The operation to replace your knee takes about 1 – 2 hours. At the end of the surgery, the anaesthetist will take you to the recovery area for a short period of assessment. The drip in your arm should be removed once you are tolerating food and fluids. Your pain control will be established and your vital signs monitored. You will remain there under the care of a specially trained recovery nurse, until it is time for you to go to the orthopaedic ward.

Pain management

You should expect some discomfort following surgery. You will be given regular painkillers so you are able to do exercises and move your new knee. Please see the section on management of pain following surgery for further information.

Painkillers include paracetamol, ibuprofen-type drugs (non-steroidal anti-inflammatory drugs) and morphine-like drugs (opioids). Initially, you will need strong painkillers to help you to move. We will give you strong painkillers for one or two days after your surgery. Sometimes, these strong painkillers are given to you through a drip into your arm.

Please remember to let the doctors and nurses know if your pain score is 2 (moderate) or above or if the pain stops you doing your exercises. We may need to alter or increase your painkillers.

Pain Score

How is pain assessed?

After your operation your pain will be assessed regularly, pain will be measured by using a pain score. You will be asked to describe your pain on a scale of 0 – 10. Zero being no pain and ten being severe pain.

Some patients experience side effects from painkilling drugs.

These can include:

  • Drowsiness (feeling sleepy)
  • Nausea or sickness
  • Indigestion (heartburn)
  • Constipation

If you have any concerns about your pain or the painkillers that you are given, you may discuss this with your nurse or doctor. You can also be referred to the pain specialist nurses if your pain is difficult to manage.

Day One to Three

Day one – after surgery

  • You will be assisted to wash and you will get dressed.
  • You must not attempt to get out of bed until you have been assessed. You will be helped out of bed and sat in a chair.
  • If you are drinking sufficiently your drip will be discontinued.
  • The dressing on your wound will be checked daily.
  • You will be seen by a member of the medical team.
  • Your pain levels will be assessed and pain relief will be given as appropriate.
  • You will be given regular pain relief medication by mouth.
  • Many of these medications make you constipated and you may need laxatives to counteract this.
  • Throughout your stay please let the nurses know if you have not had your bowels open so they can address the problem.
  • The Physiotherapist will see you and start your exercise regime. (See video links below for the exercises you must perform)
  • On day one or two, bloods tests will be taken and you may need a blood transfusion or to commence iron tablets.
  • Your drain and urinary catheter, if you have one, may also be removed.

Day two

  • You will be assisted to sit in a chair for your breakfast and your wash.
  • You will be asked to get dressed.
  • From now on you will be expected to sit in a chair for all meals.
  • The physiotherapist will continue with your exercises and progress your mobility with a walking aid.
  • You will be taught to go up and down stairs if you are ready.
  • You will be assisted to walk to the toilet and if possible back again.
  • If you have not been seen by the occupational therapist (OT) before your operation an initial assessment will be made today.
  • Day three and onwards
  • The physiotherapist will continue with your exercises and progress your mobility with a walking aid. They will also check that you are familiar and comfortable with your exercise regime.
  • You will be taught to go up and down the stairs if you have not already done so.
  • You will be encouraged to walk to the bathroom for your wash. The nurses will assist you as required.
  • The Therapy Team will see you to confirm your discharge arrangements.
  • They will ensure that you can transfer on and off the bed, chair and toilet unassisted before you go home.
  • You will be ready to go home as soon as you have met your discharge goals.

After your knee surgery exercises

These exercises are essential for a complete recovery and satisfactory outcome from your surgery. Some focus on improving your range of movement whilst others are to regain your strength. Your exercises will take you approximately 20 minutes and should be done at least four times a day. If you find any exercises difficult, build up to the suggested number gradually.

  1. Ankle pumps
  2. Static quads (knee push-downs)
  3. Inner range quads
  4. Straight leg raises
  5. Heel slides
  6. Extension stretch
  7. Knee extension (bend and straighten)
  8. Seated knee flexion

Occupational therapy

  1. Transfer out of bed
  2. Transfer into bed
  3. Stair assessment
  4. Sitting to standing
  5. Transfer into the car as a passenger

The vast majority of patients make a good recovery after their knee replacement operations and experience no serious problems. However it is important you understand that a knee replacement is a major operation and that complications can occur.

General surgical risks

Thromboses and emboli (blood clots)

Blood clots in the leg veins (deep vein thrombosis) and blood clots on the lungs (pulmonary embolus) are a risk associated with joint replacement surgery.

The simplest way of reducing this risk is early mobilisation (exercises and walking).

Whilst in hospital you may also be prescribed blood thinning treatment, usually in the form of tablets. These tablets reduce the risk of clot formation.

Patients already receiving anti-coagulant therapy will be assessed and advised accordingly. After discharge, it is important that you inform your General Practitioner if you notice increasing swelling in your calf accompanied by pain; chest pain or if you start coughing in the early weeks after surgery.

Urinary problems

Some patients, particularly those who may have previously experienced difficulty passing water, may sometimes need a catheter to be inserted into the bladder prior to or after the operation. Except in certain circumstances, this should be removed the morning after surgery.


