Tag Archive | metal-on-metal

JBJS 100: Metal-on-Metal Hips and Shoulder Function

JBJS 100Under one name or another, The Journal of Bone & Joint Surgery has published quality orthopaedic content spanning three centuries. In 1919, our publication was called the Journal of Orthopaedic Surgery, and the first volume of that journal was Volume 1 of what we know today as JBJS.

Thus, the 24 issues we turn out in 2018 will constitute our 100th volume. To help celebrate this milestone, throughout the year we will be spotlighting 100 of the most influential JBJS articles on OrthoBuzz, making the original content openly accessible for a limited time.

Unlike the scientific rigor of Journal content, the selection of this list was not entirely scientific. About half we picked from “JBJS Classics,” which were chosen previously by current and past JBJS Editors-in-Chief and Deputy Editors. We also selected JBJS articles that have been cited more than 1,000 times in other publications, according to Google Scholar search results. Finally, we considered “activity” on the Web of Science and The Journal’s websites.

We hope you enjoy and benefit from reading these groundbreaking articles from JBJS, as we mark our 100th volume. Here are two more:

Metal-on-Metal Bearings and Hypersensitivity in Patients with Artificial Hip Joints
H-G Willert, G H Buchhorn, A Fayyazi, R Flury, M Windler, G Köster, C H Lohmann: JBJS, 2005 January; 87 (1): 28
At the turn of the 21st century, many efforts were underway to discover why some patients who had received second-generation metal-on-metal hip replacements were having postoperative problems. This clinical and histomorphological study, illustrated with detailed tissue sections, showed that a lymphocyte-dominated immunological response could be involved.

Observations on the Function of the Shoulder Joint
V T Inman, J B deC M Saunders, L C Abbott: JBJS, 1944 January; 26 (1): 1
Back in the days when 30-page JBJS articles were not uncommon, these authors set out to examine the whole shoulder mechanism, with detailed anatomical drawings, radiographic analysis, and action potentials derived from living shoulder muscles. This comprehensive, “eclectic approach” was published at a time when polio was endemic, but it is still relevant today.

With New Technologies, Slow Adoption is Best

MoM for OBuzzThe enemy of the good is the better. It’s an axiom we hear during our surgical training, and it was my first thought when reading the article by Hunt et al. in the February 7, 2018 edition of JBJS.  The authors examine failure rates associated with the rapid adoption and widespread use of metal-on-metal (MoM) total hip arthroplasties (THAs) and hip resurfacings.

Carefully analyzing data from the National Joint Registry for England, Wales and Northern Ireland from 2003 to 2014, Hunt et al. ascertained that MoM hip resurfacings and MoM total hip arthroplasties resulted in 10-year revision rates that were almost 3 and 5 times higher, respectively, than the expected revision rates for standard hip procedures. This meant that within 10 years, there were almost 8 excess revisions for every 100 MoM hip resurfacings and almost 16 excess revisions for every 100 MoM total hip arthroplasties. Just as troubling was the finding that 20% of those excess revisions needed at least one additional revision within 7 years.

As orthopaedic surgeons, we strive to make things better for patients, which may tempt us to try a “new and improved” technology for a nominal (or presumed) improvement in outcome, when the one we are currently using works just fine. It is our responsibility as surgeons not to be blind to the unintended consequences new technologies may have on our patients.

I agree with the blunt directive Hunt et al. issue in the final sentence of their abstract: “This practice of adopting new technologies without adequate supporting data must not be repeated.”

Chad A. Krueger, MD
JBJS Deputy Editor for Social Media

JBJS Reviews Editor’s Choice–How Should New Orthopaedic Technology Be Introduced?

Over the past several decades, orthopaedic surgery has enjoyed an explosion in the development of new technologies. These technologies have largely improved the quality of orthopaedic care. The development of new technologies results in both disruptive and nondisruptive evolution and requires that orthopaedic surgeons gain specific knowledge of their appropriate use in clinical practice.

