Posterior fusion compared with posterior interbody fusion in segmental spinal fixation for adult spondylolisthesis.

OBJECT:
Clinical and radiographic results in 30 consecutive patients who underwent posterior lumbar fixation and posterior facet joint or posterior interbody fusion for Meyerding Grade II/III spondylolisthesis were assessed: 1) to address the suitability of a dynamic stabilization; and 2) to investigate whether there are differences in terms of clinical and functional results and biomechanical properties between these two types of arthrodesis.

METHODS:
Between June 1998 and April 2000, 16 patients underwent posterior interfacet fusion and implantation of the SOCON-SRI system. In 14 patients posterior lumbar interbody fusion (PLIF) and placement of the same system were performed. Clinical, economic, functional, and radiographic data were recorded pre- and postoperatively. The average changes in the Prolo Scale economic and functional scores were 1.25 and 1.62, respectively, in patients who underwent posterior fusion; the average measured preoperative vertebral slippage was 47.8% (range 30-65%), and postoperatively it was 18.5% (range 15-25%). In patients in whom PLIF was performed, the average changes in economic and functional score were 1.21 and 1.36, respectively, and the average preoperative vertebral slippage was 43.5% (range 30-55%) compared with 20% (range 15-25%) postoperatively.

CONCLUSIONS:
The use of a segmental pedicle screw fixation with the SOCON-SRI system successfully combines the goal of solid fusion with the requirements of nerve root decompression. When the two fusion techniques were compared, an overall superior reliability and resistance of the systems was associated with the PLIF procedure (p = 0.04) but clinical outcomes did not differ greatly (p < 0.05).