Kinematic analysis of posterior spinal fusions in pigs

Five pigs operated upon by posterior spinal fusion were examined by a roentgen stereophotogrammetric method during provoked motion. The healing process leading to marked rigidity within the spine was followed in two of the pigs. Varying degrees of stability in the fused area were achieved in the five animals. Movements were detected, not only when the fusions were not healed, but also in two cases of incomplete bony union between two operated segments.