Biomechanical design of a vertebral distractor for fractured bodies useful in Kyphoplasty

Nowadays, vertebral fractures represent a worldwide health problem. In the last decade, several advances in the development of techniques for the treatment of these fractures have been reported. These are the special surgery techniques called “vertebral augmentation techniques”. The purpose of this paper is to show a definitive design of a biomechanically assembled mechanism which has the function of separating the collapsed walls of the fractured vertebral body and to aid to get the necessary space to fix an implant. The function of this mechanism was tested under the surgical technique called “Kyphoplasty”, which is necessary in the treatment of vertebral fractures. With this design the intention is that the mechanism has functional characteristics such as: do to not leave it permanent taken into the fractured vertebral body as well as to have the ability to separate the collapsed walls of the healthy adjacent vertebral body. It is expected to be reusable a finite number of times after a sterilization process. The design methodology used was the QFD (The quality function deployment), and a final concept design was obtained. Some lumbar vertebrae porcine specimens (8 months old of the Duroc breed) were used in order to know the mechanical strength, necessary for the design of the mechanism. The final design of the device will be analyzed by the finite element method (FEM), in order to know the mechanical behavior under simulated working conditions. These studies will provide the necessary data which will be the main support to decide the best material to propose for the final mechanism and its manufacturing. However, these FEM results are not reported on this paper .