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Total Knee Replacement (TKR) is an effective solution to consider for knee pain and deformity due to Osteoarthritis, Rheumatoid or Post-Traumatic Arthritis. TKR is one of the most common orthopaedic surgeries performed worldwide and can lead to dramatic improvement in quality of life.
During a TKR, the worn surface of the knee is taken away and replaced with metal and plastic components through an incision at the front of the knee.
Younger patients or those with pain localized to part of the knee joint may be suitable for a Unicompartmental Knee Replacement (UKR). This surgery may be performed using a robot (see Robotic Surgery section on website).
Causes of Knee Pain
Osteoarthritis – degenerative age-related wear and tear, leading to loss of cartilage, knee stiffness and deformity. This usually occurs in patients over 50 years of age, but may occur in younger patients. Younger patients may be more suitable for a Unicompartmental Knee Replacement (UKR).
Rheumatoid Arthritis – an autoimmune disease causing inflammation of the lining of the knee joint (synovitis) leading to joint destruction. This may affect many joints and body organs, and may occur in younger patients. It is part of a spectrum of conditions called ‘inflammatory arthropathies’ and is treated with the help of a Rheumatologist (medical joint specialist).
Post-Traumatic Arthritis – This can follow an injury to the cartilage or fracture of the bone. Over time more cartilage may be lost and degenerative change can occur.
If your knee pain is severe and you have difficulty in walking, stair climbing, and have pain at night, you may be a suitable candidate for TKR or UKR. You may also have a stiff and deformed knee. If you have tried taking pain killers, physiotherapy exercises and even knee joint injections (such as steroid or hyaluronic acid injections) without success then joint replacement may be the next step for you.
At the consultation, a careful history and examination is taken to assess the severity of your joint disease, and to exclude pain referred from the hip and spine. You will have weightbearing X-rays of the knees to accurately assess the degree of joint damage. Some patients also undergo a CT scan if undergoing robotic surgery or even other surgery services. A careful discussion will be made with you regarding the risks and benefits of the procedure and what to expect in the long term. You should feel free to ask questions, and express any fears and concerns that you have regarding the orthopaedic surgery. Please bring a friend or close family member also, as my aim is to ensure that you and your family are well informed and prepared, and have realistic expectations regarding the surgery.
Patients with active infection, lack of sensation at the knee joint, poor muscle function in their thigh muscles (quadriceps), as well as severe medical conditions such as blood vessel disease in the leg (arterial blockage and peripheral vascular disease) may not be suitable to undergo a TKR or UKR or may need to undergo medical treatment first.
I am commonly asked this question by relatives of patients. The answer is no – it depends on your general health and what you can gain from the surgery, rather than your absolute age.
Older people tend to suffer more from a worn out knee joint and therefore are more likely to need a joint replacement. I have replaced the knee joints of patients over 90 years of age, who went on to enjoy their remaining years without knee pain.
With the regards to younger patients, I have also treated patients in their 40’s have who severely worn out parts of their knees and have benefited from a partial or total knee replacement.
Knee replacement for the right reasons can be suitable for all adult age groups.
The knee joint can be divided into three compartments – the inside of the knee (medial compartment), the outside of the knee (lateral compartment) and the space between the kneecap and the thigh bone (patellofemoral joint).
Patients suitable for TKR may have loss of cartilage in all three compartments, have severe deformity, ligamentous injury or inflammatory joint disease.
Patients suitable for UKR may have localised joint disease in one compartment only.
Both procedures can be performed with an excellent degree of accuracy using a robotic system such as Makoplasty, Navio or Robodoc.
Some of the possible advantages of UKR over TKR include a smaller incision, less tissue damage and postoperative pain, less blood loss, faster recovery and return to work / sport, greater range of postoperative movement.
For those with two worn out knees, replacing both sides at once (bilateral joint replacement) is an option. Replacing both knees means a longer operation and anaesthetic time, as well as increased risk of complications. Recovery is slightly longer than having one knee replaced. However it does mean that you do not have to worry about about having to take more time off in future to have the second knee replaced and also avoid the cost of a second hospitalisation.
