The effect of Harrington instrumentation on the sagittal configuration and mobility of the spine in scoliosis.

The spinal mobility and sagittal configuration in 96 scoliotic patients treated according to Harrington were investigated with a Debrunner kyphometer and a Myrin inclinometer. The more distal the fusion limit in the lumbar spine, the more reduced was the lumbar lordosis and flexion. The patients' own estimation of lumbar rigidity and pain, scored on visual analogue scales, increased as the fusion limit increased distally. The results for the thoracic spine's sagittal configuration and mobility were analogous but the trend was less pronounced. The patients' estimation of thoracic rigidity had little correlation with the number of segments fused. This study shows that fusion of the lumbar spine below L3 is to be avoided, except when specifically indicated. Furthermore, the study shows that the present technique does not adequately preserve the sagittal configuration of the thoracic and lumbar spine.