Convex Instrumented Hemiepiphysiodesis with Concave Distraction: A Preliminary Report

Abstract

The convex growth arrest (CGA) procedure has been well accepted for treatment of congenital scoliosis as it is a simpler procedure with successful results. However, unpredictability of curve behavior, slow and usually inadequate correction, and necessity of anterior surgery for completeness of the epiphysiodesis are its shortcomings. In a preliminary study we asked whether a modification of the CGA procedure using convex instrumented hemiepiphysiodesis with concave distraction would correct the coronal plane Cobb angles and would correct or maintain sagittal plane local and global kyphosis angles. We also identified complications. We retrospectively reviewed five female patients who underwent the modified procedure. Their mean age at the index operation was 40 months (range, 17-55 months). The patients underwent concave distractions every 6 months. The magnitude of the convex instrumented and concave distracted curves and sagittal plane parameters were determined on the preoperative and most recent followup radiographs. Minimum followup was 26 months (mean, 34 months; range, 26-40 months). In the coronal plane, the preoperative magnitude of the convex instrumented congenital curve averaged 48A degrees. It was corrected to 36A degrees (25%) postoperatively and was further improved to 27A degrees (44%) at the latest followup. For the distracted segment, the mean preoperative curve was 35A degrees, corrected to 16A degrees postoperatively and to 8A degrees at the latest followup, for an average correction of 77%. Sagittal plane alignment was minimally affected from the procedure. In four of the five patients we identified partial pullout of screws for the concave distraction; these were revised at the time of planned lengthening. This procedure may obviate the need for multiple osteotomies and long thoracic fusions in young children with long sweeping thoracic deformities involving multiple anomalous vertebrae. Implant-related complications on the concave side may be avoided using paired pedicle screws at the proximal and distal anchor sites. Level IV, therapeutic study. See the guidelines online for a complete description of level of evidence.