Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tracing the life cycle of a manmade disease

22.12.2004


MGH surgeon tells 40-year tale of investigation and innovation into the challenge of hip implant failure



A remarkable story of how a new disease was inadvertently caused by successful medical treatment, ultimately understood, and eventually defeated by scientific innovation is being told a major player in the process. In the December issue of Clinical Orthopedics and Related Research, William Harris, MD, DSc, of Massachusetts General Hospital (MGH), describes how the development of total hip replacement led to an unexpected problem, erosion of bone adjacent to the implant, and how his team and others both identified the process underlying that breakdown and helped to develop new materials that avoid the problem. "The history of the unraveling and prevention of this worldwide, unique, severe disease is a fascinating story of the integration of surgical innovation, molecular biology and material science," writes Harris, who is Alan Gerry Clinical Professor of Orthopaedic Surgery at Harvard Medical School.

Harris was a pioneer in the field of joint replacement, beginning in the late 1960s. But he and other surgeons gradually observed that hip implants could loosen starting about 5 years after surgery and eventually fail completely. There were many theories about the cause of that loosening, several which focused on the adhesive used or the possibility of infection.


In 1976 Harris reported that implant failures appeared to be caused by a biological response at the site of the implant, which resulted in erosion of the bone. Looking further into the complication, Harris and colleagues found that, when the metal head of the implant rubbed against the polyethylene joint socket, small particles of polyethylene broke off over time. As the immune system reacted against these foreign particles, eventually it would attack and destroy the bone tissue, loosening the implant to the point of failure. It turned out that this complication was an entirely new manmade disease called periprosthetic osteolysis – a condition spawned inadvertently by the medical pioneers who, in finding a treatment for debilitating hip disease, had created a whole new problem.

In the early 1990s, Harris and his team began to focus their attention on finding a way to decrease the wear and tear of the polyethylene cushion in the joint, with an ultimate goal of eliminating osteolysis. The team’s initial work involved designing a hip simulator that could accurately replicate the motions and forces of the human hip and measure the wear performance of the implant. The MGH group then turned to a team of polymer chemists from Massachusetts Institute of Technology (MIT) for help in figuring out just how to make a polyethylene cushion that would resist wear and erosion through years of constant motion and weight. They eventually found the solution by "crosslinking" the polyethylene, which involves using a high dose of irradiation to bond molecules more tightly together, producing a much stronger and more durable material. Out of this MGH-MIT collaboration emerged a highly crosslinked, ultra-high-molecular-weight polyethylene.

The research team improved and refined the material by putting it through a melting process to eliminate any free radicals that could cause oxidation and lead to the degradation of the implant material. The material continued to prove strong and reliable in several studies, showing virtually no wear even after being subjected to excessive use and intense abuse. In 1999, the FDA approved highly crosslinked polyethylene for use in implants, the manufacture of which has been licensed to Zimmer, Inc. In subsequent years, the compound has continued to hold up exceptionally well, improving the long-term outlook for patients and expanding the field of total joint replacement.

"The availability of implants with crosslinked polyetheylene has made a great deal of difference for patient care," Harris says. "For example, we used to be reluctant to do total hip replacements in young people because of the long-term risk of periprosthetic osteolysis, which led to doing some less satisfactory types of procedures that only postponed the need for an total hip. While we are still careful about doing hip replacements in any patients, current evidence suggests that the incidence of osteolysis is extraordinarily low with the new implants, making the procedure appropriate for a broader range of patients."

Peter L. Slavin, MD, MGH president, recently said of this accomplishment, "The key beneficiaries of this work are patients throughout the world who, thanks to Dr. Harris and his team, now have the chance to experience a better quality of life for a much longer time."

Sue McGreevey | EurekAlert!
Further information:
http://www.mgh.harvard.edu

More articles from Health and Medicine:

nachricht Research offers clues for improved influenza vaccine design
09.04.2018 | NIH/National Institute of Allergy and Infectious Diseases

nachricht Injecting gene cocktail into mouse pancreas leads to humanlike tumors
06.04.2018 | University of Texas Health Science Center at San Antonio

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

Im Focus: Like a wedge in a hinge

Researchers lay groundwork to tailor drugs for new targets in cancer therapy

In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...

Im Focus: The Future of Ultrafast Solid-State Physics

In an article that appears in the journal “Review of Modern Physics”, researchers at the Laboratory for Attosecond Physics (LAP) assess the current state of the field of ultrafast physics and consider its implications for future technologies.

Physicists can now control light in both time and space with hitherto unimagined precision. This is particularly true for the ability to generate ultrashort...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Electromagnetic wizardry: Wireless power transfer enhanced by backward signal

19.04.2018 | Physics and Astronomy

Ultrafast electron oscillation and dephasing monitored by attosecond light source

19.04.2018 | Physics and Astronomy

This 2-D nanosheet expands like a Grow Monster

19.04.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>