The biomechanics of posterior lumbar interbody fusion (PLIF) in spondylolisthesis.

A biomechanic analysis of the lower lumbar segments leads to the recommendation that during posterior lumbar interbody fusion it is desirable to preserve the dorsal structures, particularly of the facet joints. The area of the interbody graft should cover an area as large as possible in order to attain the benefit of the compression forces through the tension of the anterior longitudinal ligament. Preservation of the midline structures or application of a tension clamp to add dorsal tension aids bony fusion. Salvage operations in patients with previously excised posterior elements require the addition of dorsal or dorsolateral fusion to PLIF.