ADDING POSTERIOR LUMBAR INTERBODY FUSION TO PEDICLE SCREW FIXATION AND POSTEROLATERAL FUSION AFTER DECOMPRESSION IN SPONDYLOLYTIC SPONDYLOLISTHESIS

Study Design. This is a retrospective study analyzing 76 patients trea ted by decompression, pedicle screw instrumentation, and fusion for sp ondylolytic spondylolisthesis with symptomatic spinal stenosis. Object ives. To verify the advantages of adding posterior lumbar interbody fu sion to the usual posterolateral fusion with pedicle screw instrumenta tion. Summary of Background Data. Stabilization after decompression of spondylolytic spondylolisthesis is difficult because of a lack of fus ional bone bases, gap between the transverse process bases, and incomp etent anterior disc support. Posterior lumbar interbody fusion offers anterior support, reduction, and a broad fusion base. Methods. Forty p atients were treated with posterolateral fusion, and 36 were treated w ith additional posterior lumbar interbody fusion. They were compared f or union, reduction of the deformity, and clinical results. Results. T he patients were followed up for more than 2 years. Nonunion was obser ved in three patients who underwent posterolateral fusion (7.5%), and no cases of nonunion was found in patients who underwent posterior lum bar interbody fusion. Reduction of slippage was 28.3% in those who und erwent posterolateral fusion and 41.6% in those who had posterior lumb ar interbody fusion (P < 0.05). In the posterolateral fusion group, ei ght patients (20%) had recurrence of deformity, with loss of reduction more than 50%. Hardware failures occurred in two patients who had pos terolateral fusion. There was no major neurologic complications in bot h groups. Both groups had satisfactory results in more than 90% of pat ients, with marked improvement of claudication. However, subjective im provement of back pain by Kirkaldy-Willis criteria revealed difference s in the excellent results. An excellent result was reported by 45% in the posterolateral fusion group and by 75% in posterior lumbar interb ody fusion group. Conclusions. The addition of posterior lumbar interb ody fusion to posterolateral fusion after a complete decompression and pedicle screw fixation is a recommended procedure for the treatment o f spondylolytic spondylolisthesis with spinal stenosis.