Essential Product Information for Patients
Total and Unicompartmental Knee Prostheses
This Essential Product Information does not include all of the information needed for proper use and care of a prosthetic knee implant. Please consult your physician for additional information.
The longevity (how long it will last) of a prosthetic knee varies from patient to patient. It depends on many factors, such as a patient’s physical condition and activity level, body weight and the surgical technique. Prosthetic joints are not as strong or durable as a natural, healthy joint, and there is no guarantee that a prosthetic joint will last the rest of a patient’s life. All prosthetic knees may need to be replaced at some point.
Total knee prostheses replace the entire knee joint while unicompartmental knee prostheses replace half of the joint.
Your physician may determine that a knee replacement is appropriate for you if you have severe pain or significant disability resulting from one or more of the following conditions:
- Deterioration of the knee joint cartilage (osteoarthritis).
- Inflammation in the lining of the knee joint (rheumatoid arthritis).
- Physical injury to the knee joint resulting in arthritis (traumatic arthritis).
- Moderate valgus (knock-kneed), varus (bowlegged), or flexion (bending) deformities.
- A loss of blood supply to the lower portion of the upper leg bone (femoral condyle) which leads to tiny breaks within the bone and possible collapse (avascular necrosis).
- To correct problems caused by previously failed surgeries.
- Certain breaks in the knee joint bones (fractures).
Your doctor may decide that knee replacement surgery is not appropriate if:
- You have an infection.
- You do not have enough bone or the bone is not strong enough to support the prosthesis.
- You have injured certain nerves and/or nerve networks in the knee area.
- You have injured or non-functional knee muscles.
- Your knee is severely unstable, possibly due to unstable knee ligaments.
- You have one of several conditions known as neuromuscular disease.
- Your knee joint has a stable fusion (arthrodesis) which is functional and painless.
In addition, implanting a unicompartmental knee is not appropriate if:
- You have rheumatoid arthritis.
- You have a varus or valgus deformity greater than 15 degrees.
- There is evidence of calcium being deposited in the joint cartilage (chondrocalcinosis or pseudogout).
Warnings and Precautions
Excessive physical activity, injury, and obesity can result in loosening, wear, and/or fracture of your knee implant.
Failure to follow through with the required rehabilitation program or failure to govern your physical activities as directed by your physician may cause your knee implant to fail.
Activities that place a lot of stress on the joint implants, as may be the case with more active patients, may reduce the service life of the prosthesis. Implant loosening and wear on the plastic portions of the implant can lead to additional surgery to replace the worn components, or all of the components. Talk with your doctor about the following points, and how they might affect the longevity and success of your knee replacement:
- Staying healthy.
- Avoiding “impact loading” sports such as running, jogging, downhill skiing, singles tennis, etc.
- Consulting your surgeon before beginning any new sport or activity, to discuss what type and intensity of sport or activity is appropriate for you.
- Any restrictions on movement.
- Maintaining appropriate weight.
- The following events are possible complications of knee replacement surgery. Additional surgical procedures may be required to address the complications.
- Loosening or fracture of the prosthetic knee components.
- Dislocation and/or joint instability of the prosthetic knee.
- Malalignment of the prosthetic knee components.
- Disassembly of the prosthetic knee components.
- Bone fracture or nerve damage.
- Leg length discrepancies.
- Poor range of motion.
The following complications are also possible:
- You may have adverse reactions to the materials contained in the prosthetic knee. These reactions may range from an allergic reaction to cancer and/or tumors. Discuss these possible complications with your physician, especially if you have a history of allergies, metal sensitivity, or Paget’s disease.
- Debris generated from unavoidable wear of the prosthetic knee may cause bone disintegration (osteolysis) and loosening of the prosthetic knee components, resulting in the need for additional surgery.
- Blood clots in one or more veins (venous thromboembolic disease).
- Corrosion of the prosthetic knee components may occur, and may result in the need for additional surgical intervention.