High-Grade Isthmic Dysplastic Spondylolisthesis

In Brief Study Design. A prospective single arm cohort. Objective. To study the results of distraction reduction of high-grade isthmic dysplastic spondylolisthesis with posterior lumbar interbody fusion and posterior compression in a consecutive, prospectively collected series of adolescent patients. Summary of Background Data. High-grade isthmic dysplastic spondylolisthesis has been associated with a high complication and failure rate regardless of the method of surgical treatment, including in situ fusion, cast correction and fusion, anterior fusion, posterior instrumented fusion, and combination procedures. Methods. A total of 18 adolescents with the diagnosis and a minimum 50% slip underwent the procedure of Gill decompression, temporary distraction with reduction of the deformity, complete lumbosacral discectomy, posterior lumbar interbody fusion with Harm’s cage and autogenous iliac graft, and posterior monosegmental compression instrumentation with pedicular fixation. Results. Follow-up ranged from 2.3 to 5 years. Slip improved from 77% to 13% and slip angle from 35° to 3.8° initially and 4.3° at final follow-up. One patient had loss of 16° of slip angle but achieved arthrodesis. Sacral inclination improved from 28° to 39°. There were no neurologic or infectious complications. There were no overt instrumentation failures. Arthrodesis was achieved in every instance. Two patients had structural complications, neither of which underwent reoperation. Conclusions. The index procedure provided near-anatomic correction of high-grade spondylolisthesis, which is maintained at a minimum 2-year follow-up without significant complications. There were two structural complications. Anterior column structural support and posterior compressive instrumentation help restore the necessary biomechanics to allow clinical fusion and success. This series has led the senior author to evolve his technique tooften include caudad fixation to the pelvis and/or cephalad fixation to L4. Eighteen adolescents with > 50% isthmic dysplastic spondylolisthesis were treated with Gill procedure, wide L5 nerve root exposure, posterior lumbar interbody fusion with sacral dome excision, distraction reduction, structural interbody graft, and posterior compression instrumentation. Follow-up exceeded 2 years in all patients. There were no neurologic or instrumentation failures. All patients achieved arthrodesis. One patient had a distal bending through the S1–S2 interspace.