ConforMIS Inc. won 510(k) clearance from the Food & Drug Administration for its custom knee implant system, the iTotal CR.
Unlike standard implants, iTotal CR devices are based on an individual’s CT scans and tailored for their knee bones using computer-aided design.
Standard implants come in six or seven different sizes, meaning that surgeons must measure a patient’s bones after an incision to select the best fit, according to ConforMIS founder and CEO Philipp Lang.
"The challenge that you have with this technique is that the implant can never fit quite right," he told MassDevice.
The ConforMIS total knee implants, designed for patients with knee damage from conditions such as osteoarthritis, are individually built using three-dimensional CT scans of the patient’s knee. Software corrects for deformities caused by joint damage and the implants are manufactured at the company’s Massachusetts facility and shipped to the site of the surgery. ConforMIS also makes the iDuo and iUni G2 knee implants, both of which won CE Mark approval for sale in the European Union.
The key design rationale is to make the patient’s new knee feel like their own knee, Lang said, noting that the technique avoids under-sizing, which can cause early failure, and implants that are too large, which can cause soft-tissue impingement and pain. The implant, because it’s "exactly fitted" to the patient’s joint, brings back the bone’s "natural curvature" to make it feel like a normal knee.
The procedure also cuts down on the length of rehab after surgery, he added. Lang said there’s a lot of discussion in the orthopedic community about the "breach" of the marrow space needed for joint resurfacing procedures, which require that part of the device be inserted into the femur. The disposable surgical "iJig" instrumentation used with the ConforMIS device cuts down on that breaching, he said.
ConforMIS doesn’t yet have clinical data to back up the surgeons’ positive feedback on the iTotal CR, Lang said, but hopes to soon begin collecting data from the field. Between $6 billion and $8 billion dollars are generated annually from knee replacements, he noted, making it the orthopedic market’s largest sector.
The Burlington, Mass.-based company also has prototypes for other joints, but is rolling out the knee technology because of its market potential, Lang said.