Cytotoxicity of novel hybrid composite materials for making bone fracture plates.

Bone fracture plates are usually made from steel or titanium, which are much stiffer than 
cortical bone. This may cause bone "stress shielding" (i.e., bone resorption leading to plate 
loosening) and delayed fracture healing (i.e., fracture motion is less than needed to stimulate 
callus formation at the fracture). Thus, the authors previously designed, fabricated, and 
mechanically tested novel "hybrid" composites made from inorganic and organic materials as 
potential bone fracture plates that are more flexible to reduce these negative effects. This is the 
first study to measure the cytotoxicity of these composites via the survival of rat cells. Cubes 
of carbon fiber/flax fiber/epoxy and glass fiber/flax fiber/epoxy had better cell survival vs. 
Kevlar fiber/flax fiber/epoxy (57% and 58% vs. 50%). Layers and powders made of carbon 
fiber/epoxy and glass fiber/epoxy had higher cell survival than Kevlar fiber/epoxy (96-100% 
and 100% vs. 39-90%). The presence of flax fibers usually decreased cell survival. Thus, 
carbon and glass fiber composites (with or without flax fibers), but not Kevlar fiber composites
(with or without flax fibers), may potentially be used for bone fracture plates.