Non-Contact anterior cruciate ligament (ACL) injuries are a major problem in modern football (soccer). The stud design of the football shoes is suspected to be one important risk factor for ACL injuries.
The aim of this thesis was therefore to investigate whether or not the football shoe stud design corresponds to the loads occurring in the ACL. As direct measurements as well as subject tests (ethical reasons) are not possible, mechanical tests of the shoe-surface interaction are the only way to answer the research question. Hereby the realistic loading of the football shoes during the experimental tests is of major importance in order to get reliable and meaningful measurement results.
Therefore the kinematics and ground reaction forces of real ACL injury situations were determined by means of the Poser method and the resulting joint moments were calculated via computer simulation using an inverse dynamics approach. The results of the Poser analysis and the computer simulation were the basic condition for the experimental setup comparing four different stud designs using a novel pneumatic driven test device called TrakTester.
The measurement data showed significant differences of the measured forces and torques between the different stud designs. In order to estimate the influence of the stud design on the loading of the ACL risk potentials were derived from the measurement data for each loading scenario considering also medical and biomechanical knowledge. These risk potentials lead to the conclusion that the stud design influences the loading of the ACL. But they depend substantially on the specific boundary conditions and the loading scenario. This thesis basically contradicts the assumption that the use of football shoes with bladed studs causes a higher risk for the ACL compared to shoes with conventional round studs. In summary the new method developed during this thesis enables in combination with the TrakTester a considerably more realistic investigation of the shoe-surface interaction than approaches used up to now. Beside their role as boundary conditions for the experimental setup the results of the Poser analysis and the computer simulation provide furthermore a lot of biomechanical perceptions regarding the injury mechanism of non-contact ACL-injuries.
Die Biomechanik umfasst natur-, ingenieur- und sportwissenschaftliche sowie medizinische Aspekte. Unter Berücksichtigung all dieser Aspekte leistet die vorliegende Arbeit einen Beitrag zum besseren Verständnis von Verletzungsmechanismen ausgewählter Sportarten. Dabei stellen numerische Verfahren ein adäquates Mittel dar, wenn Messtechnik an ihre Grenzen stößt oder experimentelle Untersuchungen aus ethischen Gründen nicht oder nur bedingt durchführbar sind. Den Schwerpunkt in dieser Arbeit bildet daher der Aufbau und die Überprüfung detaillierter physikalischer Modelle, sog. Mehrkörpersysteme (MKS), ausgesuchter Regionen des menschlichen Körpers. Die entsprechenden Bereiche des Bewegungsapparates wurden anatomisch detailliert besprochen und die mechanischen Eigenschaften der einzelnen Strukturen untersucht.
Degenerative changes in the spine as well as back pain can be considered a common ailment. Incorrect loading of the lumbar spine structures is often considered as one of the factors that can accelerate degenerative processes, leading to back pain. For example, a degenerative change could be the occurrence of spinal stenosis following spondylolisthesis. Surgical treatment of spinal stenosis mainly focuses on decompressing the spinal canal with or without additional fusion through dorsal spondylodesis. There are differing opinions on whether fusion along with decompression provides potential benefits to patients or represents an overtreatment. Both conventional therapies and surgical methods aim to restore a “healthy” (or at least pain-free) distribution of load. Surprisingly little is known about the interindividual variability of load distribution in “healthy” lumbar spines. Since medical imaging does not provide information on internal forces, computer simulation of individual patients could be a tool to gain a set of new decision criteria for these cases. The advantage lies in calculating the internal load distribution, which is not feasible in in-vivo studies, as measurements of internal forces in living subjects are ethically and partially technically unfeasible. In the present research, the forward dynamic approach is used to calculate load distribution in multi-body models of individual lumbar spines. The work is structured into three parts: (I) Load distribution is quantified depending on the individual curvature of the lumbar spine. (II) Confidence intervals of the instantaneous center of rotation over time are determined, with which the motion behavior of healthy lumbar spines can be described. (III) Lastly, the effects of decompression surgeries on the load distribution of lumbar spines are determined.