Navigation Links
Archive of failed joint replacements provides tips to building a better hip replacement
Date:2/7/2012

A study by Hospital for Special Surgery researchers has provided the first comprehensive look at just how metal-on-metal total hip replacements are failing in patients around the country. Made possible by what is thought to be the largest archive of failed joint replacements, the research should help doctors develop a better hip replacement for future patients. The study will be reported at the upcoming annual meeting of the American Academy of Orthopaedic Surgeons, Feb. 7-11.

"This paper is the first step in what is a path to try to understand what the problems are with metal-on-metal joints," said Timothy Wright, Ph.D., Kirby Chair of Orthopedic Biomechanics at Hospital for Special Surgery (HSS). He said that information gleaned from the study should be useful in improving metal-polyethylene implants, the most common hip implant put in patients today.

"We still use metal implants. We may rub them against polyethylene instead of against another metal, but anything we can learn about these mechanisms of damage could be important," he said. He also pointed out that evidence suggests that the physical structure of the implant might play a role in the failed metal-on-metal implants and not the metal itself. In recent years, advances in the materials have allowed implants with bigger heads to be used, which increases stability, but now evidence suggests this may cause other problems.

"What we learn about the effect of head size and learn about the effect of positioning these components, and certainly what we learn about the biologic reaction to metallic debris is going to help us understand problems in general with total joint replacements," said Dr. Wright. "It's not enough to say, because some metal-on-metal implants have adverse reactions, it has got to be all about the metal and let's just condemn an entire technology. We need to understand, in a systematic way, what is going on."

Since 1977, whenever a patient has undergone a joint revision surgery at Hospital for Special Surgery, doctors have collected and saved the failed implants for research. At the same time, they have created a web-based system to file information on the implant, such as the manufacturer, and on the patient, such as age, weight and activity level. Doctors at HSS perform roughly 8,000 joint replacement surgeries per year and roughly 10% are revision surgeries, so this database is growing by about 800 specimens per year. Many patients who have had their joint replacement surgeries elsewhere come to Special Surgery to have revision surgery.

In the current study, HSS researchers, who did not have any ties to hip implant manufacturers, examined 46 retrieved metal-on-metal total hip replacements from 44 patients. The most common revision diagnoses were wear-related clinical concerns including osteolysis and adverse soft tissue reactions (16), loosening (11), instability (8) and infection (5). The researchers used scanning electron microscopy to determine the ways the hips were damaged, called damage modes. They found that 98 percent of the cups of the implant and 93 percent of the heads showed moderate to severe scratching. Moderate to severe pitting was found in 43 percent of the cups and 67 percent of the heads. They identified areas near the cups and heads that had completely lost their sheen.

"This study represents one of the largest collections of retrieved metal-on-metal implants," said Douglas Padgett, M.D., chief of the Adult Reconstruction and Joint Replacement Division and chief of the Hip Service at Hospital for Special Surgery. "There appears to be unique damage patterns which to date have not been identified. A follow-on analysis using high resolution laser profiling to quantify damage is in process which may yield further clues."

The patterns and similarities of the damage modes will shed light on the mechanisms behind the damage. "The goal with these hard metal-on-metal bearings is to drag a fluid film in between the two metal surfaces so that they never touch, so the wear is theoretically zero," explained Dr. Wright. "The fact that we look at these surfaces and see scratches and wear patches means that these surfaces are touching one another. That is problematic because if you had the clearances just right, they might never touch, just like the cylinder in an engine block."

He pointed out that the study could only be done at a hospital with a large number of archived hips. Spotting patterns and variations is easier if you look across a large patient population.

Researchers will next focus on what is causing the damage patterns. If it is a corrosive problem, is the solution to change the metallurgy? If the location is always the same and the damage is always near the edge of the implant, is that because they are being installed incorrectly? Is there a way to change the design? "What we see in the retrieved implants will begin to give us a picture of what is causing this problem," Dr. Wright said.

The multidisciplinary team of HSS clinicians, biologists, engineers and imaging researchers has further studies planned to understand the problem more fully. The retrieval archive and database will allow researchers to continue to look for correlations between implants that fail and factors such as patient characteristics, the physical shape and quality of the hip replacement, surgical factors, and the biological response from a body that has an implant.

The work for this study was conducted in the recently established Mary and Fred Trump Institute for Implant Analysis.


'/>"/>

Contact: Phyllis Fisher
phyllis.fisher@gmail.com
212-606-1724
Hospital for Special Surgery
Source:Eurekalert

Related biology news :

1. Why King Kong failed to impress
2. New clue to lupus: Failed autoimmune suppression mechanism
3. Environmental education has failed and must be revamped, new book argues
4. DOE Joint Genome Institute completes soybean genome
5. Exercise no danger for joints
6. Imperial College London and NTU collaborate to offer joint Ph.D. programs in engineering and science
7. Joint statement by German science organizations on green genetic engineering
8. Joint research into an enzyme that causes genetic diseases
9. Laser processes promise better artificial joints, arterial stents
10. Joint US-Norwegian study provides new insights into marine ecosystems and fisheries production
11. TNO and Seventh Wave sign letter of intent on joint preclinical pharmaceutical outsourcing services
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:3/29/2017)... , March 29, 2017  higi, the health IT ... North America , today announced a ... the acquisition of EveryMove. The new investment and acquisition ... of tools to transform population health activities through the ... data. higi collects and secures data today ...
(Date:3/27/2017)... , March 27, 2017  Catholic Health ... and Management Systems Society (HIMSS) Analytics for achieving ... Adoption Model sm . In addition, CHS previously ... U.S. hospitals using an electronic medical record (EMR). ... its high level of EMR usage in an ...
(Date:3/24/2017)... , Mar 24, 2017 Research and ... Access System Market Analysis & Trends - Industry Forecast to 2025" ... ... to grow at a CAGR of around 15.1% over the next ... This industry report analyzes the market estimates and forecasts for all ...
Breaking Biology News(10 mins):
(Date:10/10/2017)... , ... October 10, 2017 ... ... cancer-focused pharmaceutical company advancing targeted antibody-drug conjugate (ADC) therapeutics, today confirmed licensing ... HPLN (Hybrid Polymerized Liposomal Nanoparticle), a technology developed in collaboration with Children’s ...
(Date:10/10/2017)... International research firm Parks Associates announced today that ... TMA 2017 Annual Meeting , October 11 in Scottsdale, ... security market and how smart safety and security products impact the competitive ... Parks Associates: Smart Home Devices: Main ... "The residential security market has experienced continued ...
(Date:10/10/2017)... ... 10, 2017 , ... The Pittcon Program Committee is pleased ... scientists who have made outstanding contributions to analytical chemistry and applied spectroscopy. Each ... leading conference and exposition for laboratory science, which will be held February 26-March ...
(Date:10/9/2017)... ... 09, 2017 , ... At its national board meeting in North Carolina, ... University’s Departments of Physics and Astronomy, has been selected for membership in ARCS ... for the 2015 Breakthrough Prize in Fundamental physics for the discovery of the accelerating ...
Breaking Biology Technology: