ESPE Abstracts

Background: Osteogenesis imperfecta (OI) is a hereditary connective tissue disorder due to mutations related to collagen type 1. OI presents itself with low bone mass, resulting in high bone fragility. Bone mass is relevant for determination of the severity of OI. Although bisphosphonate treatment is able to increase areal bone mineral density (aBMD) measured by DXA, there is no correlation to fracture rates.

Objective and hypotheses: The aim of this study was to retrospectively analyse the trabecular bone score (TBS) in children with OI, who were treated with bisphosphonates during the first year and with denosumab during the second year. TBS, already used in adults with osteoporosis, is supposed to represent the cancellous bone and by that the stability of the bone more accurately than aBMD.

Method: Three DXA scans (GE lunar iDXA, lumbar spine) of six children with OI were performed at intervals of 12 months each. The first two scans were carried out during bisphosphonate treatment. The last was performed after 1 year of denosumab treatment. Paediatric TBS assessment was realized with a custom version of TBS iNsight (Med-Imaps SASU, France). TBS and BMD variations were expressed in % from baseline and normalized at 12 and 24 months.

Results: DXA assessment showed an increase in aBMD of about 8.9%/17.6% after 12/24 months. TBS showed an increase of 1.7/3.4%. In single case analysis there is a difference between trends of aBMD and TBS.

Conclusion: In our pilot trial no correlations between TBS and DXA parameters have been observed. The minimal increase of TBS demonstrates a stronger effect of antiresorptive drugs on cortical than trabecular bone. Even without available reference data at the moment TBS offers the possibility to analyse trabecular bone in more detail without a bone biopsy.