A proposal for a surgical classification of pediatric lumbosacral spondylolisthesis based on current literature

The classification presented in this paper is the first specifically designed to guide surgical treatment of L5-S1 spondylolisthesis in children and adolescents. It also presents objective criteria to differentiate between low- and high-dysplastic spondylolisthesis and incorporates recent knowledge in the study of sagittal spinopelvic balance. The proposed classification is based on the following: (1) the degree of slip, (2) the degree of dysplasia, and (3) the sagittal spinopelvic balance. To classify a patient, the degree of slip is quantified first to determine if it is low-grade, high-grade, or a spondyloptosis. Then, the degree of dysplasia is evaluated based on seven criteria, in order to separate patients with low- and high-dysplastic spondylolisthesis. Finally, the sagittal spinopelvic balance is assessed from the measurement of the pelvic incidence (PI), sacral slope (SS), and pelvic tilt (PT). For low-grade spondylolisthesis, it is classified as low PI/low SS (nutcracker type) or high PI/high SS (shear type). For high-grade spondylolisthesis, it is classified as high SS/low PT (balanced pelvis) or low SS/high PT (retroverted pelvis). Such a comprehensive classification could allow to better evaluate and compare available surgical techniques, and to optimize the treatment of L5-S1 spondylolisthesis. Because the classification was designed so that groups are organized in an ascending order of severity, it becomes easier and more intuitive to develop an associated surgical algorithm because the complexity of the surgery should increase as the severity of the spondylolisthesis increases. A tentative treatment algorithm is proposed but it is not definitive because further studies are required to define the most appropriate treatment for each group.