However, despite the advances developed from orthopaedic innovation, many discoveries have been associated with unanticipated adverse events. As an example, the original total hip replacement developed by Charnley featured a 1-piece femoral component with a 22.5-mm head. This was later changed to a larger-diameter head, resulting in increased volumetric wear of conventional polyethylene. In addition, new implants with sharp corners led to cement fractures and the development of so-called cement disease. More recently, metal-on-metal articulations have been associated with metallic particles and ion-induced bone and soft-tissue destruction. Ceramic-on-ceramic articulations may lead to implant breakage, striped wear, and squeaking. There is no question that total hip arthroplasty is an exceptionally successful technology, but there is concern regarding the way in which improvements and innovations gain regulatory approval and surgeon acceptance.

In the May 2016 issue of JBJS Reviews, Goodman et al. discuss the introduction of new technologies in orthopaedic surgery. They review the use of novel biologics and combination products and, in particular, single out platelet-rich plasma for the insufficient clinical evidence to support its use. Moreover, they describe the initial enthusiasm regarding the use of recombinant human BMP-2 for spine fusions but note that a review of clinical trials has revealed that there may be concerns regarding insufficient numbers of patients to assess safety, under-reporting of serious complications, conflict of interest among the investigators, and potential bias.

Goodman et al. address some very simple but nonetheless profound issues. For example, they ask, “How should new technologies be introduced into orthopaedics?” They further ask, “How should a surgeon learn to use new technology?” Perhaps most importantly, they raise the issue of ethical considerations related to the use of new technology.

The future of orthopaedic innovation looks bright. Some have commented that there are too many perceived barriers to gaining regulatory approval of new technologies. Recently, the structure and methodology by which approval of new medical technology is managed across the United States has come under increased scrutiny.

I do not think you can ever be too safe or too careful. This article by Goodman et al. is an excellent review of the issues and considerations. It’s a quick read but leaves plenty of room for thought!

Thomas Einhorn, Editor

JBJS Reviews

Metal-on-Metal Hip Arthroplasty: Where Do We Go From Here?

OrthoBuzz occasionally receives posts from guest bloggers. This guest post comes from Richard S. Yoon, MD.

We’re entering the “midterm” follow-up period for the metal-on-metal (MoM) hip devices implanted in the early 2000s, and recent reports from around the world are confirming early concerns. Several studies published during the first few months of 2016 report unacceptably high failure rates.

In the Open Orthopaedics Journal, Mogensen et al. reported an 18.4% revision rate in more than 100 CONSERVE MoM hips, at a mean follow-up of 4.5 years. These results led the Danish authors to terminate the use of MoM at their centers.

In the BMJ Open, Langton et al. reported a 16% failure rate among more than 350 Pinnacle MoM hips after about nine years of follow-up. Greiner et al. published a follow-up of prior research in a recent edition of the Journal of Arthroplasty. Among more than 150 MoM modular acetabular components with 5- to 12-year follow-ups, the results related to adverse local tissue reactions and revisions were inferior when compared with those of metal-on-polyethylene articulations. Dhotare et al., in Hip International, reported an alarming failure-rate increase from 7% at six years to 29% at ten years for the Birmingham MoM cup and large metal head.

While we cannot turn back the clock on the past use of MoM devices, we have some information about surveillance and treatment that may help us prevent catastrophic failure.

Data regarding the effects of increasing serum metal ions are mixed. Some studies have found a direct correlation between high metal ion levels and the incidence of adverse tissue reactions (and the need for subsequent revision), while other studies have not.  A recent JBJS study identified cobalt-ion thresholds that could help stratify patients with Birmingham and Corail-Pinnacle hips who are at low risk of metal-debris adverse reactions.

The systemic effects of increased serum metal ions are also being debated. Some case reports have cited neurotoxicity presenting as tinnitus, gait imbalance, and other issues, while a more recent, larger longitudinal study published in the Journal of Arthroplasty did not confirm this correlation. Those authors surmised that increased serum ion levels may cause neurotoxicity-associated symptoms primarily in MoM patients with metal hypersensitivity.

