Metacarpal morphometry in children with osteogenesis imperfecta in treatment with neridronate

Metacarpal morphometry, made at the midpoint of the second metacarpal, is the measure of total outer width (W), medullary inner width (w) and of the metacarpal index (MI) calculated as the ratio of cortical width to total width (W-w)/W. Its a simple and readly available technique and represents an inexpensive assessment of fracture risk in clinics where evaluation of bone age is common Osteogenesis imperfecta (OI) is a heritable disorder of bone formation resulting in low bone mass and propensity to fracture. The disorder is currently classified into seven types based on differences in clinical presentation and bone architetture. Our aim was to determinate the metacarpal morphometry in prepuberal children with types I-III-IV OI, before and after bisphosphonate treatment. Subjects The patients population comprised 14 consecutive prepuberal children with OI, aged 1.5 to 12.5 years (6 female; age 2-10.3 years and 8 males; age 1.5-12.5 years). The patients were clinically classified according to the criteria established by Sillence. The control population consisted of 60 age.mached children age 1.2-12.5 years (30 females, age 2-10.5 and 30 males; age 1.5-12). Six patients (3 males and 3 females) were treated with intravenous neridronate (2 mg/Kg) every three months for one yearResults Metacarpal morphometry did not show any significant difference in respect to the sex in control and patient groups. In patients group we found a significant decrease of cortical width (1.74±0.78 vs 2.81±0.78; p<0.001) with no significant change in medullary inner width (3.49±0.89 vs 3.16±0.27; p=0.11) and total outer width (5.23±1.04 vs 5.85±0.78; p=0.03). As consequence MI showed values significatly lower than the pre-treatment levels (0.33. ±0.13 vs 0.45±0.05; p<0.001). In six patients, after neridronate treatment, it has been observed a significant increase of cortical width (2.25±0.69 vs 1.71±0.71, p<0.005) with higher MI (0.41±0.15 vs 0.33±0.13; p<0.003) whereas no significant increase differences have been found regarding the total outer width 5.61±1.05 vs 5.24±1.39; p=0.2) and no significant reduction medullary inner widhth (3.36±1.2 vs 3.53±1.24; p=0.1) was observed.. Conclusions Our results demonstrate that MI, feeling the effects of bisphosphonate treatment in children with Oi, is a useful parameter to evaluate the biomechanical properties of cortical bone. Therefore the simple radiographs of the hand, performed in these children to assess skeletal age, may lead, by means of metacarpal morphometry, to further understanding of bone-strenght related factors