Knee pain is one of the most common ailments and can affect patients of any age particularly the older generation. 

The knee joint is made up of three main bones called the femur (thigh bone), tibia (leg bone) and the patella or knee cap. There are two semicircular pieces of cartilage between the thigh bone and leg bone called ‘menisci’ and these act as shock absorbers or buffers. Furthermore, there are two ligaments called ‘cruciate’ ligaments, which stabilise the joint.

The joint itself sustains significant forces when walking but particularly when running and in young patients, especially athletes or footballers, injuries may occur. These can include breaks or fracture of the bones around the knee but particularly in twisting injuries there may be damage to the menisci or cruciate ligaments. This may result in swelling and pain in the knee and if left untreated may result in symptoms of persistent pain over the joint. It may be associated with knee locking and the knee giving way if the semicircular cartilages are torn or with symptoms of instability if the cruciate ligaments are damaged.

There may also be inability to walk, run or play sport. Following appropriate investigations, including X-rays and MRI scans, the patient in most cases may require keyhole surgery where a camera is placed inside the knee joint and the torn cartilage may be repaired or in most cases the torn part trimmed off. Torn cruciates cannot be repaired but replaced by other tendons in the body, including the hamstring tendon or the knee cap tendon.

In older patients the cause of knee pain is usually arthritis but other conditions such as infection, gout or tumour may also be the cause.

Arthritis is a condition of wear and tear where part or all of the cartilage lining the knee joint can erode away such that the bones start rubbing against each other. In most patients there is no apparent cause for the arthritis and this is called primary arthritis.

Total knee replacement remains the most reliable surgical way of treating knee arthritis

Rarely, however, the arthritis may be due to an underlying cause e.g. prior injury, prior break to the knee bones or some underlying inflammatory joint condition such as rheumatoid arthritis. On some occasions pain may also be referred from the hip joint. The patient usually complains of pain and swelling due to fluid in the knee as well as stiffness and locking. The pain may affect the walking distance as well as night time sleep and walking up and down stairs particularly if the front part of the knee joint is affected. 

In most cases the diagnosis is made by history and examination and confirmed with appropriate X-rays of the joint. Treatment would normally involve physiotherapy, weight loss, exercise and muscle building or use of an external aid such as a stick.

The use of steroid injections is controversial and while some studies report good results in cases of early osteoarthritis, others reveal equivocal effects. Other infiltrations which are popular include a class of drugs called “viscosupplementation” where viscous substances are injected into the knee joint. They act as buffers and are thought to regenerate the cartilage lining. The results from these injections are, however, mixed.

Recently the use of PrP (platelet rich plasma) injections has increased in popularity. In this technique which I have recently used, a sample of the patient’s own blood is extracted, centrifuged and the deposit then injected into the knee. The PrP is thought to stimulate the body to grow new healthy cells and promote healing.

In cases where non-operative treatment fails surgery may be indicated. This may include a washout of the knee using keyhole surgery, a technique which is normally only effective in patients with early arthritis and when the patient complains of mechanical symptoms, including locking and knee giving way in addition to the pain. Total knee replacement, however, remains the most reliable surgical way of treating knee arthritis. This is a major operation with a number of risks and complications. However, scientific studies repeatedly report significant improvement in the quality of life in patients undertaking this procedure.

Recent studies have shown improvements in the lifespan of these artificial joints, which are now being recommended even in younger patients with debilitating knee arthritis.

Alistair Pace is a consultant orthopaedic surgeon.