Adolescent idiopathic scoliosis is a type of curvature of the spine that affects mostly girls. It starts to show up at about age 10. Sometimes, the curves get worse over time. If the curves in the spine begin to bend too far, surgery may be needed. In some cases, doctors will do a fusion surgery to immobilize the spine and keep it from bending. When the surgery is done along the back part of the spine, it is called posterior fusion. Fusing the front part is called anterior fusion.
Surgeons have questioned whether doing a posterior fusion alone leads to a problem called the crankshaft phenomenon. This is where a fused spine keeps growing and starts to get too much tension built up. It is thought that younger, immature spines are prone to developing this problem because younger patients have more growing left to do.
This study followed 18 children with scoliosis who had only posterior fusion surgery. Researchers looked at the children’s medical records over an average of three years after surgery. None of the patients developed crankshaft problems. The results were the same for the patients who were older, and thus closer to the end of their growing years, as for the younger patients.
Only one of the children showed significant worsening of the curves. She was one of the earliest patients. The researchers believe that the older, less-advanced kinds of implants–such as screws, wires, and hooks–used in her surgery may have contributed to her problems. The authors conclude that the newer types of implants that are now available may help avoid problems with the crankshaft phenomenon.