Unicondylar Knee Replacement

Advantages

• Smaller operation
  
• Smaller incision
  
• Not as much bone removed
  
• Shorter hospital stay
  
• Shorter recovery period
  
• Blood transfusion rarely required
  
• Better movement in the knee
  
• Feels more like a normal knee
  
• Less need for physiotherapy
  
• Able to be more active than after a total knee replacement

The big advantage is that if for some reason it is not successful or fails many years down the track it can be revised to a total knee replacement without difficulty.

Disadvantages

• Not quite as reliable as a total knee replacement in taking away all pain
  
• Long term results not as good as a total knee replacement

• Patients ideally should be over 50 years of age
  
• Patients for whom pain and restricted mobility interferes with their lifestyle
  
• Only one compartment involved clinically and confirmed on X-ray

• Patients with arthritis affecting more than one compartment
  
• Patients with severe angular deformity
  
• Patients with inflammatory arthritis e.g. rheumatoid arthritis
  
• Patients with an unstable knee
  
• Patients who have had a previous osteotomy
  
• Patients who are involved in heavy work or contact sports

Dr Coolican will send you for routine blood tests and any other investigations required prior to your surgery. You should also have a general medical check-up with your GP. You should have any other medical, surgical or dental problems attended to prior to your surgery.

• Make arrangements for help around the house prior to surgery
  
• Cease aspirin or anti-inflammatory medications 10 days prior to surgery as they can cause bleeding
  
• Cease any naturopathic or herbal medications 10 days before surgery
  
• Stop smoking as long as possible prior to surgery

You will be admitted to the hospital, usually on the day of your surgery. Further tests may be required on admission.

You will meet the nurses and answer some questions for the hospital records. You will meet your anaesthetist, who will ask you a few questions. You will be given hospital clothes to change into and have a shower prior to surgery.

The operation site will be shaved and cleaned. Approximately 30 minutes prior to surgery, you will be transferred to the operating room.

Each knee is individual and knee replacements take this into account by having different sizes for your knee. If there is more than the usual amount of bone loss, sometimes extra pieces of metal or bone are added.

Surgery is performed under sterile conditions in the operating room under spinal or general anaesthesia. You will be on your back and a tourniquet applied to your upper thigh to reduce blood loss. Surgery takes approximately two hours.

You will be positioned on the operating table and your leg prepped and draped. A tourniquet is applied to the upper thigh and the leg is prepared for the surgery with a sterilising solution. An incision around 7cm is made to expose the knee joint. The bone ends of the femur and tibia are prepared using a saw or a burr. Trial components are then inserted to make sure they fit properly.

The real components are then inserted with or without cement and the knee is again checked to make sure things are working properly. The knee is then carefully closed and drains usually inserted, and the overlying skin dressed and bandaged.

When you wake, you will be in the recovery room with intravenous drips in your arm, a tube (catheter) in your bladder and a number of other monitors to check your vital observations. You will usually have a button to press for pain medication through a machine called a PCA machine (Patient Controlled Analgesia).

Once stable, you will be taken to the ward. In general, your drain will come out at 24 hours and you will sit out of bed and start moving you knee and walking on it within a day or two of surgery. The dressing will be reduced usually on the 2nd post op day to make movement easier. Your rehabilitation and mobilisation will be supervised by a physiotherapist.

To avoid lung congestion, it is important to breathe deeply and cough up any phlegm you may have.

Dr Coolican will use one or more measures to minimise blood clots in your legs, such as inflatable leg coverings, stockings and injections into your abdomen to thin the blood clots or DVT's.

Usually, you will remain in the hospital for 3-5 days. Then, depending on your needs, either return home or proceed to a rehabilitation facility. You will need physiotherapy on your knee following surgery.

You will be discharged on a walker or crutches and usually progress to a cane at six weeks.

Your sutures are sometimes dissolvable but if not, are removed at approximately 10 days.

A lot of the long term results of knee replacements depend on how much work you put into it following your operation.

When you go home you need to take special precautions around the house to make sure it is safe. You may need rails in your bathroom or to modify your sleeping arrangements, especially if they are up a lot of stairs.

Bending your knee is variable, but by 6 weeks should bend to 90 degrees. The goal is to obtain 110-115 degrees of movement.

Once the wound is healed, you may shower. You can drive at about 6 weeks, once you have regained control of your leg. You should be walking reasonably comfortably by 6 weeks.

More physical activities, such as sports previously discussed, may take 3 months to do comfortably.

You will usually have a 6 week check up with your surgeon who will assess your progress. You should continue to see your surgeon for the rest of your life to check your knee and take X-rays. This is important as sometimes your knee can feel excellent but there can be a problem only recognized on X-ray.

You are always at risk of infections especially with any dental work or other surgical procedures where germs (Bacteria) can get into the blood stream and find their way to your knee.

If you ever have any unexplained pain, swelling or redness or if you feel generally poor, you should see your doctor as soon as possible.

As with any major surgery, there are potential risks involved. The decision to proceed is made because the advantages of surgery outweigh the potential disadvantages. It is important that you are informed of these risks before the surgery takes place.

Infection
Infection can occur with any operation. In the knee this can be superficial or deep. Infection rates vary. If it occurs, it can be treated with antibiotics but may require further surgery. Very rarely your new knee may need to be removed to eradicate infection.

Blood clots (deep venous thrombosis)
These can form in the calf muscles and can travel to the lung (pulmonary embolism). These can occasionally be serious and even life threatening. If you get calf pain or shortness of breath at any stage, you should notify your doctor.

Stiffness in the knee
Ideally your knee should bend beyond 100 degrees but on occasion, the knee may not bend as well as expected. Sometimes manipulations are required. This means going to the operating room where the knee is bent for you and under anaesthetic.

Wear
The plastic liner eventually wears out over time, usually 10 to 15 years and may need to be changed.

Wound irritation or breakdown
The operation will always cut some skin nerves, so you will inevitably have some numbness around the wound. This does not affect the function of your joint. You can also get some aching around the scar. Vitamin E cream and massaging can help reduce this.

Occasionally, you can get reactions to the sutures or a wound breakdown that may require antibiotics or rarely, further surgery.

Cosmetic appearance
The knee may look different than it was because it is put into the correct alignment to allow proper function.

Leg length inequality
This is also due to the fact that a corrected knee is more straight and is unavoidable.

Dislocation
An extremely rare condition where the ends of the knee joint lose contact with each other or the plastic insert can lose contact with the tibia (shinbone) or the femur (thigh bone).

Patella problems
Patella (knee cap) can dislocate. This means it moves out of place and it can break or loosen.

Ligament injuries
There are a number of ligaments surrounding the knee. These ligaments can be torn during surgery or break or stretch out any time afterwards. Surgery may be required to correct this problem.

Damage to nerves and blood vessels
Rarely these can be damaged at the time of surgery. If recognised they are repaired, but a second operation may be required. Nerve damage can cause a loss of feeling or movement below the knee and can be permanent.

Fractures or breaks in the bone can occur during surgery or afterwards if you fall. To repair these, you may require surgery.

You will have the opportunity to discuss your concerns thoroughly with your Dr Coolican prior to surgery.

General issues with any surgery
Medical complications include those of the anaesthetic and your general well being. Almost any medical condition can occur so this list is not complete. Complications include:

• Allergic reactions to medications
  
• Blood loss requiring transfusion with its low risk of disease transmission
  
• Heart attacks, strokes, kidney failure, pneumonia, bladder infections
  
• Complications from nerve blocks such as infection or nerve damage
  
• Serious medical problems can lead to ongoing health concerns, prolonged hospitalisation or rarely death