iDuo™ Bicompartmental Knee Resurfacing Device

The iDuo bicompartmental resurfacing device is an FDA cleared implant designed for the treatment of moderate to severe osteoarthritis.  It is a unique treatment alternative for patients with arthritic damage or worn cartilage affecting one of the tibiofemoral compartments and the patellofemoral compartment.  Together with the iUni, the iDuo provides surgeons with a range of partial knee resurfacing options.

       iDuo Implant with Matching iJig Femoral Cutting Guide

Many patients with advanced osteoarthritis have cartilage damage affecting one of the tibiofemoral compartments in addition to the patellofemoral compartment.  Traditionally, if the patellofemoral compartment is affected by osteoarthritis, with one of the tibiofemoral compartments, a total knee replacement was the only available treatment.  The iDuo eliminates the need to move to a total knee procedure when one of the tibiofemoral compartments still has viable and functioning cartilage. 

How it Works

The patient-specific iDuo is designed from a CT scan of an individual patient’s knee using the ConforMIS iFit technology.  The iFit design process interactively maps the diseased area and defines the extent of misalignment present in the knee. Using the patient-specific bone geometry, iFit defines the shape and size of the femoral and tibial components as well as the patient-specific instrumentation. 

The cobalt chrome femoral component conforms to the surface of the patient’s femoral condyle, replacing the damaged cartilage with a smooth articulating surface.  Because of its patient-specific conformity to the subchondral bone, it is a true resurfacing product, requiring only cartilage removal from the diseased area and one small posterior bone cut.  The weight bearing portion of the subchondral plate is kept intact.
 
The patellar component uses a standard polyethylene button.  It is implanted using an iJig cutting guide that precisely matches the geometry of the patellofemoral joint.  The unique design of the two components permits precise resurfacing of the affected compartments, while preserving the healthy cartilage and bone in the unaffected compartment.  The iDuo also preserves the anterior and posterior cruciate ligaments.  Both features may be particularly important for younger, more active patients who are not yet indicated for total knee replacement.

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 MCL tensioning using the iJig patient-specific instrumentation, a small amount of the tibial plateau is removed to receive the implant.

iDuo Features

• Available for the patellofemoral and medial or lateral compartments
• Preserves bone and cartilage in unaffected compartments and future surgical options
• Preserves anterior and posterior cruciate ligaments, helping to maintain knee kinematics
• Precise, anatomic fit to ensure ROM without impingement or overhang
• Anatomic component alignment to reduce implant wear
• Complete cortical rim coverage to reduce risk of tibial implant subsidence and loosening
• Disposable, patient-specific iJig instrumentation with built-in image guidance
  
• Simple, reproducible surgical technique
• Potential for less post-operative pain and shorter post-operative recovery time

Who is a Candidate

The iDuo was developed for patients with advanced osteoarthritis affecting one of the tibiofemoral compartments along with the patellofemoral compartment.  The bone and cartilage preserving features of the iDuo may be especially valuable for young and active patients who are considered too early for traditional knee replacement, but who suffer from arthritis in one or two compartments.  The iDuo allows the patient to preserve their joint for future surgical options, while receiving an implant with the potential to prevent or delay the need for a more invasive surgery.

Indications

The ConforMIS iDuo is intended for use in patients with severe knee joint pain and disability whose conditions cannot be solely addressed by the use of a prosthetic device that treats only a single knee compartment, such as the unicondylar or patellofemoral prosthesis. The indications for use include restoring joint function and relief of pain due to:

• Painful joint disease due to osteoarthritis, traumatic arthritis or rheumatoid arthritis of the knee
• Post traumatic loss of joint function
• Failed osteotomies, hemiarthoplasties and unicondylar implants

Contraindications

Absolute

• Active infection
• Severe instability due to advanced loss of osteochondral structure or the absence of collateral or cruciate ligament integrity
• Flexion contracture > 15 degrees

• Tricompartmental disease > Grade III