Prosthetic Knee Type May Determine Cost of Care

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Despite growing data that more advanced technology reduces falls and improves physical capabilities among patients with transfemoral amputations, patients with lower K-levels are usually ineligible for a microprocessor knee. Access to improved knee technology can help patients become more agile, more balanced, and less likely to fall; without access to such technology, they may become more vulnerable and less active. A study published June 22 in Prosthetics and Orthotics International described the direct medical costs of falls in adults with a transfemoral amputation to provide policymakers with information to evaluate the value of more expensive technology, according to the researchers. Using standardized Medicare cost data, they found that the average additional cost in the six months following a fall can be substantial. The additional fall cost for individuals requiring an emergency department visit was $18,000. For patients who had to be hospitalized, this extra expense was more than $25,000.

"It is important to look beyond the initial cost differences of a microprocessor knee compared to a mechanical knee and understand what downstream costs might be avoided with a better prosthesis," said Benjamin Mundell, PhD, a health economist and the study's lead author. "Microprocessor knees are designed to help improve balance and reduce falls," he says. "The fear of falling for those with mechanical knees likely reduces their overall physical activity and if they do fall and require hospitalization, the cost of care is almost as expensive as a microprocessor knee."

Using the Rochester Epidemiology Project, a health records linkage collaboration in Minnesota and Wisconsin, the team examined the records of 77 individuals who received a transfemoral amputation between 2000 and 2014. They found that 46 of these patients had received a prosthetic knee. Of these, 22 individuals experienced 31 falls that resulted in an emergency department visit or hospitalization. If they fell more than once during an 18-month period, both incidents were excluded from the cost analysis to prevent misalignment of costs.

"Understanding the costs is part of basic health economics," says Kenton Kaufman, PhD, PE, the study's senior author, who is a biomedical engineer and orthopedics researcher at Mayo Clinic, Rochester, Minnesota. "This study quantifies the cost of falls that require medical attention—providing evidence that it may not be economical to withhold microprocessor knees from patients with moderate ambulatory capabilities."

Kaufman believes the costs to patients are much higher than the study shows.

"We know our cost estimate underestimates the true cost of a fall, because we didn't include indirect costs, such as lost wages, caregiving expenses, and transportation costs," he said.

"Value is the new metric in healthcare as we try to contain costs," said Mundell. "Part of understanding the value of advanced medical devices is measuring what future costs they can help patients avoid."

Editor's note: This story was adapted from materials provided by the Mayo Clinic.

To read more about Kaufman's research using Rochester Epidemiology Project data, visit "O&P Research Supports Evidence-Based Care" in the March 2017 issue of The O&P EDGE.