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Designing for Lower Torso and Leg Anatomy
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
In simplest terms, the knee joint is a synovial hinge joint (refer to Figure 5.10), consisting of the two distal, rounded, cartilage-covered femoral condyles, which articulate with relatively flat condyles of the proximal tibia. Medial (tibial) and lateral (fibular) collateral ligaments (on the joint sides) help to stabilize the joint. A pair of ligaments (the anterior and posterior cruciate ligaments) bridge between the femur and the tibia, crossing in an X-shape within the joint, and attaching to a non-articular area between the tibial condyles. Each femur has a medial and lateral epicondyle protruding from the condyles that can be palpated from the surface and which serve as landmarks for wearables. The medial and lateral menisci (plural of meniscus), partially movable crescent-shaped cartilage spacers between the femur and tibia, deepen the tibial articular surface (Jenkins, 2002, p. 277). Lip-like, they attach to the edges of the tibia along the medial and lateral aspects of the joint. The thin innermost portions of the menisci, particularly the medial menisci, are vulnerable to tears with knee trauma, and contribute to knee locking and/or buckling when damaged.
Biomechanical topics in soft tissues
Published in Benjamin Loret, Fernando M. F. Simões, Biomechanical Aspects of Soft Tissues, 2017
Benjamin Loret, Fernando M. F. Simões
Some specific sport activities contribute significantly to knee injuries, which amounts to 45% of all athletic injuries. The rupture of the ACL, medial meniscus and lateral meniscus contribute, respectively, to 20.3%, 10.8% and 3.7% [Majewski et al. 2006]. This study was performed in Switzerland and Germany and the sports leading to most injuries are skiing and soccer. In fact, the occurrence of the rupture of ACL is seven times higher for athletes. Analysis of video-taped handball matches has shown that ACL rupture was associated with a valgus knee flexion and tibia rotation. Knee braces constraining extension and modifying flexion at landing have been suggested to limit ACL rupture in skiing, basketball and handball [Yu et al. 2004].
Lower extremity injuries
Published in Youlian Hong, Roger Bartlett, Routledge Handbook of Biomechanics and Human Movement Science, 2008
William C. Whiting, Ronald F. Zernicke
The magnitude of joint compressive forces accepted by the menisci depends on joint position. In full extension the menisci accept 45–50 per cent of the load, and in 90˚ of flexion they accept 85 per cent of the load (Ahmed and Burke, 1983; Ahmed et al., 1983). Load distribution also differs between the medial and lateral menisci. The lateral meniscus assumes 70 per cent of load transmission, while the medial meniscus shares the compressive load equally with the articular cartilage (Seedhom and Wright, 1974; Walker and Erkman, 1975).
Modelling and simulation of sprinters’ health promotion strategy based on sports biomechanics
Published in Connection Science, 2021
Wang Huifeng, Achyut Shankar, G.N. Vivekananda
The distribution of internal and external contact stress is affected by the joint position (due to the different position of the joint). The peak value of tibiofemoral joint contact stress at 1 degree is larger than that at 15 MPa. The average contact stress between 35 and 95 degree is smaller than that at 7 MPa. The stress increases from 45 degree to 140 degree and the buckling reaches 30 MPa. During flexion, the internal and external contact stresses of the tibiofemoral joint vary. However, sprinters often start too much because of inaccurate judgment, which makes the knee joint continuously exert force or twist from the flexion position, so that the patellar joint surface will continue to produce dislocation, twist, impact and friction. At this point, if the two knees are clamped, the medial collateral ligament is stretched very tightly, which is easy to cause injury. Extreme traction of the lateral capsule of the knee joint can also lead to indirect injury of the lateral meniscus margin. On the whole, the amount of force depends on the number of muscles and muscle fibres involved in the work. The force rate and the time programme of exertion are the interaction of muscle tension and relaxation. Therefore, for the sprinter, the form of coordination ability is the rapid contraction of the coordination muscles that need to be coordinated at the same time when the movement is completed, and the machine is quickly relaxed. Thereby shortening the length of the sarcomere, this is called the micro-sliding doctrine of muscle contraction. Muscle contraction is always the first action potential of the sarcolemma, and then the relative sliding contraction of the muscle microfilament occurs. Therefore, the kinematics of the hip joint largely reflects the athlete's sprint level, and the strength and flexibility of the hip determine the athlete's athletic ability to a large extent.