Radiographic Characteristics Of Scoliosis In Arthrogryposis Multiplex Congenita

Part one:Radiographic characteristics of scoliosis in arthrogryposis multiplex congenitaObjective:To investigate the radiographic characteristics of scoliosis in arthrogryposis multiplex congenita (AMC).Methods:From November 2001 to April 2013, a total of 41 AMC patients who visited our hospital initially for scoliosis, including 21 males and 20 females with the age ranging from 4 to 28 years (average,15.6±3.9 years), was reviewed retrospectively. Curve pattern and levels of involved vertebrae were recorded. The following parameters were measured:the Cobb angle of main curve, flexibility, pelvic obliquity, thoracic kyphosis(TK) and lumbar lordosis (LL). Correlation analysis was performed between pelvic obliquity and coronal curve.Results:7 cases were associated with congenital vertebral anomalies. Single curve was found in 37 cases (90%), among whom there were 21 with a single thoracic curve and 16 with a single thoracolumbar curve. Only 4 cases (10%) had double curves that were thoracic and lumbar curves. The main curve averagely spanned 9±1 levels. The Cobb angle averaged 80°±29°, and the flexibility averaged 20°±11%. There were 22 cases (54%) who had pelvic obliquity with the angle ranging from 7° to 27°(average, 16°±5°). Significant positive correlation was found between pelvic obliquity and the Cobb angle of main curve (r=0.612,P<0.05). On the sagittal plane,20 cases (49%) had thoracic lordosis,5 (12%) had decreased thoracic kyphosis and 24 (59%) had lumbar hyperlordosis.Conclusions:Single curve pattern is predominantly seen in scoliosis with AMC. The curves are always rigid. Congenital vertebral anomalies may also be detected in part of patients. Single curve with rigid flexibility and pelvic obliquity on the coronal plane, and thoracic and lumbar hyperlordosis on the sagittal plane are the typical features of scoliosis in AMC. Pelvic obliquity strongly correlates with severity of scoliosis.Part two:Does addition of crosslink to pedicle-screw-based instrumentation impact the development of the spinal canal in children younger than 5 years of age?Objective. To determine the influence of the screw-rod-crosslink complex on the development of the spinal canal.Methods. This study reviewed thirty-four patients with congenital scoliosis (14 boys and 20 girls) who were treated with posterior-only hemivertebrectomy and pedicle-screw-based short-segment instrumentation before the age of 5 years. The mean age at surgery in this cohort was 37±11 months (range,21-57 months). They were followed up for at least 24 months. Of these patients,10 underwent only pedicle screw instrumentation without crosslink, and 24 with additional crosslink placement. The vertebrae were divided into three regions as follows:(1) S-CL (screw-crosslink) region, in which the vertebrae were inserted with bilateral pedicle screws and two rods connected with the crosslink; (2) S (screw) region, in which the vertebrae were inserted with bilateral pedicle screws but without crosslink; (3) NS (no screws) region, which comprised vertebrae cephalad or caudal to the instrumented region. The area, anteroposterior and transverse diameters of the spinal canal were measured at all vertebrae on the postoperative and last follow-up computed tomography axial images. The instrumentation-related parameters were also measured, including the distance between the bilateral screws and the screw base angles. The changes in the above measurements were compared between each region to evaluate the instrumentation’s effect on the spinal canal growth.Results. The mean follow-up was 37±13 months (range,24-68 months) and the mean age at the last follow-up was 74±20 months (range,46-119 months). In each region, the spinal canal dimensions significantly increased during the follow-up period. There was no significant difference in the spinal canal growth rate between the S and NS regions or between the S-CL and NS regions. Besides, a comparison of the S-CL and S regions regarding the changes in the measurements of the instrumentation construct revealed no significant differences.Conclusion. Pedicle-screw-based instrumentation does not cause retardation of the development of the spinal canal in young children. Moreover, use of the crosslink added to the screw-rod instrumentation also demonstrates no negative effect on the growth of the spinal canal. Thus, the addition of the crosslink to screw-based instrumentation is recommended to increase fixation stability in growing patients, even in very young pediatric population.