Long Term Outcome In Neuromuscular Scoliosis Fused Only To Lumbar 5

Correction of scoliosis and pelvic obliquity in neuromuscular disease using spinal instrumentation is an accepted surgical procedure. Controversy exists as to the caudal extent of fusion and instrumentation: Lumbar 5 or the Sacrum. A recent study recommended fusions in neuromuscular disease should be carried to the pelvis, instrumentation to Lumbar 5 was associated with lesser degrees of correction and postoperative progression of scoliosis and pelvic obliquity. In our hands, segmental instrumentation terminating in pedicle screws at Lumbar 5 has demonstrated consistent correction of scoliosis and pelvic obliquity with long-term correction equal to that accomplished with pelvic instrumentation.

Methods: Patients with progressive neuromuscular scoliosis underwent spinal fusion with segmental instrumentation using a U-rod terminating in pedicle screw fixation at Lumbar 5 with no fusion or instrumentation across the lumbosacral joint. Scoliosis correction is accomplished by segmental instrumentation, pelvic obliquity correction occurring through stability of the Lumbar 5 Sacral 1 disc and iliolumbar ligaments. A continuous U-rod was used to avoid rod translation during scoliosis correction and the need for cross- links.

Results: From 1998 - 2002, 28 patients with neuromuscular scoliosis underwent instrumentation and fusion to Lumbar 5. 25 patients, all having longer than 2-year follow-up were reviewed. Average follow-up was 4 years. Average age at surgery was 13.9 yrs. (9.5 -17.5). Surgery was either anterior/posterior or posterior alone.

Measurements: Measurements included the Cobb angle, Lumbar 5 tilt compared to the intercrystal line and pelvic obliquity measured by the method of Maloney pre- and post-operatively.

Discussion: Average correction of scoliosis of 74% and pelvic obliquity of 68% with instrumentation to Lumbar 5 compares favorably with results of instrumentation to the sacrum. Previous studies have shown good correction of scoliosis and pelvic obliquity with instrumentation to Lumbar 5 in small curves (> 40°) and mild pelvic obliquity (> 20°) with maintenance of correction. Larger curves or greater degrees pelvic obliquity demonstrated poor initial correction and greater loss of long-term correction. A continuous U-rod with pedicle screw fixation at Lumbar 5 overcomes these problems avoiding rod translation during correction or long-term and pelvic obliquity correction occurs due to stability at the Lumbar 5 Sacral 1 disc space and the iliolumbar ligament. The best results occurred if the apex of the lumbar curve was Lumbar 2 or higher. If below Lumbar 2, or in the face of an oblique take off of Lumbar 5 Sacral 1, fusion should be carried to the sacrum.

Conclusion: Instrumentation and fusion to Lumbar 5 is a simpler procedure with less technical difficulty, decreased surgical time, decreased blood loss and less risk of infection compared to instrumentation and fusion to the pelvis. Postoperative and long-term follow-up indicated that fusion to Lumbar 5 can correct scoliosis and pelvic obliquity, similar to reports with fusions to the sacrum and can maintain this correction long-term.