The surface topography of retrieved femoral heads

Abstract

Excessive wear of UHMWPE sockets is considered detrimental to the long-term performance of total hip replacement procedures. Although many factors contribute to the wear process, laboratory experiments have indicated that one of the most important factors affecting the wear rate is surface topography and in particular, the arithmetic mean surface roughness, Ra, of the hard counterface. Surface roughness values were therefore obtained from the heads of 37 explanted and five new Charnley prostheses. The surface topography was measured using a Rodenstock RM 600 non-contacting profilometer. Five parameters were used to give a quantitative characterization of the surface texture; arithmetic mean surface roughness, Ra, root mean square (RMS) surface roughness, Rq, peakto valley height, Rt, average single peak to valley height from five adjoining sample lengths, Rz, and the skewness of the height distribution, Sk. Further, qualitative investigations were undertaken using a JoeI-JSM-IC848 scanning electron microscope (SEM). The median values of Ra, Rq, Rt and Rz for explanted heads showed statistically significant increases when compared with values from new prostheses. No significant difference was found between any of these parameters measured in the anterior-posterior and the medial-lateral directions. This result may have important implications for the design of joint simulators. No correlation was found between any of the parameters and implant period.

May the surface roughness of the retrieved femoral head influence the wear behavior of the polyethylene liner?

“…51 The roughness data recorded were all end-term values. In agreement with other authors, 15,52 no linear relationship has been found between the roughness data summarized in Table II and the fu times summarized in Table I for the two sets of retrievals under study. This result shows that the roughening of the prosthesis is not a gradual process; in other words, the femoral heads roughened in a distinct event (i.e., a discrete roughening event occurred).…”

Surface structure of retrieved ICLH femoral cups

“…Bauer et al (1994) reported that an increased surface roughness (Sa value) of retrieved prostheses was relatively common compared with unused implants. Hall et al (1996) found a statistical significant increase in height descriptive parameters for used Chamley prostheses, as compared to unused ones. We found some areas full of scratches on the retrieved cups, as a result of surface damage, and traces of the retrieval operation, while most areas could not be distinguished from unused implants.…”

Wavelet Analysis for the Extraction of Morphological Features for Orthopaedic Bearing Surfaces

“…Looking at these surfaces, it must be noted that the most important factors that affect the life of the femoral head are the isolated peaks/pits and scratches rather than the nano-scalar roughness. From the function assessment point of view, the isolated peaks/pits and scratches will significantly interfere with the wear mechanics and tribological properties [6][7][8][9]27]. Using the complex wavelet, all the isolated features are extracted precisely as shown in …”