Development rationale for an articular surface replacement: A science-based evolution

Abstract

Hip resurfacing has an enduring appeal because of the advantages of bone conservation and maximal joint stability. However, a far from satisfactory experience with earlier resurfacing designs led to its virtual disappearance in the 1980s. The concept was reintroduced in the late 1990s. The current generation of resurfacing devices generally consisted of a large-diameter metal-on-metal articulation, the femoral components being cemented and the acetabular components utilizing various forms of cementless fixation. The encouraging medium-term results, with a follow-up of up to 8 years using the current generation of surface replacement joints, combined with favourable reports related to long-term performance of some metal bearings have led to a rapid increase in the use of such components with these devices. This trend is most marked in younger, more active patients who have expectations of restoration of lifestyle in addition to improved mobility and pain relief and in whom failure with conventional total hip replacement is much higher than previously reported with more sedentary patients. The aim of this paper is, firstly, to highlight a number of areas of improvement and, secondly, to explain how these may be addressed by making modifications to the design of both implants and instrumentation and to the surgical technique. The areas identified for improvement were tissue preservation (thinner components, and reduced steps between sizes), acetabular cup issues (fixation, insertion, and positioning), femoral component issues (design, loading, and cementation), improved bearing surface characteristics, and simplified precise instrumentation with a low-trauma surgical technique.

Effect of bearing size on the long‐term wear, wear debris, and ion levels of large diameter metal‐on‐metal hip replacements—An in vitro study

“…Another important factor to consider is the effect of the tribochemical layer which involves the incorporation of proteins into a nanocrystalline surface layer which can regenerate and repair itself inducing low wear rates. 27 Initially, there was an apparent difference in the steady state wear rates (1)(2)(3)(4)(5) between the two bearing sizes. However, in late steady state (10)(11)(12)(13)(14)(15) Mc) the wear rates were similar.…”

“…The advantages and disadvantages of surface replacement arthroplasty have been discussed previously. [1][2][3] Bearing diameter, clearance and the resultant effective radius (R) are key parameters in the tribology of MoM hip replacements. Previous simulator studies on MoM total hip replacements have demonstrated a 2-3-fold reduction in wear with increasing head size.…”

Acetabular Cups in 60 mm Metal-on-Metal Bearings Subjected to Dynamic Edge-Loading with 70° Peak-Inclination in 10-Million Cycle Simulator Study

“…A hip simulator study represents a complex undertaking while still representing an over-simplification of patient conditions. A major body of work over the years identified fluid-film lubrication as the ideal condition for success in MOM bearings [12,13,16]. However, MOM bearings failing in patients have demonstrated adverse wear mechanisms that can produce significantly high volumes of CoCr debris within a few years [21][22][23].…”

“…In hip simulator laboratories, a major body of research identified fluid-film lubrication as one of the goals for achieving success with hip bearings [12][13][14][15][16][17][18]. Large MOM bearings appeared particularly suited to this concept.…”

Effects of Reamer-Femoral Component Offset on Cement Mantle Penetration in Hip Resurfacing Arthroplasty

“…Hip resurfacing is a type of hip arthroplasty that is commonly compared to total hip replacement. Total hip replacements involve resecting the femoral neck and placing a long stemmed femoral component into the proximal shaft of the femur (Isaac, Siebel et al 2006). The two types of arthroplasty seen in figure 1 show the fundamental differences between the two systems.…”