pre- and one year postoperatively. The electromagnetic tracking system is evaluated against a base line CT or MRI scan serving as reference standard pre- and postoperatively.

Internal rotation crouch gait is a common deformity in patients with spastic diplegia. The treatment includes soft tissue and bony correction. Especially the bony procedures e.g. femoral extension and derotation osteotomies have proven to be effective both in short term and long term evaluation. Nonetheless there is still a relevant number of patients that suffer from over- or under-correction and recurrence over time. The reasons are diverse and include false measurement of the amount of extension and/or derotation in OR. The study now evaluates electromagnetic tracking for femoral extension and derotation to improve these results. The patients are recruited from the outpatients department and included if they meet the criteria. A baseline rotational CT or MRI scan and a 3D gait analysis are performed preoperatively. The patients are randomized into a electromagnetic tracking group or a classical goniometer group. The extension and derotation are measured with the EMT system or with a classic Moeltgen goniometer in the OR. Goal is to achieve the planned amounts of extension and derotation more accurately. The surgical procedure follows standard rules and does not need alterations because of the study. After the operation a second CT or MRI scan is performed and the extension and derotation are precisely evaluated by two raters and later compared to the results of the intraoperative electromagnetic tracking system. One year postoperative a second 3D gait analysis is performed to measure and compare the functional and dynamic outcome.