Long-Term Outcomes of Femoral Derotation Osteotomy for Individuals With Cerebral Palsy
| Status: | Enrolling by invitation |
|---|---|
| Conditions: | Neurology, Neurology |
| Therapuetic Areas: | Neurology |
| Healthy: | No |
| Age Range: | 25 - Any |
| Updated: | 7/19/2018 |
| Start Date: | September 12, 2017 |
| End Date: | March 2019 |
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.
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.
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.
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.
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:
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