A recent study revealed large variability among a group of 32 spine surgeons in the preoperative instrumentation strategies for the same 5 adolescent idiopathic scoliosis (AIS) patients. The surgical plans were determined to be surgeon and curve-type dependent. It is hypothesized that this variability may be attributed to different objectives for correction. This study is presented to document and analyze 3-dimensional (3-D) surgical correction goals for AIS as determined by a sample of experienced spine surgeons.
Fifty surgeons from the Spinal Deformity Study Group were surveyed and asked to rank 20 parameters of scoliosis correction and to provide weights for correction in the coronal, sagittal, and transverse planes and for mobility (number of unfused vertebrae) according to their importance for an optimal 3-D correction. Responders were also asked to complete a more detailed survey where the correction objectives were assessed for each of the 6 Lenke curve types. Importance and variability of the correction parameters were evaluated using median (M) and interquartile range (IQR) of the rank (1-20). Intraobserver reliability was assessed by means of intraclass correlation coefficients.
Twenty-five surgeons completed the first questionnaire. There was overall agreement that sagittal (M, 1; IQR, 1) and coronal (M, 2; IQR, 0.5) balance were the most important parameters for an optimal correction. Apical vertebral rotation was the least important. All other parameters were highly variable. The Cobb angles were moderately important, with ranks between 8 and 11 (IQR, 3-5.75). Lumbar lordosis (M, 6.5; IQR, 6.5) had a better rank and consensus than thoracic kyphosis (M, 13; IQR, 10). Results for individual parameters were in agreement with the weights given for an optimal 3-D correction in the coronal (36%) and sagittal (34%) planes. A subgroup of 10 surgeons completed the second survey. Mobility was more important for Lenke curve types 3 to 6 than for types 1 and 2 (P < 0.032). The coronal plane was more important for curve types 2 and 4 than for the other types (P < 0.032). The intraobserver reliability for determining the different parameters of scoliosis correction was poor to moderate.
There is a large variability in scoliosis correction objectives. The variability is both surgeon and curve-type dependent. The variability in instrumentation goals may explain the documented variability of spine instrumentation strategies among surgeons. Aside from achieving sagittal and coronal balance, the goals of surgical correction in AIS remain to be further determined and agreed upon by a consensus of spine deformity surgeons.
From the *Department of Mechanical Engineering, École Polytechnique de Montréal; †Research Center, Sainte-Justine University Hospital Center, Montréal, Québec, Canada; and ‡Department of Orthopedic Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL.
This study was funded by the Natural Sciences and Engineering Research Council of Canada, the Canada Research Chair Program, and an unrestricted educational grant from Medtronic Sofamor Danek.
Reprints: Carl-Eric Aubin, PhD, PEng, Canada Research Chair "CAD Innovation in Orthopedic Engineering", Department of Mechanical Engineering, École Polytechnique, P.O. Box 6079, Station Centre-ville, Montréal, Québec, Canada H3C 3A7. E-mail: firstname.lastname@example.org.