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Hip wear simulation

Two hip joint simulators are available to investigate the wear behavior of total hip prostheses. The servo-hydraulic testing machines (MTS Minibionix plus hip simulator attachment) with their four driven degrees of freedom are able to simulate the kinematics and kinetics, which act in hip joints. It is possible to simulate extension/flexion, abduction/adduction, an internal/external rotation and the compression forces of the joint. To simulate normal walking, the system can be operated according to testing standards (e.g. ISO 14242-1). It is also possible to define other activity patterns.

Depleted calf serum with antibacterial additives heated to 37C is used as lubricant. Typically, implants run for 500.000 cycles (representing 500.000 steps) at a frequency of 1 Hz. After reaching this value, the lubricant has to be changed and the system is disassembled. Wear will be measured by the gravimetrical method, with CMM, or using the hr-ICPMS method. The investigation typically ends after 5 million cycles, which represents an in-vivo duration of about three years.

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