Anterior single-rod instrumentation of the thoracic and lumbar spine: saving levels

To evaluate the ability of single-rod anterior instrumentation to save or preserve fusion levels and improve thoracic hypokyphosis in patients with adolescent idiopathic thoracic, thoracolumbar, or lumbar scoliosis. To provide indications for single anterior rod instrumentation for the treatment of adolescent idiopathic scoliosis and demonstrate effectiveness in properly selected cases. Posterior multisegmented dual rod instrumentation is the most commonly used instrumentation for the surgical treatment of adolescent idiopathic scoliosis. The issue of longer fusion levels and inability to correct hypokyphosis with posterior instrumentation continues to be debated in the literature. Anterior instrumentation has the ability in certain curve patterns to preserve distal and proximal levels as well as correct thoracic hypokyphosis. A brief discussion of the Lenke adolescent idiopathic scoliosis classification system is presented. Surgical treatment options for each of the curve types are discussed in detail. Single-rod anterior instrumentation for adolescent idiopathic scoliosis will predictably save levels in Type I curves without hyperkyphosis as well as Type 5 curves; however, it is usually contraindicated in Type 2, Type 4, and Type 6 curves. Single-rod anterior instrumentation can occasionally be utilized in Type 3 curves if the magnitude of the lumbar curve is significantly less than the thoracic curve and the flexibility of the lumbar curve approaches 25 degrees on the side-bending radiograph. Single-rod anterior instrumentation will often saved one to three distal fusion levels when treating isolated major thoracic, thoracolumbar, or lumbar curves. Fusion levels should include upper to lower Cobb levels. Additionally, anterior single-rod instrumentation because its kyphogenic nature will predictably correct hypokyphosis of the thoracic spine.