Statistical analysis of VEXLPE wear against alumina produced by a new 200-station, multidirectional pin-on-disk device.

With low wear rates shown by contemporary bearing materials of total hip prostheses, the standard deviation of wear rate is relatively high. Therefore, large sample sizes are needed for an adequate power of test. Because wear tests take a long time, it is practical to test several samples simultaneously.

Performance of thin Vivacit-E hip liners: no relevant wear during ex vivo testing at high acetabular inclination angle.

Background And Purpose: There is concern among clinicians regarding the performance of thin, highly cross-linked polyethylene acetabular liners at high inclination angles that cause edge contact and high contact stresses. We studied ex vivo wear performance of thin, vitamin-E grafted, highly cross-linked polyethylene (Vivacit-E) liners in relation to high acetabular inclination angle.

Materials And Methods: Wear of Vivacit-E acetabular liners (thickness 4.

Friction RandomPOD-A new method for friction measurement in noncyclic, multidirectional, dynamic pin-on-disk tests for orthopaedic bearing materials.

The 16-station, computer-controlled RandomPOD wear test device was re-designed into a friction measurement device, Friction RandomPOD. The motion was implemented by a servo-electric x-y-stage and the load was proportional-pneumatic. The direction of sliding, velocity (v), acceleration, and the magnitude of the load (L) varied randomly and continuously.

Effect of random variation of input and various daily activities on wear in a hip joint simulator.

The ISO 14242-1 standard specifies fixed, simplified, sinusoidal motion and double-peak load cycles for wear testing of total hip prostheses. In order to make the wear simulation more realistic, random variation was added for the first time to the motion and load control signals of a hip joint simulator. For this purpose and for the simulation of various daily activities, computer-controlled, servo-electric drives were mounted on a biaxial hip simulator frame and successfully introduced.

Effect of inward-outward rotation on hip wear simulation.

The ISO 14242-1 standard specifies a three-axis motion for the wear testing of prosthetic hips. Multidirectionality of the relative motion and serum-based lubrication are known to be necessary for the reproduction of clinical wear mechanisms. For multidirectionality however, biaxial motion has been shown to be sufficient.