The Role of Metal-on-Metal Bearings in Total Hip Arthroplasty and Hip Resurfacing

Abstract

Background: The current role of metal-on-metal (MoM) bearings in hip arthroplasty remains controversial. The low wear offered by MoM bearings compared to metalon-polyethylene and the possibility of a lower risk of dislocation with larger head sizes, encouraged a trend towards the re-introduction of the MoM bearing couple. However, recent evidence has shown that not all designs of the MoM bearing have been successful. Questions/Purposes: The purpose of this paper is to provide an update on the use of MoM bearings and address the following issues: (1) the reintroduction of metal-on-metal bearings in total hip arthroplasty, (2) the failure of metal-on-metal bearings in stemmed total hip arthroplasty, (3) the role of metal-on-metal hip resurfacing in modern orthopaedics and (4) metal-on-metal hip resurfacing versus total hip arthroplasty. Methods: A literature search strategy was conducted using various search terms in MEDLINE and Embase. The highest quality articles that met the inclusion criteria and best answered the topics of focus of this review were selected. Key search terms included 'metal-on-metal', 'total hip arthroplasty' and 'hip resurfacing'. Results: The initial search retrieved 1240 articles. Twenty-two articles were selected and used in the review. Conclusion: Metal-on-metal hip resurfacing is still a suitable treatment option in specific patient populations with the appropriate implant design and surgical skill, while stemmed metal-on-metal total hip arthroplasty should be avoided in all patient populations. Continued follow-up of patients undergoing metal-on-metal hip resurfacing is critical in order to further understand the long-term outcomes of these patients and why certain complications tend to occur with this procedure.

Metal Ion Release, Clinical and Radiological Outcomes in Large Diameter Metal-on-Metal Total Hip Arthroplasty at Long-Term Follow-Up

“…The use of MoM bearings has been discontinued due to biological concerns, local and systemic release of metal ions [ 32 , 33 , 34 , 35 ] with frequent reports of ARMD [ 36 ]. The diagnosis of ARMD in MoM THA is a multifactorial process that involves mechanical, radiological and clinical factors [ 37 ].…”

Variability in stem taper surface topography affects the degree of corrosion and fretting in total hip arthroplasty

“…Ceramic femoral heads are extensively used due to low wear characteristics 28 and in response to controversial complications in metal-on-metal bearings 29 , 30 . The use of ceramic heads has also guided the design of stem tapers: due to the brittle nature of ceramics, the head and stem taper angle are chosen such that most contact occurs at the center of the head to minimize stresses and prevent burst fracture 31 – 33 .…”

Pseudotumors in Small-Head Metal-on-Metal Total Hip Arthroplasties at a Minimum Follow-Up of 20 Years

“…Metal-on-metal (MOM) surfaces have been used for a long time and are still used nowadays in some young and active patients, because of their hardness and their reduced risk of wear. [4][5][6] These bearings have shown high survival rates and very satisfying clinical results, but there is the risk of metal ion release and systemic accumulation. As a consequence, carcinogenicity, neurological, cardiovascular and endocrine deficits can result.…”