Introduction and purpose: We present the results of our surgical method involving nerve decompression, reduction and circumferential spinal fusion via posterior approach for severe spondylolisthesis.

Materials and methods: We studied 14 patients with spondylolisthesis and slippage greater than 50%; mean age 24. Mean slip angle 37° and mean preoperative slip 74%.

Procedure: Via a posterior approach we performed neural decompression and placed pedicle screws in L5-S1 (in one case we instrumented L4 for associated L4-L5 spondylolisthesis) and iliac screws (except in three cases). We removed the annulus fibrosus, the L5-S1 disc and the rounded proximal edge of the sacrum. Following distraction of L5-S1 we inserted bone graft cages (from 3 to 5). We adjusted the bars with spanners to reduce slippage and achieve final curvature of the spine.

The cases were monitored with evoked potentials and epidural catheter.

We studied preoperative, postoperative and final check X-rays. The clinical histories were also reviewed.

Results: One rupture of the dura. Two patients with anterior slippage of a cage. One posterior slippage of L5 screws, without revision surgery. One postoperative infection resolved by surgical cleaning and antibiotic therapy.

After mean follow-up of 32 months the radiographic study showed no pseudoarthrosis. Final mean slippage was 15% and slip angle 5°. Ten patients had no pain or physical limitations. Two presented mild lumbar discomfort and occasional limitation.

Conclusions: The procedure we used was shown to be effective in correcting the deformity with excellent clinical results.