Fig. 1.

Mechanical forces involved in endochondral bone formation. Bone morphology is regulated by mechanical forces at different levels, as demonstrated by the various developmental and functional aberrations that arise in the absence of muscle contraction. (1) Bone elongation is impaired due to reduced chondrocyte proliferation in the growth plate. (2) Additionally, the organization of resting chondrocytes into columns is impaired, which can also affect skeletal elongation. (3) Bone eminence growth is arrested, resulting in smaller or absent eminences. (4) Differential appositional growth is lost, resulting in a circular circumferential shape. (5) Joint formation is impaired during embryonic development, leading to joint fusion.