The problem of double thoracic idiopathic scoliosis: a non-systematic literature review

Abstract

Objective. To analyze the current situation in the community of spine surgeons regarding the determination of the zone of posterior spinal fusion for double thoracic idiopathic scoliosis.Material and Methods. The content of 16 publications containing the results of surgical correction of double thoracic scoliotic deformities was analyzed. The number of studied clinical cohorts was 25, of which in 13 groups only the right-sided main thoracic (MT) curve (MT group) was blocked, and in 12 – both MT and left-sided proximal upper thoracic (PT) curve (MT + PT group). Four parameters were analyzed in both groups: preoperative Cobb angle, preoperative curve mobility, deformity correction, and postoperative deformity progression.Results. Significant differences were found in the MT and MT + PT groups only in two cases: for the initial Cobb angle of the PT curve and the magnitude of its correction (Cobb angle before surgery minus Cobb angle immediately after the intervention). When choosing the extent of the instrumental fusion zone, the authors of the publications included in the review were guided, first of all, by the initial magnitude of the Cobb angle of the proximal thoracic curve. In the MT + PT group, it averaged 37–40° and was 11–13° more than in the MT group. At the same time, PT curve mobility in both groups is not statistically different. The achieved correction was statistically significantly greater in the МT + РT group, despite a more severe proximal curvature as compared to the MT group. Postoperative dynamics of kyphosis (both T2–T5 and T5–T12) is insignificant. The length of the instrumental spinal fusion zone has virtually no effect on the parameters of the sagittal contour of the thoracic spine. A fairly high frequency of the adding-on phenomenon development (20.6 %) indicates the presence of a connection between this complication and the dynamics of PT curve, but the available data are not enough to formulate a final conclusion. Literature data regarding patients’ self-assessment of quality of life after surgical treatment of Lenke types 1 and 2 scoliosis are scarce, although the majority of those operated on assess the result of treatment as positive.Conclusion. The problem of determining the extent of the instrumental fusion zone for double thoracic scoliosis remains unresolved. Most surgeons focus not so much on the mobility of the proximal curve, but on its magnitude. There is no consensus in predicting the development of the adding-on phenomenon; there is little information about changes in the quality of life of patients after surgery. New research is needed.