Metal-on-metal bearing in hip prosthesis generates 100-fold less wear debris than metal-on-polyethylene (original) (raw)

Wear of surface engineered metal-on-metal hip prostheses

Journal of Materials Science: Materials in Medicine, 2000

The wear of existing metal-on-metal (MOM) hip prostheses (1 mm 3 /million cycles) is much lower than the more widely used polyethylene-on-metal bearings (30±100 mm 3 /million cycles). However, there remain some potential concerns about the toxicity of metal wear particles and elevated metal ion levels, both locally and systemically in the human body. The aim of this study was to investigate the wear, wear debris and ion release of fully coated surface engineered MOM bearings for hip prostheses. Using a physiological anatomical hip joint simulator, ®ve different bearing systems involving three thick (8±12 mm) coatings, TiN, CrN and CrCN, and one thin (2 mm) coating diamond like carbon (DLC) were evaluated and compared to a clinically used MOM cobalt chrome alloy bearing couple. The overall wear rates of the surface engineered prostheses were at least 18-fold lower than the traditional MOM prostheses after 2 million cycles and 36-fold lower after 5 million cycles. Consequently, the volume of wear debris and the ion levels in the lubricants were substantially lower. These parameters were also much lower than in half coated (femoral heads only) systems that have been reported previously. The extremely low volume of wear debris and concentration of metal ions released by these surface engineered systems, especially with CrN and CrCN coatings, have considerable potential for the clinical application of this technology.

A lexicon for wear of metal-on-metal hip prostheses

Journal of Orthopaedic Research, 2014

Research on metal-on-metal (MoM) hip bearings has generated an extensive vocabulary to describe the wear processes and resultant surface damage. However, a lack of consistency and some redundancy exist in the current terminology. To facilitate the understanding of MoM tribology and to enhance communication of results among researchers and clinicians, we propose four categories of wear terminology: wear modes refer to the in vivo conditions under which the wear occurred; wear mechanisms refer to fundamental wear processes (adhesion, abrasion, fatigue, and tribochemical reactions); wear damage refers to the resultant changes in the morphology and/or composition of the surfaces; and wear features refer to the specific wear phenomena that are described in terms of the relevant modes, mechanisms, and damage. Clarifying examples are presented, but it is expected that terms will be added to the lexicon as new mechanisms and types of damage are identified. Corrosion refers to electrochemical processes that can remove or add material and thus also generate damage. Corrosion can act alone or may interact with mechanical wear. Examples of corrosion damage are also presented. However, an in-depth discussion of the many types of corrosion and their effects is beyond the scope of the present wear lexicon. ß

Wear and Lubrication of Metal-on-Metal Hip Implants

Clinical Orthopaedics and Related Research, 1999

The implication of polyethylene wear particles as the dominant cause of periprosthetic osteolysis has created a resurgence of interest in metalon-metal implants for total hip arthroplasty because of their potential for improved wear performance. Twenty-two cobalt chromium molybdenum metal-on-metal implants were custom-manufactured and tested in a hip simulator. Accelerated wear occurred within the first million cycles followed by a marked decrease in wear rate to low steady-state values. The volumetric wear at 3 million cycles was very small, ranging from 0.15 to 2.56 mm3 for all implants tested. Larger head-cup clearance and increased surface roughness were associated with increased wear. Independent effects on wear of From the

Wear evaluation of cobalt–chromium alloy for use in a metal‐on‐metal hip prosthesis

Journal of Biomedical …, 2004

Wear of the polyethylene in total joint prostheses has been a source of morbidity and early device failure, which has been extensively reported in the last 20 years. Although research continues to attempt to reduce the wear of polyethylene joint-bearing surfaces by modifications in polymer processing, there is a renewed interest in the use of metal-on-metal bearing couples for hip prostheses. Wear testing of total hip replacement systems involving the couple of metal or ceramic heads on polymeric acetabular components has been performed and reported, but, until recently, there has been little data published for pin-on-disk or hip-simulator wear studies involving the combination of a metallic femoral head component with an acetabular cup composed of the same or a dissimilar metal. This study investigated the in vitro wear resistance of two cobalt/chromium/molybdenum alloys, which differed primarily in the carbon content, as potential alloys for use in a metal-on-metal hip-bearing couple. The results of pin-on-disk testing showed that the alloy with the higher (0.25%) carbon content was more wear resistant, and this alloy was therefore chosen for testing in a hip-simulator system, which modeled the loads and motions that might be exerted clinically. Comparison of the results of metal-on-polyethylene samples to metal-on-metal samples showed that the volumetric wear of the metal-on-polyethylene bearing couple after 5,000,000 cycles was 110 -180 times that for the metal-bearing couple. Polyethylene and metal particles retrieved from either the lubricant for pin-on-disk testing or hip simulator testing were characterized and compared with particles retrieved from periprosthetic tissues by other researchers, and found to be similar. Based upon the results of this study, metal-on-metal hip prostheses manufactured from the high carbon cobalt/chromium alloy that was investigated hold sufficient promise to justify human clinical trials.

Volumetric wear assessment of failed metal-on-metal hip resurfacing prostheses

Wear, 2011

Recent advancements in hip arthroplasty have allowed the operation to boast excellent results and high survivorship. However, failures do still occur and a major cause is complications arising from wear debris. It is essential therefore that debris is minimized by reducing wear at the bearing surface. One proposed method of achieving this wear reduction is through the use of metal-on-metal articulations. One of the latest manifestations of this biomaterial combination is in designs of hip resurfacing which are aimed at younger, more active patients who might wear out a conventional metal-on-polymer hip prosthesis. However, do these metal-on-metal hip resurfacings show less wear when implanted into patients?

Analysis of failed metal-on-metal hip prostheses

Replacement joints, or prostheses, are an important tool for reducing pain and restoring functionality to patients with diseases such as arthritis. However, even the most modern prostheses have a limited life span and a major cause of failure is wear.

A finite element method comparison of wear in two metal-on-metal total hip prostheses

Proceedings of The Institution of Mechanical Engineers Part H-journal of Engineering in Medicine, 2006

The contact mechanics of two metal-on-metal (MOM) total hip prostheses was studied by means of the finite element method (FEM). The purpose of the work was to compare two total hip replacements (DuromTM and MetasulTM) with regard to the amount of wear debris released. Wear on the bearing surfaces was evaluated following Reye hypotheses from the pressure distribution, computed by means of three-dimensional FEM models; an approximate analytical model based on Hertz contact theory has also been developed and discussed. The results show that in the dry friction condition the DuromTM joint releases almost twice as much wear volume as produced by the MetasulTM joint. Therefore, while DuromTM implants can improve hip stability by increasing the prosthetic impingement-free range of motion (PIF-ROM), MetasulTM prostheses can be a valuable solution whenever wear represents a critical choice factor. could be attributed to the larger bearing diameter but also to the elasticity of the underlying bone