Anterior cruciate ligament injury and impingement against intercondylar notch: An in-vitro study using robots



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The anterior cruciate ligament (ACL) is a major component for healthy knee function, and provides stability to the knee during specific movement. Research has indicated that a smaller intercondylar notch could cause contact between the ACL and the femoral notch which may predispose individuals to an increased rate of ACL injury. The contact between the lateral notch wall and the anterior cruciate ligament could increase the strain past the structural integrity of the ligament.

A biomechanical study using robotic manipulators was conducted to investigate the occurrence of impingement in human cadaver specimens and verify if such impingement causes excessive strain. The use of robotic manipulators provides an accurate method to impose and control complex biomechanical movements of the knee joint. The knee was instrumented with contact force sensors and displacement sensors to gather valuable information for analysis of ACL injury. This research provides the first such experimental analysis of the force between the lateral notch wall and the ACL, and the corresponding strain in the ligament during impingement.

The results obtained in this thesis reveal that impingement occurred in both male and female specimens. Impingement occurred most prominently in combination loading of valgus and external rotation. The corresponding strain due to impingement was small or compressive. The lack of increased force or increased moments when impingement was measured shows that impingement does not affect the healthy function of the knee. Finally, the analysis shows that impingement may not be a main cause of ACL injury.



Ligament injury, In-vitro study