High-grade lumbosacral spondylolisthesis is a heterogeneous developmental disorder that often manifests clinically in childhood and adolescence. Pain, hamstring tightness, cosmetic deformity, neurologic symptoms, and sagittal malalignment are common accompanying symptoms that may result in varying degrees of functional and psychological disability. Associated disability and health-related quality of life (HRQoL) scores have been consistently correlated with severity of global sagittal malalignment and abnormal lumbopelvic alignment in children and adolescents with high-grade lumbosacral spondylolisthesis. In this chapter, we present a case of an adolescent with a high-grade dysplastic spondylolisthesis (Labelle type 5) that was initially treated with in situ posterolateral fusion and instrumentation. Eight years after the operation, she developed instrumentation failure with associated pseudarthrosis. We discuss the revision operation used to address this complication as well as the most current evidence to support how this complication may have been prevented with a different initial surgical strategy using interbody support and a reduction to improve regional and global sagittal malalignment.