EFFECT OF SAGITTAL SPINAL ALIGNMENT ON LOW BACK PAIN FOLLOWING DECOMPRESSION AND STABILIZATION WITH DYNAMIC, SEMIRIGID AND RIGID INSTRUMENTATION. A MULTIFACTORIAL ANALYSIS.

Abstract

Background data. The clinical outcome of decompression and posterolateral spinal fusion for patients with degenerative lumbar spinal stenosis may be influenced by a variety of pathophysiologic factors. Among them, sagittal balance of the spine has gained new interest regarding its correlation with low back pain following lumbar spine surgery.

Objectives. To study the effect of sagittal spinal alignment on low back pain in patients operated for degenerative lumbar spinal stenosis.

Study design. Multifactorial analysis.

Materials and Methods. In this prospective randomized comparative study 45 consecutive patients were included, who underwent decompression for symptomatic degenerative lumbar spinal stenosis and two-, three- or four levels posterior transpedicular fixation with three instrumentations of different stiffness (dynamic, semirigid and rigid) plus posterolateral fusion. All patients were followed up for an average period of four-year radiologically and with SF-36 (domain Bodily pain) to investigate possible correlations between anthropometric parameters, stiffness and extension of instrumentation, roentgenographic sagittal balance, motion in adjacent free level and low back pain.

Results. Bodily pain scores improved with the time lapsed from index operation (P< 0.0001). As the distance of the apical lumbar vertebra from plumbline increased, bodily pain score improved significantly (P=0.0006). At the last observation following surgery patients had better Bodily pain score than that they had preoperatively (P=0.0001) and six months postoperatively (P< 0.0001) respectively. Patients, who received four levels instrumentation had higher Bodily pain score (P=0.0245) than their counterparts who received two levels instrumentation.

Discussion. Maintenance or even improvement of lumbar lordosis, instrumentation of three and four vertebrae, and time lapsed from index operation was associated with improvement of back pain. On contrary, patients’ age, gender, instrumentation stiffness, vertebral inclination, thoracic kyphosis and sagittal lumbar flexibility did not affect the surgical outcome regarding back pain in adult patients who underwent decompression and stabilization 2 to 4 levels for degenerative lumbar spinal stenosis.