CS Type Knee Replacement

Cruciate Substituting (CS) Knee Replacement

A Cruciate Substituting (CS) knee replacement is
a type of total knee replacement where the posterior cruciate ligament (PCL) is removed and its function is replaced by the design of the implant itself, specifically a highly congruent polyethylene liner.

This design aims to offer the ease of use associated with posterior stabilized (PS) designs while also preserving bone, similar to cruciate-retaining (CR) designs.

Understanding the Basics:

Cruciate Ligaments:
The knee joint has two main cruciate ligaments: the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). These ligaments help stabilize the knee and control its movement.

Total Knee Replacement (TKR):
In a TKR, the damaged parts of the knee joint (femur, tibia, and sometimes the patella) are replaced with artificial implants.

How CS Implants Work:

• The CS design relies on the geometry of the implant, specifically the highly congruent polyethylene liner, to provide stability and control knee movement.
• The medial side of the implant (inner side) is typically more constrained, with a single radius of curvature that matches the polyethylene liner, while the lateral side (outer side) is more mobile.
• This design is often referred to as a “medial pivot” knee replacement because the medial side rotates around a fixed point, while the lateral side allows for more natural rolling and gliding movements.

Benefits of CS Implants:

• Bone Preservation: CS implants can preserve more bone than PS designs, similar to CR designs.
• Potential for Improved Kinematics: The design aims to provide a more natural feeling knee movement.
• Ease of Use: CS designs are often considered easier to implant than CR designs.

Considerations:

• Surgeon Experience: CS implants may require more surgical experience to ensure proper balancing and alignment.
• Patient Selection: Not all patients are suitable for CS implants. Factors like anatomy and activity level are considered.
• Long-term Outcomes: Long-term studies comparing CS to other TKR designs are still ongoing.

In summary:
CS knee replacement offers a unique approach to total knee arthroplasty, aiming to combine the benefits of both CR and PS designs while potentially offering improved outcomes.