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

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

Official Title
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Controlling Femoral Extension and Derotation Osteotomy In Cerebral Palsy With Electromagnetic Tracking - A Randomized Controlled Trial

Conditions
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Interal Rotation Gait, Crouch Gait, Cerebral Palsy, Malalignment

Intervention / Treatment
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* Procedure: Femoral Extension and Derotation Osteotomy (ExtFDO)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Cerebral palsy GMFCS level I-III Functionally disturbing internal rotation gait Indication for femoral derotation osteotomy Exclusion Criteria: No capacity of consent Inability to perform all needed types examinations Minors: Inability of getting a MRI rotational scan (i.e. pacemaker)

Ages Eligible for Study
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Minimum Age: 6 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Randomization into two study arms: Classic control of extension and derotation using a Moeltgen goniometer intraoperatively Control of extension and derotation using an electromagnetic tracking device intraoperatively
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Goniometer<br>Extension FDO: classic procedure with goniometer controlled extension and derotation | Procedure: Femoral Extension and Derotation Osteotomy (ExtFDO)<br>* Correction of malrotation of the femoral bone and flexed knee gait by osteotomy, derotation and osteosynthesis<br>|
| Experimental: EMT<br>Extension FDO: procedure with electromagnetic tracking (EMT) controlling extension and derotation | Procedure: Femoral Extension and Derotation Osteotomy (ExtFDO)<br>* Correction of malrotation of the femoral bone and flexed knee gait by osteotomy, derotation and osteosynthesis<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Comparing the mean hip rotation between the groups | Measuring the functional outcome with the mean hip rotation comparing pre- and postoperative gait analysis of the patients. | One year after surgery | 
| Comparing the minimum knee flexion in stance phase between the groups | Measuring the functional outcome with the minimum knee flexion in stance phase comparing pre- and postoperative gait analysis of the patients. | One year after surgery | 
| Comparing the anterior pelvic tilt between the groups | Measuring the functional outcome with the anterior pelvic tilt comparing pre- and postoperative gait analysis of the patients. | One year after surgery | 
| Comparing the pelvic rotation between the groups | Measuring the functional outcome with the pelvic rotation comparing pre- and postoperative gait analysis of the patients. | One year after surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Comparing the bony derotation between the groups | Measuring the actual amount of derotation in degrees in a postoperative CT or MRI scan. | Shortly after surgery (not ore than 3 month) and again one year after surgery | 
| Comparing the bony extension between the groups | Measuring the actual amount of extension in degrees in a postoperative CT or MRI scan. | Shortly after surgery (not ore than 3 month) and again one year after surgery | 
| Evaluate the accuracy of bony derotation between the groups | Comparing the the planned amount of derotation in degrees with the intraoperative electromagnetic tracking values and the postoperative rotational MRI values in degrees to evaluate the accuracy of implementing a certain amount of bony derotation. | Shortly after surgery (not ore than 3 month) and again one year after surgery | 
| Evaluate the accuracy of bony extension between the groups | Comparing the the planned amount of extension in degrees with the intraoperative electromagnetic tracking values and the postoperative rotational MRI values in degrees to evaluate the accuracy of implementing a certain amount of bony extension. | Shortly after surgery (not ore than 3 month) and again one year after surgery |