To evaluate the efficacy of posterior lumbar interbody fusion utilizing pedicle screw fixation and chip bone graft, and to compare the radiologic and clinical results in two group which use local chip bone and autoiliac chip bone respectively.

We analyzed 58 cases of single segment chip bone posterior lumbar interbody fusion which were followed up for more than 1 year. Group I was operated with local chip bone and group II with autoiliac chip bone. Radiologic union was assessed, based on Brantigan & Steffee method and functional outcome by Kirkaldy-Willis criteria. Student t-test and Fisher's exact test were used for statistical analysis.

Clinical satisfaction of group I and II were 81.3% and 88.1% respectively (p>0.05). Though 12% of group II complained about pain on the donor site, no one among them were assessed as unsatisfactory. Radiological union was confirmed in 75% in group I and 90% in group II (p>0.05). Twenty five percent of group I and nineteen percent of group II showed collapsed union without significant differences. There were no significant differences between group I and II in loss of disc height, segmental lordosis, operation time and blood loss.

Both local and autoiliac chip bone posterior lumbar interbody fusion are useful methods in the aspect of radiologic union and functional outcome and there are no significant differences between two groups. However, considerable collapsed unions were observed in both groups. It is necessary to investigate long term influence of collapsed union on the adjacent segment and functional outcome.