Photograph by Aaron M. Conway/OMS
For our January 2015 Top Doctors issue, we talked to Christ Hospital Orthopaedic Surgeon Glenn Reinhart, M.D. about giving knee implant patient a truly custom fit:
“One of the issues with current knee replacement surgery is that there are a group of patients who appear to have reasonable function in their knee—they have good strength, good movement, and their knees are stable—but they continue to have pain. That may be up to 15 percent of patients. The thought is that we’re stressing the soft tissue. We’re not aligning the structures in the knee exactly the way they were originally meant to be, so patients have pain because there’s this mismatch.
I’m coming from a sports medicine background as opposed to a joint replacement background. In sports medicine the idea is to recreate normal anatomy. That’s what the original design was, so it’s probably going to function better for the patient. I’ve done about 30 cases with ConforMIS products [3D-printed knee replacements] over the past three years. I started to use the system primarily because of my patient age group. Younger patients [age 50 and below] tend to have higher demand, and some are actually better suited for partial knee replacements; for some people it makes more sense, if only one portion of their joint is worn out. In other techniques, you have to take the patient’s anatomy, their bone structure, and shape it in a way that will fit a standard-shaped prosthesis. With a ConforMIS joint replacement you’re trying to fit the prosthesis to the patient. It’s not a matter of saying, “We’re going to try to fit everybody into something that looks like an average, normal knee.” They take each individual and recreate their normal anatomy. At the same time, you as a surgeon get special instrumentation that allows you to cut the bones and shape the knee so that it will fit exactly.
Once we decide you need a partial knee replacement and you’re interested in this technique, you go for a CT scan. The data from the CT scan is sent to the company. They process the scan and come up with a computerized design and build the prosthesis. The whole process takes about six weeks. The only additional charge for patients is a CT scan.
This type of partial knee replacement is a straightforward operation compared to doing a different system. You don’t remove nearly as much bone. It’s a little shorter, technically simpler. It has the potential to preserve more of the normal anatomy, and theoretically we expect someone who has less trauma to their knee, or has a more natural fit, will recover faster. There’s not enough data yet, [but] the preliminary data is that this compares favorably to other available options. It’s at least as good, and it’s potentially going to be better. With partial knee replacement you don’t have as much margin for error. ConforMIS allows your precision to be exceptionally high. My experience has been all of the implants fit exactly right.” —as told to Cait Barnett