Scripps Researchers Use Smart Knee Implant to Test Anti-Gravity Treadmill for Rehabilitation

Patients with one-of-a-kind artificial joint help scientists analyze the potential of a rehab device built with NASA technology

Scientists at the Shiley Center for Orthopaedic Research and Education (SCORE) at Scripps Clinic are conducting a study to test a new anti-gravity treadmill used for rehabilitation. They are gathering data from patients with a unique artificial joint called the electronic knee—or e-knee. The prosthesis contains transducers that measure actual forces inside the knee.

“The e-knee is unique in the research community and gives us an unprecedented ability to collect data,” said Darryl D’Lima, MD, PhD, laboratory director at SCORE. “Before we created it, information about the amount of force generated in the knee by various activities came from untested mathematical formulas.”

SCORE made history in 2004 when Clifford Colwell, MD, implanted the first e-knee into a patient. Four people now have the prosthesis; all of them are participating in the study, which is led by Dr. Colwell and sponsored by the rehabilitation device maker, AlterG Anti-Gravity Treadmill.

The treadmill was built with NASA technology and is available at the Scripps Memorial Hospital Encinitas rehabilitation center. Designed to simulate a weightless environment, it uses air pressure to lift the patient and reduce gravitational forces on the lower extremities. This “unloads” the knee joint and allows people to run or walk at a fraction of their weight. For those recovering from knee surgery, less force on the joint often means less pain.

“As the e-knee patients run or walk on the treadmill, the recorded data will tell us precisely how much weight is unloaded from the joint. With that information, we can determine how effective the treadmill is for unweighting the knee,” said Dr. Colwell. “Physical therapists may be able to use this data to refine rehabilitation protocols with the treadmill and speed up recovery following lower joint surgeries, which are becoming more popular as baby boomers age.”

Due in part to the aging and active boomer generation, demand for total knee replacements in the U.S. is predicted to grow by 673 percent – reaching 3.48 million – by the year 2030, according to a study published in the Journal of Bone and Joint Surgery. By 2014, more than half of those needing total knee replacements will also be younger than 65 years.

“Research like ours is going to become increasingly more important as health reform begins and insurance companies demand proof of efficacy before offering reimbursement for treatment,” said Dr. D’Lima. “It’s a critical part of our health care evolution—and the e-knee makes it possible.”

About Scripps Health

Founded in 1924 by philanthropist Ellen Browning Scripps, Scripps Health is a $2.2 billion, private not-for-profit community health system based in San Diego, Calif. Scripps treats a half-million patients annually through the dedication of 2,500 affiliated physicians and 13,000 employees among its five acute-care hospital campuses, home health care services, and ambulatory care network of physician offices and 19 outpatient centers and clinics.

Scripps is recognized as a leader in the prevention, diagnosis and treatment of disease, and is at the forefront of clinical research and graduate medical education. More information can be found at

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