Bone Abstracts

Objective: Individuals with Developmental Coordination Disorder (DCD) have difficulty coordinating movements and are often unable to perform common, age-appropriate tasks. Approximately 5–6% of school-aged children are affected by DCD and the condition may persist throughout adolescence and into adulthood. Australian adolescents with DCD have poor bone health compared to European normative data. It can be hypothesized that this is due to a lack of loading resulting from decreased physical activity levels. This study examines whether these differences remain when compared with non-DCD Australian age-matched adolescents with a similar environmental opportunity for physical activity.

Method: Analysis of peripheral Quantitative Computed Tomography (pQCT) data from Australian adolescents aged 12–18 years with (DCD, n=39) and without movement difficulties (non-DCD, n=147). Outcome measures were Stress Strain Index (SSI, mm³), Total Bone Area (TBA, mm²), Functional muscle bone unit (FMBU: (SSI/bone length) and Robustness (SSI/bone length³). A general linear model was used to determine differences between groups controlling for gender, age and bone length. Specific group differences were examined using Mann-Whitney U Test.

Results: DCD participants were younger (mean=14.4 years S.D.=1.3) than the non-DCD group (15.3 years S.D.=1.8) (P=0.007), gender was equally represented for radius (54.1% male) and tibia (53.2% male), although sample size differed for each bone site due to motion artefact (DCD radius n=26, tibia n=39, non-DCD radius n=96, tibia n=147). DCD participants had lower scores for tibial SSI, TBA and Robustness, and no gender-group interaction was observed. A significant gender-group interaction was found for tibial FMBU (P=0.021) with DCD males having lower tibial FMBU scores (mean=36.7 S.D.=8.0) than the non-DCD group (41.7 S.D.=6.5) (P=0.004). In contrast tibial FMBU scores were not significantly different between female groups: 40.4 S.D.=13.6 compared to 38.1 S.D.=6.3, P=0.542. No significant group differences were observed for radial bone measures.

Conclusion: Comparisons in bone measures between motor competence groups are similar to European results however gender differences were found in the present study. Australian male adolescents with DCD have weaker bones compared to Australian non-DCD peers, whereas there was no difference between female groups. These differences may be due to lower levels in habitual weight –bearing physical activity in DCD boys. It needs to be further explored whether male individuals are at higher risk of developing bone changes resulting from decreased activity levels than females.

Disclosure: The authors declared no competing interests.