Higher fracture prevalence and smaller bone size in patients with hEDS/HSD-a prospective cohort study.

Abstract

The Ehlers-Danlos syndromes (EDS) comprise a group of heritable connective tissue disorders caused by defects in the biosynthesis, secretion, and/or organization of fibrillar collagens which might impair bone strength. Our aim was to compare fracture prevalence, volumetric and areal bone mineral density (BMD), bone geometry, muscle size and the muscle-bone interaction, body composition and longitudinal changes therein between patients with hypermobile EDS (hEDS) or hypermobility spectrum disorder (HSD), and healthy control subjects. Cross-sectional data comprised 39 female hEDS/HSD patients (age 41 ± 11years) and 43 age-matched controls. After 8years, 27 hEDS/HSD and 17 control subjects were re-evaluated. Tibial trabecular and cortical volumetric BMD, bone mineral content (BMC), cortical bone geometry, and lower leg muscle cross-sectional area (CSA) were measured using pQCT. Body composition, areal BMD, and BMC were determined by DXA. At baseline, patients with hEDS/HSD presented with a smaller cortical bone area, smaller cortical thickness and muscle CSA, and a higher fracture prevalence than control subjects (all p < 0.05). No differences in areal or volumetric BMD were found. Longitudinally, muscle CSA decreased in both groups and muscle density decreased in the hEDS/HSD group (p < 0.001) whereas all bone parameters remained unchanged. hEDS/HSD patients have a cortical bone size deficit compared with controls, possibly contributing to their increased fracture risk. They presented with decreased muscle CSA but normal bone/muscle area ratio, suggesting that this bone size deficit is likely secondary to decreased mechanical loading. Further, there were no arguments for accelerated bone loss in hEDS/HSD subjects.