To investigate the necessity of additional posterolateral fusion in posterior lumbar interbody fusion (PLIF) by comparing the clinical and radiological results of PLIF with circumferential fusion.

In 22 cases of circumferential fusion and 21 cases of PLIF, clinical outcomes were analyzed by Kirkaldy-Willis method. Intensity of pain, usage of analgesics and patient's satisfaction were also investigated. The fusion rates and changes of the heights and angles of discs in fused and adjacent segments were analyzed radiologically.

No significant radiologic differences were found between two groups in terms of fusion rate, changes of disc height and angles in fused and adjacent segments. In each group, good or excellent results were obtained in 71% and 73%, respectively. A longer operation time was needed and the amount of blood loss was larger in the circumferential fusion groups.

The addition of posterolateral fusion seems to have no more advantages than PLIF only.