Injury Thresholds of Knee Ligaments Under Lateral–Medial Shear Loading: An Experimental Study

Abstract

Objective: Knee ligament injuries frequently cause devastating impairment to the injured. In car–pedestrian impact accidents, lateral–medial shear displacement is one of principal mechanisms of knee ligament injuries. The current study aims to investigate injury thresholds of knee ligaments under lateral–medial shear loading to improve pedestrian safety.

Methods: Ten isolated human knee joints without surrounding muscles were tested under dynamic lateral–medial shear loading in 2 groups: 3 left knee joints were tested in the shearing of medial tibial translation, and other knee joints were tested in lateral tibial translation. Based on combined analysis of experimental videos and force curves, the primary failure time of knee ligaments and the corresponding shear displacement were determined.

Results: Under lateral tibial translation and medial tibial translation, both primary injury types of knee ligaments and force curves showed essential differences. It appears that the majority of primary failure modes were anterior cruciate ligament (ACL) injury when the tibia was displaced medially and posterior cruciate ligament (PCL) injury when the tibia was displaced laterally. Overall experimental results indicated that the injury threshold of the knee joint under lateral–medial shear loading varied from 11.4 to 17.6 mm, with an average level approximately 14.3 mm.

Conclusion: Based on the bone–ligament–bone complex experiment of the knee, we present injury occurrences of the knee joints in lateral and medial shear loading. The testing data provide a basis for improving knee injury criteria that regulate passenger cars to reduce their aggressiveness to pedestrians.

Supplemental materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention to view the supplemental file.

Keywords:

• knee
• ligaments
• pedestrian
• lateral–medial shear loading
• injury threshold

Acknowledgments

We acknowledge the “Fondation en Sécurité Routière” for funding and providing administrative support for the ASP (Amélioration de la Sécurité des Piétons) project. We also acknowledge all partners in the ASP project (Faurecia, Plastic Omnium, Altair, Université de Strasbourg, Université Claude Bernard Lyon 1, Politecnico di Torino) for their contributions. The authors are also grateful for support from the China Scholarship Council.