Surgical treatment of adolescent idiopathic scoliosis: the basics and the controversies.

Decisions about when to operate should be based on more than just an arbitrary Cobb measurement. The patient's skeletal maturity, balance, and other parameters of curve size also should be considered. Although it is desirable to fuse as few segments as possible, there is no benefit to fusing short if the top and bottom of the fusion is not neutral and stable. Especially for lumbar fusions, the last instrumented vertebra must be stable, neutral, and horizontal to the sacrum postoperatively. Many thoracic/lumbar curve patterns are Type II (false double major) and not double major curves. They often can be treated with selective thoracic fusion. However, many variables are involved, and the potential for decompensation should be discussed with the patient and the patient's family so they know that it may be necessary to later add the lumbar curve. The rod rotation maneuver and anterior segmental spinal instrumentation often may save fusion levels over what may have been needed with Harrington instrumentation. However, there are many variables here as well. Surgeons should be particularly concerned with maintaining and re-creating enough segmental lordosis for the patient so the spine can withstand the inevitable aging process.