Interfacial relative motion

A. Falkenberg, M.M. Morlock, G. Huber

Metal debris in the patient’s body, originating from prostheses, can trigger several symptoms such as necrosis or osteolysis. Relative motions between mating surfaces of taper junctions in modular hip prostheses are assumed to be a significant source in the generation of those debris. The aim of this study was the quantification as well as characterisation of local relative motion occurring within taper junctions.

The bases of this approach are small-sized windows cut through the female taper in order to expose the male taper surface to the observer. This enables the direct visual investigation of interfacial relative motion. Optical microscopic measurement of the taper junction under different states of loading was conducted and analysed with means of image matching algorithms.

Measurements exhibited interfacial relative motion on the micron level; covering a range between 2 to 16 µm, depending on the location of the observation.

The novel method gives insight into the behaviour of taper junctions under different states of loading. Determining critical factors generating relative motion might improve the understanding of implant failures.

Publications:

Falkenberg A., Drummen P., Morlock M.M., Huber G. (2016) Local measurement of micromotion at the taper junction of modular total hip prostheses. Congress of the European Society of Biomechanics