Purpose: The purpose of this study was to investigate the forces occurring in human anterior meniscotibial attachment structures under various loading conditions.
Methods: Twelve human knee joints were exposed to eight loading conditions (tibial rotations and varus/valgus stress) using a previously described knee joint simulator. Subsequently, the joints were axially compressed (1,000 N at 0° 30° and 60° knee flexion) using a materials testing machine. Then, we performed a tensile test to failure of the ligaments. Finally, we used the strains that occurred during the loading tests and the force-elongation diagrams obtained from the tensile test to recursively assess the resulting forces.
Results: In the anterior meniscotibial ligaments, we found maximum mean strains of 3.8 ± 2.3% under external moments and 1.5 ± 0.9% for axial compression. With an ultimate load of 454 ± 220 N for the anterolateral meniscotibial ligament and 397 ± 275 N for the anteromedial meniscotibial ligament, we estimated maximum forces of up to 50.2 N for the knee simulator tests and 22.6 N for the axial compression tests.
Conclusions: The low forces found in the meniscal ligaments suggest that for normal daily activities, meniscal replacement implants and allografts do not require a very rigid fixation at their bony insertions. However, it remains unknown, what level of force occurs in the meniscotibial ligaments under traumatic situations or impact knee loads. Furthermore, the results of the present study could help to optimize meniscal re-fixation and to improve the properties of meniscal replacement materials, such as tissue-engineered artificial menisci. Moreover, the results could be used for the validation of finite element models of the knee joint with the main focus on the meniscus and its biomechanical relevance for tibiofemoral contact pressure.