Introduction
If a previous knee replacement procedure needs to be corrected, this is referred to as a 'revision knee replacement'. There are several reasons this may be necessary, including for example:
Wear / loosening of components due to:
- Age of components (knee replacement components have a life of 15-20 years).
- High impact activity (this includes some sports or any running).
- Weight gain (and subsequent increased wear of components).
Other factors such as:
- Spread of arthritis to other parts of the knee (where the original knee procedure was a partial knee replacement).
- Infection.
- Other injury, including ligament injury or periprosthetic (i.e. near the artificial joint) bone fracture.
- Osteolysis.
Preoperative Instructions
- Existing medication(s) – some medications can impact surgery, especially any anti-coagulant medication and medicine for diabetes; we will advise if any of your medication needs to be stopped (and when) well ahead of the day of surgery. Any other medication should be taken the morning of surgery with a little water (half a cup maximum).
- You should not shave (or wax) skin near where any surgical incisions will be made.
- No solid foods (cow's milk and drinks containing cow's milk are considered food) should be consumed within 6 hours of surgery; clear fluids (e.g. water, cordial) may be consumed until 3 hours before surgery and then nil by mouth from that point.
- Please advise us if you have a cold or fever, a cough or any other injuries or infections (e.g.: urinary tract infection or cuts / tears to the skin) – your procedure may need to be postponed as any of these may make anaesthesia or surgery unsafe.
- Please bring all imaging (e.g. x-rays / CT scans / MRI scans) with you to hospital.
- Please come to hospital at least one hour before your planned surgery, unless we advise you otherwise.
In very general terms make sure you follow a healthy and balanced diet before surgery and continue any regular physical activity up until the day of the procedure. If you smoke, you should ideally stop smoking at least four weeks before the procedure and otherwise as a minimum at least one week before.
Procedure
Revision knee replacement procedures are more complicated than standard knee replacements, since original components have to be removed and new sections of bone need to be removed from the femur and tibia before the new components are fitted. This may require bone grafts or special components called 'platform blocks' or 'metal augments' to make sure both that the new joint functions properly and that leg length is maintained.
A revision knee replacement is otherwise quite similar to a total knee replacement - an incision is made, in most cases in the exact location of the original incision and the kneecap and tendons are moved to expose the existing artificial joint. The original components are then inspected for damage or wear and surrounding tissue is checked for any signs of infection.
If components need to be replaced, they are carefully removed, along with any bone cement to maximise preservation of healthy bone tissue. If blocks or grafts are needed, they are fixed in place at this point and any new components are fitted. Finally, the new knee components are checked for correct movement and soft tissue damage is repaired and the incision is closed and dressed.
Due to the complexity of a revision, the procedure can take up to three hours.
In some cases, surgery may need to be 'staged', which is where two procedures are required, generally the second around six weeks after the first. The first procedure is to remove the previous knee components and fit an 'antibiotic spacer' into the knee, and the new knee components are then fitted (once the spacer is removed) in the second procedure.
Postoperative Instructions
As with all knee replacement procedures it is important to be out of bed and walking as soon as possible after the procedure – this encourages new bone growth and bonding with the new components. A revision knee replacement often results in a longer recovery period than is the case with the initial procedure.
Total Knee Replacement
Immediately after surgery the affected leg may be put into a 'CPM' machine ('Continuous Passive Movement') while the patient is still lying down to allow the new joint to flex.
After a total knee replacement, the patient is encouraged to move the legs and feet in bed to promote blood circulation and by the second or third day, patients should be able to get out of bed and walk around for very short distances. Patients normally remain in hospital for 5-7 days and stitches are removed around 10 days after surgery. Patients will be placed on a blood thinning medication for 2 weeks after surgery to prevent blood clots forming in the leg. Most patients are able to resume driving 6 weeks after surgery and return to some level of sport 4-6 months after surgery. People with knee replacements are recommended not to undertake any activity, including any sports, which involve running, as this will cause extra wear to the knee components.
Partial Knee Replacement
Unlike a total knee replacement, patients who have undergone a partial knee replacement can generally leave hospital on the second or third day after surgery and are encouraged to put weight on the new knee.
More details on the rehabilitation program after either procedure are given to patients after surgery.
Risks
90% of people who undergo revision knee replacement surgery find that their previous symptoms and pain have either reduced significantly or disappeared. However, as with any surgery, there is always a risk of:
- Pain.
- Bleeding.
- Scarring.
- Infection (of the incision site, or in the chest).
- Blood clot (leg or lung).
- Stroke.
- Heart attack.
Some specific risks of revision knee replacement surgery include:
- Artificial components of the knee may wear out or become loose over time.
- Nerve damage may cause numbness of the knee (or in severe cases foot paralysis).
- Damage to blood vessels may cause blood circulation problems.
- With partial knee replacement, the healthy section may develop arthritis.