Total knee replacement is usually a very successful operation. Most people live an active life, free of pain following this procedure. The Australian Joint Replacement Registry data shows that at 15 years only 6.5% (from the top 7 % of knee replacement combinations) require replacement.
Indications for revision knee replacement
Implant loosening and wear
In order for a total knee replacement to function properly, the components need to attach firmly to the bone. At the time of surgery this is achieved using cement or press fit with the expectation of bone to grow into the surface of the prosthesis. Loosening of the prosthesis may be caused by high impact activities, excessive body weight and wear of the plastic between the metal components. Also, younger patients who have undergone knee replacement may “outlive” the life expectancy of the knee prosthesis.
Sometimes, tiny particles that wear off the plastic spacer may cause a body immune response which can also destroy healthy bone, as well leading to osteolysis. In osteolysis the bone surrounding the implant deteriorates making the implant loose and unstable.
Loosening may cause difficulty walking, deformity and swelling of the knee and pain.
Infection is a potential complication in any surgical procedure and may occur while in the hospital or even years later- where it is usually caused by infections elsewhere in the body.
This is the second most common cause of knee replacement failure. Once infected the knee becomes stiff and painful. The type of bacteria, the longevity of infection, the degree of infection and patient medical condition will determine the approach to treatment.
Washing out and debridement of the knee joint under anaesthetic is the first approach to managing infection. This can be done several times in conjunction with intravenous antibiotics. The length of antibiotic treatment will be determined by the bacteria grown and may continue for several months and is guided by the Infectious Disease Specialist.
If this approach fails, a one or two stage revision Surgery is required.
Some patients develop laxity of the ligaments around the knee joint following knee replacement surgery which causes a feeling of instability and pain. This may cause recurrent swelling and the feeling that the knee is giving way. Sometimes this may be treated with physical therapy and bracing but revision surgery may be needed.
A peri-prosthetic fracture is a broken bone that occurs around the components of the knee replacement. They are usually the result of a fall and usually require revision therapy.
Pre-operative patient education
At the time of consultation, Dr Lane will give a full explanation of what is involved in a revision knee replacement operation, expected recovery (often protracted if surgery complex) and eventual outcomes.
The following guide further informs the patient. Educational leaflets supplied by the Australian Orthopaedic Association are also supplied. The patient is asked to attend the pre-admission clinic at the hospital, (Sunshine Coast Private Hospital, Buderim or the Sunshine Coast University Hospital, Birtinya). There the patient will see experienced nurses and physiotherapists who will discuss the pre- and post-operative course. The patient may also see the anaesthetist in the clinic. Increased knowledge of events leads to a less stressful recovery.
This follows a similar pathway to primary knee replacements. Pre-operative review by other medical specialist may be required to optimise pre-existing medical condition.
Pre-operative investigations are performed which include blood tests, cross matching for blood, ECG, CXR and urinalysis.
The admission, pre-operative and anaesthetic course is similar to primary knee replacement and covered in "Total Knee Replacement".
Revision knee replacement is more complex and takes longer than the primary knee replacement. The length of surgery will be determined by the causes of the failure of the original knee replacement and may take 2–6 hours.
The incision site is made over the previous incision scar but it may need to be longer to allow the old components to be removed.
At the time of operation, Dr Lane will examine the soft tissue in your knee to make sure they are free of infection. He will further assess the metal and / or plastic parts of the prosthesis to determine which components have become loose.
The surgical options may include:
- Simple exchange of the tibial plastic insert. This is a straight forward procedure. It involves removing the plastic insert which has excessive wear but leaving the remaining prosthetic components which are well fixed to the bone.
- Removal of femoral and / or tibial components.
- Insertion of new prosthesis. This specialised revision prosthesis is usually larger and longer than the original one. Significant bone loss around the knee may be compensated by use of metal augments and platform blocks.
- Bone grafting. Occasionally bone graft material may be required to rebuild the knee. The graft may come from your own graft (autograft) or from a donor (allograft). The latter is tested for communicable diseases (in a similar way to blood donation) prior to insertion.
Soft tissue surrounding the knee is then repaired that are damaged and the knee is carefully tested to assess the range of motion and stability.
A reperfusion drain is inserted and the wound closed.
When there has been infection in the knee prosthesis, surgery will often involve 2 stages:
- Firstly, the knee prosthesis is removed along with any infected tissue. An antibiotic loaded cement spacer is inserted.
- 6 to 8 weeks later the spacer is removed and the new prosthesis inserted.
This follows similar pathway to “Total knee Replacement”.
Usually the patient will be mobilised out of bed the day following surgery.
Due to the complexity of surgery the patient will have protected weight bearing for 6 weeks following surgery.
General risks associated with Anaesthetic
During this type of surgery, your body is stressed and pre-existing conditions such as heart, respiratory and circulatory conditions may worsen.
- Death (rare).
- Myocardial infarction (heart attack) and cardiac arrhythmia.
These events are uncommon:
- Pneumonia (lung infection).
- Short term confusion.
- Deep venous thrombosis (blood clots). These occur in legs but can rarely break off and travel to lungs (pulmonary embolus). This can be potentially fatal.
- Bladder and prostrate problems. A catheter is placed in the bladder prior theatre to avoid this.
- The bowel may become paralysed after surgery which causes bloating, pain, nausea and vomiting for a few days.
- Infection. Superficial infection is not common and usually responds to antibiotics. Deeper infections can occur at any time, is rare but has serious consequences. Infection often requires difficult staged revision knee replacement. Sometimes revision surgery is not possible and the knee needs to be fused or surgically stiffened. Extremely rarely amputation may be required.
- Knee stiffness. A small proportion of patients need to be returned to theatre in the first 3 months for knee manipulation to help the knee bend.
- Knee stiffness and pain following surgery. Sometimes the cause is not clear.
- Rarely the patient may develop a painful, swollen red and stiff knee with abnormal sensation. This is due to an abnormal nerve condition that can develop and is difficult to treat.
- Foot drop. Nerves around the knee can be injured.
- Occasionally fracture of tibia or femur around the knee components. This is usually recognised at the time of surgery and can be corrected but does delay recovery.
- The new joint may loosen or wear over time and may require revision surgery.
Patients with diabetes, obesity, pre-existing multiple medical conditions, advanced age and frailty, and smokers will have an increased risk of adverse complications.