Once you have decided to have a knee replacement, you will be screened for any medical conditions that may need treating, and undergo a series of tests such as a chest X-ray, Electrocardiogram and blood tests. You should stop smoking immediately. You are advised to stop blood thinning medications and TCM herbs (which may also cause bleeding) two weeks before your operation. The anaesthetist may offer you either a General Anaesthetic (where you are asleep during the procedure) or a Spinal Anaesthetic (injection to the spine which numbs the legs). You will not feel anything during the operation. On the day of surgery, for safety reasons it is important not to eat or drink anything 8 hours before the procedure.
Whenever possible, I perform my joint replacements through a small incision (around 10cm or less). Complex and revision cases may not be suitable for minimally invasive surgery. The body tissues are handled very gently during surgery.
During the procedure I remove the worn joint surfaces from the thigh bone (femur) and shin bone (tibia). I take care to balance the soft tissues so that the knee is stable throughout the range of movement. I replace the joint surface with metal implants (usually cobalt chrome alloy) which are cemented onto the bone. Finally a plastic liner (highly crosslinked polyethylene) is placed between the two metal surfaces to allow a smooth gliding motion and reduce friction.
During the surgery I use a technique called local infiltration anaesthesia which involves injecting a local anaesthetic into cut tissues. This combined with a improves chances for a swift recovery.
I appreciate that pain is the main fear of patients, and I do my utmost to ensure that pain is minimised following surgery. As a result most of patients are able to stand and walk hours after surgery.
Usually the knee replacement surgery takes less than an hour. Following the operation you will be transferred to the Recovery area where you will be monitored for several hours until fit for discharge back to the General Ward.
Whenever possible I aim to get my patients standing and walking immediately following the surgery. I work closely with my physiotherapy colleagues to follow an ‘Enhanced Recovery’ Protocol so that patients start exercising on Day 1 of surgery. The eventual aim is for discharge from the ward on or before Day 3 of surgery.
All surgical procedures have an element of risk and potential complications. Fortunately the risks are usually low. Commonly following surgery there may be temporary pain, swelling, bruising and stiffness. You will take medicine to relieve the pain. Infection is the main concern (around 1% risk) following joint replacement, and great care is taking during surgery to reduce this risk including being given antibiotics during after the surgery via a drip. A blood clot in the legs (Deep vein thrombosis) or lungs (pulmonary embolism) is less common, and precautions such as mechanical foot pumps and/or blood thinning medications are used to reduce your risk. You will have an in depth discussion with your knee surgeon regarding potential risks of surgery.
The wound may take 2 weeks to heal and it is important to keep it clean and dry during this time. Patients may need to use crutches or walking aids for several weeks following surgery. It is very important to perform the knee exercises and attend physiotherapy to get the best out of your surgery.
Most patients can drive six weeks following knee replacement. You are advised not to fly long haul for at least six weeks following the operation to reduce risk of blood clot in the legs (deep vein thrombosis) or lungs (pulmonary embolism). Patients undergoing UKR can sometimes return to work at six weeks or earlier depending upon their occupation. Patients undergoing total knee replacement often need longer to recover – on average between six to twelve weeks in my experience, although there are exceptions.
In the days and weeks following surgery, you will be followed up closely in orthopaedic clinic, to monitor your progress, general wellbeing and to monitor for any complications that might occur.
My aim is to relieve your pain and restore function to your limbs through joint replacement. Although it can take some time and effort to recover, most patients can achieve an excellent result.
Dr Alan Cheung is a Consultant Orthopaedic Surgeon specialising in Sports Injuries such as torn ligaments and tendons, and cartilage injury in the knee, hip and shoulder, Adult Joint Reconstruction including total and partial Knee Replacement and Total Hip Replacement for osteoarthritis, and Robotic Surgery (Makoplasty, Navio and Robodoc systems). He has also received extensive training in trauma (fixing broken bones) and musculoskeletal tumour (bone cancer) surgery.