Total Knee Replacement

What is knee arthritis?

Arthritis of the knee is damage to the articular cartilage of the joint. This often leads to pain, stiffness and ultimately loss of function of the knee.

The X-Ray below shows typical osteoarthritis of the medial side (inside) of the knee with joint space narrowing, osteophytosis ( new bone formation), bone sclerosis (increased density of the bone) , cyst formation (cavities within the bone) and varus deformity of the lower leg (becoming bow legged).

What can I do to get rid of my knee pain?

There are a variety of non-operative treatments that can relief your symptoms of knee arthritis. It is good to keep as active as possible however you may be required to limit certain activities that exacerbate the pain.

Exercise using an exercise bicycle are especially suited for most patients with knee problems. Anti-inflammatory medication and pain killers of different strengths may also be helpful.

Dietary supplements such as glucosamine and chondroitin sulphate as well as omega-3-fatty acids now have scientific evidence that they provide symptomatic relief, especially in knee arthritis.

The knee joint is particularly affected by being overweight, and a weight loss program may well help to improve knee symptoms.

Soft shoe inserts, such as silicon heel cups, may reduce the forces travelling to the knee. This may make walking more comfortable.

Also a knee brace may be helpful in certain types of knee arthritis. Injections into the knee either with steroids or visco-supplementation (Hyaluronic acid) may provide lasting pain relief when the arthritis is moderate.

Sometimes, with the right indications an injection or knee can be very helpful. The injection can be done using long acting steroids, hyaluronic acid, and also PRP injections (Platelet rich plasma) can be used.

What do I do, if my arthritic knee symptoms, are not improved by non-surgical methods?

Eventually, over a period of time, non-surgical treatment measures may not provide adequate symptomatic relief, and a surgical solution may have to be considered.

There are several types of surgical treatments that can be considered if non-surgical management regimes do not control your symptoms. The most common options are knee arthroscopy, an osteotomy around the knee or a type of knee replacement, either a partial or a total knee replacement.

What is total knee replacement?

Total knee replacement, is the resurfacing of the bones in your knee joint with a prosthesis (artificial knee joint). The artificial total knee joint consists of 3 or 4 separate parts (components). Like a normal knee your prosthesis has smooth weight-bearing surfaces.

The femoral component covers the bottom of your thigh bone, the tibial component covers the top of your shin bone, and the patellar component covers the underside of your knee cap.

The tibial and femoral components are metal while the patella and tibial spacer are a special type of polyethylene (plastic). Both the femoral, tibial and the patellar components are usually fixed to the bone with bone cement.

An X-Ray of a total knee replacement from the front and the side, showing the different components constituting a total knee replacement.

How long does the operation take?

The operation itself takes about one hour to an hour and a half. It is most often done with a tourniquet around the thigh bone to reduce the blood loss and provide clean interfaces for cementing the components of the knee replacement.

There is quite a bit of work to do!

Total knee replacement in a minute. (NB This clip contains images that some people may find disturbing)

Altogether, from the time the patient leaves the ward, to returning to the ward after the operation can take 3-4 hours. 6-8 hours after surgery, you will be sitting out of bed, and you will be encouraged to walk around the room or the ward.

Will the operation be painful?

After discussion with the anaesthetist you will either receive a general anaesthetic or regional anaesthetic (spinal or epidural) you will be advised by the anaesthetist what may be best for you but most of the time the decision is yours to make.

The great majority of patients have their knee replacement done with a regional spinal anaesthetic. At the same time the anaesthetist will put some “gin and tonic” equivalent through a vein which will make you completely unaware of the operation. Some patients wish to stay awake and listen to music. That is also possible, please let your anaesthetist know!

You will receive an intra-operative injection with a mixture of painkilling medication which in the majority of cases will give you a pain free knee for 14-16 hours post operatively.

The video clip below shows a patient 20 minutes after having a total knee replacement having had the intra operative peri-articular injection with pain killing medication.

MR Busch published a popular article on this method of pain relief which is used around the world! Click the image to read the article.

Knee-article-image.jpg

What sort of scar will I have?

The surgeon will try and make the incision large enough to perform a good operation but, will keep it as small as possible, to get the best cosmetic result. It is almost inevitable that there will be an area of numbness, to the outside of the scar. This area will reduce in size over time, but some loss of sensation is often permanent. Most patients do not notice this at all.

This patients has an above average sized incision.

What are the complications of knee surgery?

Infection: The risk of infection is less than 1-2% and peri-operative antibiotics are given to prevent this from happening.

Deep vein thrombosis (Clot in a leg vein): This is prevented by giving blood thinners and the use of compressive stockings. Also mobilising as soon as possible after the surgery is a good way of preventing a clot in the leg. If a clot occurs it will be treated with specific blood thinners. Very rarely a clot can move to the lungs and cause a pulmonary embolism.

Nerve and blood vessel damage: It is unlikely that any major nerve or vessel will be damaged. An area of numbness to the outside of the incision is however very common but few patients find this is a problem.

Prosthesis failure: The prosthesis may fail due to the plastic wearing out and it may require revision.

Reflex sympathetic dystrophy: Very rarely a condition can occur where the leg becomes stiff, hypersensitive and painful. This requires specific treatment by a pain management specialist.

Excessive bleeding: This usually settles but may require an operation to remove the haematoma (Blood clot).

Excessive scarring: Some skin will scar up significantly (called keloid scarring).

Pain with kneeling: Kneeling following total knee replacement is the exception rather than the rule. Some patients can and some can’t. Most knee replacement are not designed for kneeling.

It has to be remembered that overall the complication rate for patient having total knee replacement is quite low. Patients should be aware that complications may occur and therefore the right indications for performing surgery should always be followed.

The images below show this 75 year old lady had bilateral valgus knees (knock kneed). She had a complex total knee replacement using a rotating platform knee. The picture on the right shows her right knee pre-operatively. She had her left knee done with the same implant 3 months previously.