The history of metal-on-metal bearing began with K. Mc Kee. Several "episodes" have marked the history of metal-on-metal articulations, and each has contributed to a better understanding of this type of tribology. But to date the indications for this bearing are debated and are subject to reservations because of the existence of permanently elevated levels of circulating metal ions. It therefore appears that the monitoring of our patients, the documentation of our revisions and the collaboration with our industry partners as well as communicating with our biology and pathology colleagues is necessary to help us solve these problems.Metal-on-metal: history, state-of the-art (2010) Typically, the first total hip implant with a metal-on-metal articulation is attributed to P. Wiles who, in 1938, implanted a couple made of steel [53]-but this was prehistory!The more recent experience starts with McKee whose name will always remain associated with first generation metal-on-metal. However, a high number of failures discredited this metal-on-metal articulation; even more so, because the good tolerance of polyethylene underlined the qualities of the metal-on-polyethylene articulation advocated by J. Charnley who would also became the gravedigger of this first generation.An elaborate analysis of the failures led Weber to initiate and then promote a second generation of metal-on-metal, cemented at first, then rapidly followed by non-cemented prostheses.In 1996, a special edition of Clinical Orthopaedics and Related Research was dedicated to this bearing. Its particular complication, ALVAL, would be documented by Willert.The tribology of metal-on-metal, thus better known, reopened the door to bipolar resurfacing, and the complicated treatment of fractured necks led to the development of conventional total hip prostheses with a large diameter head.It is this evolution towards a large diameter that gave reason to reconsider the consequences of excessive wear of metal-on-metal articulations. The adverse reaction to metal debris (ARMD) also deserves to be analyzed! Eventually, because of these never resolved uncertainties, which are still a topic due to the high potential risk related to the permanently circulating metal ions, the metalon-metal bearing appears to be the "bad boy" among the joint bearing made available to surgeons today.Thus, several "episodes" have marked the history of metal-on-metal articulations, and each has contributed to a better understanding of this type of tribology.Metal-on-metal: episode 1 While G.K. McKee stands for metal-on-metal coupling, also K.M. Sivash, P. Ring, J. Scales, A. Hugler, M. Müller and M. Postel deserve mention. They have all participated in the development of this bearing surface and have honestly faced up to the limits and the failures of their work [40].McKee had to rapidly give up steel for a chrome-cobaltmolybdenum alloy promoted by Venable, and the acetab-P. Triclot

We carried out a prospective randomised study designed to compare the penetration rate of acetabular polyethylene inserts of identical design but different levels of cross-linking at a minimum of four years follow-up. A total of 102 patients (102 hips) were randomised to receive either highly cross-linked Durasul, or contemporary Sulene polyethylene inserts at total hip replacement. A single blinded observer used the Martell system to assess penetration of the femoral head. At a mean follow-up of 4.9 years (4.2 to 6.1) the mean femoral head penetration rate was 0.025 mm/year (SD 0.128) in the Durasul group compared with 0.106 mm/year (SD 0.109) in the Sulene group (Mann-Whitney test, p = 0.0027). The mean volumetric penetration rate was 29.24 mm(3)/year (SD 44.08) in the Durasul group compared with 53.32 mm(3)/year (SD 48.68) in the Sulene group. The yearly volumetric penetration rate was 55% lower in the Durasul group (Mann-Whitney test, p = 0.0058). Longer term results are needed to investigate whether less osteolysis will occur.

New friction couples, initially intended to limit osteolysis risk due to debris, have enabled larger implant head diameters to be developed to resolve the problem of hip implant dislocation. The Symposium demonstrated that, whatever the configuration, increased head diameter significantly reduced the incidence of dislocation, but that none of the friction couples fulfilled the mechanical and/or biomechanical charge-book for consistently reliable use of large diameter heads. The greatest caution is therefore recommended in their implementation.

IV. Retrospective series.

No abstract