Weak at the Knees

Loulou Brown explains why our knees need looking after

Knees are in constant use, as we get older they are likely to attract problems.

The knee consists of four main elements: bones, cartilage, muscles and tendons, and ligaments.

• Ligaments act as a hinge, connecting the thigh bone (femur) to the shin bone (tibia) in the leg.

• Cartilage is a rubbery, fibrous, dense, connective tissue. It covers the ends of the bones and underside of the kneecap, and acts as a cushion and bearing surface between the bones, allowing them to glide smoothly over each other with almost no friction.

• The meniscus is a pad of cartilage functioning as a shock absorber between the bones. Muscles around the knee provide strength and power, and help to stabilise the joint.

• The ends of the muscles are called tendons that connect to the bones. Ligaments are band-like tissue, like bits of string, that connect bone to bone. They act as a rope, holding the bones together and providing stability. There are four main ligaments in the knee.

Consequences of a torn meniscus

A sudden twist or repeated squatting can tear the meniscus, which has a tendency to degenerate and weaken as part of the ageing process. This may make the knee hurt and/or swell.

A physical examination of the knee can usually determine a torn meniscus, although a further diagnostic study, such as a MRI scan that provides a detailed image of the knee joint, may be required. Torn tissue on the inside of the meniscus is usually removed, although torn tissue on the outer edge of the meniscus is sometimes repaired if there is enough blood to allow for healing to take place.

Meniscus tears are usually treated with minor outpatient surgery known as an arthroscopy. Partial weight bearing with crutches is recommended for the first few days following surgery, and then walking is allowed.

Elevation, applying ice and anti-inflammatory medication help to decrease pain and swelling. After about a week, light exercise will be possible, although returning to all previous activities may take several weeks or even months.

A fall, twist or direct blow may tear a ligament, which may cause pain and/or swelling, as well as instability. A ligament can be reconstructed by grafting tissue from an area near the knee.

Ageing or injury can wear away cartilage

A piece (called a ‘loose body’) may break off in the joint and this is likely to cause pain, stiffness or grinding, so any loose bodies may be removed from the area. If the cartilage has worn away so that the bone is exposed, an area beneath the bone may be drilled to stimulate growth.

Ageing, overuse or even a direct blow may damage the cartilage underneath the kneecap (patella), the small bone at the front of the knee, and thus restrict joint movement. Treatment will depend on whether there is wear-and-tear or a structural problem. The patella may be shaved to smooth it, or a laser may be used to remove bands of cartilage under the patella.

Osteoarthitis

Another problem with knees for older people is osteoarthritis, also known as degenerative joint disease. The exact cause is unknown, but contributory factors include injury, ageing and obesity. With osteoarthritis, the articular cartilage, the whitish-coloured material covering the ends of the bones in the knees, breaks down.

If you have osteoarthritis of the knee, you will feel pain, muscle tension and fatigue. The pain may initially be no more than a mild soreness and slight ache, but may progress to severe pain, even during rest. You may also lose easy movement, because the joints no longer glide smoothly as the cartilage wears away.

Unfortunately, as yet there is no cure for osteoarthritis. The disease usually progresses slowly over many years. Treatment includes decreasing pain, swelling and inflammation, while increasing or maintaining joint function. Non-operative forms of treatment may include physical therapy, icing, modification of activity, and bracing.

Medication, such as aspirin or anti-inflammatory drugs, helps decrease the pain and swelling. Glucosamine and chondroitin sulfate, which can be bought over the counter, can be taken long term to help alleviate symptoms and possibly slow progression of the disease. Cortisone injections into the joint may reduce acute symptoms for some months. (Three or four steroid injections may be given each year in each affected joint without harm.)

If only half the knee joint is arthritic, with the rest relatively normal, an osteotomy may be considered. In this operation the surgeon cuts and realigns a portion of the shin bone (tibia) to allow most of the load with weight-bearing activities to pass through the unaffected side of the knee.

If stress is taken off the arthritic cartilage, this results in significant pain reduction and improved function of the knee for up to ten to fifteen years.

As a last resort, a joint replacement can be performed. The worn surfaces of the joint are removed and replaced with metal and plastic components. Ninety per cent of knee joint replacement surgeries are successful.


See DonJoys Orthopaedic Update focusing on the knees: www.donjoy.eu

If in any doubt about any of the information covered in health related articles and it's relevance for you, consult your GP.

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