Muscle mass deficits are associated with bone mineral density in men with idiopathic vertebral fracture.
OBJECTIVE
The causes of idiopathic vertebral fractures (IVF) in men are poorly understood. We hypothesised that in IVF, areal bone mineral density (aBMD) deficits would be associated with reduced muscle mass.


METHODS
In this case-control study, 48 men (61.5 +/- 12.1 years old) presenting with symptomatic IVF were compared with 48 healthy controls matched for age (+/-5 years) and stature (+/-5 cm). The aBMD and soft-tissue body composition were determined by dual energy X-ray absorptiometry (DXA). Muscle mass was defined as the ratio of appendicular lean mass to the square of height (ALMI). Sex hormones, IGF-I and its binding protein IGFBP-3 were measured by immunoassay.


RESULTS
ALMI was significantly lower in IVF patients (8.27 +/- 0.90 vs 8.65 +/- 0.88 kg/m(2), t = 2.193, df = 47, P = 0.033 by paired sample t-test). Hierarchical regression analysis revealed that for IVF patients, ALMI explained the greatest proportion of variance in BMD at the lumbar spine, femoral neck and total hip (R (2) (change) = 16.4-22.7%, P = 0.012-0.002) and only IGFBP-3 explained variance in ALMI (R (2) (change) = 19.9%, P = 0.006).


CONCLUSIONS
In men with IVF, ALMI was reduced and associated with IGFBP-3. ALMI was identified as a novel factor that explained a greater proportion of variance in BMD than either fat mass or serum biochemistry.
Macdonald
J H
JH
School of Sport, Health and Exercise Sciences, University of Wales, George Building, Bangor, Gwynedd LL57 2PZ, UK. j.h.macdonald@bangor.ac.uk
Evans
S F
SF
Davie
M W J
MW
Sharp
C A
CA
D015502:Absorptiometry, Photon / Q000379:methods; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition / Q000502:physiology; D001827:Body Height / Q000502:physiology; D016022:Case-Control Studies; D015331:Cohort Studies; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000502:physiology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000473:pathology*; D010024:Osteoporosis / Q000209:etiology* / Q000378:metabolism / Q000503:physiopathology; D012044:Regression Analysis; D016103:Spinal Fractures / Q000209:etiology* / Q000378:metabolism / Q000473:pathology
D018972:Insulin-Like Growth Factor Binding Protein 3