Treatment of severe spondylolisthesis by reduction and pedicular fixation. A 4-6-year follow-up study.

Ten consecutive patients with severe spondylolisthesis were treated with reduction and pedicular fixation (four Internal Fixator instrumentations, six Cotrel-Dubousset instrumentations). There were six Grade III spondylolisthesis and four spondyloptoses at the L5/S1 level. All patients had complete clinical and radiographic evaluation with an average follow-up of 56 months (range, 43-75 months). The percentage of slippage averaged 78.5% preoperatively and 39.6% postoperatively. The slip angle averaged 43 degrees preoperatively and 17 degrees postoperatively. Four patients with spondyloptosis were treated with combined posterolateral and interbody fusion and had solid fusion without loss of reduction. Five of six patients in whom reduction and stabilization was performed by a single posterolateral fusion demonstrated loss of reduction, nonunion, and implant failure. Four of these patients were reoperated. Ultimately all patients had resolution of pain, solid fusion, and no further slip progression. Reduction, pedicular fixation, and combined posterolateral and interbody fusion is a technically demanding procedure, which should be reserved for selected patients. Pedicular fixation systems may only allow permanent reduction and stabilization of high-grade spondylolisthesis in conjunction with a combined interbody and posterolateral fusion.