Peripheral quantitative computed tomography (pQCT) reveals low bone mineral density in adolescents with motor difficulties.
This is the first reported study to describe local bone mineral density, assess parameters of fracture risk and report history of fractures in adolescents with motor difficulties. Motor difficulties evidenced by poor coordination in adolescence should be considered a new risk factor for below-average bone strength and structure and fracture risk.


BACKGROUND
Adolescents with motor difficulties are characterised by poor coordination and low levels of physical activity and fitness. It is possible these deficits translate into below-average bone strength and structure. The objectives of this study were to describe local bone mineral density (BMD), assess parameters of fracture risk (stress-strain index, SSI) and report history of fractures in this group.


METHODS
Thirty-three adolescents (13 females), mean age of 14.3 (SD = 1.5) years, with motor difficulties underwent peripheral quantitative computed tomography (pQCT) measurements at proximal (66 %) and distal (4 %) sites of the non-dominant radius (R4 and R66) and tibia (T4 and T66). One sample t test was used to compare Z-scores for total BMD, trabecular density, cortical density and stress strain index (SSI) against standardized norms.


RESULTS
Significant differences were present at R4 total density mean Z-score = -0.85 (SD = 0.7, p < 0.001), R66 cortical density mean Z-score = -0.74 (SD = 1.97, p = 0.038), R66 SSI mean Z-score = -1.00 (SD = 1.08, p < 0.001) and T66 SSI mean Z-score = -0.70 (SD = 1.15, p < 0.001). There was a higher incidence of fractures (26.9 %) compared to the normal population (3-9 %).


CONCLUSIONS
Motor difficulties in adolescence should be considered a risk factor for below-average bone strength and structure and fracture risk. Strategies are needed to improve bone health in this high-risk-group.
Institute for Health Research, The University of Notre Dame Australia, 19 Mouat Street, PO Box 1225, Fremantle, WA, 6959, Australia. beth.hands@nd.edu.au.
B
B
Hands
Institute for Health Research, The University of Notre Dame Australia, 19 Mouat Street, PO Box 1225, Fremantle, WA, 6959, Australia.
P
P
Chivers
School of Health Science, The University of Notre Dame Australia, 19 Mouat Street, PO Box 1225, Fremantle, WA, 6959, Australia.
F
F
McIntyre
Institute for Health Research, The University of Notre Dame Australia, 19 Mouat Street, PO Box 1225, Fremantle, WA, 6959, Australia.
F C
FC
Bervenotti
School of Health Science, The University of Notre Dame Australia, 19 Mouat Street, PO Box 1225, Fremantle, WA, 6959, Australia.
T
T
Blee
Department of Diagnostic Imaging, Princess Margaret Hospital, Perth, Australia.
B
B
Beeson
Department of Diagnostic Imaging, Princess Margaret Hospital, Perth, Australia.
F
F
Bettenay
Institute for Health Research, The University of Notre Dame Australia, 19 Mouat Street, PO Box 1225, Fremantle, WA, 6959, Australia.|Department of Endocrinology and Diabetes, Princess Margaret Hospital, Perth, Australia.
A
A
Siafarikas
D000058:Accidental Falls / Q000706:statistics & numerical data; D000293:Adolescent; D000886:Anthropometry / Q000379:methods; D015992:Body Mass Index; D015519:Bone Density / Q000502:physiology*; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology; D000068079:Motor Disorders / Q000150:complications* / Q000503:physiopathology; D010024:Osteoporosis / Q000209:etiology* / Q000503:physiopathology; D058866:Osteoporotic Fractures / Q000209:etiology / Q000503:physiopathology; D011627:Puberty / Q000502:physiology; D011884:Radius / Q000503:physiopathology; D012307:Risk Factors; D012727:Sex Characteristics; D013977:Tibia / Q000503:physiopathology; D014057:Tomography, X-Ray Computed / Q000379:methods
Adolescents; Bone health; Fracture risk; Motor difficulties; pQCT