ASSESSMENT OF BONE IN EHLERS-DANLOS-SYNDROME BY ULTRASOUND AND DENSITOMETRY

Objective - Ehlers Danlos syndrome (EDS) is an inherited disorder of c onnective tissue characterised by hyperextensible skin, joint laxity, and easy bruising. There are phenotypic similarities with osteogenesis imperfecta, but in EDS a tendency to fracture or altered bone mass ha s not previously been considered to be a cardinal feature. Method - Th is case-control design study investigates whether 23 patients with EDS had differences in fracture rates, bone mass, and calcaneal ultrasoun d parameters compared with age and sex matched controls. Results - 23 cases of EDS (mean (SD) age 38.5 (15.5)) were compared with 23 control s (mean age 37.8 (14.5)). A significant reduction in bone density meas ured by dual energy x ray absorptiometry was found at the neck of femu r by 0.9 SD, p = 0.05, and lumbar spine by 0.74 SD, p = 0.02. At the c alcaneum, broad band ultrasound attenuation and speed of sound were si gnificantly reduced compared with controls by 0.95 SD (p = 0.004) and 0.49 SD (p = 0.004) for broad band ultrasound attenuation and speed of sound respectively. Broad band ultrasound attenuation and speed of so und remained significantly reduced after adjusting for bone mineral de nsity (BMD). After adjusting for functional status (HAQ), age and sex, hypermobility was inversely correlated with broad band ultrasound att enuation and SOS, but not BMD at hip or spine. Previous fracture was 1 0 times more common in EDS (p < 0.001), with 86.9% of patients reporti ng a total of 47 low impact fractures, compared with 8.7% of controls. Conclusion - This study has identified a tendency of EDS patients to fracture, have low bone mass and abnormal bone structure. The aetiolog y is likely to be multifactorial, with an inherited structural element , accentuated by immobility or reduced exercise. This is one of the fi rst clinical studies to suggest ultrasound can detect structural diffe rences in bone, independent of dual energy x ray absorptiometry.