Operative Results of Adolescent Idiopathic Scoliosis Correction using Low-Density Instrumentation with 5-Year Follow-up

Background: The treatment of idiopathic scoliosis has shifted to pedicle screw fixation. The present study was conducted to assess the intermediate-term effectiveness of posterior correction with low-density all-pedicle-screw constructs. Objective: To review the intermediate-term outcome of low-density posterior-only pedicle screw constructs for a 5-year minimum follow-up. Materials and Methods: The retrospective review included 30 patients who underwent posterior correction with low-density all-pedicle-screw constructs during 2004 to 2008. The radiographic measurements at pre-operation, immediate post-operation, 2-years post-operation, and 5-years post-operation were evaluated. Results: Four males and 26 females were included in the present study. The mean follow-up was 6.1 years (range: 5.0 to 9.0). The average age at operation was 14.2+2.2 years. The pre-operative Cobb angle of the major curve was 55.3+12.8°, which was significantly corrected to 15.6+7.8° immediately post-operation, and significantly increased to 17.2+8.2° and to 18.5+8.7° at 2-years post-operation and 5-years post-operation, respectively. The major curve correction loss rate was 25.2%. In the normal thoracic kyphosis group (range: 10° to 40°), the pre-operative thoracic kyphosis angle was 28.0+12.3°, which was non-significantly decreased to 24.1+9.1°, 25.8+8.1°, and 25.8+8.5° at immediately post-operation, at 2-years post-operation, and 5-years postoperation, respectively. Pre-operative lumbar lordosis non-significantly decreased from 42.7+13.0° to 39.5+10.1°, 40.5+9.1° and 41.2+9.4° at immediately post-operation, 2-years post-operation and 5-years post-operation, respectively. Screw density was 0.9 screw per level or 51%. Conclusion: The present study reviewed the 5-year post-operative outcome of posterior correction with low-density all-pedicle-screw constructs. The Cobb angle in coronal alignment correction was improved, but was significantly lost at 2- and 5-years postoperation. Thoracic kyphosis and lumbar lordosis were improved but did not significantly change at 2- and 5-years post-operation.