Background: EhlersDanlos syndrome (EDS) comprises a group of inherited connective tissue disorders, caused by various defects in the biosynthesis or secretion of fibrillar collagens. As collagen represents a major constituent of the bone matrix as well as of tendons and muscle, bone strength in EDS patients might be impaired both via direct and indirect pathways. Although decreased muscle strength, decreased areal bone mineral density (BMD) and increased fracture risk have been reported, no studies have investigated volumetric bone parameters in these patients.
Objective: We aimed to compare volumetric BMD (vBMD) and cortical bone geometry in patients with EDS hypermobility type (EDS-HT) and age- and sex-matched controls.
Methods: Forty-two female EDS-HT patients (mean age 40.0±10.8 years) and 42 controls were included in a cross-sectional study. vBMD and bone geometry at the tibia (4 and 66% region) as well as lower leg muscle cross-sectional area (CSA, 66% region) were measured using pQCT.
Results: Although EDS-HT patients did not differ from controls with regard to trabecular or cortical vBMD, they presented with about 6.3% smaller trabecular bone area (P=0.014), 8.9% smaller cortical bone area (P=0.005), 6.6% smaller cortical thickness (P=0.021), and, albeit non-significant, 2.9% smaller periosteal circumference (P=0.101). As a result, strength-strain index was 9.8% lower in EDS-HT patients as compared with controls (P=0.039). Furthermore, EDS-HT was associated with a 10.8% decreased muscle CSA (P=0.004) without differences in muscle density. Bone/muscle CSA ratio was within the normal range and did not differ between groups.
Conclusions: EDS-HT patients present with both a trabecular and cortical tibial bone size deficit as compared with controls, which might contribute to their increased fracture risk. As indicated by the decreased muscle CSA and normal bone/muscle CSA ratio, this bone size deficit is probably secondary to decreased mechanical loading in these patients with known muscle dysfunction.
14 May 2016 - 17 May 2016