Abstract
We observed reductional effects by a two-dimensional photoelastic model, to compare those two effects-in prone position and in supine position using our reductions apparatus. Specially the stress concentration of anterior aspect of spine were observed and compared. The results were summerized as follows;
(1) In the prone position: the tension stress increased from the upper thoracic vertebra to the lower lumbar vertebra. Weak stress concentration was found at the anterior aspect of the injured vertebra.
(2) In the supine position: the tension stress decreased from the injured vertebra to both the upper vertebrae and the lower vertebrae. Strong stress concentration was found at the anterior aspect of the injured vertebra.
Furthermore, we experimented a model consisting of five vertebrae, the center vertebra of which was injured, in order to observe the distribution of inner principal stress.
(1) In the prone position: the inner principal stress lines density was observed in the anterior section of spine, which was increased towards the lower vertebrae.
(2) In the supine position: the inner principal stress was strongest in the anterior section of injured vertebra and the stress was decreased towards both upper and lower vertebrae.
According to the above results, the stress concentration in the anterior aspect of injured vertebra was stronger in the supine position than in the prone position.
Thus we understood that reduction using our apparatus was more effective.
