Objective      To compare clinical results of posterolateral fusion and posterior lumbar interbody fusion techniques in the treatment of lumbar spondylolisthesis.       Methods      Between January 1

2003 and December 31

2009

there were 133 cases of patients with lumbar spondylolisthesis treated in our department. All of the 133 cases of patients were treated with open reduction

decompression

bone graft fusion and internal fixation

via

the posterior appr

oach. The patients were divided into 2 groups: isthmic spondylolisthesis and degenerative spondylolisthesis. Ten cases of isthmic spondylolisthesis were treated with posterolateral fusion technique

and 42 cases of isthmic spondylolisthesis with lumbar interbody fusion technique. Twenty-six cases of degenerative spondylolisthesis were treated with posterolateral fusion technique

55 cases of degenerative spondylolisthesis with lumbar interbody fusion technique. A score of JOA was used to assess clinical outcome.       Results      All cases were followed up for an average of 18 months. At final follow-up

the JOA score was 25.7±1.2

significantly higher than before surgery(17.3±1.6

P

<

0.01). The reduction rate was 74.3% and fusion rate at one year follow-up was 90.4% in the isthmic spondylolisthesis group. The reduction rate was 89.3% and fusion rate at one year follow-up was 98.4% in the degenerative spondylolisthesis group. We found the loss of reduction in 5 cases of isthmic spondylolisthesis treated with posterolateral fusion technique. Two of the 5 cases needed a revision surgery

and the other 3 cases needed a conservative treatment to obtain bone fusion.       Conclusion      The lumbar interbody fusion for isthmic spondylolisthesis results in good stability of the spine

but there is a risk of reduction loss and internal fixation failure when isthmic spondylolisthesis is treated with the posterolateral fusion. Both the posterolateral fusion and the lumbar interbody fusion for degenerative spondylolisthesis lead to good stability of the spine.