Knee arthritis is one of the most common causes of knee pain, as we get older, although it can also affect younger people following previous injury or due to certain medical conditions.

It occurs when the protective cartilage within the knee gradually wears away, leading to pain, stiffness, swelling and reduced mobility.

Everyday activities such as walking, climbing stairs or standing for long periods can become increasingly difficult.

While knee replacement surgery can provide excellent results for some patients with advanced arthritis, the first step is to look at conservative options, such as physiotherapy, exercise modification, weight management, medication and image-guided injections before contemplating surgery.

The menisci are two C-shaped pieces of cartilage that act as shock absorbers within the knee, helping to distribute load and provide stability.

A meniscal tear can occur suddenly during twisting movements, particularly in sport, or develop gradually as part of the ageing process. Symptoms often include pain, swelling, clicking, locking or a feeling that the knee is catching during movement.

Following a thorough assessment and, where appropriate, MRI imaging, treatment may involve rehabilitation, especially lower leg strengthening work.

In some cases arthroscopic (keyhole) surgery may be appropriate to repair the meniscus, depending on the type and severity of the tear.

The ligaments of the knee provide stability and help control movement during everyday activities and sport.

Injuries to the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL) or lateral collateral ligament (LCL) commonly occur during twisting movements, sudden changes of direction or direct impact to the knee.

Depending on the severity of the injury, symptoms may include pain, swelling, instability and difficulty bearing weight.

Treatment ranges from specialist physiotherapy and rehabilitation to ligament reconstruction surgery for patients with significant instability or those wishing to return to higher levels of sport and physical activity.

Spontaneous osteonecrosis of the knee (SONK), also known as subchondral insufficiency fracture of the knee, is a condition that typically causes the sudden onset of severe knee pain without any significant injury.

It most commonly affects adults over the age of 50 and is often associated with pain on the inner side of the knee, particularly when walking or bearing weight.

Early diagnosis with appropriate imaging is important, as prompt treatment can help protect the joint and reduce the risk of further damage.

Management depends on the severity of the condition and may include activity modification, protected weight-bearing, medication, injection therapies or, in more advanced cases, surgical treatment such as joint preservation procedures or knee replacement.

Patellar instability occurs when the kneecap (patella) moves out of its normal position or is prone to slipping or dislocating.

It most commonly affects younger, active individuals and usually develops following an injury such as a patella dislocation, or due to issues in the shape or alignment of the knee.

Symptoms can include pain at the front of the knee, swelling, a feeling that the kneecap is giving way and repeated dislocations.

Treatment depends on the underlying cause and may involve physiotherapy to improve muscle control and stability, bracing or, in some cases, surgery to restore normal alignment and prevent further dislocations.

The tendons around the knee connect muscles to bone and play an essential role in movement, strength and stability.

Overuse, repetitive activity or sudden increases in training can lead to tendon injuries such as patellar tendinopathy (jumper's knee), Pes anserine bursitis, iliotibial band (ITB) pain or quadriceps tendinopathy.

These conditions often cause pain during activities such as running, jumping, squatting or climbing stairs and can become persistent if left untreated.

Most tendon injuries respond very well to a structured rehabilitation programme, activity modification and, where appropriate, image-guided injection therapies, allowing patients to return safely to their usual activities, without any need for surgery.

Most patients experience excellent pain relief and improved function following knee replacement surgery, but occasionally symptoms may persist or develop months or years after the procedure.

Ongoing pain can be caused by a number of factors, including implant loosening, instability, stiffness, infection, wear or problems involving the surrounding soft tissues.

A careful assessment is essential to identify the underlying cause and determine the most appropriate treatment.

While many problems can be managed without further surgery, some patients may benefit from revision knee replacement, a specialist procedure that involves replacing part or all of an existing knee replacement to restore function, relieve pain and improve quality of life.