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Effect of Vibration
Published in Verna Wright, Eric L. Radin, Mechanics of Human Joints, 2020
J. E. Smeathers, P. S. Helliwell
Clinicians are familiar with the patient who presents with pain in the foot as a result of a calcaneal fracture after jumping from a height onto a hard surface. In this situation a high-amplitude, short-duration shock (or vibration) has exceeded the mechanical strength of the biological tissue (trabecular bone of the calcaneum), resulting in a pathological state. What is less clear is the relationship between continuous exposure to vibration of smaller amplitude, in which the vibration dose accumulated over a longer period may exceed that received from vibration of higher amplitude over a shorter time. This may be particularly important if the vibratory stimulus coincides with the natural frequency of the tissue under vibration, in which the response and load may be amplified two to three times. Furthermore, continuous low-amplitude vibration may accelerate normal creep in cartilaginous structures, accentuating load-induced changes in the dimensions of the tissue.
Biomechanics of calcaneus impacted by talus: a dynamic finite element analysis
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Mengquan Huang, Bin Yu, Yubiao Li, Chunlai Liao, Jun Peng, Naiming Guo
Axial compression was identified as the primary cause of calcaneal fractures (Gallenberger et al. 2013; Stephens and Grujic 2020). The fractures were caused by stress on the calcaneus when it was positioned between the ground and the talus during a fall. There were two classic theory on calcaneal fracture (Essex-Lopresti 1952; Carr et al. 1989). Carr et al. (1989) used eighteen cadaveric tibia specimens to model intra-articular calcaneal fractures and found that the fracture comprised of two basic fracture lines. The first fracture line divided the calcaneus into medial and lateral portions, extending to the calcaneocuboid joint and the anterior subtalar articular. The second fracture line divided the calcaneus into anterior and posterior parts, extending from the Gissane Angle to the medial wall of the calcaneus. Essex-Lopresti (1952) suggested that the primary calcaneal fracture line initially formed between the lateral talar process and lateral calcaneal margin, and that the lateral wall of the calcaneus and the body of the calcaneus were separated at the Gissane Angle, followed by an anterolateral fracture, a compression fracture, or a tongue-type fracture of the calcaneus. These findings were obtained through direct observation of the experiment. Biomechanics have been proposed as the basis for managing intra-articular calcaneal fractures (Lowery and Calhoun 1996; Lewis 1999; Rammelt and Zwipp 2004), but the stress changes associated with different types of calcaneal fractures were not yet fully understood.