Multitude of bone changes contribute to fracture risk in OI
MedWire News: People with the hereditary disorder type I osteogenesis imperfecta (OI) exhibit a multitude of alterations in bone microstructure, geometry, and mass, a case-control study indicates.
The findings, reported by a Danish team, help explain why OI patients are at increased risk for fractures as compared with the general population.
Lars Folkestad (Odense University Hospital) and colleagues studied 39 individuals with a clinical diagnosis of type I OI (median age 53 years, 13 men) and 39 healthy controls matched for age and gender.
All participants underwent high-resolution peripheral quantitative computed tomography (HR-pQCT) for assessment of bone geometry, volumetric bone mineral density (BMD), and microarchitecture of the nondominant distal radius and distal tibia.
They also underwent dual-energy X-ray absorptiometry for assessment of areal bone mineral density (aBMD) at the lumbar spine, total hip, femoral neck, and trochanteric region.
Writing in the Journal of Bone and Mineral Research, Folkestad et al say they identified five major differences between OI patients and controls.
First, aBMD was significantly lower at the hip and spine in OI patients versus controls (hip: 0.851 vs 0.920 g/cm2; spine: 0.845 vs 0.969 g/cm2).
Second, the trabecular volumetric BMD was significantly lower at the radius and tibia in OI patients versus controls (radius: 285 vs 316 mgHA/cm3; tibia: 215 mgHA/cm3).
Third, total bone area at the radius was 5% lower while cortical bone area at the tibia was 18% lower in OI patients versus controls.
Fourth, in terms of microstructure, the number of trabeculae at the radius and tibia was significantly lower in OI patients versus controls (radius: 1.29 vs 1.97/mm; tibia: 1.3 vs 1.94/mm).
Finally, trabecular spacing was significantly higher at both radius and tibia in OI patients versus controls (radius: 0.69 vs 0.44 mm; tibia: 0.68 vs 0.44 mm).
The researchers conclude: "To the best of our knowledge, this is the first study published using HR-pQCT to investigate bone structure in patients with OI…
"Our results suggest that the increased risk of fractures in patients with type I OI is a combined result of altered bone matrix quality, low bone mass and altered bone microstructure and geometry."
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By Joanna Lyford