The Composite Structure of Cactus Spines

Standard in surgical treatment of bone fractures is the use of metal im­plants, with well defined characteristics in stiffness and strength. New materials could however be used to create implants, which change their mechanical properties. The development of implants made of resorbable composite structures could be an approach to achieve such a target. Nature has for a long time dealt with the problem of producing lightweight but robust composite structures, which in addition are able to change, or adapt, their mechanical properties. Spines of cacti are one of these structure. Cactus spines were tested for their bending stiffness and examined by both light and electron microscopy to determine their structural properties. Based on these findings, experimental implants made of bioresorbable material were produced, which consisted of longitudinally oriented fibres, welded with a proprietary method into plates - mimicking the cactus spine mor­phology. The fibres produced for these implants could be made twice as strong as fibres described in the literature. The plates finally were more than 80 times stiffer than any similar specified commercial product, used on the market to date.