Partial Reduction, Decompression and Posterior Lumbosacral Transfication in Treatment of High Grade Spondylolisthesis

Twee T. Do, MD,
Obeneba Boachie–Adjei, MD,
Bernard Rawlins, MD
Hospital for Special Surgery, New York, New York
and Children's Hospital Medical Center, Cincinnati, Ohio, USA

PURPOSE:
To determine the effectiveness of a technique using partial reduction compression and an isolated posterior approach to lumbosacral pedicle screw transfixation to treat high grade isthmic spondylolisthesis.

BACKGROUND:
The optimal surgical treatment for high–grade spondylolisthesis is still controversial. The options range from fusion in situ to reduction and stabilization via an anterior/posterior spinal fusion. While fusion in situ is very successful at achieving arthrodesis in low to moderate grade slips, the same technique in high grade spondylolisthesis can be associated with up to 50% incidence of pseudarthrosis. Increased fusion rates may be obtained by reduction of the slip, however, reduction can place the patient at higher risk for neurologic injuries. In an attempt to increase fusion while decreasing the neurologic risk associated with complete reduction of high grade spondylolisthesis, we have utilized a technique using posterior decompression, partial reduction, and pedicle screw transfixation of the lumbosacral junction.

METHODS:
Five patients with high–grade spondylolisthesis (IV–V) were treated by this isolated posterior technique. All five patients presented with pain and radiculopathy. Postoperatively, the patients were evaluated for pain control, self–image perception and return to function. The radiographic measurements included the slip angle, the percentage slip, and the sacral inclination. An SRS outcome score was also obtained on all five patients.

FINDINGS:
The average length to follow up is 34 months (range 24–48 months). All patients were solidly fused by the 12 month follow–up. Preoperative slip angle averaged 60.6° and improved to 29.0° postoperatively (p<0.05). The percentage slip improved from 88% to 8l% (p>0.05). Sacral inclination increased from 36.8° to 44.4° (p>0.05). No progression of the slip angle or percentage slip was noted on the follow up radiographs. Complications included two intraoperative dural tears that were identified and repaired. There were no neurologic complications. The SRS outcome instrument demonstrated that four out of the five patients had improved pain control, function and self–image. The remaining patient's pain level, self image and functional status was essentially unchanged.

SIGNIFICANCE:
In high–grade spondylolisthesis, this posterior approach is safe and effective in obtaining a solid arthrodesis, restoring sagittal balance and improving function. These results reinforce the impression that is it the partial reduction of the slip angle, not the percentage slip, in high grade spondylolisthesis that is important in obtaining optimal results.