@paige1616 Rita, that's a great question, and I didn't know, but I did some digging and found literature talking about materials used in spine surgery implants and rods. This is a good conversation to have with a sine specialist, but keep in mind, surgeons have preferred hardware that they are trained on and use regularly, and they may not offer all the options that are out there. There is always research ongoing about new hardware to solve spine problems and it is talked about at the spine surgery conventions attended by the surgeons.

They have used PEEK which creates a rod that is semi rigid as opposed to Titanium rods that are rigid, and there is also mention of PEEK rods reinforced with carbon fiber which are described more than just PEEK rods alone. There are studies about the stresses of rods when placed in the spine measured in tests on animal cadaver spines, and there are studies of the carbon fiber+PEEK rods vs. titanium outcomes for people who have have them implanted during spine surgery. The PEEK rods are described as "stress shielding" or simply put, a bit of flexibility so as not to transfer the force as heavily onto the next segment of the spine that is not fixed, ie. the adjacent segment that can wear out from increased stresses.

The advantage of PEEK (a type of plastic) and carbon fiber+PEEK in implants is that it is supposed to be inert in the body and it is radiolucent which means that it doesn't interfere with imaging or treatments involving radiation for example something like the Proton beam used in cancer treatment for inoperable tumors. Some literature describes treatment of spine tumors and how PEEK implants allow the proton beam radiation to focus on an area without interference. Titanium metal implants cause shadowing on an MR imaging creating artifacts in the imaging like dark areas and scattering of radiation.

Here are a few of the links I found in case you are interested. There are many more links at the end for studies that are cited in the literature.
https://pubmed.ncbi.nlm.nih.gov/23075859/
https://pubmed.ncbi.nlm.nih.gov/28815357/
https://pubmed.ncbi.nlm.nih.gov/32173153/
https://pubmed.ncbi.nlm.nih.gov/33508491/
Are you currently seeing a specialist for your scoliosis and considering surgery?

Jennifer