Long-Term Outcomes of Femoral Derotation Osteotomy for Individuals With Cerebral Palsy

Study Overview
=================
Brief Summary
-----------------
Excessive anteversion is commonly observed in the cerebral palsy (CP) population. This can be treated by an orthopedic surgery, called femoral derotation osteotomy (FDO), to de-rotate the femur. It is a vital aspect of patient care to understand if the effects of an FDO are maintained long-term. The results of this study will have direct clinical impact by equipping providers with the necessary information to counsel families by providing families the information needed to make the most informed decision possible about this aspect of their child's healthcare.

Detailed Description
-----------------
Excessive anteversion is commonly observed in the CP population. If individuals do not internally rotate their femurs as a compensation for this bony torsion, excessive anteversion decreases the coronal plane moment arm of the hip abductors-a phenomenon often called lever arm dysfunction. Considering that adequate hip abductor strength is a crucial factor for normal walking and many other functional activities, the compensatory mechanism theory hypothesizes that individuals with excessive anteversion will internally rotate their hips to restore the coronal plane moment arms. Excessive internal hip rotation (IHR) is observed in the gait of approximately 50% of individuals with CP. It has been postulated, though, that while IHR may restore hip abductor function, it is cosmetically unappealing and may lead to trips and falls. Therefore, FDOs are considered the standard treatment for correcting excessive anteversion and IHR in individuals with CP. Notably, it is one of the top two orthopedic surgeries performed at Gillette Children's Specialty Healthcare. Among the  4000 individuals with CP who have been seen in the gait lab, almost 1350 individuals (>2200 limbs) have undergone at least one FDO. Short-term ( 12 months postoperative) improvements of transverse plane hip rotation during gait range from only 33% to 94%. Despite FDO's widespread use, long-term outcomes of the procedure have only begun to be studied, with our 2016 study the only one that included a control group. Without a control group, the natural history of bony remodeling or gait adaptations is unknown. However, our prior study is limited by two main factors, 1) all data were extracted from our database retrospectively, so the potential for a large bias exists since outcomes reflect only patients with clinically-initiated gait visits, and 2) outcomes of hip abductor function were only measured by hip rotation (or hip abductor moment during gait, which is only available for individuals who can walk without assistive devices), so the true ability of the hip abductors to generate moment has not been tested. Furthermore, the vast majority of individuals were <18 years old at their long-term visit ( 5 years after their preoperative gait visit), which precedes the reported gait or functional decline more commonly occurring in one's 20s and beyond. Counseling families on the long-term outcomes after an FDO is currently not possible and is necessary for families and health-care providers to make informed decisions. It remains unclear whether individuals who receive an FDO experience long-term beneficial effects on function, activity, and comfort as compared to those who receive other or no treatment for their excessive anteversion and/or IHR. Briefly, anteversion as measured by the trochanteric prominence angle test (TPAT) is the most common method used by clinicians to determine if an FDO is warranted, in addition to anteversion being an important predictor of predicted short-term outcomes after an FDO23. However, data from our lab suggests that there is 10-15° of measurement error associated with this method. As such, our secondary purpose was to compare anteversion as measured by the TPAT to that of a radiographical gold standard, EOS. EOS delivers 4-30 times less radiation to the gonads and lower extremities compared to computed tomography (CT)24, making it very suitable for research purposes. Additionally, accuracy of quantifying femoral anteversion is not compromised versus the current gold standard, CT, with a mean difference of  3° reported.

