What is knee replacement?

Knee replacement is a safe and effective procedure that can help to relieve pain, increase motion, and correct leg deformity so you can go back to enjoying life and normal activities. Knee replacement has also been coined as knee “resurfacing” as essentially only the surface of the bones is replaced.


There are two kinds of Knee Replacement Surgery:

Partial knee placement (unicompartmental knee arthroplasty)

: where the arthritis is confined to only one part of the knee, and only that diseased part is replaced, while retaining the rest of the healthy knee. This removes the pain associated with the diseased part of the knee while maintaining the normal biomechanics of the native knee joint.


Total knee replacement (total knee arthroplasty)

: where the arthritis involves the whole knee, and the entire knee surface needs to be replaced.

A skeletal image of a knee in red highlight

When is knee replacement recommended?

Knee replacement surgery is recommended for patients who are experiencing:

  • Severe knee pain or stiffness that limits daily activities like walking
  • Moderate or severe knee pain even while resting
  • Chronic knee inflammation and swelling 
  • Deformity where there is bowing in or out of the knee
  • Failure to improve with other treatments like medications and physical therapy


Although most patients who undergo knee replacement surgery are aged between 50 to 80, there is no absolute age restriction for this procedure. The surgeon will evaluate several considerations before deciding on a knee replacement for you


The considerations include:

  • Medical history – your orthopaedic surgeon will gather information about your general health and ask questions related to your knee pain. 
  • Physical examination – your orthopaedic surgeon will access your knee mobility, strength, and alignment.
  • X-rays – imaging helps your orthopaedic surgeon determine the extent of damage in your knee, and the overall knee alignment.
  • MRI – an MRI scan may be needed to determine the condition of your cartilage and bone and whether the meniscus and ligaments are damaged.



Surgical procedure

A knee replacement consists of two important steps – choosing the implant components and the actual procedure.


Implant components

There are different types of knee implants; the femur and tibia surfaces are usually replaced with metal, with a high durability plastic surface in between to act as the bearing surface. In addition, there are different implant designs to suit different needs. Your orthopaedic surgeon will discuss with you before deciding on the best type of implant to meet your needs.



Your orthopaedic surgeon will make an incision over your knee and use special guiding instruments to remove the damaged cartilage and bone. The metal components are then usually cemented onto your bone to keep them in place, and the plastic bearing surface is inserted. This helps to restore the alignment and function of your knee.


Advances in knee replacement technology have allowed increased longevity of knee replacements, allowing patients to greatly improve their quality of life. These include improved surgical techniques for accurate positioning of the knee components, such as patient specific instrumentation, robotic assisted knee replacement, and improved bearing surfaces and designs that improve the stability and range of motion of the replaced knee, with reduced wear rates of the implants.

Knee Replacement

Commonly Asked Questions

Planning for the surgery

Your orthopaedic surgeon may recommend consulting your primary doctor or anaesthetist to check your general medical condition and do blood tests, a chest X-ray, and an electrocardiogram to assess your fitness for surgery.

You will either be admitted to the hospital for one to three days or go home on the same day. The plan should be further discussed with your orthopaedic surgeon prior to the operation.

It is best to consult your orthopaedic surgeon for specific instructions. You may have to stop taking supplements and medications before the surgery, complete any major dental procedures beforehand and even do some home planning such as installing handrails in the shower for support.

The most common types of anaesthesia for knee replacement surgery are general anaesthesia where you go to sleep or spinal, epidural or regional block anaesthesia where your body is numb from the waist down.

A knee replacement will typically take between one to two hours.


The risk of complications in knee replacement surgery is low, with serious complications occurring in less than 2% of patients. However, complications such as infection, blood clots in the veins, fractures, nerve and vessel injury, and implant problems may occur although they are uncommon.


Feeling some pain is part and parcel of the healing process after surgery. Rest assured that your doctor will prescribe medications for short-term pain relief.

Paracetamol, non-steroidal anti-inflammatory drugs, and opioids are common temporary pain relief medications that will be prescribed. Your doctor might also recommend aspirin or other blood thinning medication to reduce the risk of blood clots in the veins.

Your orthopaedic surgeon may prescribe inflatable leg coverings and blood thinners to reduce the risk of blood clots in the veins. Foot and ankle movement is encouraged to increase blood flow in your leg muscles. Avoid getting your wound wet and go for dressing changes according to the instructions given by your orthopaedic surgeon to reduce the risk of wound infection. You should have a balanced diet to promote proper tissue healing and restore muscle strength.


Physical therapy is started inpatient and continued outpatient to train you to walk properly and strengthen your muscles. You may initially need a walking aid until your limping stops, after which you are encouraged to walk independently. Doing simple exercises is critical during the recovery process and you should be able to resume light activities in three to six weeks.

Take special precautions to avoid falls and injuries, participate in light exercises (no high-impact exercises) and see your orthopaedic surgeon for routine follow-up checks and X-rays.