Retrived total knee replacement component demonstrating asymmetric (posteromedial) wear of the polyethylene bearing surface. (Adapted from Naudie DDR, Rorabeck CH: Sources of osteolysis around total knee arthroplasty: Wear of the bearing surface. Instr Course Lect 2004;53:251-259.)


Published 10/1/2007
Jennie McKee

Combating osteolysis and implant wear

AAOS/NIH research symposium to address tough issues in joint replacement surgery

Some of the brightest minds in orthopaedics will meet in Austin, Texas, this fall to examine one of the most critical problems in joint replacement surgery: implant wear and the subsequent effects of wear debris.

On Nov. 9-11, orthopaedic surgeons, researchers, young investigators, and industry and government representatives will participate in Osteolysis and Implant Wear: Biological, Biomedical Engineering, and Surgical Principles, an invitation-only AAOS/National Institutes of Health (NIH) research symposium organized by principal investigators Stuart Goodman, MD, PhD, and Timothy Wright, PhD.

Updating the issues
Since the last workshop on implant wear in 2000, the importance of the issue has increased. Patients are more active—and thousands more people are having total knee and total hip replacement surgeries. The increased numbers and activity levels mean that the potential for implant wear is significant.

“Joint replacement is among the most successful surgeries performed in orthopaedics,” says Dr. Wright. “But, the longevity of the implant components remains a limiting factor, with wear of the bearing surfaces that form the artificial joint being the biggest obstacle.”

“Approximately 500,000 total knee replacements and between 250,000 and 300,000 total hip replacements are performed every year, not including those for hip fractures,” explains Dr. Goodman. “Approximately 10 percent of those surgeries are revision surgeries to replace worn components. Those surgeries are harder, take more time, have a higher complication rate, and often don’t have as good an outcome as primary hip or knee replacement.”

Experts to explore key issues
More than 40 faculty members will address clinical, biological, and engineering/materials questions related to implant wear during the symposium.

“By bringing experts from around the world to our symposium, we hope to achieve consensus on important questions about the wear problem. We will also emphasize the major findings since the last symposium on this topic,” says Dr. Wright.

Symposium participants will address 18 different questions on implant wear, ranging from the diagnosis of wear-related problems to local and systemic biological reactions and mediators. Wear debris and host factors that determine or modulate the biological response to wear particles will also be discussed. Participants will also weigh-in on the influences of new sterilization techniques, new forms of polyethylene, new designs, and how new types of joint replacement have influenced wear.

To learn more about the symposium, visit and select “2007 Research Symposium: Osteolysis and Implant Wear.”

ORS Young Investigators and invited guests
The Orthopaedic Research Society (ORS) Young Investigator initiative is giving a small group of young investigators the opportunity to participate in the symposium. The five attendees include James Huddleston, MD; Francis Y. Lee, MD; Amanda D. Marshall, MD; Ebru Oral, PhD; and Jeremy Wilkinson, PhD, FRCS (Orth).

Bioengineers, material scientists, biologists, clinicians, and clinician scientists applied to participate. The final selections were made by Drs. Wright and Goodman, along with Steven A. Goldstein, PhD, of the ORS.

“All the applications were of high quality; it was extremely difficult to select only five,” says Dr. Goodman. “What sets these five apart is their extraordinary clinical/research activities and the high level of excellence they have demonstrated. We believe that they will not only learn a lot from the symposium participants, but that they will contribute to the symposium in a very substantial way because of their cutting-edge research and clinical investigations.”

Invited guests include AAOS past president Richard F. Kyle, MD; Tad L. Gerlinger, MD, LTC, Society of Military Orthopaedic Surgeons; James S. Panagis, MD, MPH, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS); Fei Wang, PhD, NIAMS; and Rosemarie D. Hunziker, PhD, Director, Technology Development and Industrial Relations. In addition, Denis Clohisy, MD, chairman of the AAOS Research Development Committee, will be in attendance.

Grant support for the symposium comes from the AAOS, the American Association of Hip and Knee Surgeons, The Knee Society, the Orthopaedic Research and Education Foundation, and the ORS. The symposium also received grant funding from the NIAMS/NIH, through a U-13 grant. Industry supporters include DePuy Spine, Smith & Nephew, Stryker Orthopaedics, Synthes, and Zimmer.

Research directions
Although Dr. Wright says it is difficult to predict future research directions, he believes that one focus will be the continued need to collect reliable clinical and implant retrieval data.

“Joint registries are our best bet for broadly monitoring the osteolysis problem and for assessing the clinical efficacy of solutions, such as highly cross-linked polyethylenes intended to have less wear,” he says.

Other possibilities include the development of biological markers for assessing osteolysis; methods for interrupting the biological pathways that lead to bony destruction; the performance of alternative bearing materials with improved wear resistance, both in the laboratory and in clinical trials; as well as implant design issues and the untoward effects of the generation of wear debris.

Post-symposium publication
Proceedings of the symposium, including the future directions for research, will be published in a special issue of The Journal of the AAOS in mid-2008. According to Dr. Wright, disseminating the conclusions to orthopaedists as well as to patients is crucial.

“By broadly publicizing the answers developed by the symposium participants, we will provide orthopaedic surgeons, other health care professionals, and most importantly, patients considering joint replacement with the latest information on osteolysis and implant wear so that they can better understand this complex topic,” he says.

Jennie McKee is a staff writer for AAOS Now. She can be reached at