A comparative study between the internal and external bone fixation methods

الملخص EN

The basic goal of fracture fixation is to stabilize the fractured bone, to enable fast healing of the injured bone, and to return early mobility and full function of the injured extremity [1].

The computerized tomography scan slices of the femur bone of one patient were translated to the ANSYS V.(10) program and then the solid model (3-D) model was built and analysed by the finite element method under different loading conditions for each method of fixation.

Finite element analysis would help to reveal stress pathways across the shaft of the femur bone and the sites of the 8 screws or pins fixed at the shaft of the femur above and below the fracture site.

In the internal fixation method two types of screws' materials can be studied.

Firstly stainless steel and secondly cobalt chromium.

The stress distributions were studied for each screw material for different body weights.

While in the external fixation method the stress distributions for only stainless steel pins were studied.

The stress distributions for six pins or screws fixed at the fractured bone above and below the fracture site for each method of fixation were studied.

The von mises stresses of the cobalt chromium screws fixed internally are less than the von mises stresses of the stainless steel for each of the body weight.

The stresses of the pins fixed externally are greater than the stresses of the same screws fixed internally.

When decreasing the number of the screws or the pins the stress values will increase; therefore when using eight screws or pins the stresses are less than those when used six screws or pins for each method of fixation (internal and external).