The surgical treatment of large spinal (scoliosis) curves in children has evolved over the past four decades. In the 1960s, rods were used to distract or separate the vertebral bodies, put them in good alignment, and hold them there while the child or teen grew. But a better way was found to correct the spinal curve in all three planes (3-D correction) and that was with segmental wires and hooks. Instead of a long rod holding the spine in place, these smaller components linked several segments together. Hooks proved to be safe, easy to place, and effective.
In the last 10 years, the surgical correction of scoliosis has taken another turn. Now pedicle screws are used to achieve fusion in all three planes and improve correction of spinal deformity in children with adolescent idiopathic scoliosis. This type of spinal curvature occurs in older children and teens with no known cause. That’s what idiopathic means (unknown).
Pedicle screws are placed posteriorly (from the back of the spine) into a column of bone called the pedicle. The pedicle connects the body of the vertebra to the vertebral arch or ring behind the vertebral body. The vertebral arch goes around the spinal cord to protect it, leaving an opening called the spinal canal for the spinal cord to travel from the brain down to the bottom of the spine.
In this review article, the benefits and disadvantages of an all-pedicle-screw treatment for severe scoliosis are presented. Most of the information comes from expert opinion and consensus (agreement) of many orthopedic surgeons rather than from Level I evidence. Level I evidence is the highest form of research and in this case would be based on comparative studies (results using rods versus hooks versus pedicle screws). For now, studies of the all-pedicle-screw approach are confined to case series and cadaver studies. Cadaver studies involve experimentation on spines preserved after death for scientific study.
Despite some concerns about the safety of pedicle screws, they have been found to be completely safe as well as effective in correcting spinal deformity and maintaining that correction. Surgeons have found that it is possible to get better correction in all three planes of spinal deformity by using pedicle screw fixation. Studies show the screws are stronger than hooks and better able to resist being pulled out of the bone (again when compared with hooks). The procedure can be done without an anterior (from the front of the spine) incision. That feature alone is very helpful in reducing the risk of complications (e.g., damage to nerves and major blood vessels).
Best of all, patients can get up sooner and have fewer complications like nonunion or fusion failures. There is also evidence that lung function improves with pedicle screw correction. There is a hope that with all these benefits, the child/teen will not need further (revision) surgery or develop degeneration of the vertebrae above and below the fusion where there is more motion.
The downside of an all-pedicle-screw approach is that successful long-term results depend on very skillful, careful surgical work. Part of the vertebral bone must be removed without causing any spinal cord or spinal nerve damage. Accurate placement of the screws is important, especially in the thoracic spine because there’s no safety zone between the pedicle and the dura (outer covering of the spinal cord). If the screw is put in the wrong place, it can go through the bone right into the spinal canal. A breach of this kind can cause serious neurologic damage.
To help surgeons avoid such potential complications, the authors provide a detailed review of pedicle anatomy and surgical techniques for the placement of thoracic pedicle screws. A description is given and photos are included to show how pedicle screws are used to correct the rotation of the vertebral bodies. Pressure from the screws helps derotate the vertebrae. The screw is placed through a special post to lock the vertebrae in the derotated position.
Bone grafting is used to help the fusion process and performing this part of the procedure requires another set of unique skills in order to be successful. And the cost is much higher for the pedicle procedure, though it’s possible that with fewer complications and less chance of a second surgery, the benefits may even things out cost-wise.
The authors conclude that there’s no doubt the all-pedicle-screw treatment of severe adolescent idiopathic scoliosis is safe and successful. Long-term studies are still needed to show what happens over time with this approach. It’s clear that this type of surgery is best done by spine surgeons with complete knowledge and understanding of spinal anatomy and advanced specialized training. It is a potentially dangerous procedure with risk of serious complications. High-volume centers where large numbers of patients are treated this way have the best results.