Operative Results of Adolescent Idiopathic Scoliosis Correction using Low-Density Instrumentation with 5-Year Follow-up
Chotigavanichaya C, MD1, Saisamorn K, MD1, Ariyawatkul T, MD1, Ruangchainikom M, MD1, Luksanapruksa P, MD1, Wilartratsami S, MD1, Chotivichit A, MD1, Thanapipatsiri S, MD1
Affiliation : 1 Department of Orthopaedic Surgery, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
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 post-
operation, 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 post-
operation. Thoracic kyphosis and lumbar lordosis were improved but did not significantly change at 2- and 5-years post-operation.
Keywords : Adolescent Idiopathic scoliosis, pedicle screws, posterior spinal fusion all-pedicle-screw constructs, low screw density (Spinal fusion)
