Background: Ehlers-Danlos Syndrome (EDS) is a group of connective tissue disorders caused by defects in the biosynthesis or secretion of fibrillar collagens, which might impair bone strength in EDS patients.
Objective: Comparing volumetric bone mineral density (vBMD), areal BMD (aBMD), bone geometry, muscle size and body composition between patients with EDS hypermobility Type (EDS-HT) and controls.
Methods: Cross-sectional data comprised 43 EDS-HT females (age 41.0±10.8 years) and 43 age-matched females, 8 years later 30 EDS-HT and 17 control subjects were re-evaluated. Tibial vBMD, bone geometry and lower leg muscle cross-sectional area (CSA) were measured using pQCT. Dual-energy x-ray absorptiometry determined body composition and aBMD.
Results: Although EDS-HT patients did not differ from controls regarding vBMD, periosteal- and endosteal circumference, muscle density and bone/muscle area ratio (BMR), they had significant smaller trabecular bone area and content, cortical bone area, cortical thickness, aBMD and muscle CSA (all p<0.05). Longitudinal data showed similar decreases in lumbar and subtotal aBMD and muscle CSA in both groups, EDS-HT patients showed a significant decrease in muscle density (all p<0.05). Conclusion: EDS-HT patients have a trabecular and cortical bone size deficit compared to controls, possibly contributing to their increased fracture risk. Decreased muscle CSA and normal BMR suggest that this bone size deficit is secondary to decreased mechanical loading. Further, there were no arguments for accelerated bone loss in EDS-HT subjects. Decreases in muscle CSA were comparable between both groups although only EDS-HT subjects showed a decline in muscle density.