Possible mechanisms for observed pathophysiological variability in experimental spinal cord injury by the method of Allen.

Experimental spinal cord injuries were induced in dogs by dropping calibrated weights through a vented tube onto a small impounder resting on the surgically exposed cord. The motion of the impounder and the drop-mass were recorded by high-speed photography and the resulting data were compared to those obtained from a computer simulation of the dynamics of the injury mechanism. It is concluded that this method of induced spinal cord injuries may yield markedly different degrees of cord compression depending upon the parameters of the animal material and apparatus even when the gm-cm of impact energy is maintained at a constant value. Some approaches to standardization of this injury model are suggested.