Knee Replacement

Over 70,000 knee replacement procedures are carried out in the UK each year and over 350,000 in the U.S making it one of the both countries most common surgeries. The procedure was previously considered an operation reserved for the over 60’s, due to the limited ‘shelf life’ of the knee replacements. However, with improving technology in this area, artificial knees are now more durable and long lasting, meaning that younger people can now benefit from them too.

Osteoarthritis is the most common reason for a knee replacement and put simply, is a natural age related degeneration of the bone and cartilage of the joint. There are many symptoms associated with this condition which vary from one person to the next. The typical ones are as follows:

• Joint pain.
• Joint swelling.
• Reduced mobility and stability of the joints.

Knee replacement surgery is not a life saving operation and therefore the decision to have the operation comes down to you. Your GP or Orthopaedic specialist will discuss your options with you and they are likely to suggest the following non surgical methods first:

• If you are overweight then you will be encouraged lose some weight. This will reduce the stress on your knees by exerting less pressure on them, thus often reducing your pain.
• Cortisone injections in your knee and anti-inflammatory medications.
• Use a walking stick to help take the weight off your affected knee.

If you have tried all the non surgical options without success then your only remaining options are to either continue on as you have been doing or go ahead with the operation. Following knee surgery 90 – 95% of patients report reduced pain and nearly all benefit from increased mobility. Most patients regain near normal motion of the knee joint and are able to do leisurely activities that they were unable to do pre-operatively. Knee replacements are generally very successful with 85% of them still functioning 15 years after the operation.

The anatomy: Knee:

To understand the operation it is best to first explain the anatomy of the knee:

• The knee acts as a hinge between 2 bones: the thigh bone (femur) which is above the knee and the shin bone (tibia) which is below the knee.
• Normally the ends of these 2 bones glide over each other within the knee joint.
• Cartilage lines the end of each bones ensuring a smooth and pain free movement.

If the cartilage is worn away as a result of osteoarthritis then the 2 bones rub together thus causing pain and stiffness of the joint.

What’s involved: Knee replacement:

Knee replacement surgery is typically carried out under a general anaesthetic and normally takes around 2 hours. You are normally required to stay in hospital for a period of 4 – 5 days depending on how you are recovering. The knee replacement procedure is as follows:

• A 15 – 30 cm single incision is made down the front of the knee. This incision is sometimes shorter depending on the particular technique your surgeon is using.
• The knee cap is placed to the side so that the surgeon can access your affected knee joint.
• The end of your thigh bone(femur) and shin bone (tibia) are removed and surfaced in such a way to fit your new knee replacement.
• The end of your thigh bone is replaced with a single piece of curved metal.
• The end of you shin bone is replaced with a channelled plastic piece with a metal stem.
• These 2 components work together to replicate you old knee joint.
• A plastic button sometimes added under the knee cap if it is showing signs of damage.
• The wound is then stitched up and covered with a tight dressing.

Recovery Period: Knee Replacement:

• Immediately following the operation you will be on an intra venous drip to maintain you fluid levels and administer antibiotics.
• Tubes will be attached to the surgical wound to drain off any excess fluid.
• You will be wearing special pads on your lower legs which are attached to a pump. This pump intermittently inflates the pads to encourage healthy blood flow, therefore reducing the risk of Deep vein thrombosis (DVT).
• You may also be wearing compression stockings on your legs to maintain good circulation.
• Your physiotherapy will start from day one!
• Dressings will be over your wound for 1 – 2 days.
• You will normally be allowed to go home after 4 – 5 days.
• Most day to day activities will be difficult for about 2 weeks.
• Normally no driving is recommended for 6 weeks.
• You will be on crutches for 4 – 6 weeks after which you may be able to go back to work.
• Continue with your exercises as advised by your physiotherapist.

What are the risks: Knee replacement: 

• Blood clot in the legs (DVT)
• Blood clots in lungs - always a risk with major surgery
• Difference in leg size.
• Stiffness of the joint caused by a build up of scar tissue which often requires another operation.
• Infection of the joints.
• Nerve/blood vessel damage can occur during the operation.
• Knee not fully stable which may require another operation.
• Knee cap can dislocate after surgery.

Be sure to discuss all the potential risks with your surgeon.

‘This information is intended as a guide only and should not be used as a substitute for medical information from your own doctor’