Joints biomechanics

A significant aspect of hip joint biomechanics is that the stmctural components are not normally subjected to constant loads. Rather, this joint is subject to unique compressive, torsion, tensile, and shear stress, sometimes simultaneously. Maximum loading occurs when the heel strikes down and the toe pushes off in walking. When an implant is in place its abiUty to withstand this repetitive loading is called its fatigue strength. If an implant is placed properly, its load is shared in an anatomically correct fashion with the bone. 

The biomechanical assay systems are of special importance when functional impairment of joints may be a critical issue of the therapeutic principle under investigation. As chondrocytes are known to metabolically behave very distinct, even controversial in conventional culture conditions compared to those under biomechanical forces much closer to their natural environment, a mechanically well-defined assay system is expected to yield results more representative of joint biomechanics, and such even bridge the gap to an in vivo model. 

Atkinson, P.J., Ewers, B.J., and Haut, R.C. Blunt injuries to the pateUofemoral joint resulting from transarticular loading are influenced by impactor energy and mass, J. Biomech. Eng., 123, 293, 2001. Cooper, G.J. et al. The biomechanical response of the thorax to nonpenetrating impact with particular... 

Mabuchi K, Obara T, Ikegami K et al 1999 Molecular weight independence of the effect of additive hyaluronic acid on the lubricating characteristics in synovial joints with experimental deterioration. Clinical Biomechanics 14 352-356... 

OA joint may reflect compensatory processes to maintain function in the face of ongoing joint destruction. As such, the pathogenesis of OA involves not only biomechanical forces, but also inflammatory, biochemical, and immunologic factors. To understand the pathophysiology of OA, famiharity with the normal joint is essential. To this end, a review of the biochemistry and function of normal cartilage and of the diarthrodial joint is provided. 

Amis AA, Kempson AS, Campbell JR and Millee JH (1988) Anterior cruciate ligament replacement Biocompatibility and biomechanics of polyester and carbon fiber in rabbits. J Bone Joint Surg Br 70 628. 

Einhorn T, Lane J, Burstein A. The healing of segmental bone defects induced by demineralized bone matrix a radiographic and biomechanical study. J Bone Joint Surg Am 1984 66 274-279. 

An example of the important dynamic data for workplace design is range of joint mohUity (Table 3) which corresponds to postures illustrated in Figure 1. Very useful anthropometric data, both static and dynamic, are provided by the Humanscale (Henry Dreyfuss Associates 1981). When anthropometric requirements for the workplace are not met, biomechanical stresses, which may manifest themselves in postural discomfort, low back pain, and overexertion injury, are likely to occur (Grieve and Pheasant 1982). Inadequate anthropometric design can lead to machine safety hazards, loss of motion economy, and poor visibility. In other words, the consequences of anthropometric misfits may of be a biomechanical and perceptual nature, directly impacting worker safety, health, and plant productivity. 

Figure 1 Illustration of Joint Mobility. (Adapted from Chaffin et al.. Occupational Biomechanics, 3rd Ed. Copyright 1999. Reprinted by permission of John Wiley Sons, Inc., New York.)...

Schultz, A., Andersson, G. B. J., Ortengren, R., Haderspeck, K., and Nathemson, A. (1982), Loads on Lumbar Spine Validation of a Biomechanical Analysis by Measurements of Intradiscal Pressures and Myoelectric Signals, Journal of Bone and Joint Surgery, Vol. 64-A, pp. 713-720. 

Chao, E. Y, and Rim, K. (1973), Application of Optimization Principals in Determining the Applied Moments in Human Leg Joints During Gait, Journal of Biomechanics, Vol. 29, pp. 1393-1397. 

Modeling of a human body with the emphasis to the extremities is the prerequisite for the synthesis of analytic control [3(U33]. Human extremities are unlike any other plant encountered in control engineering especially in terms of joints, actuators, and sensors. This fact must be kept in mind when applying the general equations of mechanics to model the dynamics of functional motions. A simple extension of analytical tools used for the modeling of mechanical plants to the modeling of biomechanical s) tems may easily produce results in sharp discrepancy to reality. 

The prosthesis for total knee joint replacement consists of femoral, tibial, and patellar components. Compared to the hip joint, the knee joint has a more complicated geometry and movement biomechanics, and it is not intrinsically stable. In a normal knee, the center of movement is controlled by the geometry of the ligaments. As the knee moves, the ligaments rotate on their bony attachments and the center of movement also moves. The eccentric movement of the knee helps distribute the load throughout the entire joint surface [Burstein and Wright, 1993]. 

Friedman, R.J. 1992. Advanced in biomaterials and factors affecting implant fixation. In Instructional Course Lectures, R.E. Eilert (Ed.),pp. 127-135, The American Academy of Orthopaedic Surgeons. Goel, V.K. and Blair, W. 1985. Biomechanics of the elbow joint. Automedica 6 119. 

Studies of the normal biomechanics of the proximal wrist joint have determined that the scaphoid and lunate bones have separate, distinct areas of contact on the distal radius/triangular fibrocartil-age complex surface [Viegas et al., 1987] so that the contact areas were localized and accounted for a relatively small fraction of the joint surface, regardless of wrist position (average of 20.6%). The contact areas shift from a more volar location to a more dorsal location as the wrist moves from flexion to extension. Overall, the scaphoid contact area is 1.47 times greater than that of the lunate. The... 

Engsberg J.R. 1987. A biomechanical analysis of the talocalcaneal joint in vitro. J. Biomech. 20 429. 

Iseki F. and Tomatsu T. 1976. The biomechanics of the knee joint with special reference to the contact area. Keio. /. Med. 25 37. 

Morrey B.F. and Chao E.Y.S. 1976. Passive motion of the elbow joint a biomechanical analysis. /. Bone Joint Surg. 58A 501. 

Pagowski S. and Piekarski K. 1977. Biomechanics of metacarpophalangeal joint. /. Biomech. 10 205. 

Palmer A.K. and Werner F.W. 1984. Biomechanics of the distal radio-ulnar joint. Clin. Orthop. 187 26. 

Sato S. 1995. Load transmission through the wrist joint a biomechanical study comparing the normal and pathological wrist. Nippon Seikeigeka Gakkai Zasshi-Journal of the Japanese Orthopaedic... 

Viegas S.E, Patterson R.M., Todd P. et al. October 7,1990. Load transfer characteristics of the midcarpal joint. Presented at Wrist Biomechanics Symposium, Wrist Biomechanics Workshop, Mayo Chnic, Rochester, MN. 

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