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Construction of a functional skeleton is accomplished
through co-ordination of the developmental processes of chondrogenesis,
osteogenesis, and synovial joint formation. Infants whose movement in
utero is reduced or restricted and who subsequently suffer
from joint dysplasia (including joint contractures) and thin hypo-mineralised
bones, demonstrate that embryonic movement is crucial for appropriate
skeletogenesis. This has been confirmed in mouse, chick, and zebrafish
animal models, where reduced or eliminated movement consistently yields
similar malformations and which provide the possibility of experimentation
to uncover the precise disturbances and the mechanisms by which
movement impacts molecular regulation. Molecular genetic studies have
shown the important roles played by cell communication signalling
pathways, namely Wnt, Hedgehog, and transforming growth factor-beta/bone
morphogenetic protein. These pathways regulate cell behaviours such
as proliferation and differentiation to control maturation of the
skeletal elements, and are affected when movement is altered. Cell
contacts to the extra-cellular matrix as well as the cytoskeleton
offer a means of mechanotransduction which could integrate mechanical
cues with genetic regulation. Indeed, expression of cytoskeletal
genes has been shown to be affected by immobilisation. In addition
to furthering our understanding of a fundamental aspect of cell control
and differentiation during development, research in this area is
applicable to the engineering of stable skeletal tissues from stem
cells, which relies on an understanding of developmental mechanisms
including genetic and physical criteria. A deeper understanding
of how movement affects skeletogenesis therefore has broader implications
for regenerative therapeutics for injury or disease, as well as
for optimisation of physical therapy regimes for individuals affected
by skeletal abnormalities. Cite this article: Bone Joint Res 2015;4:105–116