Nowadays, blood transfusion following a knee replacement is rarely needed. If your blood count is very low or if you are showing symptoms of anaemia (low blood count), the team looking after you may recommend a blood transfusion.


Most joints are made of stainless steel or cobalt chromium and polyethylene. A very small level of nickel is present. It is extremely unlikely that you will have an allergy to your implant even if you have experienced a rash to your watch or earrings. Tell your surgeon if you are concerned.

Superficial infection

You will not be discharged from hospital unless the appearance of the wound is satisfactory. After discharge, if you have any concerns about your wound, please inform your GP or Practice Nurse.

Deep infection

A deep infection of the joint most often starts when bacteria gain access to the tissues at the time of surgery and great lengths are taken in theatre to reduce the risks of this happening. Operations are carried out in an ultra-clean air theatre and sterile clothing is worn by the surgical team. You will be given preventative antibiotics at the time of surgery. All patients are screened for MRSA during their Pre – Assessment Clinic appointment. If you are found to be a carrier of MRSA you will be given treatment prior to your operation. A specimen of your urine taken to your Pre – Assessment Clinic appointment will be screened for bacteria. If bacteria are found in your urine, you will be informed and treatment given if needed. Despite all the precautions taken, infections can still occur.

An early deep infection (within the first six weeks) may sometimes be treated by washing the joint out in theatres, followed by an extended course of antibiotics. However, it is sometimes necessary to remove the new knee, treat the infection with a long course of antibiotics and then replace the knee again at a later date. An infection can occur at any stage in the life of a knee. The reason for this is that any infection in the body can circulate in the blood and settle on the surface of the new knee joint. Once there it forms its own environment, or ‘bio-film’, which makes it difficult to treat with antibiotics alone. Although the symptoms of infection can often be suppressed with antibiotics the only way to eliminate this deep infection is to remove the artificial implant as described above. If you develop signs of an infection (e.g. urine or chest infection, tooth abscess, leg ulcer) at any time after your operation, please remind your GP/dentist that you have a knee replacement. If your knee suddenly becomes painful, it is important to see your GP so that infection in your knee replacement can be ruled out.

Remember infection is a serious complication. If you develop any new redness around the wound or if the wound leaks after leaving hospital, it is important that you see your GP.


It is common to see bruising around the knee in the days after surgery and, occasionally, this bruising will extend down the leg, sometimes into the foot.


You may find your knee and lower leg swell. This is a normal response to surgery. It may be many months before this settles. Often the shape of the knee is altered. Occasionally, the knee will always remain slightly larger than a normal joint.

Some warmth around the knee is another common occurrence and is due to increased blood flow through the tissues during healing. Again, this may take many months to settle. You should continue to do the exercises detailed in this link even if your knee is swollen. Walking can help reduce the swelling, but standing unnecessarily should be avoided. You should also aim to lie flat for at least 20 minutes once or twice a day. Whilst lying, it may be beneficial to elevate the leg ideally with “foot higher than heart”.

If the swelling does not reduce over night or is accompanied by tenderness in the calf or groin, a temperature or breathing problems you should ask your GP for advice.

Medical problems

Complications of myocardial infarction (heart attack), stroke or death can occur after knee replacement as with other forms of major surgery. These complications are very rare and the anaesthetist will not allow the operation to proceed if it is felt that the risks are significantly higher than normal. In this circumstance, it may be that you are sent for further tests or treatment prior to surgery being performed.

Specific risks

Stiffness and range of movement: Most people are delighted with their knee replacement. Some people describe aching or stiffness in the joint or have a limp which does not improve. It is vital to follow your rehabilitation programme to achieve the best possible outcome. It can take many months to gain a good range of movement. The ease and range of movement with a knee replacement will vary from person to person. This is due to many factors such as:

  • your general health before the operation
  • the position of your knee before the operation
  • the range of movement before the operation
  • the medication you are normally prescribed
  • your weight
  • Any post-operative complications

Pain after your knee operation is inevitable, although everyone experiences pain differently. Good pain relief is important and is an essential part of your care.

We aim for your pain to be at an acceptable level on movement, and should not prevent appropriate function e.g. physiotherapy and mobilisation. Attempts to completely remove pain usually result in side effects from pain-killing medication, which are counter-productive to your speedy recovery.

Pain control is an essential part of your care

How can we reduce your pain? The nurses and pain team are able to give you advice and support. Pain relief is available in different forms and strengths. Oral Medication Pills, tablets or liquid to swallow.

When you are able to drink and eat then you will begin taking your painkillers by mouth. Most patients will need to take painkilling medication regularly after surgery to keep their discomfort to a minimum. These will be prescribed by your anaesthetist, and will be given routinely at the time stated on your prescription chart. There will always be backup painkillers prescribed which you can ask for if your pain is not well controlled. These take at least half an hour to work, so ensure that you request them in good time before allowing pain to become severe. Nerve Blocks and Local Anaesthetics Most patients will receive a spinal anaesthetic and will have a long-acting pain killer added to this injection, this can provide very effective pain relief for up to 24 hours after the operation. Injecting local anaesthetic drugs close to the nerves supplying the knee or at the operation site blocks painful messages from being sent to the brain. This is carried out at the time of your operation and will give a numbing sensation for up to 24 hours, depending on which block is used.