Effect Of Pedicle Screw Fixation On Vertebral Body And Spinal Canal Development In Children Under 5 Years Old

Background:Segmental pedicle screws instrumentation is the most advanced and effective treatment of scoliosis. Compared to other treatments, it demonstrated better correction rate, lower revision rate, less fusion segments, less blood loss and surgical time. Because this procedure may damage the neurocentral synchrondrosis, some authors fears that the application of this treatment in very young children could result in retardation of vertebral development. This hypothesis has been demonstrated in a plenty of experiments in animal models. However, a few reports concerning about the same issue in very young pediatric patients showed no retardation of vertebral growth.Methods:All patients with a diagnosis of congenital scoliosis or congenital kyphosis were retrospectively reviewed. The patients who underwent pedicle screw fixation younger than 5 years old and have been followed for at least 5 years were enrolled in this study. Preoperative and the last follow-up radiological data were obtained. The values of pedicle length, vertebral body length, anteroposterior diameter of the spinal canal, transvers diameter of the spinal canal and area of the spinal canal in preoperative images and the last follow-up images were measured in all instrumented vertebrae and adjacent non-instrumented vertebrae. The growth values during the follow-up time were calculated and analyzed statistically.Results:1、 13 patients were enrolled in this study. A total of 107 levels of vertebrae were measured. The mean age at surgery of all patients was 40.5 months, ranging from 24 months to 60 months. The mean follow-up time was 86.4 months, ranging from 60 months to 132 months.2、 Significant differences existed in pedicle length, vertebral body length, anteroposterior diameter of the spinal canal and area of the spinal canal between all instrumented vertebrae and non-instrumented vertebrae.3、 In thoracic region, no significant differences existed between instrumented vertebrae and non-instrumented vertebrae. In lumbar region, differences existed in pedicle length and area of the spinal canal between instrumented vertebrae and non-instrumented vertebrae4、significant differences existed in pedicle length between thoracic vertebrae and lumbar vertebrae in the non-instrumented group, while no significant differences existed between thoracic vertebrae and lumbar vertebrae in the instrumented groupConclusion:Pedicle screws instrumentation may have dual effect on the vertebral growth, promoting the growth of posterior vertebral elements and also inhibiting the growth of anterior vertebral elements. The underlying reason for the accelerated growth of posterior vertebral elements maybe the multiple positive effects of dynamic compression imposed on cartilage tissue. The mechanism for the negative effect on the growth of vertebral body is not explicit.