SOFT-TISSUE COMPOSITION, QUADRICEPS STRENGTH, BONE QUALITY AND BONE MASS IN RHEUMATOID-ARTHRITIS

Objectives To examine differences in soft tissue composition, bone qua lity, bone mass and quadriceps strength between women with rheumatoid arthritis (RA) and healthy controls. Methods 79 women with RA (median disease duration 10 yrs) were studied. Most were or had been on steroi ds. 67 healthy age-matched women served as controls. The lean tissue m ass (LTM) and fat mass (FM) of the total body and of the major body su bregions, as well as the bone mineral density (BMD, g/cm(2)) of the fe moral neck, spine (L2-L4) and distal forearm were measured by dual ene rgy x-ray absorptiometry (DXA). Bone quality expressed as the speed of sound (SOS, m/sec), broadband ultrasound attenuation (BUA, dB/MHz) an d stiffness was assessed by an Achilles ultrasound device, and isometr ic quadriceps strength by an isokinetic dynamometer. Results No betwee n-group differences were found for the body mass index (BMI, weight/he ight(2)), total or regional percentage fat, LTM and FM. However, women with RA had 20% lower quadriceps strength than controls. BMD at the f emoral neck and distal forearm, and SOS, BUA and stiffness were signif icantly lower in patients than in controls. No difference was found fo r spine BMD. In the RA group, z-scores for SOS and stiffness were sign ificantly more reduced than those for BMD. Multiple regression analyse s indicated negative associations between ultrasound parameters and th e cumulative steroid dose. Conclusions Reductions in BMD and muscle st rength in RA were not accompanied by changes in soft tissue compositio n. Bone quality assessed by ultrasonography was compromised in RA and may be modified by steroids.