Pulmonary Function After Thoracoplasty in the Surgical Treatment of Adolescent Idiopathic Scoliosis

Study Design: Retrospective case series review. Objective: To compare two similar groups of adolescents surgically treated for their spinal deformity either by posterior segmental fusion alone (PSF) or by posterior spinal fusion and thoracoplasty (PSF+T); attention was focused on the long-term effects of thoracoplasty on pulmonary function in the surgical treatment of adolescent idiopathic scoliosis. Summary of Background Data: Posterior spinal arthrodesis with thoracoplasty and an open anterior approach, with respect to a posterior only fusion have been found to have a deleterious effect on pulmonary function for as long as five years postoperatively after surgical treatment of adolescent idiopathic scoliosis. Methods: A group of 40 consecutive adolescent patients, surgically treated between 1998 and 2001 by posterior spinal fusion and thoracoplasty, was compared with a similar cohort of 40 adolescents treated in the same period by posterior segmental fusion alone. Pedicle screw instrumentation alone and a minimum five-year follow-up were requested as inclusion criteria. Both a radiographic analysis and a chart review was performed, evaluating the pulmonary function tests (PFTs), the SRS-30 score questionnaire and the Lenke classification system. A radiographic Rib Hump (RH) assessment was also performed. Results: The entire series was reviewed at an average clinical follow-up of 8.3 years. There were no statistically significant differences between the two groups in terms of gender, age (PSF+T: 16.3 y vs. PSF: 15.2 y), Lenke curve type classification and preoperative Cobb's main thoracic (MT) curve magnitude (PSF+T: 661 vs. PSF: 631), whereas both final MT percent correction (PSF+T: 53.03% vs. PSF: 51.35%; P<0.03), RH absolute correction (PSF+T: -2.1 cm vs. PSF: -1.05; P<0.01) and RH overall percent correction (PSF+T: 55.4% vs. PSF: 35.4%; P<0.0001) were greater in the thoracoplasty group. No statistical differences were observed between the two groups in PFTs both pre-operatively and at last follow-up. Nevertheless, comparing preoperative to final PFT'S within each group, only in the PSF group both forced vital capacity and forced expiratory volume in one second showed a statistically significant improvement at final evaluation. At last follow-up visit, the SRS-30 scores did not show any statistical difference between the two groups (total score PSF+T: 4.1 vs. PSF: 4.3). Conclusions: Our findings suggest that thoracoplasty did not adversely affect long-term PFTs in AIS patients treated by posterior spinal fusion alone using pedicle screws instrumentation, as already highlighted by previous reports. A trend towards better coronal plane correction and rib hump improvement was seen, although not clearly reported in a self-assessment disease-specific questionnaire.