Pediatric Reference Centiles of Bone Mineral Density and Body Composition of Lower Limbs.

Localized neurological diseases such as spina bifida are often accompanied by normal upper limb and spinal bone mineral density (BMD), whereas regional BMD of the lower limbs may be decreased. Therefore, regional BMD measurements may be more accurate to quantify regional bone health. Until now, no pediatric reference centiles of bone mineral density and body composition of the lower extremities are available for Hologic DXA systems. The objective was to generate age-and sex specific reference centiles of DXA scans of lower limbs for Hologic DXA systems. Data from the National Health and Nutrition Examination Survey of the period 1999-2004 (age 8 - 20 years) were used to generate age-specific and sex-specific reference centiles for the non-Hispanic Black, non-Hispanic White and Mexican-American NHANES study population. The LMS method was used to calculate the reference centiles. Data of DXA scans of 2233 non-Hispanic black children (880 females), 1869 non-Hispanic white children (803 females) and 2350 Mexican American children (925 females) were used to create age-specific and sex-specific reference curves. We presented age-and sex-specific reference centiles for regional bone mineral density, bone mineral content, lean body mass and fat mass at the lower limbs for children and adolescents which were ethnicity specific and directly applicable to Hologic QDR-4500A fan-beam densitometer.

Osteogenesis imperfecta-pathophysiology and therapeutic options.

Osteogenesis imperfecta (OI) is a rare congenital disease with a wide spectrum of severity characterized by skeletal deformity and increased bone fragility as well as additional, variable extraskeletal symptoms. Here, we present an overview of the genetic heterogeneity and pathophysiological background of OI as well as OI-related bone fragility disorders and highlight current therapeutic options.The most common form of OI is caused by mutations in the two collagen type I genes. Stop mutations usually lead to reduced collagen amount resulting in a mild phenotype, while missense mutations mainly provoke structural alterations in the collagen protein and entail a more severe phenotype. Numerous other causal genes have been identified during the last decade that are involved in collagen biosynthesis, modification and secretion, the differentiation and function of osteoblasts, and the maintenance of bone homeostasis.Management of patients with OI involves medical treatment by bisphosphonates as the most promising therapy to inhibit bone resorption and thereby facilitate bone formation. Surgical treatment ensures pain reduction and healing without an increase of deformities. Timely remobilization and regular strengthening of the muscles by physiotherapy are crucial to improve mobility, prevent muscle wasting and avoid bone resorption caused by immobilization. Identification of the pathomechanism for SERPINF1 mutations led to the development of a tailored mechanism-based therapy using denosumab, and unraveling further pathomechanisms will likely open new avenues for innovative treatment approaches.