Sometimes scoliosis (curvature of the spine) occurs in children for unknown reasons. But it can also develop when there are deformities of the bone such as a hemivertebra. Hemivertebra means only half of the spinal bone formed. The other side is missing, which causes the bones above and below the deformed bone to tip or collapse to one side. The result is a curved spine.
If this problem is diagnosed early (before age six), the deformed half of a vertebra can be removed surgically. Studies show that these children have excellent results with this procedure. But this approach doesn’t work when the problem isn’t recognized until the child is older. Treatment is especially challenging if the spine has matured (bone growth is complete or nearly complete).
In this study, spinal surgeons from the University School of Medicine in Shanghai, China try a new technique to correct the problem of late diagnosed congenital spinal deformity. It’s called a posterior unilateral pedicle subtraction osteotomy of hemivertebra for the correction of adolescent congenital spinal deformity.
To understand what’s done, imagine the surgeons entering the spine from the back rather than the front of the body. That’s what posterior means. Unilateral tells us only one side is operated on. And an osteotomy is removing a wedge-shaped piece of bone.
In this procedure, the surgeon removed this pie-shaped piece from the deformed hemivertebra. Along with the piece of vertebral bone, they also removed the transverse process — that’s the bony bump you feel along the back of your spine. The effect is to allow the remaining edges of bone to collapse toward each other.
The surgeon guided either side of the remaining bone fragments to move together — enough to close the gap formed by removing the piece of bone. The end result is correction of the curve. It’s called a subtraction osteotomy because only a portion of the deformed vertebra is removed or taken away (subtracted).
Then screws and rods are placed above and below the level operated on to hold them in place until healing occurs. This part of the procedure is called corrective fixation or instrumented fusion.
Doing the procedure this way saves the bone and the discs between the deformed hemivertebra and the spinal bones above and below it. Having those discs in place helps stabilize the spine.
The procedure also has the advantage of being simpler with less time in the operating room. The risk of bleeding is less and there are fewer other complications compared with removing the entire deformed half-vertebra.
When should this surgical approach be used? Well, as mentioned, older children with a painful scoliosis that has not been helped by bracing or other conservative measures may benefit. How well does it work?
The results of this first study are still considered preliminary (early). But in all cases, after four years, the fusion held and the spine remained stable. Pain relief was obtained for everyone.
Further study of this group is still needed to see what happens over a longer period of time such as 10 to 20 years after corrective surgery. Identifying the ideal patient for the posterior unilateral pedicle subtraction osteotomy must also be determined. It’s likely that the age of the patient, level of skeletal maturity, severity and location of the curve, and type of hemivertebra will be factors to consider.