In one study, researchers at a leading academic institution compared the knee motion, or kinematics, of patients implanted with a ConforMIS iTotal CR customized total knee replacement to patients implanted with an off-the-shelf Zimmer-Biomet NexGen (“Legacy”) or Persona (“Modern”) total knee replacement. The study demonstrated that ConforMIS iTotal patients exhibited assessed motion patterns more closely resembling a normal knee than patients with Legacy or Modern implants.
When a healthy knee bends, the lateral condyle, or outer portion of the end of the thigh bone or femur, rolls back on the shin bone or tibia and rotates externally, towards the outside of the knee, known as the “screw home mechanism”. In this multi-center study, financially supported by ConforMIS, researchers assessed the kinematics of 59 patients (25 patients with a ConforMIS iTotal CR implant, 15 patients with a Legacy implant and 19 patients with a Modern implant) using advanced real-time mobile x-ray imaging and 2D-3D registration. Patients who received a ConforMIS iTotal CR, compared to the Legacy and Modern off-the-shelf knee replacement implants, demonstrated greater lateral femoral rollback (3.99mm vs. 1.17* and 2.06 mm, respectively) and greater axial rotation (6.25 deg. vs. 4.41 and 1.54* deg., respectively) during deep knee bend, which is consistent with normal knee motion. (Note: * indicates statistical significance with p≤0.05)
“Replicating the normal motion pattern of a patient’s knee is an important aspect of achieving a more stable, natural feeling knee and restoring normal function,” said William Kurtz, MD, chief of orthopedics at Baptist Hospital in Nashville, TN and clinical investigator in the study. “This study supports my clinical observations; ConforMIS patients achieve natural knee movement and stability unlike patients with legacy and modern generation off-the-shelf implants. I am very encouraged by my patients’ recovery with ConforMIS implants, namely better outcomes, faster recovery and higher return to normal everyday activities.”
Other studies presented at BASK relating to customized ConforMIS knee replacements showed favorable patient outcomes:
- Another multi-center, prospective study of more than 300 patients with a ConforMIS iTotal knee replacement assessed range of motion (ROM), Knee injury and Osteoarthritis Outcome Score (KOOS), and Knee Society Score (KSS) preoperatively, and at 6 months, 1 year, and 2 years post-operatively. Results demonstrated that patients experienced statistically significant improvements across all 5 domains of the KOOS (pain, symptoms, activities of daily living, recreation and quality of life) and across 3 out of 4 domains of the KSS (objective, satisfaction and functional scores). Patients in this study also experienced low blood transfusion rates (1.5%) and manipulations (2.8%) as compared to published literature on off-the-shelf implants.
- In a prospective study of 25 patients with a ConforMIS iUni unicompartmental knee replacement, patients experienced statistically significant improvements in KOOS, KSS and range of motion. Additionally, no patients required a blood transfusion and there have been no revisions to date for any reason. This data compares favorably to published scores and revision rates for off-the-shelf unicompartmental knee implants.
- In a prospective, multi-center study of 79 patients with a ConforMIS iDuo bicompartmental knee replacement (an alternative option to performing a total knee replacement that preserves both the posterior (PCL) and anterior (ACL) cruciate ligaments), patients experienced statistically significant KOOS and KSS improvements. Additionally, range of motion increased an average of 18 degrees at 1 year compared to pre-operative levels. Lastly, none of the patients required a blood transfusion.
“The breadth of these clinical results supports our view that our iTotal CR and partial knee implants offer meaningful benefits to patients,” said Philipp Lang, MD, MBA, chief executive officer and president of ConforMIS. “Published literature supports that on average one out of five patients are not satisfied with the results of their total knee replacements. The new kinematic study conducted at a leading academic institution in the United States is part of a growing body of direct, comparative evidence demonstrating how our customized implants are improving patient outcomes. The iTotal CR and the recently launched iTotal PS are the only fully customized total knee replacement systems available today. It is our belief that customizing the implant for each patient can address the shortcomings of traditional off-the-shelf knee implants. Previously released data demonstrated that iTotal CR patients, compared to off-the-shelf patients, were less likely to have an adverse event and less likely to be released to costly acute care facilities. We believe that comparative studies like these are especially relevant as the Comprehensive Care for Joint Replacement (CJR) model is set to begin on April 1, 2016, which will hold many hospitals accountable for the quality of care they deliver to Medicare fee-for-service beneficiaries for hip and knee replacements.”