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Knee joint replacement

guidelines for patients

Dr Rob Nicholas

Total knee replacement information

This describes a normal knee joint, the arthritic joint and the cause of pain, the indications for knee replacement surgery, what you can expect from knee replacement surgery, the possible complications and what exercises and activities will help restore your mobility and strength.

If your knee has been damaged by arthritis or trauma activities such as walking and getting in and out of a chair may become significantly painful and difficult. With this your knee joint may become stiff and you may even develop an ache at rest and your sleep may be disturbed.

If medication, changes in your everyday activities, and the use of walking aids such as a cane are not helpful anymore, you may want to consider knee replacement surgery.

With total knee replacement a new artificial lining is introduced into the knee joint in order to provide relief of pain and increased motion, with the aim of getting you back to enjoying everyday activities.

Since the 1970’s knee replacement surgery has become successful and increasingly popular. During the past thirty years improvements in technology and surgical techniques have turned into a very successful procedure.

Anatomy and Pathology

The knee is a large weight bearing joint (the biggest joint in the body). It is a hinge type articulation between the lower end of the femur ( thigh bone) and the upper end of the tibia (shin bone).

The lower end of the femur is covered by a smooth layer of hyaline cartilage, as is the upper end of the tibia. Between these two layers of cartilage you also have two meniscal cartilages, one medial and one lateral. The cartilages give a smooth bearing surface with a cushioning affect, enabling the two bones to move smoothly on each other.

With arthritis the cartilage surfaces wear out and then the rough bone surfaces move on each other, with resultant pain and stiffness.

Knee joint replacement surgery provides artificial linings to the different bone surfaces.

Indication for knee replacement surgery

You may benefit from a total knee replacement if:

What to expect from knee replacement surgery

An important factor in deciding whether to have knee replacement surgery is understanding what the procedure can and cannot do.

Most people who undergo knee replacement surgery experience dramatic reduction of knee pain and a significant improvement in their ability to perform the common activities of daily living. You should be able to walk for exercise again, take a four to five kilometer walk if you want to, cycle, play bowls and golf.

However, knee replacement surgery will not enable you to do more than you could before your knee problem developed.

Following surgery, you will be advised to avoid certain activities and high impact sports, for the rest of your life. You will also not be able to squat down on your haunches. In some patients kneeling on this knee remains painful and unpleasant.

Even with normal use and activities, an artificial joint (prosthesis) develops some wear over time. If you participate in high impact activities or are overweight, this wear may accelerate and cause the prosthesis to loosen and become painful.

Preparing for surgery

Medical evaluation
If you decide to have knee replacement surgery, you may be asked to have a complete physical examination by a physician before your surgical procedure. This is needed to assess your health and identify conditions that can interfere with your surgery or recovery.

Several tests may be needed to help plan your surgery: blood and urine samples may be tested and a cardiogram and chest x/rays( radiographs) may be obtained.

Preparing your skin
Your skin should have not have any infections or irritations before surgery. If either present, contact your orthopaedic surgeon for a programme to improve your skin before surgery.

Stop Disprin and anti-inflammatory drugs seven days before surgery. Ask your doctor if you are not sure.

Weight Loss
If you are overweight, your doctor may ask you to lose some weight before surgery to minimize the stress on your new knee and possibly decrease the risks of surgery.

Social Planning
Although you will be able to walk with crutches or a walker soon after surgery, you will need some help for several weeks with such tasks as cooking, shopping, bathing and laundry.

If you live alone, your orthopaedic surgeon’s office or a discharge planner at the hospital can help you to make advance arrangements to have someone assist you at your home.

A short stay in an extended –care facility during your recovery after surgery may also be arranged.

Home Planning
The following is a list of home modifications that will make your return home easier during your recovery:

Your surgery

You will most likely be admitted to the hospital the day before surgery. Prior to surgery the anaesthetist will evaluate you. The most common type of anaesthesia for knee replacement surgery is epidural anaesthesia with or without general anaesthesia. The epidural anaesthetic will continue for twenty four hours post-operatively to give pain relief. The anaesthetist will discuss these choices with you and help you to decide which type is best for you.

The surgical procedure takes about two hours.

The damaged cartilage and bone is removed from the knee joint and metal surfaces are applied to the lower end of the femur and the upper end of the tibia. The metal surfaces are cemented onto the bone surfaces. Then an ultra-high density polyethylene disc is positioned between the metal surfaces. The knee articulation therefore is between highly polished metal and polyethylene.

If only the inner compartment is damaged, and if certain other criteria are met, it may be feasible to replace only the inner compartment of the knee, that being called a unicompartmental knee replacement.

Total Knee Replacement

Unicompartmental Knee Replacement

You will usually stay in the hospital five to eight days. Walking and light activity are important to your recovery and will begin the day after surgery. Most patients who undergo total knee replacement begin standing and walking with the help of the physiotherapist and crutches or a walking frame the day after surgery. The physiotherapist will teach you specific exercises to strengthen the muscles round the knee and to restore movement.
You will be taught how to negotiate stairs.

The overall complication rate following knee replacement is low. Major medial complications, such as heart attack, occur less frequently. However chronic illnesses may increase the potential for such complications. Although uncommon, when these complications occur they can prolong or limit recovery or even cause death. For this reason you are required to see a physician before surgery.

Wound and joint infection is a serious complication. It is rare and occurs in less than 1% of cases, but once deep seated infection occurs it can be difficult to eradicate and may loose to loss of the artificial joint. For this reason surgery is always done in a clean air lamina flow theatre, with the use of systemic antibiotics and also antibiotics in the bone cement.

Blood clots in the leg veins or pelvis are the most common complication of knee replacement surgery. In order to prevent this one or more measures are prescribed, such as special support hose, ankle / foot pumps and blood thinners.

Other complications such as nerve and blood vessel injury, bleeding, bone fracture and joint stiffness can occur, but these are very rare. In a small number of patients some pain can continue after surgery or new pain may develop.

Over years following surgery the knee prosthesis may wear out or loosen. With wear and loosening bone loss can also occur. If the patient is overweight or participates in high impact sport this is more likely to occur. More than 90% of knee implants last more than ten years and 70 to 80% last twenty years.

The success of your surgery will depend in large measure how well you follow your orthopaedic surgeon’s instructions regarding home care during the first few weeks after surgery.

Full recovery takes twelve months.

The knee will be swollen and it will feel warm and you may also experience some swelling of your ankle. All this takes about six months to settle.

Your physiotherapist will give you instructions regarding exercise and please follow these upon discharge. It is important to take a walk twice a day and to increase your walking distance gradually.

Upon discharge from hospital you will be given an appointment to see Dr Nicholas again four to five weeks later. Outpatient physiotherapy is not usually necessary, but will be arranged if indicated.

If you have any queries you must please phone Dr Nicholas or Orthpaedic sister Elwyn.