Gain in spinal height from surgical correction of idiopathic scoliosis.

Background: A relationship between spinal distraction and correction of the curvature of scoliosis has long been recognized. While attempts have been made to define the height that is lost with progression of scoliosis, much less information is available to define the height that is gained as a result of surgical correction of the curve and to quantify additional spinal growth after spine fusion.

Methods: The present study included 116 patients (mean age, 14.8 years) who underwent spinal instrumentation and fusion for the treatment of idiopathic scoliosis. The study group included ninety-one female patients and twenty-five male patients; all Lenke curve types were represented. The Cobb angle and the T1-L5 spinal height were evaluated on preoperative, postoperative, and two-year follow-up radiographs. Kyphosis, lordosis, and T1-L5 spinal length were measured on lateral radiographs. The Scoliosis Research Society (SRS) questionnaire was completed prior to surgery and at each visit. Multivariate linear regression defined the relationship between spinal height gain, Cobb angle correction, and other variables as well as final spinal height.

Results: The mean spinal height gain due to surgery was 27.1 mm (median, 25.1 mm; interquartile range, 14.5 to 37.9 mm; range, -3.8 to 66.1 mm). The magnitude of curve correction (mean, 38.2°; range, 6° to 67°), the number of vertebral levels fused (mean, 9.9; range, three to sixteen), and the preoperative stature (standing height) of the patient were all significant predictors (p < 0.01) of spinal height gain (R2 = 0.8508 for multivariate model). The mean changes in kyphosis and lordosis were small and were not significant predictors. An additional 4.6 mm of mean spinal height was gained at the time of the two-year follow-up; this increase was significantly related to young age, male sex, shorter fusions, and a Risser stage of ≤2 at the time of surgery (p < 0.01 for all in multivariate analysis). The SRS-30 scores improved significantly (p < 0.0001), independent of spinal height gain.

Conclusions: Patients undergoing surgical correction of idiopathic scoliosis gain substantial height related to the magnitude of surgical correction, the number of levels fused, and preoperative stature. Continued spine growth by two years after surgery is associated with shorter fusions, skeletal immaturity, young age, and male sex. Height gain is a quantifiable outcome of the surgical correction of scoliosis.