100% of Custom-Fit Knees “Feel Normal” Say Clinical Reports

Results relating to the ConforMIS, Inc. iTotal® patient-specific total knee replacement have been presented at the British Association for Surgery of the Knee (BASK) meeting in Norwich, UK. If you buy them, they look rather good.


It’s been a few years since we were updated with news about the ConforMIS iTotal patient specific knee system, the device having been dribbled into commercial use since 2011. The intervening period has seen a fair amount of data gathering in support of the system, culminating in two posters and an oral presentation at the recent BASK meeting.

The iTotal system, the only patient-specific total knee replacement system on the market, demonstrated zero blood transfusions in 106 patients receiving the iTotal knee system, contrasting with a recent study reporting a 12% rate of blood transfusions for traditional, off-the-shelf knee replacements.

Furthermore, and again contrasting with off-the-shelf implants, 100% of iTotal patients reported a normal feeling knee only seven months after the procedure. Standard implants have been reported to result in dissatisfaction rates ranging from 15% to 39%.

So why would a custom-fit implant deliver such strikingly better results?  Well, assuming you believe the hype, it makes sense when you think it through. If an implant is optimized to the size and shape of a patient’s anatomy they’ll be less aware of it, it’ll more closely replicate the behaviour of the original knee, it has the potential to be less painful and not suffer implant loosening to the same extent that an implant that is only a close match rather than a perfect fit may demonstrate. That’s the theory, and these data sets somewhat bear it out.

Company comments

“We are very pleased to see further clinical evidence showing that the ConforMIS patient-specific technology is not only helping surgeons to improve patient outcomes with knee replacements, but the technology is also contributing meaningful cost savings to the healthcare system,” said Philipp Lang, M.D., Chairman and CEO of ConforMIS. “We believe that by providing a patient-specific implant, patients will recover faster, quickly return to normal, everyday activities and ultimately forget they even had a knee replacement.”

Excerpts from ConforMIS clinical results presented at BASK

“Early Outcomes Utilizing a First-Generation Customized Patient-Specific TKA Implant” (P0185). Lead researcher William Kurtz, M.D. shared the clinical results of patients implanted with the first-generation patient-specific iTotal implant. In a population of 89 patients and 106 knees treated, no patients required blood transfusions and mean pre-op range of motion (ROM) was regained within an average of four months. No patients reported any dissatisfaction in four of five Knee Scoring System (KSS) categories, including pain while sitting and function while performing recreational activities. Unprecedented to any published reports on standard, off-the-shelf implants, all patients receiving iTotal reported a “normal” feeling knee seven months after the procedure.

“Intraoperative Assessment of Mechanical Alignment Accuracy Determined by Computer Navigation in a Patient-Specific TKA (Total Knee Arthroplasty) System” (Session 6). Data presented by Gary A. Levengood, M.D. demonstrated that in a population of 63 patients treated with iTotal, 100% achieved alignment within ± 2° of the neutral mechanical axis. Restoration of alignment within 3° of neutral is a widely confirmed indicator of improved long-term survivorship in TKA.

“In Vivo Tibial Fit Analysis of Customized, Patient-Specific TKA Versus Off-the-Shelf TKA” (P0181). Data demonstrated that use of iTotal significantly improves tibial fit when compared to off-the-shelf TKA implants. The study concluded, “this could play an important role in reducing knee pain and patient dissatisfaction … as well as implant loosening.”

Source: ConforMIS, Inc., Business Wire


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