Official Title
-----------------
Long-Term Outcomes of Femoral Derotation Osteotomy for Individuals With Cerebral Palsy

Conditions
-----------------
Cerebral Palsy, Femoral Derotation Osteotomy, Outcomes

Intervention / Treatment
-----------------
* Diagnostic Test: Motion Analysis
* Diagnostic Test: sterEOS Imaging of Lower Extremities
* Behavioral: Surveys


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Diagnosed with bilateral CP (i.e., hemiplegics excluded) Minimum age of 25 years presently Had a preoperative gait analysis Underwent only 1 external, proximal FDO per side Minimum 5 years since an FDO FDO implants have been removed No prior pelvic osteotomy Able to speak and read English Not pregnant Control group (-FDO): Same as cases, except no FDO Matched to cases at baseline (using a matching algorithm) Exclusion Criteria: none

Ages Eligible for Study
-----------------
Minimum Age: 25 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Cases (+FDO)<br>Patients who underwent an FDO | Diagnostic Test: Motion Analysis<br>* Gait and Motion Analysis, comprised of 3-dimensional kinematics and kinetics, electromyography, energy expenditure, and physical exam (range of motion, strength, spasticity, etc.)<br>Diagnostic Test: sterEOS Imaging of Lower Extremities<br>* Bi-planar imaging of the lower extremities to evaluate femoral anteversion and hip dysplasia and subluxation.<br>Behavioral: Surveys<br>* 9 surveys assessing function, activity, participation, pain, quality of life, and treatment history.<br>|
| Controls (-FDO)<br>Same as cases but did not undergo an FDO | Diagnostic Test: Motion Analysis<br>* Gait and Motion Analysis, comprised of 3-dimensional kinematics and kinetics, electromyography, energy expenditure, and physical exam (range of motion, strength, spasticity, etc.)<br>Diagnostic Test: sterEOS Imaging of Lower Extremities<br>* Bi-planar imaging of the lower extremities to evaluate femoral anteversion and hip dysplasia and subluxation.<br>Behavioral: Surveys<br>* 9 surveys assessing function, activity, participation, pain, quality of life, and treatment history.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Gait and Motion Analysis | Compare gait kinematics and kinetics across groups | long-term research visit (on average,  10 years post-baseline) | 
| sterEOS imaging | femoral anteversion determined by 3-D reconstruction of bi-planar sterEOS imaging | long-term research visit (on average,  10 years post-baseline) | 
| Change in Gait and Motion Analysis | Compare change in gait kinematics and kinetics within groups | baseline (qualifying exam, pre-FDO or gait analysis at which controls matched cases) compared to long-term research visit (on average,  10 years post-baseline) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| sterEOS imaging | Assess hip dysplasia and/or subluxation in qualifying limb across groups | long-term research visit (on average,  10 years post-baseline) | 
| Number of hip abduction repetitions | Assess hip function across groups | long-term research visit (on average,  10 years post-baseline) | 
| Seconds to complete Timed Up and Go | Assess function across groups | long-term research visit (on average,  10 years post-baseline) | 
| Quality of Life as assessed by WHOQOL-bref | self-reported survey | compare scores across groups at long-term research visit (on average,  10 years post-baseline) | 
| Pain as assessed by the Brief Pain Inventory | self-reported survey | compare scores across groups at long-term research visit (on average,  10 years post-baseline) | 
| Fear of Falling as assessed by Falls Efficacy Scale-International | self-reported survey | compare scores across groups at long-term research visit (on average,  10 years post-baseline) | 
| Hip Function as assessed by Harris Hip Function | self-reported survey | compare scores across groups at long-term research visit (on average,  10 years post-baseline) | 
| General Function as assessed by Functional Assessment Questionnaire | self-reported survey | compare scores across groups at long-term research visit (on average,  10 years post-baseline) | 
| Walking Function as assessed by Function Mobility Scale | self-reported survey | compare scores across groups at long-term research visit (on average,  10 years post-baseline) | 
| Participation as assessed by Child/Adolescent Frequency of Participation Questionnaire | self-reported survey | compare scores across groups at long-term research visit (on average,  10 years post-baseline) | 
| Satisfaction with Life as assessed by Deiner Satisfaction with Life Scale | self-reported survey | compare scores across groups at long-term research visit (on average,  10 years post-baseline) |