Partial Knee Replacement

Patellofemoral Partial Knee Replacement

Patellofemoral knee replacement is a procedure that resurfaces the damaged kneecap and the corresponding area on the femur bone to allow for improved alignment and pain relief.

What is a Patellofemoral Partial Knee Replacement?

Due to wear and tear, the kneecap (patellofemoral joint) may be worn out and will need to be replaced. The degree of arthritis or damage in the kneecap will be determined by the surgeon. If other parts of the knee besides the kneecap are damaged and need to be repaired, then this procedure will not fit the patient and a more suitable procedure will be recommended.

Anterior knee pain in the joint is felt between the kneecap and the thighbone. This area is where the patellofemoral partial knee replacement procedure is performed. By resurfacing the trochlea (end of the thighbone), the pain will then be reduced.

To perform the procedure, an incision is made in the front of the knee. The worn-out kneecap is resurfaced and cartilage is removed from the bone in the area under the femoral implant. The implant located between the kneecap and the thighbone is then positioned into place.

The implant is designed to provide the patient with the joint's natural kinematics of the kneecap. The movement and motion of the patella and thighbone should feel less painful, and have a smoother more natural motion. The shape and motion of the knee will be different than with the natural knee, so the muscles and ligaments will need to adapt. At first, this may lead discomfort and fatigue for the patient. A patellofemoral knee replacement usually lasts 10 to 15 years.

Who is a Candidate?

Patients with:

• Anterior osteoarthritis.
• A damaged patella, but still have great function in the rest of their knee.
• Joint deterioration that limits them from their daily activities.

Good candidate for partial knee replacement over a total knee replacement if:

• The patient has anterior and medial knee pain.
• The patient has an almost normal range of motion in their knee (90 degrees).
• The patient's knee is stable.

Benefits of this Procedure

The benefits of this procedure compared to a total knee replacement are:

• Preservation of bone
• Decreased blood loss
• Decreased post-operative pain
• Shorter hospital stay
• Faster rehab/recovery time
• Retain a better range of motion in the knee
• More normal knee kinematics
• Smaller implant

The Allergic Alternative

If a patient is allergic to any type of metal that the implant is made of, then the surgeon will change the type of metal to make it possible for the patient to have the procedure.

Rehabilitation/Recovery

If the patient has reoccurring pain, then painkillers will be prescribed as necessary. Physical therapy will work the patient to get their knee bending again. Only days after surgery, a physical therapist will work with the patient to get their knee bending again. A list of exercises will be given to the patient from the physical therapist. Most patients will return to work and other daily activities within 4 to 8 weeks post operation.

The patient should avoid the following things to have their implant last longer:

• Stressful physical activities
• All contact and impact sports
• Heavy lifting (more than 40 pounds)
• Jumping from a long distance or from heights 

Bicompartmental Partial Knee Replacement

The bicompartmental partial knee replacement removes both the medial (inside) compartment and the patellofemoral (kneecap) compartment and replaces them with an implant.

What is a Bicompartmental Partial Knee Replacement?

To perform a bicompartmental partial knee replacement, the surgeon will make a 3-4 inch incision in the front of the patient's knee. The surgeon will properly balance the patient's knee.

The patellofemoral and the medial compartments are resurfaced to accommodate the implant. The third, healthy compartment remains untouched. The new bi-compartment implant is properly positioned into place. The incision is then closed and a bandage is applied.

Medial and patellofemoral compartment arthritis accounts for approximately 75% of knee arthritis. The bi-compartmental knee replacement targets the medial and patellofemoral compartments, sparing the lateral condylar bone and cruciate ligaments. Bone preservation is important for younger, active patients. Ligament preservation may be even more important for natural feeling during physical activity.

Since the normal knee kinematics is changed by having knee replacement, it may feel different to perform daily activities. The shape and motion of the knee will be different than with the natural knee, so the muscles and ligaments will need to adapt. At first, this may lead discomfort and fatigue for the patient.

Who is a Candidate?

Patients who have pain and arthritis in the patellofemoral (kneecap) compartment and medial (inside) compartment.

A good candidate for partial knee replacement over a total knee replacement if:

• The patient has anterior and medial knee pain
• The patient has an almost normal range of motion in their knee (90 degrees)
• The patient's knee is stable

Benefits of This Procedure Compared to a Total Knee Replacement

• Preservation of all ligaments of the knee, including the ACL and PCL
• Less tissue trauma due to a minimally invasive approach
• Preservation of bone
• Decreased blood loss
• Decreased post-operative pain
• Reduced post-operative medication
• Faster rehab/recovery time
• Shorter hospital stay
• Better range of motion in the knee
• More normal knee kinematics

The Allergic Alternative

If a patient is allergic to a type of metal that the implant is made of, then the surgeon will change the type of metal to make it possible for the patient to have the procedure.

Rehabilitation

After the procedure, the patient will need a walker or crutches for 2 weeks. Most patients are discharged from the hospital two days after surgery. After physical therapy, patients should only perform low-impact activities so their bones and muscles can adjust to the new implant.

Call Your Surgeon If You Have

• Increased swelling in the knee or lower leg
• Persistent pain not relieved by pain medication
• Abnormal side effects from anesthesia or medication
• Increased drainage or redness from the incision site

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