What is a knee replacement?

A knee replacement is a surgical procedure aimed at reducing pain and increasing the function and movement of an arthritic knee.

What is arthritis?

The knee joint is a hinge joint where the tibia (shin bone) and femur (thigh bone) meet. There is also another smaller joint between the patella (kneecap) and femur. The knee joint absorbs the stress of all weight-bearing movements. It can move freely, as the ends of the bones are covered in a smooth soft tissue called articular cartilage. This acts as a natural shock absorber.

Over time this articular cartilage can begin to wear out and is unable to repair itself. As this happens there is little protection between the ends of the bones, which can cause you to feel pain. This process is known as osteoarthritis. Rheumatoid arthritis and traumatic arthritis, caused by a specific injury, can also cause cartilage to wear away.

The operation

An incision is made on the front of your knee. A small amount of bone from the tibia and the femur is removed and replaced with a new, smooth metal surface. The worn cartilage is also replaced with a plastic component. The underside of the kneecap, which is often worn too, may be replaced with a small plastic layer. Following your operation you will have improved function in your knee and less pain.

Risks and complications

The two most common complications after surgery are deep vein thrombosis (DVT) and infection. The common signs of DVT are pain, redness, heat and swelling around the calf and/or groin area. Wearing your TED (thrombo-embolism-deterrent) stockings as instructed, mobilising regularly and doing your ankle pumps will help decrease the risk of DVT.

The common signs and symptoms of infection are oozing from the wounds, excessive swelling, heat and redness, unremitting pain and feeling generally unwell.

After your discharge, if you have any of these complications, contact the hospital ward immediately or seek medical help from your GP or local Accident and Emergency department.

Enhanced recovery

Enhanced recovery is an evidence-based approach that helps you recover faster. Research has shown that the earlier a person gets out of bed and starts walking, eating and drinking after their operation, the shorter their recovery time will be.

Before you have your surgery you can help enhance your recovery by:

Remaining active: staying physically active prior to your surgery will stop your muscles from becoming weaker and prepare you for the rehabilitation process.

Nutrition: try and eat a balanced diet and drink plenty of water before your surgery as well as after. Ensuring you give your body the fuel it requires to repair itself is vital.

What to expect after surgery

Immediately following your surgery, you will be taken from the operating theatre to the recovery area. You will be monitored by specialist nursing staff to ensure that you recover from your anaesthetic safely and comfortably. You will then be taken back to your room.

You will have a large bandage around your knee. Beneath this will be a dressing which you should leave alone until your follow-up appointment.

You will be wearing TED stockings to reduce the risk of blood 4 clots. You will continue to wear these while you are in hospital and when you first go home. Your nurse will tell you how much longer you need to wear them for. They should be removed if they need washing or for showering and bathing.

You will have an IV line in your arm through which fluids and antibiotics will be administered. Pain relief will be given when you require it. It is vital that your pain is controlled after surgery. If your pain is not at a tolerable level you must tell your nurse. The medications and anaesthesia may cause you to feel nauseous. If so, your nurse can give you anti-nausea medication.

You will be taught some exercises by your physiotherapist to start immediately. These will include deep breathing exercises that help to keep your lungs clear, static quadriceps (front thigh muscle strengthening) exercises and ankle pumps (moving the feet up and down at the ankle joint). These exercises will start to strengthen your thigh muscles and contract and relax the calf muscles. They will help to maintain circulation and reduce the risk of blood clots.

It is normal and expected that you will have swelling and bruising after your operation. You can manage this swelling with a combination of resting, elevating and putting ice on your leg. When elevating your leg ensure that the knee is kept straight and supported. A machine can be used to deliver ice and compression therapy to the knee. This will help to reduce the swelling and offer some additional pain relief. Your physiotherapist can give you information about hiring one of these machines.

Rehabilitation

Your physiotherapist or nurse will help you walk, if possible, on the same day as your surgery. You will need to use walking aids (likely crutches) for a couple of weeks, but as you progress and require less support you will be able to walk without them.

Physiotherapy will play a vital role in your successful rehabilitation from your knee replacement. You will need to complete the exercises given to you in between your formal sessions with your physiotherapist. It is important that you motivate yourself to do these. Exercises will be given to you after your operation on a separate print out personalised to you.

