Abstract
Introduction
Ten explanted pyrolytic carbon components of a number of finger prostheses were obtained at revision surgery for wear analysis. Implants were removed for either dislocation or failure of fixation. Hypothesis Failure of the components was due to wear from the articulating surfaces, as occurs in many hip and knee prostheses.
Methods
The articulating surfaces were examined using a ZYGO NewView 5000 non-contact profilometer with a resolution of 1nm, to determine the roughness average (RA) of the surface. A total of 86 RA measurements were taken. Detailed images of the surface displayed as a 3D map of were acquired. The RA values for each component were averaged and compared against the British standard for orthopaedic implants, which states that the articulating surfaces of devices made of metal or ceramic should have RA values lower than 0.050 µm.
Results
The low surface roughness demonstrated that the vast majority of the articulating surfaces of the components were relatively unworn with RA values lower than British standard, even following use in vivo. ZYGO images showed light unidirectional scratching on four of the explanted components, but despite the scratching, the RA values of these components were still low (<0.050 µm) showing that this was superficial damage. No other significant damage was observed.
Discussion
Due to the lack of damage on the articulating surfaces and the low RA values recorded the failure of these prostheses is not considered to be wear related. Significance This is the first report of ex vivo analysis of pyrolytic carbon finger prostheses.
