Juvenile idiopathic scoliosis treated with posterior arthrodesis and segmental pedicle screw instrumentation before the age of 9 years: a 5-year follow-up

STUDY DESIGN Retrospective study. OBJECTIVE To evaluate the radiological results of fusion with segmental pedicle screw fixation in juvenile idiopathic scoliosis with a minimum 5-year follow-up. SUMMARY OF BACKGROUND DATA Progression of spinal deformity after posterior instrumentation and fusion in immature patients has been reported by several authors. Segmental pedicle screw fixation has been shown to be effective in controlling both coronal and sagittal plane deformities. However, there is no long term study of fusion with segmental pedicle screw fixation in these group of patients. METHODS Seven patients with juvenile idiopathic scoliosis treated by segmental pedicle screw fixation and fusion were analyzed. The average age of the patients was 7.4 years (range 5-9 years) at the time of the operation. All the patients were followed up 5 years or more (range 5-8 years) and were all Risser V at the most recent follow up. Three dimensional reconstruction of the radiographs was obtained and 3DStudio Max software was used for combining, evaluating and modifying the technical data derived from both 2d and 3d scan data. RESULTS The preoperative thoracic curve of 56 +/- 15 degrees was corrected to 24 +/- 17 degrees (57% correction) at the latest follow-up. The lumbar curve of 43 +/- 14 degrees was corrected to 23 +/- 6 degrees (46% correction) at the latest follow-up. The preoperative thoracic kyphosis of 37 +/- 13 degrees and the lumbar lordosis of 33 +/- 13 degrees were changed to 27 +/- 13 degrees and 42 +/- 21 degrees , respectively at the latest follow-up. None of the patients showed coronal decompensation at the latest follow-up. Four patients had no evidence of crankshaft phenomenon. In two patients slight increase in Cobb angle at the instrumented segments with a significant increase in AVR suggesting crankshaft phenomenon was seen. One patient had a curve increase in both instrumented and non instrumented segments due to incorrect strategy. CONCLUSION In juvenile idiopathic curves of Risser 0 patients with open triradiate cartilages, routine combined anterior fusion to prevent crankshaft may not be warranted by posterior segmental pedicle screw instrumentation.