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 scoli osis. Objectives. The results obtained preoperatively, after the Zielk e operation, postoperatively after the Harrington instrumentation, and at the follow-up evaluation were compared to investigate which change s of the elements of the rib cage deformity are caused by each of the two instrumentations. Summary of Background Data. Previously, Wojcik r eported on the effects of a Zielke operation on the lower rib in mild S-shaped idiopathic scoliosis. No previous data exist regarding the lo wer rib cage deformities in severe idiopathic double major-pattern sco liosis and their changes after combined VDS-Zielke and Harrington inst rumentation. 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 i ncluded Cobb angle and a segmental analysis (T7-T12) of each of convex and concave rib-vertebra angles, rib-vertebra angle differences, vert ebral rotation, and vertebral tilt. Results. In this series, the apica l convex ribs showed an increased droop preoperatively compared with t he concave apical ribs. The VDS-Zielke operation corrected the lumbar scoliosis in an average of 63% of patients, whereas the thoracic scoli osis showed an immediate spontaneous correction of 30%. The VDS-Zielke operation also produced a significant correction of the scoliosis-rel ated 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. Th e Harrington instrumentation did not change the vertebral rotation, th e vertebral tilt, the convex rib-vertebra angle, or the L4 obliquity, but significantly changed the apical concave rib-vertebra angle. The c ombined Zielke-Harrington instrumentation reduced the thoracic kyphosi s and the thoracolumbar junction-kyphosis significantly, whereas the l umbar lordosis remained practically unchanged. Conclusions. Only the a nterior VDS-Zielke instrumentation significantly corrects severe spina l deformities, elevates the three lower ribs on the concavity, and inc reases the droop of the two lower ribs on the convexity in the severe idiopathic double major curve-pattern scoliosis combined operated (Zie lke-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.