A KYPHECTOMY TECHNIQUE WITH REDUCED PERIOPERATIVE MORBIDITY FOR MYELOMENINGOCELE KYPHOSIS.

John F. Sarwark, MD;
John J. Grayhack, MD;
Mark Nolden, MD;
Arnand Vora, MD
Chicago, IL, USA

INTRODUCTION:
The benefits of restoring sagittal spinal alignment in myelomeningocele patients with severe lumbar kyphosis deformity to achieve postural stability and improved sitting balance is generally accepted. The optimal method of deformity correction, extent of instrumentation and role of limited arthrodesis remains undefined.

PURPOSE:
To critically examine our experience using the subtraction (decancellation) vertebrectomy technique combined with posterior instrumentation for myelomeningocele kyphosis in children ages 2–5 years.

METHODS:
We reviewed the charts of 41 myelomeningocele patients who were treated surgically for lumbar kyphosis between 1990 to 1998. The inclusion criteria for the 12 patient study group: a subtraction (decancellation) vertebrectomy was performed as part of the surgical reconstruction; age <6 years at the time of the index operation; minimum 2 years follow–up; spinal cord and thecal sac were preserved; and instrumentation used with limited arthrodesis. All patients had segmental instrumentation constructs with sacral/pelvic fixation. Charts and radiographs were reviewed to assess sitting balance, sagittal plane deformity and correction and complications.

FINDINGS:
Average pre–operative myelomeningocele kyphosis was +95°(57° to 120°). The apex of the kyphosis was L2 in 6 patients and L3 in 6 patients. All had thoracic motor level myelomeningocele and were noted to have kyphosis at birth. Average age at time of index procedure was 3.5 years (range 1 to 6). Posterior segmental fixation was used with limited arthrodesis and pedicle lumbosacral fixation. The average kyphosis immediately post–op was 30° (range –25° to –40°) and maintained at final follow–up. The average total sagittal correction was 125° (from +95° to –30°). There were no deaths, acute hydrocephalus, vascular complications or chronic deep wound infections. Skin breakdown up to 2 years postoperatively occurred in 3 patients.

DISCUSSION:
The subtraction (decancellation) vertebrectomy technique with preservation of the spinal cord is safe and efficacious as a technique for correction and stabilization of myelomeningocele kyphosis in young patients. Morbidity is reduced when compared to excision techniques. Instrumentation extending from sacrum into the non–dysraphic thoracic spine is emphasized. Restoration of spinal sagittal alignment at the time of initial correction and stabilization to achieve a balanced spine led to acceptable results.