Metal artifact reduction sequence (MARS) MRI has been helpful in early identification of adverse soft tissue reactions. However, there is no general consensus or guideline as to when and how often this technology should be utilized in order to provide consistent surveillance and/or indications for revision.

While we are still trying to understand the finer points of the many variables related to MoM, there is an obvious need to forge consensus. Recently, in the Bone and Joint Journal, Berber et al., representing the International Specialist Centre Collaboration on MoM Hips (ISCCoMH), conducted a survey among six international tertiary referral centers to assess the overall consensus in surveillance and treatment practices. Only a moderate agreement value (kappa = 0.6) was found. This inconsistent agreement led the group to call for international coordination to help set forth guidelines that would standardize and improve surveillance of and treatment for those with MoM hips.

Richard S Yoon, MD is executive chief resident at the NYU Hospital for Joint Diseases.

Cobalt-Ion Thresholds Could Ease Follow-Up Burden on Some MoM Patients

Cobalt.gif In the mid-2000s, before the orthopaedic community was aware of the potentially catastrophic shortcomings of metal-on-metal (MoM) hip implants, nearly half of all hip replacements used MoM components. With so many people walking around today on those prostheses, orthopaedists are looking for rational and effective ways to monitor these patients for adverse reactions to metal debris.

Findings from a diagnostic Level II study by Matharu et al. in the April 20 edition of The Journal of Bone & Joint Surgery will help identify patients who are at low risk of metal-debris adverse reactions, specifically among those who have Birmingham Hip Resurfacing (BHR) and Corail-Pinnacle MoM implants. The authors found that when measuring cobalt ions in whole blood, the optimal threshold for identifying adverse reactions to metal debris was 2.15 µg/L for BHR patients and 3.57 µg/L for Corail-Pinnacle patients. These implant-specific thresholds are lower than the non-implant-specific thresholds proposed by US and UK regulatory agencies, and in this study the cutoffs had good sensitivities and specificities, and their negative predictive values exceeded 98%.

The authors say identifying low-risk individuals will allow orthopaedists to focus surveillance efforts on patients who are at higher risk of adverse reactions to metal debris. They even suggest that patients below the implant-specific thresholds for cobalt could be excluded from regular follow-up regimens, provided they have normal clinical examinations and radiographs.

While lauding Matharu et al. for prospectively determining these thresholds, commentator Lawrence Dorr, MD says these findings need “to be tested at multiple centers to validate [their] superiority,” and he emphasizes that better methods to identify asymptomatic patients who are at high risk of adverse reactions to metal debris still must be developed.

Among Large-Diameter MoM Hip Implants, Durom Has Highest Metal Ion Level

In a May 2011 supplement to The Journal of Bone & Joint Surgery, Lavigne et al.  reported results from a prospective two-year study looking at blood metal-ion levels in patients who received one of four types of large-head, metal-on-metal THA designs. At that point, the Durom design from Zimmer showed significantly higher blood levels of cobalt and titanium ions than the three other implants (Birmingham from Smith & Nephew, ASR XL from DePuy, and Magnum from Biomet).

The February 17, 2016 JBJS provides an update on the same cohort at five years of follow-up.  By five years, the original 144-patient cohort had diminished to 134, 123 of whom were available for clinical follow-up and 93 of whom had their metal-ion levels analyzed again.

Hutt Study Graph.gif

In terms of WOMAC and UCLA function scores, there were no differences at five years among the implant types. However, the current study revealed that the Durom design produced the highest levels of metal ions in the blood and the highest number of adverse local tissue reactions and revisions. One of the most problematic design factors in all four implants, the authors say, is the junction of the femoral trunnion and head taper or adapter sleeve (see related OrthoBuzz post).

While noting that ion levels in isolation are probably not useful as either diagnostic or screening criteria, the authors say that “ion progression over time may be more useful, and ideally, a multimodal investigative protocol correlating patient symptomatology, ion levels, and cross-sectional imaging would be required.”