The knee is a vulnerable joint. It takes the full weight of the body and undergoes considerable stress in activities such as running and jumping and one of the most easily injured joints. Stability is maintained by four ligaments and the muscles around the joint. It can be susceptible to a number of problems which can lead to pain. For those patients where there is significant arthritis in the knee, and where the cartilage covering the bone within the knee has worn away, replacement of the knee with an artificial joint can offer excellent pain relief and restoration of function.
Osteo-arthritis (OA): tends to be slow and insidious and occurs in the elderly although it can affect younger people, especially if obese. Crepitus is common (crunching sound in the knee) – an X-ray may show reduction of the joint space because of loss of cartilage. I may suggest an MRI scan for further diagnosis.
Exercise and weight loss are important parts of your knee pain treatment, especially if you have arthritis. In fact, recent research has shown that obesity is one of the major factors for the development of osteo-arthritis of the knee. The force on your knees during ordinary activities going up and down stairs, walking, getting up out of a chair is somewhere between four and six times your body weight. If you’re 5 kilograms overweight, you’re asking your knees to sustain an extra 20 to 30 extra kilograms of force every time you take a step. There are several studies showing that obesity clearly increases the risk of knee osteo-arthritis in women, and that weight loss of 5 kilograms decreases the risk of knee OA by 50%. In another study, an even smaller decrease in body mass made a significant difference in pain relief and improved function.
Treatment: Total Knee Replacement
Replacement of a knee joint with a Total Knee Replacement (TKR) for osteo-arthritis involves taking a thin section of bone away from the end of the femur (thigh bone) and another section of bone away from the top of the tibia (shin bone). The bone ends are then replaced by metal surfaces, which are cemented in place with a special bone cement. A polyethylene (plastic) spacer is then placed in between the two metal surfaces. The back of the patella (kneecap), where it rubs against the front of the knee, may also be replaced with a new plastic surface cemented in place, depending on how bad the cartilage damage is in that area.
Freedom from pain is the main benefit of a knee replacement and you should find you are more mobile too. For most people a knee replacement means being able to get around much more easily. You should be able to get out of a chair, walk up and down slopes and climb stairs without difficulty. Most people find they are able to walk with little or no pain for 30 minutes or longer. Carrying out household jobs, shopping, and using public transport should all become easier. It should even be possible, if you are generally fit, to walk for up to 5 miles, drive a car, and take gentle exercise such as swimming, cycling and playing golf. It is not usually possible, however, to run, or play vigourous sport, as this increases the risk of wear and loosening of the knee replacement. However, a replacement knee can never be as good as a natural knee, although people generally rate the artificial joint as about ‘three-quarters normal’. You are still likely to experience some difficulties in movement, especially in bending the knee. Kneeling is likely to be a problem because the operation leaves a scar at the front of the knee which is uncomfortable to lean on. Initially there is likely to be some numbness on the outer edge of the scar. Although this feeling does improve over 2 years it is unlikely to recover completely. You may also be aware of some clicking or ‘clunking’ in the knee replacement. Typically a new knee joint lasts about 15 years but it is usually possible to have a second– and even a third– replacement knee.
Treatment: Osteotomy of the knee
Osteotomy of the knee is generally reserved for young, active patients, who want to delay the time until knee replacement. When done in the right patients, knee osteotomies are usually successful at decreasing pain. This surgery tends to last about 8 to 10 years, and after that time, many patients will require total knee replacement. Because the bone is cut, it needs time to heal. The total healing time is at least 8 weeks, and can take longer. Most patients need physiotherapy to regain their knee motion.
Treatment: Arthroscopy of the knee
Arthroscopy is a minimally invasive procedure that can be used for both diagnosis and sometimes treatment.
Signs that you may be a candidate for this procedure include swelling, persistent pain, catching, giving-way, and loss of confidence in your knee. When other treatments such as the regular use of medications, knee supports, and physiotherapy have provided minimal or no improvement, you may benefit from arthroscopy.
Arthroscopy can be used to diagnose and treat many of these problems:
- Torn meniscal cartilage
- Loose fragments of bone or cartilage
- Damaged joint surfaces or softening of the articular cartilage
known as ‘chondromalacia’
- Inflammation of the synovial membrane, such as
‘rheumatoid’ or ‘gouty arthritis’
- Abnormal alignment or instability of the kneecap
- Torn ligaments including the anterior and posterior cruciate
A clear view of the inside of the knee is achieved with small incisions, using a pencil-sized instrument called an ‘arthroscope’. The scope contains optic fibres that transmit an image of your knee through a small camera to a television monitor. The TV image allows the me to thoroughly examine the interior of your knee and determine the source of your problem. During the procedure, I can also insert surgical instruments through other small incisions in your knee to remove or repair damaged tissues. Torn cartilages, loose body, debris etc., can be removed.
It is carried out as a day case under general anaesthetic. You will be able to go home the same day when you feel ready. However, you will need to arrange for someone to drive you home.
After a few weeks you should be able to engage in most of your former physical activities as long as they do not involve significant weight-bearing impact. Twisting manoeuvres may have to be avoided for a longer time.
Treatment: Meniscal surgery
Cartilage is known as the ‘meniscus’. The meniscus is a C-shaped piece of fibrocartilage which is located at the peripheral aspect of the joint. There are two ‘meniscii’ in each knee, the medial meniscus (inner one) and the lateral (outer) meniscus. The majority of the meniscus has no blood supply. For that reason, when damaged, the meniscus is usually unable to undergo the normal healing process that occurs in most of the rest of the body. In addition, with age, the meniscus begins to deteriorate, often developing degenerative tears. Typically, when the meniscus is damaged, the torn piece begins to move in an abnormal fashion inside the joint. Because the space between the bones of the joint is very small, as the abnormally mobile piece of meniscal tissue moves, it may become caught between the bones of the joint (femur and tibia). When this happens, the knee becomes painful, swollen, and difficult to move. Usually this situation requires the torn piece be removed.