Biomechanical compliance

In-Vivo Percutaneous Implant Experiment. The principle of percutaneous attachment has extensive application in many biomedical areas, including the attachment of dental and orthopedic prostheses directly to skeletal structures, external attachment for cardiac pacer leads, neuromuscular electrodes, energy transmission to artificial heart and for hemodialysis. Several attempts to solve the problem of fixation and stabilization of percutaneous implants(19) have been made. Failures were also attributed to the inability of the soft tissue interface to form an anatomic seal and a barrier to bacteria. In the current studies, the effect of pore size on soft tissue ingrowth and attachment to porous polyurethane (PU) surface and the effect of the flange to stem ratio and biomechanical compliance on the fixation and stabilization of the percutaneous devices have been investigated.(20)... 

Biomechanical compliance or impedance matching of the tissue/material interface is not important for short-term implant experiments. However, for long implanting periods, cyclic fatigue failure of the tissue/material interface is caused by compliance mismatching. 

FIGURE 6.14.4 The work of breathing is the sum of two components that due to resistance and another due to compliance. The sum reaches a minimum at some particular frequency. (From Johnson, A.T., Biomechanics and Exercise Physiology Quantitative Modeling, CRC Press/Taylor Francis, Boca Raton, FL, 2007. With permission.)... 

Melvin et al. [1988] analyzed frontal biomechanics of the chest. The dynamic compliance is related to viscous, inertial, and elastic properties of the body. There is an initial rise in force, which is related to the inertia of the sternal mass, which is rapidly accelerated to the impact speed This is followed by a plateau in force, which is related to the viscous properties and is rate dependent. There is also an elastic stiffness component from chest compression that adds to the force. The force-deflection response can be modeled as an initial stiffness k = 0.26 + 0.60(17" — 1.3) and a plateau force T = 1.0 -F 0.75( V — 3.7), where k is in kN/cm, F is in kN, and the velocity of impact V" is in m/sec. The force P reasonably approximates the plateau level for lateral chest and abdominal impact, but the initial stiffness is lower at f = 0.12(17— 1.2) for side loading [Melvin and Weber, 1988). 

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