Study of Screws for Femoral Neck Fixing, Using Finite Element Calculation and In-Vitro Testing

Abstract

One of the most wide-spread illnesses of our age is osteoporosis at elder age (senilis osteoporosis), and as a consequence, the frequent hip fracture. In case of fracture of the neck of the femur a common way of the successful rehabilitation of the injured is osteosynthesis. An essential condition of the successful recovery is the enhancement of the stability of the fixation of fractures. However, at old age the layer of spongiosa becomes so porous that the threads of screws used for the treatment of the fracture of the neck of the femur virtually fulfil their fixing function only in the subchondral region – less and less in the inner layer of the spongiosa. However, in the subchondral region, the outer layer of 4 to 5 mm remains relatively dense. To increase stability, we modified the traditionally shaped canulated screws, used for the neck of the femur to date, and developed duplex-threaded screws for the neck of the femur. By finite element calculations, we would like to verify the effect of the shape of the thread of screws, playing an important role in the stability of fixation –for the neck of the femur.