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Posts Tagged ‘Orthopedic surgery’


Collaboration that corrected a major problem in Hip Replacement Surgery

Reporter:Irina Robu, PhD

British orthopedic surgeon, John Charnley performed an operation that almost miraculously restored pain-free movement and active lives to patients whose hip-joint damage had made even the simple act of walking across the room difficult.

However, with the advance in materials Charnley removed the damaged joint and replaced it with one made of Teflon. He cut off the top of the thigh bone and inserted the end of a rod like metal implant into its center, cementing it in place. The round head of the implant fits perfectly into the Teflon hip socket. The procedure seemed to work, but within some year complications arose. The routine movement of the balls in the sockets made the Teflon wear quickly, loosening the implants. Charnley was required to operate on nearly 300 patients after they developed an infection around the implant.
Charnley filled that need with a more-resistant material called high-density polyethylene, which he began using in a new version of the artificial hip joint in 1962. In 1974, a noted orthopedic surgeon at Massachusetts General Hospital had a patient who had replaced surgery but his X-ray showed that a large portion of his thigh bone had been eaten away. Even after further tests, it was confirmed that the patient was cancer free. Harris saw three similar cases that year and many more over the years and it was defined as a new disease, periprosthetic osteolysis.

The condition led not just to implant failures, hip fractures, femur fractures, and complex reoperations to install new implants. It would take decades to devise a solution, in the form of a new material , highly crosslinked polyethylene invented in the labs of Harris and his Massachusetts Institute of Technology collaborator, Edward Merrill. A few years after Harris described the condition, in 1976, another separate research effort drawn its cause to tiny particles of the cement that secured the metal thigh implant inside the femur. Those particles caused a massive immune reaction that in turn triggered osteoclasts, the only cell in the body capable of destroying bone.

The discovery led to the condition being called “cement disease,” warning the development in the early 1980s of porous-metal implants that allowed the bone to grow into the implant and hold it in place in the thigh bone. Further research displayed that particles were still there, but of the polyethylene that made up the hip socket. Nevertheless, the polyethylene was far more durable than Teflon, the even motion of the ball in the socket caused wear, producing particles that set off the same destructive immune reaction.

By that discovery, researchers finally understood what was happening in the body. With so many hip replacement surgeries ongoing around the world, what was needed was a material more durable as polyethylene. Harris had asked patients to donate implants for study after they died, and he worked with lab members to examine them under a scanning electron microscope. The long, skinny molecules of high-density polyethylene, which normally curl had become aligned in the direction of the back-and-forth motion of the joint.

Harris worked with Merrill who mentioned that he can created polyethylene into a new form: highly crosslinked polyethylene. Meanwhile in 1998, the first artificial hips using highly crosslinked polyethylene were put in patients and it shows a huge progress.

SOURCE
https://news.harvard.edu/gazette/story/2018/03/harvard-surgeon-publishes-vanishing-bone-conquering-a-stealth-disease-caused-by-total-hip-replacements/?utm_source=SilverpopMailing&utm_medium=email&utm_campaign=Daily%20Gazette%2020180306

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Reported by: Dr. Venkat S Karra. Ph.D.

A multidisciplinary research team led by Carnegie Mellon University is developing new nanostructural polymer-based treatments to eliminate pathological bone formation in soft tissue, a common occurrence following orthopedic surgeries and amputations.

Heterotopic ossification

“Our tactic is to develop a solution that will control the pathological growth of bone in muscle and tendons (called heterotopic ossification) that frequently occurs following bone trauma and orthopedic surgery,” said Jeffrey O. Hollinger, professor of biomedical engineering and biological sciences, and head of CMU’s Bone Tissue Engineering Center.

“When bone is severely injured and amputation of a limb is necessary, or as a consequence of major orthopedic procedures, unwanted new bone formation occurs in the soft tissues surrounding the operated bone and appears as pieces of gravel-like bone. Consequently, there is pain and discomfort at an amputation stump where a prosthesis is secured. We are developing a therapy that will eliminate heterotopic ossification,” he added.

Data suggests heterotopic ossification occurs in more than 60 percent of military personnel who incur bone injury resulting in limb amputation. Therefore, the CMU labs of J.C. Warner University Professor of Natural Sciences and Chemistry Professor Krzysztof Matyjaszewski are using a three-year, $2.93 million grant from the Department of Defense to work with researchers at the United States Military Academy at West Point, the University of Michigan and the Naval Medical Center in Portsmouth, Va., to produce a therapeutic solution to eliminate heterotopic ossification.

Hollinger, the principal investigator for the grant, said the patient-centric focus of the team’s research includes a nanostructural polymer composite developed by Matyjaszewski to deliver unique RNA identified in the Hollinger lab, into cells at the bone trauma site to prevent heterotopic ossification in the soft tissue.

“The problem of heterotopic ossification is more widespread than the military population,” Hollinger said. More than 90 percent of hip replacement operations in the civilian U.S. population also show signs of heterotopic ossification. Because the problem is so complex, CMU researchers report that it will take a team of clinicians and researchers to develop solutions.

“We see this collaborative research as a win for both military and civilian populations. And we see this particular research project as a great way to help us change our research paradigm at West Point,” said J. Kenneth Wickiser, director of the Center for Molecular Science in the Department of Chemistry & Life Science at the United States Military Academy. “Our cadets are gaining invaluable hands-on research experience as summer interns at CMU’s biomedical engineering labs. And we are becoming more competitive in our abilities at West Point to tackle more innovative research initiatives,” Wickiser said.

Ashley Phillips, a sophomore West Point cadet, praised the CMU internship program for its concise and rigorous approach to problem solving. “I want to be a doctor and this CMU research experience gives me an excellent platform for growth and a medium for sharing my work with other cadets,” said Phillips of Mukwonago, Wis.

CMU researchers report there is a patent pending on the therapy and a clinical trial schedule will be developed once the preventative platform is fully lab tested.

Source:

rdmag

Carnegie Mellon University

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