Primary and Revision Total Knee Replacement

Total knee replacement (TKR), also known as knee arthroplasty, is a surgical procedure to replace the weight-bearing surfaces of the knee joint to relieve pain and disability. It is commonly performed for osteoarthritis, rheumatoid arthritis, and other degenerative joint diseases. There are two main types of total knee replacement: primary and revision.

Primary Total Knee Replacement

Indications

• Severe knee pain that limits everyday activities, including walking, climbing stairs, and getting in and out of chairs.
• Moderate or severe knee pain while resting, either day or night.
• Chronic knee inflammation and swelling that doesn’t improve with rest or medications.
• Knee deformity, such as bowing in or out of the knee.
• Failure to substantially improve with other treatments such as anti-inflammatory medications, cortisone injections, lubricating injections, physical therapy, or other surgeries.

Procedure

• Incision: A cut is made on the front of the knee to expose the knee joint.
• Preparation: The damaged cartilage surfaces at the ends of the femur and tibia are removed along with a small amount of underlying bone.
• Implantation: Metal implants are positioned on the prepared bone surfaces. These implants can be cemented or press-fit into the bone.
• Patella Resurfacing: The underside of the patella (kneecap) may be cut and resurfaced with a plastic button.
• Insertion of a Spacer: A medical-grade plastic spacer is inserted between the metal components to create a smooth gliding surface.

Recovery

• Hospital stay typically lasts a few days.
• Physical therapy starts soon after surgery to aid in recovery and improve range of motion.
• Full recovery can take 6 weeks to several months, with continued improvements for up to a year.

Revision Total Knee Replacement

Indications:

• Loosening of the prosthesis: This can occur over time as the bond between the bone and the implant loosens.
• Infection: Deep infection in the knee joint can necessitate a revision.
• Instability: The knee becomes unstable or fails to function properly.
• Wear and tear: The plastic components may wear out over time.
• Fracture: A fracture around the knee replacement implant.

Procedure:

• Assessment: A thorough assessment is done to determine the cause of failure and plan the revision surgery.
• Removal of Old Implant: The old knee prosthesis is carefully removed. This can be more complex than primary surgery due to bone loss, scarring, and the need for more extensive reconstruction.
• Bone Preparation: The remaining bone is prepared to receive the new implant. Bone grafts or metal augments may be used to rebuild lost bone.
• New Implantation: New components, often larger and more specialized than those used in the primary surgery, are implanted.
• Stabilization: Additional stabilization techniques might be required, such as stems that go deeper into the bone or more extensive fixation.

Recovery

• Recovery from revision TKR is typically longer and more challenging than from a primary TKR.
• Hospital stays may be longer, and the risk of complications is higher.
• Intensive physical therapy is crucial for regaining mobility and function.
• Full recovery can take several months to a year, depending on the complexity of the surgery and the patient’s overall health.

Considerations

• Risks: As with any surgery, there are risks, including infection, blood clots, implant loosening, and complications from anesthesia.
• Outcomes: Most patients experience significant pain relief and improved function. The longevity of the implant can vary, with many lasting 15-20 years or longer.
• Lifestyle: Post-surgery, patients are usually advised to avoid high-impact activities to prolong the life of the implant.