The interaction between Sillence type and BMD in osteogenesis imperfecta.
Clinical studies with bisphosphonates in children with osteogenesis imperfecta (OI) show an increase in BMD and a decrease in fracture rate. Bone strength in children with OI is not only influenced by changes in BMD but also by changes in collagen I structure of the organic bone matrix. Therefore, we studied the interaction between these two factors in a cross-sectional, single center study including 54 children. We assumed that vertebral deformities in OI represent an unbalance between load and bone strength. Body weight was considered to be a well quantifiable load on vertebral bodies. BMD served as a marker, representing the amount of bone tissue available for vertebral load bearing, and the Sillence classification, either type I or III/IV, as a marker representing the quality of the organic bone matrix. Independent associations were observed between the prevalence of vertebral deformities and (1) Sillence type (OR: 5.7, 95%Cl:1.2-26.8), (2) BMD (OR: 0.003, 95%Cl: 0-0.25) and (3) body weight (OR: 1.15, 95%Cl: 1.05-1.25). Regarding the anthropometrical differences among the different types of OI, the BMD/body weight ratio was introduced to evaluate the BMD in relation to body size. Prevalent vertebral deformities were associated with low BMD/body weight ratios (OR: 0.04, 95%Cl: 0.008-0.2) in OI type I, but no association was found in type III/IV. It was concluded that BMD and Sillence type have independent relationships with vertebral deformities. The BMD/body weight ratio correlates with vertebral deformities in children with OI type I. Its meaning in types III/IV needs further research with larger samples because of the relatively high prevalence of vertebral deformities in this group.
Kok
D J
DJ
Department of Orthopedic Surgery, KE 4.140.5, Wilhelmina Children's Hospital, University Medical Center, 3508 AB Utrecht, The Netherlands.
Uiterwaal
C S P M
CS
Van Dongen
A J
AJ
Kramer
P P G
PP
Pruijs
H E H
HE
Engelbert
R H H
RH
Verbout
A J
AJ
Schweitzer
D H
DH
Sakkers
R J B
RJ
D015502:Absorptiometry, Photon; D000293:Adolescent; D001835:Body Weight; D015519:Bone Density; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D024022:Fibrillar Collagens / Q000032:analysis / Q000145:classification / Q000378:metabolism*; D006801:Humans; D007223:Infant; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D008297:Male; D009154:Mutation; D010013:Osteogenesis Imperfecta / Q000145:classification / Q000378:metabolism* / Q000473:pathology; D012016:Reference Values; D016474:Weight-Bearing
D024022:Fibrillar Collagens