Pathomechanical analysis of thoracolumbar burst fracture reduction. A calf spine model.

Burst fractures were created in the spines of twelve dairy calves and the mechanism of indirect canal clearance studied. The spines were reduced posturally and divided in to four subsets--control, and subsets in which either the posterior longitudinal ligament (PLL), the PLL and annulus, or posterior osteoligmentous structures were sectioned. The specimens were then instrumented and further reduction obtained through application of extension and distraction forces. Statistically significant reduction of the intracanal burst fragment occurred even if the PLL or PLL and annulus were incompetent but did not occur in that group in which the posterolateral complex had been sectioned.