Investigation of metallic and carbon fibre PEEK fracture fixation devices for three-part proximal humeral fractures.

A computational investigation of proximal humeral fracture fixation has been conducted. Four devices were selected for the study; a locking plate, intramedullary nail (IM Nail), K-wires and a Bilboquet device. A 3D model of a humerus was created using a process of thresholding based on the grayscale values of a CT scan of an intact humerus. An idealised three part fracture was created in addition to removing a standard volume from the humeral head as a representation of bone voids that occur as a result of the injury. All finite element simulations conducted represent 90° arm abduction. Simulations were conducted to investigate the effect of filling this bone void with calcium phosphate cement for each device. The effect of constructing devices from carbon fibre polyetheretherketone (CFPEEK) was investigated. Simulations of cement reinforced devices predict greater stability for each device. The average unreinforced fracture line opening (FLO) is reduced by 48.5% for metallic devices with a lesser effect on composite devices with FLO reduced by 23.6%. Relative sliding (shear displacement) is also reduced between fracture fragments by an average of 58.34%. CFPEEK device simulations predict reduced stresses at the device-bone interface.