Double Major Curves

Keith H. Bridwell

Goals of Surgical Treatment

To maintain balance, achieve acceptable correction, and minimize fusion levels.

Diagnosis

There is somewhat of a fine line between a type I curve and a double major curve. I interpret a truly type I curve as one in which the lumbar curve is structural and the thoracic curve is relatively nonstructural. A typical presentation is a right thoracic curve in conjunction with the left lumbar curve. If the lumbar curve is substantially bigger, has more rotation, and creates more deformity, one might consider a selective posterior or anterior fusion of just the lumbar curve. On the other hand, if the thoracic curve is more structural, and in particular if the right shoulder is substantially higher than the left (assume a right thoracic, left lumbar pattern), then one is more likely to fix both curves posteriorly. In most cases, I selectively fix the lumbar or thoracolumbar curve anteriorly if the patient’s shoulders are relatively level and if the lumbar curve has substantially more apical deviation and rotation than the thoracic curve. On the other hand, if the lumbar and thoracic curves are relatively similar in terms of apical deviation and rotation, then I would be more likely to fix both curves posteriorly. Also, if the right shoulder is substantially higher than the left, then I am somewhat more apt to fix both curves posteriorly. This is determined in part by physical examination and in part by the standing coronal and lateral radiographs. If there is a substantial junctional kyphosis between the two curves, then I am more apt to fix both of them. So in this chapter I discuss the situation in which I would fix both curves as opposed to just the thoracolumbar/lumbar curve.

Indications for Surgery

1. A double major curve pattern in which both the thoracic and the lumbar curves are substantial as demonstrated by their Cobb measurement, rotation, and apical deviation.

2 Either the shoulders are level or the right shoulder is substantially higher than the left, if it is a right thoracic/left lumbar curve.

3. The tidemark for fixing double curves is somewhat higher than the tidemark for single curves.

Contraindications

The relative contraindications are a presentation in which either the thoracic curve is substantially bigger than the lumbar curve or the lumbar curve is substantially bigger than the thoracic curve. In those situations, one is more apt to selectively fix one curve and not the other.

Advantages

The advantage of the posterior approach is a balanced correction of both curves and therein less likelihood of throwing the patient off-balance in the coronal plane by significantly correcting one curve more than the other.

Disadvantages

1. Long fusion.

2. Usually the lumbar curve is more flexible than the thoracic. Therefore, even if one is fixing both curves posteriorly, there may be a tendency to achieve more correction of the lumbar curve than the thoracic curve.