Partially Damaged Knees Repaired by Resurfacing the Cartilage

A novel knee-arthroplasty system resurfaces damaged cartilage, maintaining the integrity of the femoral subchondral bone-plate of the affected compartment.

The ConforMIS iUni uni-compartmental knee arthroplasty system is intended for use in patients with arthritic damage isolated to only one compartment--the medial or lateral tibiofemoral compartment--of the osteoarthritic knee, replacing the damaged area of the articular surface in those with adequate healthy bone to support the components. Candidates for unicondylar knee repair include those with joint impairment due to osteoarthritis (OA) or traumatic arthritis of the knee; previous tibial condyle or plateau fracture, creating loss of function; and valgus or varus deformity of the knee.

The patient-specific iUni is designed from a computerized tomography (CT) scan of an individual patient's knee using proprietary iFit technology. The design process interactively maps the diseased area and defines the extent of misalignment present in the knee. Using the patient-specific bone geometry, the iFit defines the shape and size of the femoral and tibial components as well as the patient-specific instrumentation. The system is composed of a femoral component designed to form fit onto the subchondral bone surface of the patient's femoral condyle, replacing the damaged cartilage with a cobalt chrome articulating surface, and a seven millimeter-thick tibial polyethylene component inserted into a cobalt chrome tray. The geometry of the tibial implant is specified to provide full cortical rim coverage on the tibia, potentially reducing the risk of implant subsidence and loosening. After proper medial collateral ligament (MCL) tensioning using the iJig patient-specific instrumentation, a small amount of the tibial plateau is removed to receive the implant.

Only a small bone cut is performed posteriorly for the femoral component; the bone cut is designed to be external to the posterior bone cut of the other uni-compartmental devices, thereby preserving future treatment options. Patients are generally able to walk and weight-bear within 2 weeks following surgery. For optimal recovery, activities that stress the knee and weight bearing should be resumed slowly and only as tolerated, allowing the knee adequate time to adapt to the implant. The iUni system is a product of ConforMIS (Burlington, MA, USA) and has been approved by the U.S. Food and Drug Administration (FDA) and the European Community CE Mark.

"The launch of the iUni represents an important milestone in ConforMIS' commitment to advancing the state-of-the-art in orthopedics with our patient-specific, minimally traumatic knee implants,” said Dr. Philipp Lang, CEO and Chairman of ConforMIS. "Our image-to-implant technology offers physicians a unique, bone preserving option for early intervention combined with a simplified and reproducible surgical technique.”


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