Age at onset of walking in infancy is associated with hip shape in early old age.

Ireland, Alex; Saunders, Fiona R.; Muthuri, Stella G.; Pavlova, Anastasia V.; Hardy, Rebecca J.; Martin, Kathryn R.; Barr, Rebecca J.; Adams, Judith E.; Kuh, Diana; Aspden, Richard M.; Gregory, Jennifer S.; Cooper, Rachel

Abstract

Bones' shapes and structures adapt to the muscle and reaction forces they experience during everyday movements. Onset of independent walking, at approximately 12 months, represents the first postnatal exposure of the lower limbs to the large forces associated with bipedal movements; accordingly, earlier walking is associated with greater bone strength. However, associations between early life loading and joint shape have not been explored. We therefore examined associations between walking age and hip shape at age 60 to 64 years in 1423 individuals (740 women) from the MRC National Survey of Health and Development, a nationally representative British birth cohort. Walking age in months was obtained from maternal interview at age 2 years. Ten modes of variation in hip shape (HM1 to HM10), described by statistical shape models, were ascertained from DXA images. In sex-adjusted analyses, earlier walking age was associated with higher HM1 and HM7 scores; these associations were maintained after further adjustment for height, body composition, and socioeconomic position. Earlier walking was also associated with lower HM2 scores in women only, and lower HM4 scores in men only. Taken together, this suggests that earlier walkers have proportionately larger (HM4) and flatter (HM1, HM4) femoral heads, wider (HM1, HM4, HM7) and flatter (HM1, HM7) femoral necks, a smaller neck-shaft angle (HM1, HM4), anteversion (HM2, HM7), and early development of osteophytes (HM1). These results suggest that age at onset of walking in infancy is associated with variations in hip shape in older age. Early walkers have a larger femoral head and neck and smaller neck-shaft angle; these features are associated with reduced hip fracture risk, but also represent an osteoarthritic-like phenotype. Unlike results of previous studies of walking age and bone mass, associations in this study were not affected by adjustment for lean mass, suggesting that associations may relate directly to skeletal loading in early life when joint shape changes rapidly.

Citation

IRELAND, A., SAUNDERS, F.R., MUTHURI, S.G., PAVLOVA, A.V., HARDY, R.J., MARTIN, K.R., BARR, R.J., ADAMS, J.E., KUH, D., ASPDEN, R.M. GREGORY, J.S. and COOPER, R. 2019. Age at onset of walking in infancy is associated with hip shape in early old age. Journal of bone and mineral research [online], 34(3), pages 455-463. Available from: https://doi.org/10.1002/jbmr.3627

• Journal Article Type: Article
• Acceptance Date: Oct 6, 2018
• Online Publication Date: Jan 15, 2019
• Publication Date: Mar 31, 2019
• Deposit Date: Sep 19, 2019
• Publicly Available Date: Sep 19, 2019
• Journal: Journal of Bone and Mineral Research
• Print ISSN: 0884-0431
• Electronic ISSN: 1523-4681
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 34
• Issue: 3
• Pages: 455-463
• DOI: https://doi.org/10.1002/jbmr.3627
• Keywords: Biomechanics; Exercise; Bone-muscle interactions
• Public URL: https://doi.org/10.1002/jbmr.3627