Abnormalities in muscle density and muscle function in hypophosphatemic rickets.
Louis-Nicolas Veilleux1, Moira Cheung, Mouna Ben Amor
1Shriners Hospital for Children, 1529 Cedar Avenue, Montréal, Québec, Canada H3G 1A6. lnveilleux@shriners.mcgill.ca
The Journal of Clinical Endocrinology and Metabolism
|May 29, 2012
Summary
Hypophosphatemic rickets (HPR) patients exhibit muscle weakness, not size deficits. Lower muscle quality and limb deformities contribute to impaired function in HPR.
Area of Science:
- Orthopedics
- Pediatrics
- Muscle Physiology
Background:
- Animal studies suggest muscle deficits in hypophosphatemic rickets (HPR).
- Clinical evidence of muscle disorders in human HPR patients remains unclear.
Purpose of the Study:
- To assess calf muscle size and density in HPR patients.
- To evaluate lower extremity muscle function in individuals with HPR.
Main Methods:
- Peripheral quantitative computed tomography (pQCT) for muscle cross-sectional area and density.
- Jumping mechanography to measure lower extremity muscle function (peak force and power).
- Comparison of 34 HPR patients (ages 6-60) with 34 age- and gender-matched controls.
Main Results:
- HPR patients showed normal muscle size but significantly lower muscle density (P=0.008).
- Peak muscle force and power were markedly reduced in HPR patients compared to controls (P < 0.001).
- Muscle function was also impaired in HPR patients with straight legs compared to controls.
Conclusions:
- Muscle weakness is a significant clinical feature of hypophosphatemic rickets.
- Reduced muscle quality and limb deformities contribute to functional deficits in HPR.
- Findings highlight the importance of assessing muscle function in HPR management.
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