Bone Cement Repair for Vertebroplasty Improved with Use of Iron Oxide Nanoparticles
People with osteoporosis (thinning bones) or certain types of cancers may end up with vertebral compression fractures, fractures in the discs of the spine. These fractures usually cause severe pain. The most common sign of someone with compressed discs is the "hunchback" that can occur as a result. To help manage the damage caused by vertebral compression fractures, doctors can do a vertebroplasty. This procedure involves the doctor injecting a special cement into the fractured bones. The cement mixture then hardens and protects the discs. This procedure doesn't involve surgery as the cement is injected with a needle.

The usual cements used are calcium phosphate bone cements, which have been used for years in dental repairs and other orthopedic (bone) repairs. However, as easily as the cement can be used in some procedures, it can be difficult in the spinal area because of the holes in the bones and around. As a result, the procedure isn't always effective. The authors of this study wanted to see if a new modified version of the bone cement, with iron oxide, would make the procedure easier and more accurate.

Researchers used a commonly used type of cement to be the control to compare with the new cement. They measured how long the cements took to set using a standard method. The researchers then tested the strength of the set cements, and how easily they were injected, and their chemical and microstructure were analyzed.

The results showed that adding the iron oxide to the cement increased both the initial setting times and final setting times, which made them easier to work with. When the cement sets too quickly, the doctors don't have a lot of time to inject the cement and may become rushed. However, the length of time increased according to how much iron oxide was in the cement - the more the iron oxide content, the longer the setting time. In comparing the strength between the control cement and the new cement, the researchers found that this also increased with the amount of iron oxide in the cement. Injectability, the ability to inject the cement, was improved as well. With the cements with iron oxide, the injections were done more easily and with less force on the syringe than with the control cement.

One concern that the researchers had was that the iron oxide-enhanced cement may cause problems if a patient were to undergo magnetic resonance imaging (MRI), a test that requires magnets to scan images. They feel that this is not an issue but there are still come worries that the dyes, or contrast agents, used for the tests may make it difficult for radiologists (doctors who specialize in reading images) to tell the difference between cement and problems in the bone.

In all, the researchers reported that adding iron oxide to the powder base of the cement used for vertebroplasty improved the cement in setting times, strength, and ease of use. They recommended that further studies be done, looking at improving the design.
Maria Daniela Vlad, BSc, et al. Iron Oxide Nanoparticles Significantly Enhances the Injectability of Apatitic Bone Cement for Vertebroplasty. In Spine. October 2008. Vol. 33. No. 21. Pp. 2290-2298.