Choice of cross-sectional plane for the shin bone (Tibia)

Artificial joint prosthesis are used for advanced wear or extreme destruction of joint surfaces. Hip prosthesis and total knee prosthesis are often necessary. A reason is the strong exposure of the knee. For example, an overweight person overloads his knee permanently. The task of the joint is the transmission of forces between bones. If the position of the joint prosthesis is bad, this function is not guaranteed any more.

Virtual cut of the shin bone (tibia)

The consequence is an alteration of the highly adaptive bone tissue. This is one reason for complications after a surgery. To avoid complications, navigation systems for precise positioning of the prosthesis are used. So far, navigation systems have only used geometric information. In the near future, bio-mechanical patient data is integrated in the surgery planning. This is possible, because of innovative imaging and efficient bio-mechanical computer simulations.

Choice of the size of the tibial plate

Appropriate methods to substantially improve navigation systems are developed at Fraunhofer ITWM in cooperation with scientists from Catania and Lima-Lto spa (Italy). The aim of this project is an improvement of quality of life of the patient, an avoidance of complications and follow-up surgeries and a reduction of rehabilitation periods. The bio-mechanical models consider the individual characteristics of bones and prosthesis.

Visualization of deformation of a shin bone under pressure load (e.g. jump) in this selection of the tibial plate

The contact zone between bones and prosthesis is of particular importance. The local mechanical demands of the contact zone produces biological stimuli. This leads to bone structure, i.e. ingrowth of the prosthesis. Adequate models, which consider the microstructure of the surface of the prosthesis and the bone are developed for the analysis of this zone. The mechanical stress on prosthesis-bone-systems are solved numerically by the finite element method (FEM). By using special efficient algorithms we simulate many variants of prosthesis-bone systems in a short time.

An user-friendly graphical interface helps surgeon to realize a virtual the surgery of bone and the positioning of  prosthesis and to test the mechanical stress on prosthesis-bone-systems by computer simulation. Such a virtual surgery can be accomplish in short time without pain for the patients. After that the surgeon can choose the best decision.