Effects of age and sex on the external induction of scoliosis in rats.

To guide inquiries into the mechanisms for progression of mild scoliosis in humans, the authors investigated the effects of age and sex on the response of spines to externally applied deforming moments using a rat model. Groups of male and female rats, with initial ages of 3, 6, or 24 weeks, were held for five weeks in restraints that laterally deformed their trunks. In response to these deforming moments, the spine of every animal studied acquired an at-least-temporarily fixed lateral curve. Without exception, when deforming moments were applied, the rats' spines deformed. Neither age nor sex was an important factor in this response. The implications of these results to possible mechanisms of scoliosis curve progression in humans are discussed.