Comparison of clinical outcomes between two methods of posterior lumbar interbody fusion in adult spondylolisthesis.

OBJECTIVE: To compare the clinical outcomes of posterior lumbar interbody fusion (PLIF) using simple cage alone fusion with pedicle screw fixation and autogenous bone grafting and cage fusion with pedicle screw fixation in adult spondylolisthesis.

METHODS: From March 2003 to March 2004, twenty-seven patients with lumbar spondylolisthesis were divided in two groups. In group A, 15 patients were treated by PLIF using simple cage alone fusion with pedicle screw fixation, including 4 males and 11 females, aging 53-68 years. Isthmic defects were located at L4 in 9 cases, at L5 in 6 cases. Four patients were smokers. The preoperative mean disc space height was 5.4 +/- 2.3 mm, the mean percentage of slip was 36.8% +/- 7.2%. In group B, 12 patients were treated by PLIF using autogenous bone grafting and cage fusion with pedicle screw fixation, including 3 males and 9 females, aging 56 years. Isthmic defects were located at L4 in 8 cases, at L5 in 4 cases. Five patients were smokers. The preoperative mean disc space height was 5.7 +/- 2.5 mm, the mean percentage of slip was 37.8% +/- 6.2%. Two groups were compared in the amount of blood loss, duration of hospitalization, back pain, radiating pain, fusion rate, the intervertebral disc space height, the postoperative degree of slip and the fusion rate.

RESULTS: All patients were followed up for 24-38 months. The mean follow-up was 29 (24-36) months in group A and 26 (24-38) months in group B. There were no statistically significant differences in follow-up period, age, sex, the location of isthmic defects, smoking, the preoperative disc space height and the percentage of slip between two groups (P > 0.05). There were no statistically significant differences in the amount of blood loss, the duration of hospitalization, the fusion time between two groups (P > 0.05). But there were statistically significant differences in the back pain score, the radiating pain score and the fusion rate between two groups (P < 0.05). The postoperative disc space height and the degree of slip of the last follow-up were 5.8 +/- 2.2 mm and 25.6% +/- 7.2% in group A, 6.2 +/- 2.5 mm and 24.1% +/- 7.4 % in group B, showing statistically significant difference (P < 0.05).

CONCLUSION: The PLIF using autogenous bone grafting and cage fusion with pedicle screw fixations is more beneficial to improving the fusion rate and preventing longterm instabilities than simple cage alone fusion with pedicle screw fixation in adult spondylolisthesis.