Over the past 50 years, orthopedic surgeons have changed and improved the way spinal deformities are corrected in children. Safer and more effective ways to correct and hold the spine straight have been developed.
It started with the use of rods placed alongside the spine to correct the curve. Then wires were used. But there was a concern about the wires poking into the spinal cord and causing problems, so hooks were tried next. Hooks provided three-dimensional correction that was better and safer than wires.
Most recently, screws placed through the pedicle (supporting column of the vertebral bones) have replaced rods, wires, and hooks. Pedicle screws are used in adults as well as children. But there is one safety concern with screws: putting them in the wrong place (misplacement). How often does that happen?
To find out just how well screws are working, surgeons from the University of Minnesota conducted a systematic literature review. They looked at all the articles published on the subject of spinal correction with screws. There were more than 1000 articles available but only 90 met their criteria for review. Seventeen of those 90 articles were analyzed.
In the end, they had enough data to evaluate 13,536 pedicle screws placed in 1353 children under the age of 18. In all cases, the diagnosis was adolescent idiopathic scoliosis (AIS). AIS is a curvature of the spine in teens. The cause is unknown. That’s what “idiopathic” means. This type of scoliosis is different from congenital (present at birth) or neuromuscular scoliosis (caused by a condition such as cerebral palsy or muscular dystrophy).
The looked at two specific outcomes: 1) how much correction was obtained in the spinal curve and 2) accuracy of screw placement.
Only studies that reported the number of screws that were misplaced or malpositioned were included. Deformity correction was measured using X-rays to calculate the before and after results. Some studies compared one type of fixation to another (e.g., screws versus hooks). Others were comparing accuracy of screw placement with and without computer-aided navigation.
They found that screws worked much better than hooks in correcting and maintaining the new spinal curves. Five per cent of the 13,536 screws were misplaced. Stated in the positive, there was a 95 per cent accuracy rate. That’s even better than the 91 per cent rate reported in other studies for adults.
This systematic review of the published literature adds one more benefit or positive advantage of pedicle screws used in children to correct spinal deformities. Besides making it possible to fuse fewer bones, improve appearance, and lower rates of reoperation, pedicle screws are safe and effective in correcting the curve and holding the new spinal alignment. The concern that smaller pedicle size in children (compared with adults) would cause problems just wasn’t supported since the children had better placement rates than adults!