You cannot move like you used to and it is becoming painful to walk the dog, climb a flight of stairs, or simply get out of a chair. Simple activities have become difficult to perform. You have tried medication, injections and physiotherapy. However none seems to work. If this what you are going through, you may need to consider a knee replacement surgery.
Also known as knee arthroplasty, knee replacement surgery is a safe and effective procedure for damaged knees from arthritis and injuries. The procedure aims to correct leg deformities, relieve pain, restore motion and help you regain the ability to resume normal activities again. What we like to say here in Singapore is to have the knee fixed with a “spare part”.
Knee replacement was first performed in 1968. Since then, significant improvements have been made in surgical materials, biomechanical engineering and surgical techniques. These have greatly increased the effectiveness and success of the procedure. During surgery, an orthopedic surgeon removes the damaged part of the knee and replaces it with an artificial joint made of metal or plastic. The artificial joint is then attached to the thigh bone, shin, and kneecap with a special acrylic cement.
Arthritis is inflammation of the joints. Any joint in the body can be affected but it is most common in the knees. Pain, stiffness and swelling are the most common symptoms. As the disease progresses, deformity of the knees can result. Arthritis makes it difficult to perform everyday activities including walking and climbing stairs. It is a serious disability in many people.
There are many different types and causes for arthritis. The more common ones are listed below.
Osteoarthritis is the most common form of arthritis in the knee. It is also known as “wear and tear” arthritis. It is a degenerative type of arthritis and it is more common in patients who are 50yrs of age or older. In osteoarthritis, the cartilage layer of the joint breaks down (degenerate) and wears away. This results in bone on bone contact causing pain, inflammation and bone spur formation.
Rheumatoid arthritis is a form of Inflammatory Joint Disease. It is an autoimmune disease where the body’s immune system attacks and destroys the normal tissue in the knee and softens the bone. This is usually a chronic disease and affects multiple joints throughout the body. The same joint on both sides are usually affected.
This is a form of arthritis that develops after an injury to the knee. The more common types of injuries include ligament or meniscus tears at sports or fractures to the bones about the knee. These injuries are increasingly common in Singapore due to higher numbers of injuries in sporting activities and road traffic accidents. Ligament and meniscus tears result in increased cartilage wear due to instability and a reduced ability in shock absorption. Over time, this can result in arthritis in the knee. Fractures, especially those involving the joint cause direct injury to the cartilage leading to arthritis development.
A knee replacement procedure is where the diseased surfaces of the knee are surgically removed, both at the femur (end of the thigh bone), the tibia (upper end of the shin bone) and in selected cases the undersurface of the patella (kneecap). The parts of the bone and cartilage which are removed are “replaced” with specialized metal components that recreate the surface of the joint. Finally, a medical grade plastic spacer is inserted in the space between to create a smooth gliding surface. The surgery usually takes about 1- 2hours to perform. The implants are carefully planned and chosen to maximize the outcome and function of the knee for the individual patient.
Based on historical data, most knee implants will last 15- 20 years with moderate use.
Having a total knee replacement is an important cooperative decision made between yourself, your family and your orthopaedic surgeon. There are many reasons why you may be recommended for a total knee replacement and most patients who have benefited from this type of surgery often have:
There are no absolute age restrictions for knee replacement surgery. Recommendations for surgery are based on the individual patient’s condition and on their general health state. Most patients who undergo such surgeries are between the ages of 60-80 but such surgeries are successfully performed at all ages.
Deformity in the left knee due to osteoarthritis.
This is the most common form of knee replacement surgery where the orthopaedic surgeon replaces the surfaces of the thigh bone and shin bone that connects to the knee.
The left knee with a total knee replacement done earlier where a similar deformity was corrected.
X-ray: A partial knee replacement of the inner compartment in the left knee.
If only one side of your knee is affected, a partial knee replacement surgery may be a possibility. This procedure is also known as a unicompartment knee arthroplasty. This is a special type of knee replacement where only the part of the knee that is affected is replaced. The rest of the knee is left intact, including the ligaments and the meniscus on the other side. The procedure is done via a minimally invasive technique where there is less tissue injury blood loss and pain. Recovery after surgery is also significantly faster than having a total knee replacement.
Bilateral knee xrays of a patient with severe arthritis in the knees
When you consult the doctor, he will gather information about your medical history and specific details about the condition of your knee. He will also examine your knees to assess the condition including the motion, areas of tenderness and overall leg alignment.
X-rays of the knees are commonly done to determine the degree and extent of damage and deformity in the knees. Other tests such as an MRI (magnetic resonance imaging) scan or blood tests may be required to further assess the condition of the knee.
