Total Knee Replacement
- What is knee arthritis?
- What can I do to get rid of my knee pain?
- What do I do if my arthritic knee symptoms are not improved by non-surgical methods?
- What is total knee replacement?
- How long does the operation take?
- Will the operation be painful?
- What sort of scar will I have?
- What are the complications of knee surgery?
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 and varus deformity of the lower leg (becoming bow legged).
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 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 may provide lasting pain relief.
Eventually, at a time often difficult to determine, non surgical treatment measures may not provide adequate symptomatic relief and a surgical solution may have to be considered.
There are three types of surgical treatments that can be considered if non surgical management regimes do not control your symptoms. The options are knee arthroscopy, an osteotomy around the knee or a type of knee replacement, either a partial or a 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.
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.
All together from the time the patient leaves to ward to returning to the ward after the operation can take 3-4 hours. Either 6-8 hours after surgery or the following day, you will be sitting out of bed and you will be encouraged to walk around the ward or room.
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. 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.
The video below is another patient having had a total knee replacement, but now three hours after surgery. The spinal injection has now worn off but the intraoperative injection is still working.
The incision for a total knee replacement is at the front of the knee. The incision needs to be big enough to do the operation but we will always try to keep the size to the minimum. (delete this sentence)The size of the incision is often related to the size of the knee that requires the knee replacement.
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 bet cosmetic result. It is almost inevitable that there will be an area of numbness, to the outside of the scar. This will reduce in area but very often is permanent. Most patients do not notice this at all!
Types of problems:
- Infection: The risk of infection is less than 1% and pre-operative antibiotics are given to prevent this from happening.
- Deep vein thrombosis: 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, usually warfarin or Rivaroxeban
- Nerve and 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) drainage. Remove the word drainage
- 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 to bend
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.