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Subject-specific modelling of lower limb muscles in children with cerebral palsy
K Oberhofer1, N S Stott, K Mithraratne
1Auckland Bioengineering Institute, University of Auckland, 70 Symonds Street, Auckland, New Zealand. k.oberhofer@auckland.ac.nz
Insights
Children with cerebral palsy (CP) show significantly smaller lower limb muscle volumes and lengths compared to typically developing children, indicating muscle atrophy. Further research is needed to understand the causes and improve management strategies for CP.
Area of Science:
- Biomedical Engineering
- Orthopedics
- Pediatrics
Background:
- Cerebral palsy (CP) significantly alters spastic muscle architecture, particularly in lower limbs.
- Limited understanding exists regarding structural muscle changes beyond the gastrocnemius in children with CP.
Purpose of the Study:
- To compare lower limb muscle lengths and volumes between children with CP and typically developing children.
- To investigate structural muscle alterations in ambulatory children with CP using advanced imaging and modeling.
Main Methods:
- Magnetic Resonance Imaging (MRI) was used to acquire lower limb scans from children with spastic hemiplegia/diplegia CP and a control group.
- Subject-specific muscle models were created using Face Fitting technique from MRI data.
- Normalized muscle volumes and lengths were calculated and compared between groups.
Main Results:
- Children with CP exhibited smaller normalized muscle volumes (22-26%) in calf, hamstring, and quadriceps muscles compared to controls.
- Statistically significant reductions in hamstring and quadriceps volumes were observed (P=0.036, P=0.038).
- Normalized muscle lengths were significantly shorter in children with CP (P<0.05), with exceptions for soleus and biceps femoris.
Conclusions:
- Ambulatory children with CP demonstrate significantly altered lower limb muscles, suggesting generalized muscle atrophy and a potential mechanical deficit.
- Investigating the root causes of muscle atrophy is crucial for refining management and treatment approaches for pediatric cerebral palsy.
Background:
Recent studies suggest that the architecture of spastic muscles in children with cerebral palsy is considerably altered; however, only little is known about the structural changes that occur other than in the gastrocnemius muscle. In the present study, Magnetic Resonance Imaging (MRI) and subject-specific modelling techniques were used to compare the lengths and volumes of six lower limb muscles between children with cerebral palsy and typically developing children.
Methods:
MRI scans of the lower limbs of two children with spastic hemiplegia cerebral palsy, four children with spastic diplegia cerebral palsy (mean age 9.6 years) and a group of typically developing children (mean age 10.2 years) were acquired. Subject-specific models of six lower limb muscles were developed from the MRI data using a technique called Face Fitting. Muscle volumes and muscle lengths were derived from the models and normalised to body mass and segmental lengths, respectively.
Findings:
Normalised muscle volumes in the children with cerebral palsy were smaller than in the control group with the difference being 22% in the calf muscles, 26% in the hamstrings and 22% in the quadriceps, respectively. Only the differences in the hamstrings and the quadriceps were statistically significant (P=0.036, P=0.038). Normalised muscle lengths in the children with cerebral palsy were significantly shorter (P<0.05), except for soleus and biceps femoris. No significant relationship was found between normalised lengths and volumes of any muscle in either group.
Interpretation:
The present results show that lower limb muscles in ambulatory children with cerebral palsy are significantly altered, suggesting an overall mechanical deficit due to predominant muscle atrophy. Further investigations of the underlying causes of the muscle atrophy are required to better define management and treatment strategies for children with cerebral palsy.
