Posterior lumbar interbody fusion using titanium cylindrical threaded cages: is optimal interbody fusion possible without other instrumentation?

This study evaluated the bony union obtained through posterior lumbar interbody fusion (PLIF) using Ray's threaded fusion cage (TFC) without other instrumentation. We assessed 25 consecutive patients who underwent treatment using this method. A bone graft was placed in the cages only. No additional instrumentation, such as a pedicle screw system, was used. The study group consisted of 12 men and 13 women. The mean age at the time of operation was 48.6 years, and the mean follow-up period was 44 months. The extent of facet joint destruction, bony union, and correction loss of spondylolisthesis were assessed. Union was assessed radiologically. Solid union was defined as the point at which complete superimposition of the fused vertebrae was detected in the flexion-extension lateral radiograph and the angle of sagittal rotation was zero. Total facetectomy was performed in 20 of the 25 cases. Solid fusion of the operative intervertebral level was achieved in 7 cases (28%), and nonunion was detected in 18 cases (72%). There was no loss of correction of the anterolisthesis in 14 patients with spondylolisthesis.