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Author Spotlight: An Economic and Efficient Method for Quantitative Evaluation of Bone Microarchitecture in a Murine Osteoporosis Model
Published on: September 8, 2023
Ambulatory children with spastic cerebral palsy have smaller bone area and deficits in trabecular microarchitecture
Elizabeth A Zimmermann1, Louis-Nicolas Veilleux2,3, Marianne Gagnon2,3
1Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montreal (QC) H3A 0C7, Canada.
Insights
Children with cerebral palsy (CP) show reduced bone density in the proximal femur and impaired tibial bone microarchitecture, linked to gait issues and reduced physical activity. These findings suggest potential skeletal fragility in ambulatory CP patients.
Area of Science:
- Orthopedics
- Pediatrics
- Biomedical Engineering
Background:
- Cerebral palsy (CP) is a neurological condition affecting muscle tone, movement, and posture.
- Bone health in ambulatory children with CP, particularly concerning bone quantity and quality, is not well understood.
- The interplay between abnormal muscle tone, functional deficits, and bone health in CP requires further investigation.
Purpose of the Study:
- To investigate bone mineral density (BMD) and microarchitecture in ambulatory children with spastic CP.
- To explore associations between BMD, gait, muscle spasticity, and overall function.
- To compare bone health parameters in children with CP to healthy controls.
Main Methods:
- Observational study involving 12 ambulatory children (3-8 years) with spastic CP.
- Dual-energy X-ray absorptiometry (DXA) to measure areal BMD at the femur.
- High-resolution peripheral quantitative computed tomography (HR-pQCT) for bone microarchitecture assessment in a subset (n=5).
- Gait analysis (Gait Deviation Index, Edinburgh Visual Gait Score) and energy expenditure measurements.
Main Results:
- Proximal femur aBMD Z-scores were lower (-1.8) in the CP group, indicating potential skeletal fragility.
- Significant correlations were observed between gait pathology and DXA-derived bone outcomes (r=0.62-0.73).
- Children with CP exhibited significantly reduced tibial metaphyseal bone geometry and trabecular microarchitecture (e.g., 35% lower total area) compared to controls.
- HR-pQCT parameters were comparable between groups at the radial metaphysis.
Conclusions:
- Ambulatory children with spastic CP may have compromised bone health, particularly at the proximal femur.
- Impaired gait and altered biomechanics likely contribute to reduced bone quality and quantity in the tibia.
- Findings suggest that altered physical activity levels or biomechanical forces play a role in the observed bone deficits, similar to disuse patterns.
Abstract:
Cerebral palsy (CP) is a non-progressive neurological syndrome resulting in abnormal muscle tone, movement, and posture. It is unclear whether ambulatory children with CP have deficits in bone quantity or quality. Furthermore, the relationship between abnormal muscle tone, altered function, and bone health remains largely unexplored. This observational study investigated bone mineral density (BMD) and microarchitecture in ambulatory children with spastic CP and associations of BMD with function, muscle spasticity, and gait. Children with spasticity in both lower limbs (n = 12) aged 3-8 years were recruited. Areal BMD was measured with dual energy x-ray absorptiometry (DXA) at the proximal femur and lateral distal femur and compared to normative data. High resolution peripheral quantitative computed tomography (HR-pQCT) was performed at the metaphyseal tibia and radius in a subset of participants (n = 5) and compared to healthy children (n = 7). Gait pathology and cardiopulmonary function were investigated with the Gait Deviation Index, Edinburgh Visual Gait Score, and energy expenditure index. DXA areal BMD (aBMD) Z-scores at the lateral distal femur were within a normal range. However, the CP group's median aBMD Z-score at the proximal femur was -1.8 (IQR: -2.2, -1.2, p = .03) indicating potential skeletal fragility. Strong correlations were found between gait pathology and DXA-based bone outcomes (correlation coefficient 0.62 [p = .04] to 0.73 [p = .01]) as well as energy expenditure index and DXA-based bone outcomes (correlation coefficient -0.63 [p = .03] to -0.98 [p ≤ .001]). At the metaphyseal tibia, children with spastic CP had significant deficits in HR-pQCT-measured bone geometry and trabecular microarchitecture: 35% lower total area, 42% lower trabecular area, and 48% lower trabecular number than controls. HR-pQCT parameters were similar between groups at the metaphyseal radius. These differences in tibial metaphysis size and trabecular microarchitecture are similar to those observed in disuse and thus could be a result of abnormal biomechanics or low levels of physical activity.
