Advances in the Surgical Management of Idiopathic Adolescent Scoliosis

Thoracoscopic anterior release and fusion is an advanced surgical technique for correction of adolescent idiopathic scoliosis (AIS). In this procedure, the thoracic spine is accessed through small incisions on the side of the chest and the surgery performed with the aid of a thoracoscope (an illuminated optical instrument). The surgical procedure involves a discectomy (removal of one or more discs). The abnormal curvature is 'released' and the spine realigned and held in place using instrumentation and fusion. The advantages to this procedure include fewer levels in the fusion, resulting in a more flexible spine; decreased pain after surgery; less scarring; and curve correction comparable to that of an open procedure.

Safety and Effectiveness Proven

Since 1991, we have been prospectively evaluating (following patients forward in time) the safety and efficacy of anterior thoracic instrumentation inserted through an open incision, and we have been inserting the instrumentation with the thoracoscope since 1996. The procedure with both insertion techniques has been shown to be safe and effective, with results comparable to those of posterior spinal fusion. In selective anterior fusion, fewer vertebrae are fused. Thus the scoliosis can be corrected while leaving the spine flexible and relatively well aligned.

Surgical Considerations

The primary indication for thoracoscopic anterior instrumentation and fusion is a thoracic curve measuring between 40 and 70° by the Cobb method (a full-length AP x-ray is to used calculate the curve angle in degrees). Patients between 10 and 21 years of age are good candidates because the vertebrae are usually fully formed and the spine flexible. Since the anterior instrumentation adds kyphosis, patients must have kyphosis measuring less than 40° (and less than 20° is ideal, because the kyphosis will then fall into the normal range following surgery).

Anesthesia Requirements

The patient must be able to tolerate one-lung anesthesia, in which one lung must be completely collapsed for the entire procedure to allow space for the thoracoscope and other instruments. Preoperative pulmonary function (lung capacity) tests are necessary. The anesthesiologist must be experienced in utilizing one-lung ventilation techniques in order for the procedure to succeed.

Study Results

For the first 30 patients (28 female, 2 male) who have undergone the thoracoscopic procedure for AIS:

Complications

Two patients developed a peroneal palsy (paralysis) of the underneath leg, which resolved by six weeks following surgery. This problem was resolved by changing the leg position in the operating room. Three patients developed a pleural effusion (fluid accumulation in the membrane encasing the lungs), which resolved without needing to insert a chest tube. In three patients a rod broke following surgery, one of which was surgically repaired and the other two are being watched. Improvements in the bone grafting technique to obtain fusion have decreased this problem.

Conclusion

If left untreated, thoracic AIS of 40º or greater may progress after the spine has finished growing. However, adolescent patients are usually concerned with the more immediate problem of trunk deformity. A procedure, which can correct and fuse AIS in a minimally invasive fashion is extremely attractive to patients, families and surgeons. The benefits of the procedure (most notably improved appearance of the thoracic deformity and a mobile lumbar spine as the patients get older) are immeasurable.