Scoliosis - Surgery

Instrumentation for Anterior Approach. Specific hardware is needed for the anterior approach, in which the surgeon performs the operation by opening the chest wall. Halm-Zielke instrumentation, for example, uses TSRH instrumentation with bone grafts constructed from ribs to prop open the spaces between the discs. It allows true three-dimensional curve correction. However, it does not solve specific problems with this approach, which are higher risks for kyphosis (an outward curve) and pseudoarthrosis (a false joint at the fusion site). Variants using two rod systems, fusion cages, or other instruments appear to improve this procedure.

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The Surgical Approach

Posterior Approach (Through the Back). Generally, surgeons have used a posterior approach for scoliosis, which reaches the surgical area by opening the back of the patient. It has been the gold standard for decades and is generally used with Harrington instrumentation. The approach has advantages and disadvantages.

Advantages of the Posterior Approach. Surgeons are familiar with it and so fusion rates are excellent, curve correction is good, and it has few complications.
Disadvantages of the Posterior Approach. There is a risk for the crankshaft phenomenon (a worsening of the curve) later on in preadolescent children. (Newer posterior instrumentation, such as the Isola instrumentation, may prevent this occurrence.) The posterior approach also does not always correct hypokyphosis (the loss of normal outward curvature) in the thoracic (upper) spine. The procedure is not always effective for curves in the thoracolumbar region (the region where the upper and lower spine meet) and may even cause spinal abnormalities there.

Anterior Approach (Through the Chest Wall). Increasingly surgeons are using the anterior approach, in which the surgeon performs the operation by opening the chest wall (called a thoracotomy). With the anterior approach, the surgeon makes an incision in the chest, deflates the lung, and removes a rib in order to reach the spine. This rib can be used during the operation as a strut to support the spine. It also may be repositioned within the patient until it is used for bone grafting during fusion.

This approach also has its advantages and disadvantages:

Advantages of the Anterior Approach. Because the frontal approach allows the procedure to be performed higher up in the spine than with standard procedures, the patient may have a lower risk for lower-back injury later on. In addition, transfusion rates are much lower with the anterior approach. With increasing experience, the anterior approach is as effective as the posterior approaches.
Disadvantages of the Anterior Approach. It is a more recent procedure than the posterior approach, and in inexperienced surgeons there is a higher risk for complications than in the more standard posterior approach. One study noted poorer lung function two years after surgery than with the posterior approach, possible because the wide chest incision produces impairs the chest muscles, which can affect lung function afterward. Anterior instrumentation poses a risk for hyperkyphosis (exaggerated outward curvature) and a higher risk for pseudoarthrosis, a painful condition in which a false joint develops at the fusion site. Hardware failure rates may also be higher with the anterior than posterior approach. Increasing experience and newer hardware designs are reducing many of these problems.