EFFECTS OF THE COMBINED VDS-ZIELKE AND HARRINGTON OPERATION ON THE FRONTAL RIB CAGE DEFORMITY OF DOUBLE MAJOR CURVES IN IDIOPATHIC SCOLIOSIS

Study Design. This study, analyzed the changes in the frontal plane of the deformed lower rib cage and the scoliosis-related alterations on the spine in patients with double major curve-pattern idiopathic scoliosis. Objectives. The results obtained preoperatively, after the Zielke operation, postoperatively after the Harrington instrumentation, and at the follow-up evaluation were compared to investigate which changes of the elements of the rib cage deformity are caused by each of the two instrumentations. Summary of Background Data. Previously, Wojcik reported on the effects of a Zielke operation on the lower rib in mild S-shaped idiopathic scoliosis. No previous data exist regarding the lower rib cage deformities in severe idiopathic double major-pattern scoliosis and their changes after combined VDS-Zielke and Harrington instrumentation. Methods. Fifteen patients who underwent the staged Zielke operation followed by Harrington rod instrumentation were followed-up for an average period of 31.1 months. The methods used in our study included Cobb angle and a segmental analysis (T7-T12) of each of convex and concave rib-vertebra angles, rib-vertebra angle differences, vertebral rotation, and vertebral tilt. Results. In this series, the apical convex ribs showed an increased droop preoperatively compared with the concave apical ribs. The VDS-Zielke operation corrected the lumbar scoliosis in an average of 63% of patients, whereas the thoracic scoliosis showed an immediate spontaneous correction of 30%. The VDS-Zielke operation also produced a significant correction of the scoliosis-related vertebral tilt (T10-T12), derotated the lumbar vertebrae and the T12 vertebra significantly, elevated the ''mobile'' concave ribs, and increased the droop of the lower (T11, T12) ''mobile'' convex ribs. The Harrington instrumentation did not change the vertebral rotation, the vertebral tilt, the convex rib-vertebra angle, or the L4 obliquity, but significantly changed the apical concave rib-vertebra angle. The combined Zielke-Harrington instrumentation reduced the thoracic kyphosis and the thoracolumbar junction-kyphosis significantly, whereas the lumbar lordosis remained practically unchanged. Conclusions. Only the anterior VDS-Zielke instrumentation significantly corrects severe spinal deformities, elevates the three lower ribs on the concavity, and increases the droop of the two lower ribs on the convexity in the severe idiopathic double major curve-pattern scoliosis combined operated (Zielke-Harrington). Therefore, the Harrington instrumentation should have only limited use in cosmetic scoliosis surgery and should be replaced with posterior multi-hook instrumentation with a derotation effect.