The orthopaedic doctor will discuss and explain the results of the evaluation and discuss the treatment options available. He will also advice if a total knee replacement is the best option to treat the arthritis in your knees.
Understanding what a total knee replacement can and cannot do for you is an important factor in deciding whether to have surgery.
Most patient who have undergone a total knee replacement experience a remarkable reduction in knee pain and ability to perform normal daily activities. A period of post-surgical rehabilitation with physiotherapy is needed. It is important to note that a total knee replacement will not be able to allow you to do more than what you could do before you developed arthritis.
The knee implant is an artificial joint. It is prone to wear and tear with use. With moderate use, the knee implant can last for as long as 20 years. Excessive activity or high impact activities can speed up the wear in the joint and cause the implant to loosen and pain in the knee. This is why most orthopaedic surgeons advice against participating in high impact activities after a total knee replacement. Low impact sports and activities such as biking, swimming, walking, tai chi is more appropriate.
Knee replacement surgery is major surgery. The success rate for a total knee replacement is high at 95%. Serious complications can happen and they happen in less than 2% of patients. Those suffering from chronic illnesses or have a poorer state of general health can be at increased risk of potential complications. It is important to discuss these with your doctor and understand their significance and impact before deciding on surgery. The more important ones are listed below.
The incidence of infection happening after knee replacement surgery is at 1%. Infection can be superficial at where the wound is or deep around the implant and prosthesis. This can happen while you are still in hospital or after you go home. It can even occur a few years later. Superficial infection can often be treated with wound dressing and antibiotics. Deep infections often require surgery to control and treat the infection. At times, the prosthesis may need to be removed and re- inserted at a later time once the infection is settled. Any infection in your body can spread to the knee replacement. Dr Lee usually advice patients to inform the dentist that they have had a knee replacement done and that they need to take prophylactic antibiotics as a precautionary measure.
The design of the total knee replacement implant and the biomaterials used have gone through significant improvements over the years. They are more anatomic, have a better range of motion and lasts longer than earlier versions. However, the lifespan of such implants are still finite and surfaces will wear down over time and with use. Appropriate modification of activities can allow the implant to last up to 20 years. High impact or high intensity activities can result in accelerated wear and premature implant failure.
Blood clots in the veins are common after knee replacement surgery. They are also known as deep vein thrombosis and are similar to “economy class syndrome”. These clots can be dangerous if they break free and travel to the lungs. When this happens, it is called a pulmonary embolism. Dr Lee has an established program to reduce the possibility of this occurring, including early onset of lower limb exercises to improve blood circulation, the use of compression stockings and medications to thin your blood.
Improvements in implant design and materials has allowed current implants to be able to flex almost the entire range of a normal knee up to 155degrees. However, the degree of motion in the knee after surgery is largely determined by the amount of motion possible in the knee prior to a knee replacement surgery. Although surgery can improve the range of motion, it is difficult to change the motion range in a badly diseased knee back to that of normal. Physiotherapy after a knee replacement is especially important to maximize the recovery after surgery. The aims of physiotherapy would be to restore range of motion and strengthen the muscles around the knee to achieve maximal function after surgery.
Injuries to the nerves and blood vessels are uncommon but can happen during surgery.
Physiotherapy working on mobility exercises for the hip and knee
After knee replacement, you will start physiotherapy on the first day after surgery. This involves exercises to put the knee through a range of motion and walking with a walking aid or a pair of crutches. Over the next few weeks, the physical therapist will take you through an activity program which will include a graduated increment for walking, strengthening exercises and functional training such as walking up and down stairs and other house hold activities.
To make your home safer after surgery, it might be easier if the following improvements can be made:
At 6 weeks after surgery, you can generally resume most daily activities such as shopping and light housekeeping. Driving is also possible at that time, if not slightly earlier if you can flex or bend your knees enough to sit in a car.
Once you have recovered, you can look forward to enjoy a variety of low impact activities without problems. Currently, more than 90% of knee replacements are still functioning well at 15years after surgery. Following the doctor’s advice and instructions after surgery and taking care of your knee and general health are important ways to contribute to the success of your surgery.
More information about complications from surgery and other details can be found in the section of “The Unicompartmental Knee Replacement”. They are similar.
Dr Lee is an experienced orthopaedic surgeon who specializes in total knee replacement. He will assess your condition and advise the best form of treatment for your condition. With proper treatment, patients can often return to their pre- injury levels.
To make an appointment, please call 6735 0081 or click here to email us.