When is a knee replacement needed?

A knee replacement is one way to correct damaged bone and cartilage in the knees by implanting a prosthetic. In this article, a consultant orthopaedic surgeon explains why and how a knee replacement surgery is performed.

What are the knees?

The knees are the joint where the end of the femur (thigh bone) meets the tibia (the shin bone). The patella (kneecap), which stabilises the joint and shields the bones, sits on top of the meniscus cartilage. Anchoring the joint are many ligaments, muscles, and tendons. The knee joint is a rotational point for the shin, but it is also used for weight distribution, balance, and stability.

The knee joint is the biggest joint in the human body, and it is fundamental for facilitating movement that is used in a wide range of activities, including but not limited to walking, jumping, crouching and sitting.

When is a knee replacement needed?

Because of the constant strain on the knees, it is common for them to suffer from injury or gradually wear away over time. When the knee joint becomes dysfunctional, it can be quite disabling and painful. Sometimes, it is recommended that the patient rest their knees to allow for recovery, wear supportive braces, or undergo physiotherapy to strengthen and stretch the knee – but this won’t be effective for every patient.

For these cases, knee replacement surgery is explored when the knee dysfunction is completely debilitating and the pain is chronic. Those whose knee dysfunction has reduced their mobility, have experienced a sudden destructive injury, or who have not responded to alternative therapies. This includes conditions such as:

• Arthritis, like osteoarthritis, rheumatoid arthritis, or post-traumatic arthritis. This is when the cartilage in the joint deteriorates and the joint becomes inflamed.
• Fractures, which can happen during accidents, impacts, and falls. Fractures that heal incorrectly can later lead to post-traumatic arthritis.
• Infections of the joints, which can also deteriorate the cartilage.

Who can get a knee replacement and what kinds are there?

Patients who are recommended to undergo knee replacement tend to be older than 60 years old. This is because knee replacements last an average of 25 years, and patients who are younger and who undergo a replacement surgery will likely need more than one replacement procedure in their lifetime – in order to avoid that, medicinal and therapeutic treatments are explored foremost.

There are two kinds of knee replacement surgery: a total, where the lower portion of the femur and the upper portion of the tibia are removed and replaced with a prosthetic, and a partial, where only one bone portion is replaced. Total knee replacements are more common, but partial knee replacements are recommended for cases where damage is only on one of the bones leading to the knee (which can happen in arthritis).

What happens during knee replacement surgery?

A knee replacement can be performed as an open or a minimally invasive procedure. Minimally invasive techniques, as opposed to open ones, use smaller incisions (around 10cm) and may be preferable for patients because of the faster recovery time and the smaller scar.

The procedure, regardless of technique, takes only a couple of hours and is performed under a general anaesthetic. The surgeon makes one long incision down the front of the knee (open) or a few smaller ones around the knee (minimally invasive) so that the knee cap can be moved away and the structures underneath can be accessed. The damaged portions of bone are sawn off and reshaped so that the prosthetic implant – made of metal, silicone, and ceramic – can be fitted on the ends. The joint is then put back into place and the kneecap reinserted on top. Finally, the wound is sealed and bandaged.

What is the recovery like after a knee replacement?

After a knee replacement, recovery is expected to take up to a year, but this will vary depending on the kind of procedure and the patient’s condition. The patient will likely spend a night or two in the hospital to recover (although some surgeons are now offering outpatient treatment) and be prescribed painkillers to assist with the aching and soreness after surgery. They are recommended to rest and keep weight off the knee for several weeks and to abstain from strenuous activities and weight-lifting for some time, even as they return to normal activities and work/school. Patients are further recommended to participate in physiotherapy to regain stability and mobility, strengthen the muscles, and learn how to use their new joint.

If you are considering a knee replacement, consult with a specialist on Top Doctors today.