The low lumbar spine below Cotrel-Dubousset instrumentation: Long-term findings

Retrospective review of long instrumented fusions down to the low lumbar spine for the treatment of adolescent idiopathic scoliosis. To evaluate whether the use of instrumentation systems that preserve the sagittal profile could reduce the incidence of early degenerative changes. Long fusions and distractive Harrington instrumentation in the surgical treatment of adolescent idiopathic scoliosis (AIS) are known to produce pain and degenerative changes in the free lumbar segments. Reports on the use of Cotrel-Dubousett instrumentation (CDI) confirm that the instrumentation maintains physiologic lumbar lordosis, but the evolution of the spine below the fusion is not addressed. Thirty-five patients with AIS and CDI were studied. Their spines were fused to L3 or lower, and they had a minimum follow-up of 10 years. Radiologic measurements were recorded from frontal and lateral radiographs. At the time of last examination, lateral flexion-extension dynamic radiographs and magnetic resonance imaging evaluated the health of the disks below the fusion. Clinical outcome was assessed with the Scoliosis Research Society instrument. A control group consisting of 35 peers without scoliosis served as a reference for the outcome questionnaire. Surgery kept the sagittal profile in a physiologic range. All but two patients were satisfied with the results of surgery. There were no differences between patients and control group insofar as pain, self-image, general function, and daily activity were concerned. Eleven patients showed instability signs in dynamic radiographs and more than half of patients showed incipient degeneration on magnetic resonance images. These findings are similar to those found in the general population, according to the literature, and could evidence normal aging processes. Cotrel-Dubousset instrumentation maintains the physiologic sagittal contour. Although there are some degenerative changes in magnetic resonance images and dynamic radiographs, the quality of life and daily activities of the patients after surgery are similar to those of a normal population of the same age.