Waterloo Surgeon Completes Iowa's First Implantable Shock Absorber for Knee

Rafael Serrano, MD and UnityPoint Clinic Orthopedics in Waterloo are the first in Iowa to use the MISHA® Knee System, the first implantable shock absorber (ISA) for knee joints. Dr. Serrano, an orthopedic surgeon and sports medicine specialist, performed the first procedure in December 2025 and is now using this cutting-edge treatment on designated patients.

The MISHA Knee System is implanted on the medial side of the knee during outpatient surgery. The device reduces peak knee forces by more than 30% and does not impose post-operative weight-bearing or activity restrictions. By decreasing the weight on the knee joint, the ISA helps to ease pain, preserve function and possibly delay joint replacement surgery.

“This is a wonderful alternative for people who want to preserve their activity level and are hesitant to undergo joint replacement surgery,” says Dr. Serrano. “It’s essentially a shock absorber for the knee, and it’s only about the size of a pinkie.”

One leading orthopedic surgeon has said the ISA is the first notable advancement in treating knee osteoarthritis in half a century.

The MISHA Knee System helps fill a major treatment gap for adults with mild to moderate knee osteoarthritis, as surgeons and patients have lacked options when non-surgical conservative care has failed – or when a patient is ineligible for, or unwilling to undergo, total knee replacement surgery.

Osteoarthritis develops when the protective cartilage that cushions the ends of the joint bones wears down over time, causing pain and swelling during normal movement. Symptomatic knee osteoarthritis is common and affects roughly 18 million Americans, more than half of whom are of working age.

“If you think about the jarring effect of running or playing sports, you begin to understand the stress placed on a person’s knee,” Dr. Serrano says. “But if you consider this implant and how it dissipates that stress through the mechanics of this small device, you understand how beneficial the procedure can be. Once implanted, it’s like 20 to 30 pounds of pressure are relieved from the joint, which can provide a lot of relief for patients.”

Learn more about orthopedic care at UnityPoint Health – Waterloo.