State of the art in hard-on-hard bearings: how did we get here and what have we achieved?

Abstract

Total hip arthroplasty has shown excellent results in decreasing pain and improving function in patients with degenerative disease of the hip. Improvements in prosthetic materials, designs and implant fixation have now resulted in wear of the bearing surface being the limitation of this technology, and a number of hard-on-hard couples have been introduced to address this concern. The purpose of this article is to review the origins, development, survival rates and potential advantages and disadvantages of the following hard-on-hard bearings for total hip arthroplasty: metal-on-metal standard total hip arthroplasty; metal-on-metal hip resurfacing arthroplasty, ceramic-on-ceramic total hip arthroplasty; and ceramic-on-metal bearings. Improvements in the manufacturing of metal-on-metal bearings over the past 50 years have resulted in implants that provide low wear rates and allow for the use of large femoral heads. However, concerns remain regarding elevated serum metal ion levels, potential teratogenic effects and potentially devastating adverse local tissue reactions, whose incidence and pathogenesis remains unclear. Modern total hip resurfacing has shown excellent outcomes over 10 years in the hands of experienced surgeons. Current ceramic-on-ceramic bearings have demonstrated excellent survival with exceptionally low wear rates and virtually no local adverse effects. Concerns remain for insertional chipping, in vivo fracture and the variable incidence of squeaking. Contemporary ceramic-on-metal interfaces are in the early stages of clinical use, with little data reported to date. Hard-on-hard bearings for total hip arthroplasty have improved dramatically over the past 50 years. As bearing designs continue to improve with new and modified materials and improved manufacturing techniques, it is likely that the use of hard-on-hard bearings will continue to increase, especially in young and active patients.

Keywords::

• alumina
• ceramic-on-ceramic
• ceramic-on-metal
• cross-linked polyethylene
• hip resurfacing
• metal-on-metal
• pseudotumor
• total hip arthroplasty

Financial & competing interests disclosure

Michael A Mont is a consultant for Stryker Orthopaedics and Wright Medical, receives royalties from Stryker and receives research or institutional support from Stryker, Wright Medical, the National Institutes of Health (NIAMS and NICHD) and Tissue Gene. Thomas P Schmalzried is a board member of the Orthopaedic Research and Education Foundation, is a member of the editorial board for Orthopedics Today, receives royalties from DePuy and Stryker, is a consultant for Stryker, receives research or institutional support from DePuy and Stryker, and holds stock or stock options in Johnson and Johnson, Smith and Nephew, Stryker and Zimmer. Michael G Zywiel serves on the editorial board of Expert Review of Medical Devices. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.