Surgeons say the Calypso device can help relieve pain for people with osteoarthritis in their inner knee region.

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Surgeons implanted the Calypso medical device into the knee of a retired firefighter last month. Photo courtesy of The Ohio State University Wexner Medical Center.

There may be some help coming for the estimated 31 million Americans who suffer from osteoarthritis.

A new device may offer relief from knee pain without replacement surgery.

Surgeons at The Ohio State University (OSU) Wexner Medical Center say they have just completed the first successful implant of the Calypso Knee System, a shock absorber that protects the knee, relieves pressure, and acts as a cushion similar to way the cartilage functions in a healthy joint.

Dr. David Flanigan, an orthopedic surgeon and director of the Cartilage Restoration Program at OSU, said the Calypso was designed to relieve knee pain and to help patients with osteoarthritis delay or avoid the need for knee replacement surgery.

More than 600,000 knee replacement surgeries are performed in the United States every year, according to the American Academy of Orthopaedic Surgeons. Nearly half of American adults develop osteoarthritis in at least one knee during their lifetime.

Chuck Stenger, 58, a retired firefighter, was the first patient in Flanigan’s clinical trial to receive the Calypso.

“We’re always looking for new and alternative solutions to help the mild to moderately arthritic patient who is not ready to have a partial or total knee replacement,” Flanigan told Healthline. “Chuck had used conservative measures like therapy, injections, and anti-inflammatories, but they failed.”

“He was looking for ways to alleviate his pain but was not ready for a partial or full knee replacement, which is a structurally altering procedure. Chuck met the clinical trial participation criteria, making him a good fit for this trial,” Flanigan noted.

For the trial, Flanigan is seeking patients who have mild to moderate osteoarthritis in their medial (inner) knee. Stenger met the trial requirements and had surgery on December 19.

“A complete recovery can take anywhere from four to six months,” Flanigan said. “Physical therapy can progress for the entire duration of recovery but is more intensive early to help patients regain motion. The program is tailored to help patients get back to full functionality and to their daily activities.”

Flanigan’s trial is expected to enroll 80 patients across four sites.

Here are some of the requirements for participants.

  • between ages 25 and 65
  • body mass index of less than 35
  • weight less than 300 pounds
  • knee flexion greater than or equal to 90 degrees, and less than or equal to 140 degrees
  • clinical symptoms such as pain localized primarily to the inner area of the study knee and generally exacerbated by weight bearing
  • failure of at least six months of nonoperative treatment

The Calypso, developed by Moximed, Inc. of Hayward, California, is designed to provide support outside of the knee joint without altering the anatomy or removing any tissue from the knee itself.

Calypso treats osteoarthritis in the inner knee, the most commonly affected area.

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Retired firefighter Chuck Stenger had the experimental knee surgery last month. Photo courtesy of The Ohio State University Wexner Medical Center

“I first experienced knee pain about five years ago while working for the fire department, but was actually diagnosed last June,” Stenger told Healthline.

Stenger learned about Flanigan’s trial when he noticed an online survey on knee pain on his Facebook news feed. He took the survey.

Stenger was contacted by the manufacturer’s representative, did a phone interview with the Wexner Medical Center, and was invited to Wexner’s Jameson Crane Sports Medicine Institute. There, he was interviewed again, examined, X-rayed, and given an MRI.

“Recovery is going great,” Stenger said. “I was walking without crutches on the first day after surgery, but only in the house and for a short distance at a time.”

Flanigan said the inner knee is the most common area to develop arthritis.

“It has to do with the mechanics of the knee and the way your knee wears and ages,” he explained.

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Image of Calypso device courtesy of The Ohio State University Wexner Medical Center

Flanigan explained how the Calypso device is implanted.

“This surgery requires a four-inch to five-inch incision on the medial aspect of the knee to go through the soft tissue,” the surgeon said. “The device is placed on the outside of the knee joint, so it doesn’t alter the bones or ligaments and helps to offload weight on the inner compartment.”

Flanigan and his OSU colleagues worked with Moximed on the Atlas System, an earlier generation of the Calypso device. The first Atlas was implanted in a patient in December 2016.

The Wexner Medical Center was one of the leading enrollers of patients in the Atlas clinical trial, he said. When Moximed developed the Calypso, it approached Flanigan and his colleagues about conducting this new trial.

“This device is really for someone who has a more isolated osteoarthritis in their medial compartment with localized pain in that area,” Flanigan said. “This device won’t work for someone who has significant arthritis throughout the knee, or has complete bone-on-bone arthritis with bony changes on their X-rays.”

Dr. Benjamin Ma, orthopedic surgeon, professor-in-residence, and chief of the Sports Medicine and Shoulder Service at the University of California, San Francisco, said the Calypso Knee System could help some patients, but stressed that “we will have to see what the results are from this early clinical trial.”

“Most of our weight goes through the inner part of the knee when we stand, so that area tends to wear out more,” Ma told Healthline. “If patients are very knock-kneed, they would have to have the device implanted on the outside of the knee.”

“Patients need to have reasonable expectations after surgery as they must for nonoperative treatments that fail,” Ma said. “Knee replacements also have successful long-term outcomes, but they are not recommended for everyone.”

For Stenger, it is now several weeks since his implant surgery.

“It’s wonderful,” he said. “I no longer have severe pain on the inside of my knee. And the only time I use crutches is when I go out in public places.”

Would he recommend the Calypso when it becomes available?

“Heck yes,” he said. “I have been telling everybody I know about this.”

Flanigan said if his clinical trial is successful, he expects the Calypso Knee System will be available soon to patients across the country.

“We’re hoping that this will be an opportunity for patients with osteoarthritis to remain active without pain for a much longer period of time,” he said.