Knee Replacement

KNEE ARTHRITIS

If your knee is affected by severe arthritis or injury it may be difficult to perform simple activities such as walking, climbing stairs or sitting comfortably for prolonged periods. You may even feel the pain lying down. In India 1 in 5 patients over the age of 65 has some form of arthritis and in 1 in 20 patients the knee is the most severely affected joint.

Osteoarthritis can develop for the following reasons

1. age - degenerative
2. rheumatoid arthritis or other inflammatory joint disease
3. trauma which can damage the joint surfaces

HOW THE NORMAL KNEE WORKS

The knee is the largest joint in the body and each knee carried half the body weight. It is the articulation between the lower part of the thigh bone (femur) and the upper part of the leg bone (tibia). These are covered by a smooth layer of cartilage called articular cartilage. There is rotation and hinge activity between these two bones. In addition the kneecap or patella is covered by articular cartilage on its under surface and slides in the groove on the front of the femur. There are two large ligaments joining the two bones together, reinforced by strong muscles and tendons at the back and the front of the joint.
Injury can damage the joint surfaces and the cartilage covering the ends of the bone. These surfaces become rough and uneven and the joint cannot move smoothly.

NON-SURGICAL TREATMENT

The initial treatment includes drugs to reduce pain and inflammation, changing activity levels, using walking supports and physiotherapy, and injections. Occasionally keyhole surgery is advised to clean out any damaged areas. However, if these are not successful in curing the symptoms, a total knee replacement may be considered. This operation resurfaces the knee joint removing diseased bone and cartilage from the lower end of the thigh bone, the upper end of the shin bone and the back of the kneecap (patella). These surfaces are replaced with metal and plastic implants which allow natural knee motion and function and at the same time relieve pain and correct any deformity, enabling you to resume a greater range of normal activities.

KNEE REPLACEMENT

Knee replacement was developed following the success of hip replacement. The early knee replacements in the 1960s and 70s were fairly basic and the results were mixed. Improvements in surgical materials and techniques have greatly increased the effectiveness so that knee replacement surgery today has a high rate of success in relieving pain and restoring mobility. The replacement will last longer in lighter people and in older people who put less demand on the materials.

When is Surgery necessary?

1. you have severe pain, swelling and stiffness in your knee joint and your ability to move the joint is significantly reduced.
2. your knee pain is so severe that it interferes with your quality of life and sleep.
3. everyday tasks, such as shopping or getting out of the bath, are difficult or impossible.
4. You are feeling depressed because of the pain and lack of mobility.
5. you cannot work or have a normal social life.

THE DECISION TO HAVE TREATMENT

This should only be made after discussion with the Orthopaedic Surgeon whose team is going to carry out the operation. The Surgeon will discuss benefits and risks of treatment, and will emphasise that surgery cannot be guaranteed to meet all expectations. There must be a realistic expectation by the patient about what the operation can achieve and, whilst over 90% of patients have dramatic reduction in pain, the operation will not allow a high level of athletic activities and in particular some high impact sports will be excluded from normal activities.

THE ORTHOPAEDIC ASSESSMENT

This consists of several components:

• A medical history
• Physical examination with assessment of knee movement, stability and strength, followed by an x-ray and blood tests.

THE ANAESTHETIC

Knee replacement can be performed under a general or spinal anaesthesia, which numbs the lower limbs but you remain awake.

THE OPERATION

Most patients are admitted the day prior to surgery. The operation usually takes place with a tourniquet around the thigh to reduce the amount of bleeding and enable the components to be fitted accurately into position. The incision can be anything from 10 to 20cm in length depending on the type of approach and the size of the leg. The components may be implanted by shaping the bone to form a tight fit with the prosthesis, which is coated with a special material which allows bone to grow on to the surface and provide fixation (uncemented prosthesis); alternatively bone cement may be used to hold the prosthesis in place (cemented). The wound is closed with internal stitches to keep all the ligaments and muscles securely together, and clips, sutures or special tape on the skin.

RECOVERY

Following the total knee replacement you will be transferred from the operating theatre into the Recovery area.
You will be given oxygen and pain killing medication, usually through an intravenous line or drip. Very occasionally a special catheter may be introduced into the bladder to drain off the urine if you are unable to feel or pass urine yourself or if you have no feeling due to the spinal anaesthetic.
The knee will have a bandage, possibly with a splint to reduce swelling.

The pain and discomfort might be quite severe in the first few days but the nurses and Anaesthetic team will usually be able to administer sufficient pain killers to reduce the pain to acceptable levels.

EXERCISE

An exercise programme is an important part of recovery. This starts with gentle exercises in bed. Patients are normally advised to get out of bed with the help of physiotherapy on the second day.

The time spent in hospital used to be a weeks; further physiotherapy may be advised at home. In the early stages you will need crutches or a walking frame as muscle strength may take some weeks to recover.
The stitches or clips are removed after 14 days.

REHABILITATION

Most patients can begin physical therapy immediately after surgery. A frame, crutches or a stick may be needed for up to 6 weeks.
During the first few weeks stretching and strengthening the muscles remain goals of treatment. As strength and motion improves you may be instructed on other activities such as distance walking, cycling and swimming. These should restore your feeling of well-being.

Following total knee replacement patients are encouraged to resume an active lifestyle but are strongly advised against activities that produce high impact such as running and jumping.

FINALLY

Report to the Doctor or Medical Staff any of the following:

• Temperatures higher than 38.5° Centigrade/102° Fahrenheit, fever, sweating, shivering or chills;
• Severe pain or tenderness;
• Heavy bleeding from the incision;
• Redness around the incision that is spreading;
• Worsening pain or stiffness of the knee;
• Loss of mobility after a fall with increased pain;
• Any concerns regarding the surgery
• Swelling and pain in the calf or ankle of either leg.