Biodegradable Polymers for Orthopaedic Applications

Abstract

Over the past decade there has been an exponential increase in the use of biodegradable polymers in the field of orthopaedics. Such materials are used to fabricate fracture fixation rods, plates, screws, staples, clips, arrows, hooks, suture anchors, sutures and more recently for producing scaffolds for musculoskeletal tissue engineering. Most biodegradable polymeric materials slowly degrade in the body due to hydrolysis or through enzymatic pathways. This renders the need for a second surgery to remove the implant unnecessary. Not only does this reduce healthcare costs but also patient morbidity. Another significant advantage in using biodegradable fixation devices is that such systems can potentially reduce the effects of stress shielding. Bone is a living tissue and remodels in response to the loads it experiences — a phenomenon commonly known as Wolff’s Law. In the presence of stiff metal implants, the load on the bone is significantly reduced, and hence, over the long term bone would have a propensity for osteopenia — a phenomenon described as stress-shielding. Fixation devices fabricated from biodegradable polymers can potentially offset this problem because as the fixation device degrades, its mechanical properties deteriorate. Thus, it can support only a decreasing level of load, which results in gradual reloading of the supported or repaired bone until full load bearing is restored.