The rationale of early functional loading in the healing of fractures: a comprehensive gate control concept of repair.

Trauma triggers nociceptive impulses that set the affected region apart from the systemic homeostasis. By rendering corresponding cord levels more sensitive to environmental stimuli and by inhibiting selective responses to central activation, they create the biologic environment conducive to cellular repair and tissue maturation. But this process is nonspecific and highly labile. It easily escalates out of its range unless checked and regulated by application, in succession, of immediate, protected, permissive and progressive functional loading.