Pulmonary Function at Minimum 10 Years After Segmental Pedicle Screw Instrumentation for Thoracic Adolescent Idiopathic Scoliosis.

Study Design: A prospective multi-center cohort study.

Objective: This study evaluates the 10-year pulmonary function outcomes for patients with structural thoracic adolescent idiopathic scoliosis (Lenke curve types 1-4, 6) after segmental pedicle screw instrumentation.

Summary Of Background Data: Adolescent idiopathic scoliosis with thoracic curves is associated with reduced pulmonary function preoperatively. It remains unclear how much pulmonary improvement can be obtained using pedicle screw instrumentation at long-term follow-up.

Methods: Out of 64 consecutively surgically treated patients with thoracic AIS (Lenke 1-4, 6) using pedicle screw instrumentation, 50 (mean age at final FU 14.7 ± 1.9, 44 females) participated in a prospective 10-year follow-up study. They were evaluated using clinical examination, spinal radiographs, and spirometry preoperatively and at 10-year follow-up. The preoperative percentage predicted values were adjusted for the height loss caused by the scoliosis according to curve size.

Results: Preoperatively 49% (20/41) had forced vital capacity (FVC) or forced expiratory volume in one second (FEV1) below 80% of the predicted normal values representing pulmonary function impairment. Major curve correction averaged 76% (SD 9%). FVC improved from preoperative 3.29 L (SD 0.78L) to 3.87 L (0.79L) at 10-year follow-up (P<0.001). This improvement averaged 510 mL (SD 560 mL) in patients having both preoperative and 10-year follow-up measurements available. The percentage predicted values for FVC showed an improvement from 83% preoperatively to 86% at 10-year follow-up (P=0.048). At 10-year follow-up 38% (19/50) of the patients had FVC or FEV1 below 80% of the predicted values.

Conclusions: FVC improved by a mean of 510 ml from preoperative to 10-year follow-up in patients undergoing pedicle screw instrumentation for thoracic AIS. Despite 76% scoliosis correction and significant improvement of absolute lung volume values, more than one-third of these surgically treated otherwise healthy young adults fulfilled the criteria for pulmonary function impairment at 10-year follow-up.

Level Of Evidence: II.