Micro Computed Tomography Analysis of Magnesium Screw Degradation & Bone Regeneration

INTRODUCTION 6.3 million cases of bone trauma happen each year in the US alone [1]. In a majority of these cases, permanent fixation implants using titanium plates and screws are used as a remedy, but they do have their drawbacks. Some of these disadvantages include bone wear and degradation, resulting in the implant to become loose. They also present a prime site for possible infection [2]. An alternative to permanent fixation implants are degradable polymers. These polymers degrade over time with no remaining materials thus significantly reducing bone wear and chances for future infections. However, some disadvantages of these polymers are that they break easily on implantation, cannot bear high loads and cause swelling because they have an acidic pH when they degrade [3]. Addressing these fallbacks is the solution of degradable metals, specifically magnesium to these polymers are degradable metals specifically magnesium. Magnesium degrades over time and has similar properties to bone including strength, which makes them much less likely to break. Dr. Frank Witte’s study compared degradation properties of polymer and magnesium [4]. Dr. Witte’s group implanted magnesium and polymer screws in the femur of a rabbit model. His study showed that the polymer, after degradation, did not show bone regeneration, while the magnesium implant promoted it. Dr. Witte’s group used a micro Computerized Tomography (CT) scan to further characterize the degradation of magnesium [5]. Computerized Tomography (CT) combines a series of X-ray views taken from a 360 degree angle. CT scans allow 3D reconstruction without destroying the sample.