Influence of scoliosis corrrection in the thoracic spine on posture compensation in patients with King's type II scoliosis (Lenke's IB, IC).

Background. The aim of our study was to assess the course and outcome in scoliosis without spondylodesis in the lumbar spine after surgical correction performed in the thoracic segment with the C-D method in patients with King's type II scoliosis (Lenke's IB, IC). Material and methods. 42 patients with idiopathic scoliosis were operated in the thoracic spine. The Cobb's angle averaged 635 +/- 9.2 degrees , together with coexistent lumbar scoliosis of 50.1 +/- 13.2 degrees . The mean observation time after surgery with the C-D method was 4.3 +/- 1.8 years. Both curvatures of correction, thoracic kyphosis, and lumbar lordosis were evaluated, as well as the thoracic-lumbar angle and shape of the lumbar scoliosis in relation to the central vertical sacral line were analyzed. Results. C-D surgery corrected thoracic scoliosis up to 28.8 +/- 8.3 degrees (54.6% scoliosis correction). Secondary correction of lumbar scoliosis not treated with C-D instrumentation made it possible to obtain a Cobb's angle of 28.9 +/- 9.7 degrees (42.3% scoliosis). Selective instrumentation and spondylodesis of scoliosis in the thoracic spine coexisted with transient decompensation of the posture on the left after surgery in 7 patients. Subsequent postsurgical observation showed the percentage of scoliosis correction in the lumbar spine decreasing to 32.7% and then to 29%. The number of patients with posture decompensation decreased to 2 cases. Conclusions. Equilibrated correction of scoliosis at the thoracic level reaching 50-60% of initial value is correlated in postsurgical observation with a small percentage of secondary decompensation of posture. The number of patients with postoperative decompensation decreases with corrections in the lumbar spine not treated with instrumentation during scoliosis surgery.