Orthopaedics study will impact artificial knee design

A study by a team of researchers in the UNMC Department of Orthopaedic Surgery has challenged a doctrine surrounding knee replacement design.

With science and medicine helping people live longer, people now often outlast the life of their joint cartilage.

Dr. Haider receives the Adult Reconstructive Knee Poster Prize at the American Academy of Orthopaedic Surgeons Annual Meeting in March.

“Technologists and surgeons have designed artificial knees which can alleviate pain and permit almost normal motion for daily living activities. In fact, good knee replacement designs can now last the lifetime of a patient,” said Hani Haider, Ph.D., professor and principal investigator of the study.

“In the evolution of knee replacements since the 1970s, designers focused on stress reduction in the bearings to reduce wear, which should be avoided for many reasons,” Dr. Haider said. “They did so by increasing contact area of the bearings to spread the load, which was vital for the older generation of bearing materials and early designs of the artificial joint.”

The team’s study — “For Lower Wear of Total Knee Replacements, Is Higher or Lower Contact Area Better?” — was awarded the best poster prize in the category of Adult Reconstructive Knee at the recent American Academy of Orthopaedic Surgeons Annual Meeting in New Orleans March 6-10. Ten first-place posters were awarded from 7,000 entries.

Using test data from UNMC’s Biomechanics and Advanced Surgical Technologies Laboratory, Dr. Haider and colleagues found that increasing contact area to reduce stress with contemporary joint materials is like a law of diminishing returns. When taken too far, larger total knee replacement sizes and contact area can actually increase wear with modern designs and materials. This was confirmed by eight separate studies in Nebraska contracted with UNMC by multiple companies from the orthopaedic industry.

“Working closely with multiple companies from industries worldwide makes our results meaningful, relevant and makes them translate to tangible benefits,” Dr. Haider said. “In this case, our results were described to shine a new beacon for artificial knee designers everywhere.”

Bone and joint health problems are the leading cause of disability in the U.S., accounting for more than half of all chronic conditions in people over the age of 50, according to the American Academy of Orthopaedic Surgeons. The organization projects that the demand for knee replacements will increase by 674 percent between the years 2012-2030.

“This is yet another tremendous achievement by our faculty, and we wish to thank all who have supported this research resulting in further international recognition,” said Kevin Garvin, M.D, professor and chair of the Department of Orthopaedic Surgery and Rehabilitation.