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Total Knee Replacement

Introduction

If you are reading this leaflet then you have probably been sent by your GP to see an orthopaedic surgeon who considers that you would benefit from a knee replacement operation.  This leaflet will briefly outline what this will involve for you as a patient and mention some risks and complications of this type of surgery.

 

What is a total knee replacement?

Modern knee replacements were developed in the 1970s and involve removal of the diseased ends of the femur, tibia and patella bones that form the knee joint.  These are replaced with metal and plastic parts (called a prosthesis) which are usually cemented in place.

 

The aim of the operation is to replace a knee joint that is painful, stiff and often deformed with one that is not painful, moves more easily and is correctly aligned.

 

What can you do to help?

Prior to surgery there are several things you can do to help:-

 

Visit your dentist for a check up
Try and lose weight
Stop smoing
Take good care of your feet
Take as much exercise as your knee allows

 

You may be seen in an assessment clinic shortly before your surgery where your fitness for surgery will be assessed.  You may have blood and heart tests undertaken at this time.

 

You should have no solid food or drink for six hours before your operation.  When you arrive in theatre you will be given an anaesthetic (a spinal or general anaesthetic).  The surgery takes approximately 1 ½ hours and you will return from theatre with your leg bandaged and a plastic tube draining any blood that collects in the new joint.

 

How long do you stay in hospital?

Postoperative regimes vary between surgeons but the physiotherapist will get you bending your knee and walking a couple of days after surgery.  Once you are walking safely and bending your knee, and there are no wound complications, you may be discharged (usually 5 to 10 days) with arrangements to have your stitches removed and an outpatient appointment.

 

 

What can go wrong?

Generally a total knee replacement is a safe procedure that can dramatically improve your quality of life.  All operations however carry some risk and the most frequent and important are outlined below.

 

1.  Surgical mortality – A knee replacement is a major operation and a very small number of patients may not survive their surgery.  

 

2.  Anaesthetic – Modern anaesthetics are generally very safe.  The anaesthetist (a doctor) will explain any particular risks for you.

 

3.  Thromboembolism – Blood clots may develop in the veins of your leg during or after surgery.  Part of a clot may break off and travel to your heart, which can be fatal, but this is extremely uncommon and occurs in 2 in 1000 cases.  This risk may be increased if you are female, overweight, have varicose veins, high blood pressure, diabetes or heart disease.  Recognised ways to reduce blood clots are exercise and using stockings and foot pumps which are used here at the Hospital.

 

4.  Infection – This can be a difficult problem that may not respond to antibiotics.  You may require further surgery which could involve the removal of the knee replacement altogether leaving you in plaster for 6 to 8 weeks.  If the infection clears up the surgeon may repeat the knee replacement.  Very rarely, if the infection cannot be controlled an arthrodesis (fusion) of the knee or, more rarely, an amputation may be advised.

 

Infection of this kind occurs in fewer than 2 patients out of 100.  In order to reduce this risk antibiotics are given during the operation which is performed in a laminar flow theatre used especially for orthopaedic operations.

 

5.  Loosening, wear and fractures – Current research shows that, using modern knee replacements, 9 patients out of 10 will still be walking on their knee replacement after 15 years.  Heavy or violent physical activity over time may loosen the prosthesis or cause wearing of the plastic parts. 

 

Conversely, patients with osteoporosis rheumatoid arthritis and neurological disorders may suffer fractures in the bones around the prosthesis.  Any of these three complications may require further surgery.

 

6.  Injury to nerves and blood vessels – This is a rare complication and more likely if you have a markedly deformed knee.  These structures run close behind the knee and may be injured during surgery resulting in paralysis, weakness, numbness or pain in the leg and foot which is usually temporary, but may be permanent.

 

7.  Patellofemoral problems – In some cases there are problems with the kneecap after surgery, including dislocation, fracture, loosening and tendon rupture, any of which may require further surgery.

 

We hope this information sheet has answered any questions you might have.  If you have any further queries please feel free to discuss them with your Consultant or nursing staff either in the Clinic or on your arrival at Hospital.