Partial Knee Replacement

Knee replacements are successful operations that are designed to relieve pain in patients with knee arthritis. Once the cartilage in the knee joint wears out, the underlying bone is exposed. When bone rubs on bone, it can cause arthritic pain. In the early stages of knee arthritis, non-surgical measures such as anti-inflammatory medication, weight loss and physiotherapy can help. With advanced knee arthritis, a knee replacement can help alleviate pain and improve mobility. A partial knee replacement can treat arthritis confined to one part of the knee.

The anatomy of the knee

Your knee has three compartments:

1. Medial compartment

   • On the inside aspect of the knee.

2. Lateral compartment

   • On the outside aspect of the knee.

3. Patellofemoral compartment

   • Underneath the kneecap and the groove that it sits in.

In 50% of knees, arthritis only affects one compartment. If this is the case, you may be a suitable candidate for a partial knee replacement if non-surgical measures have not been effective.

What are the advantages?

The rate of patient dissatisfaction following a total knee replacement can be high. Some studies quote 15-20%. The rate of dissatisfaction following a well-performed unicompartmental knee replacement is lower. This is because the knee is able to function more like a normal knee does. A unicompartmental knee replacement preserves the ligaments inside your knee. The other compartments that are not affected by arthritis are left alone. The operation is smaller than a total knee replacement and has less blood loss.

What are the disadvantages?

Sometimes, arthritis will progress to involve other compartments in the knee, and patients may develop pain from arthritis in a different location. This will require a revision to a total knee replacement. This revision is technically straightforward, and it has a high success rate.

When compared to a total knee replacement, a unicompartmental knee replacement has a higher rate of revision surgery. The revision rate is significantly reduced when a surgeon regularly performs partial knee replacement surgery, uses robotic assistance and selects appropriate patients for this procedure.

What is the recovery like after surgery?

Patients that have unicompartmental knee replacements will recover faster and they’ll have less pain after surgery. Most patients will be discharged 1-2 days following surgery. Six weeks after surgery, their range of motion will largely return. They’ll be off strong pain relief. And they won’t need crutches to get around. After the recovery period, patients are more likely to think that a partial knee replacement feels more like a normal knee than those who’ve had a total knee replacement.

After recovering from surgery, patients can manage low-impact sports, and they’re more likely to return to sports and activities compared to those who’ve had a total knee replacement. Most studies suggest a return to activity rate of as much as 80-98%. The activities you can expect to get back into are cycling, hiking, tennis, golf and swimming.

Experience in performing unicompartmental knee replacement is essential

The Australian Joint Registry shows that the revision rate of unicompartmental knee replacements is between 10-15% percent at 10 years. Although this is comparably higher than a total knee replacement, this can be explained simply. The Joint Registry is the average result of all orthopaedic surgeons in Australia. It has been shown that surgeons who perform unicompartmental knee replacements on a regular basis have a much lower revision rate than those that don’t. Studies have shown that at least 20% of the knee replacements that a surgeon performs should be a unicompartmental knee replacement, to optimise the postoperative outcome.

During his time in the United Kingdom, Mr Pai was trained to perform conventional unicompartmental knee replacements using the uncemented Oxford prosthesis. Worldwide, this is one of the most commonly used prostheses for a partial knee replacement.  Subsequently, Mr Pai was trained to use robotic assistance to perform this operation.

What is the role of robotic knee surgery?

Robotic surgery is a useful adjunct when knee replacement surgery. It can improve the alignment of the knee components compared to performing the operation using conventional methods. Early results suggest that robotically assisted partial knee replacements have a lower revision rate. These findings are reflected in the data collected on the Australian Joint Registry, as shown on this graph. Click here to read more about robotic knee surgery.

Am I a suitable candidate for a partial knee replacement?

40-50% of patients with knee osteoarthritis are suitable candidates for a partial knee replacement.

If arthritis affects only one knee compartment, and you don’t have a significant deformity or stiffness in your knee, then this procedure may be suitable for you.

In general, people with rheumatoid arthritis or other types of arthritis with an inflammatory nature, are not suitable for this procedure because the arthritic change may affect all parts of the knee and cause failure.

Mr Pai will obtain a focused series of knee X-rays and may organise for a special alignment X-ray from your hip to your ankle. These are called long-limb alignment views. These X-rays allow him to determine which compartments are affected by arthritis, and the overall alignment at your knee. If there is any doubt whether the arthritic process affects other compartments, he will obtain an MRI scan of your knee.

How do I book surgery with Mr Pai?

Step 1: Book a consultation with Mr Pai

Mr Pai will review your symptoms, perform an examination of your knee and check your knee X-rays to determine whether a knee replacement is suitable for you.

Step 2: Get the appropriate pre-operative tests

Before a knee replacement, you will have blood tests and an ECG which will be reviewed by Mr Pai and his physician. This ensures your medical health is optimised prior to surgery. Mr Pai will arrange a CT scan of your knee which will be used to plan your robotic knee surgery.

Step 3: Book your surgery date

Mr Pai’s administrative team will organise a convenient date for you to have your knee replacement. They will talk you through the process and the hospital admission details to ensure you have a smooth and stress-free experience.

Step 4: Rehabilitate from your surgery

A structured rehabilitation program will help you recover quickly from knee replacement surgery. Most health insurance providers will fund rehabilitation in the comfort of your own home. If appropriate, a physiotherapist will come to your home after you are discharged to ensure you are meeting your goals post-operatively. If required, inpatient rehabilitation can also be organised for your following your procedure. Mr Pai works with several trusted local physiotherapists to ensure you will have expert post-operative care after your knee replacement.