Review Question - QID 28

In select patients with thoracolumbar idiopathic scoliosis, an anterior approach with a single rod and interbody cages may be indicated. Thoracic hyperkyphosis (>40 degrees ) is a risk factor for pseudoarthrosis in patients treated with this method.

In a prospective study, Sweet et al found anterior instrumented fusions using a single solid rod had good radiographic and clinical outcomes. In their treatment group they found common risk factors for pseudarthrosis were smoking, weight >70 kg, and T5-T12 hyperkyphosis of > 40 degrees. They recommend consideration should be given to alternate techniques in larger adolescents (>70 kg) with thoracic hyperkyphosis (>40 degrees ). The average coronal correction of thoracic curves was from 55 degrees to 29 degrees (47%). The average correction of thoracolumbar/lumbar curves was from 50 degrees to 15 degrees (70%). Neither of these variables were associated with pseudoarthrosis. In the sagittal plane, lordosis was maintained in thoracolumbar/lumbar fusions at -58 degrees (T12-sacrum). Improved maintenance of lumbar lordosis is considered one of the advantages of an anterior approach.

In an additional study from the same group at Wash U, Hurford et al designed a study to compare the results of anterior DUAL-rod instrumentation with their previous experience using single-rod constructs. They found the two technique were comparable in the amount of radiographic deformity correction obtained. However, they report the absence of any pseudarthroses in the 60 patients with dual-rod is a distinct advantage over the single rod technique.