Biomedical subjects

M Lengsfeld

Publications and source records attributed to M Lengsfeld.

39 records · Page 3Linked to original sources

PubMedDate not supplied

[Biomechanic study of the tensile strength of lyophilized and deep frozen human Achilles tendons following gamma and ethylene oxide sterilization].

By a failed first operation allogenic tissues, as human Achilles tendons are offered for anterior cruciate ligament replacement. The effects of freeze-drying and primary Gamma- or EO-sterilization on the mechanical properties of 62 complete and 74 bisected tendons again fresh frozen controls were investigated under axial tension. A significant decrease of tensile strength for the freeze-dried preparations of 33% for the whole and 43% for the bisected tendons were observed, while Gamma- or EO-sterilizations showed a smaller deleterious effect on the tendons. Considering only the primary mechanical strength complete freeze-dried or complete and bisected irradiated Achilles tendons show sufficient tensile strength for anterior cruciate ligament replacement.

Achilles Tendon↗

PubMedDate not supplied

[Rotation movements of the knee joint. A mathematical-kinematic model].

The kinematics of rotational motion of the knee joint is described by a three-dimensional mathematical model. It is on principle supposed, that cruciate ligaments interact in concert to guide motion. This concept is based on the idea to explain movement in the sagittal and horizontal plane by a four-bar kinematic chain. The path of the instantaneous centers of rotation is shown with the help of this concept.

Biomechanical Phenomena↗

PubMedDate not supplied

[Influence of cartilage cap modelling on FEM simulation of femoral head stress].

The present study reports on the finite element analysis (FEA) of the femoral head in a process of preparation for a program for the realistic simulation of correctional osteotomies of the proximal femur. While the material properties have been studied extensively, only few publications consider the influence of the cartilage layer geometry on FE stimulation of the hip joint. Various models of the femoral head with and without the cartilage layer are generated and analysed. On looking at the maximum surface stresses, we found a strong influence of the cartilage layer and the subchondral osseous layer on the magnitude of the von Mises equivalent stress. The model with an anatomically realistic cartilage layer and compact bone shows stresses of between 4 and 5.5 MPa, depending on the position of the joint, while the model with a concentric cartilage layer has a maximum von Mises stress of 0.8 MPa. Only on simulation of a "realistic" cartilage layer, with a maximum thickness at the "pole" and minimum thickness at the "equator" do the changes in stress distribution--determined by changes in the position of the femoral head--become visible. Owing to major artefacts and the inability to create a realistic cartilage layer, voxel-based models of the femur are not suitable for the simulation of the femoral head surface.

Cartilage, Articular↗