Biodegradable screws made of polylactic acid are already used in the medical field, but they have the drawback that when these screws degrade, they can leave holes in the bone. To avoid this, surgeons have started to use polylactic screws because they are biocompatible and biodegradable. The researchers have recently developed a moldable composite made of polylactic acid and hydroxylapatite, a ceramic which is the main constituent of the bone mineral. This composite helps the growth of bone into the implant. Depending on the structure the screws will biodegrade in 24 months.
The screws can be precision made using conventional injection moulding methods, meaning there’s no need for any post-processing such as milling. Another advantage of the composite material is that it can be compressed at just 140-degree Celsius – normally the powder injection mould has to be compressed at much higher temperatures of up to 1,400-degree Celsius. These medical screws also promote bone growth into the implant.