Your physiotherapist will let you know how many times you need to do your exercises per day. This will ensure that you build up adequate strength in the muscles surrounding the knee that give it vital support and prevent it from stiffening up.

While you are using crutches your physiotherapist will demonstrate the safe and correct method for managing stairs. Use one hand to hold onto the banister and the other to hold the crutch. You will be shown how to transport the other crutch up or down the stairs with you. When going up the stairs you will lead with the unaffected leg followed by the affected leg. When going down the stairs you will place the crutch and the affected leg down first followed by the unaffected leg. If you have stairs without a banister we can teach you a technique for this.

Pain relief

Your discomfort should be tolerable but do not expect to be pain free. We aim to use the minimum amount of pain relief required to keep you comfortable. Compression and ice therapy will also help with pain relief. Although it may seem hard to believe, regular walking can help reduce pain and stop the knee from stiffening up.

The pain that you will feel when doing your exercises, especially those that involve bending the knee, is completely normal. Do not let this pain prevent you from completing your exercises regularly. If, however, your pain is not tolerable please speak to your nurse.

Going home

You will be able to go home 1-3 days after your procedure. You will be discharged with all relevant medications.

It is important that you have the necessary support at home ready for your return. It is a good idea to have the help of family or friends during the immediate convalescent period. If you foresee any difficulties with being able to get around your home or accessing different areas, for example the bathroom, please let your physiotherapist know. They can review your home environment with you and provide education, equipment recommendations and strategies to keep you safe at home.

Wound healing

All wounds progress through several stages of healing. You may experience sensations such as tingling, numbness and itching. You may also feel a slight pulling around the wound and a hard lump forming. These are normal and a part of the healing process. However, if your wound starts swelling or oozing then you should contact us for advice.

Post-operative swelling and bruising

If there is swelling, elevate the operative leg for short periods throughout the day. It is best to lie down and raise the leg above heart level. You can put ice on your leg regularly to help with swelling. Notify us if you notice significantly increased pain or swelling in either leg, particularly behind the calf muscle. Gentle and regular mobility throughout the day will help reduce the swelling. Try not to overdo it. It can take months for your swelling to settle fully.

Sleeping

You can sleep on your back or either side. Changes in routine plus restricted or sudden movement can make sleeping difficult. You may want to take a painkiller before going to sleep. It is normal for sleep to be distrubed for up to six weeks.

Becoming mobile

Moving around regularly is important for your recovery and preventing the knee from becoming stiff. Initially try to move around every 30 minutes to one hour. You can mobilise outside as soon as you feel comfortable to do so. You should increase your walking distance daily and gradually.

On discharge from hospital, you will probably be using two crutches. Unless you have been specifically instructed not to discard your walking aids, this is the progression that you should follow: • Within two weeks you can try using one walking aid indoors. Keep this in the opposite hand to the operated leg
• You will know when you are ready for one walking aid; it is when you can manage the same with one as you can with two and without a limp. If you are limping, continue to use walking aids a little longer
• You will need to use two walking aids for longer outdoors as you will generally be walking further. It may be more uneven and sometimes more slippery
• Progress as you feel able. This will differ from person to person

Recreational activities

Remember this is a major operation, therefore it will take several months before you can return to a normal level of activity. Try to go out walking every day and increase the distance that you walk every few days. It may take time for the pain and swelling to go away. Use ice to manage this, keep active and enjoy the benefits of your new knee. If you plan on travelling abroad after your operation please ask your consultant for advice.

Driving

You can drive when you can safely perform an emergency stop. This will vary depending on which knee was operated on and if you drive an automatic or manual car.  

You are advised not to drive until you have discussed this with your consultant.

Follow-up

Follow-up appointments will be made for a wound review and to see your consultant.

Outpatient physiotherapy

Outpatient physiotherapy is important for getting the best possible result from your knee replacement surgery. It can help to increase the range of movement of your knee through manual therapy and exercise. Your exercises will be progressed as you get stronger. It is vital that you continue to strengthen the muscles around your knee as they give crucial stability. 

Your consultant will tell you when you should start physiotherapy.