Knee conditions

Knee osteoarthritis progressively damages the cartilage in one or more compartments. It can cause pain when walking, stiffness, swelling, loss of movement and a change in the alignment of the limb.

Weight-bearing X-rays complement the clinical assessment. Treatment includes therapeutic exercise, load management, weight management where relevant, and individualised medication or injection options. Osteotomy and partial or total knee replacement are considered according to the location of the disease, the deformity and the patient's goals; arthroscopy is not routinely used to treat widespread osteoarthritic damage.

A meniscus may tear during a twisting injury or undergo degenerative change over time. Joint-line pain, swelling, catching and locking can occur, but an abnormality seen on MRI is not always the cause of the pain.

Many degenerative meniscal tears are initially treated without surgery. In repairable traumatic tears, preserving and repairing the meniscus is preferred whenever possible; partial meniscectomy remains an option for selected cases.

ACL injuries commonly occur when pivoting, changing direction or landing. A popping sound, rapid swelling and the feeling that the knee gives way are characteristic signs; the meniscus or cartilage may be injured at the same time.

Clinical examination plays a central role, while MRI assesses associated structures. Treatment is chosen according to the degree of instability, activity level and personal goals, and may involve functional rehabilitation or ligament reconstruction followed by progressive rehabilitation.

The posterior cruciate ligament and collateral ligaments may be injured by direct trauma, twisting or a high-energy accident. Pain on the inner or outer side of the knee, swelling and instability may indicate an isolated injury or damage to several ligaments.

Stable isolated injuries are often treated with a brace and rehabilitation. Persistent instability, avulsion injuries and complex injuries require specialist assessment and sometimes reconstruction.

Pain at the front of the knee may worsen on stairs, during squats or running, or after prolonged sitting. The kneecap may also move out of the femoral groove, causing apprehension with movement, swelling or cartilage damage.

Patellofemoral pain is treated mainly without surgery, through activity modification and exercises for the hip and thigh. Recurrent episodes of instability or significant anatomical factors may require surgical stabilisation.

Focal lesions may develop after trauma, through overuse or as part of osteochondritis dissecans, and can cause pain, swelling or mechanical symptoms.

MRI shows the location of the lesion, but the treatment plan also depends on limb alignment, the menisci, ligaments and subchondral bone. Options range from protected weight-bearing and rehabilitation to cartilage repair or restoration procedures and, in some cases, correction of the limb alignment.

Patellar or quadriceps tendinopathy usually causes activity-related pain, while bursitis produces tenderness in a specific area. A Baker's cyst develops behind the knee and is often the result of a problem within the joint.

Treatment addresses the underlying cause and involves a gradual progression of loading. Loss of active knee extension after an injury may indicate a complete tendon rupture and requires prompt assessment.

Pain, recurrent swelling, stiffness or instability after knee replacement may have different causes, including infection, implant loosening, wear, ligament imbalance, fracture or a source outside the knee.

The assessment must identify the cause and may include X-rays, blood tests, joint aspiration and targeted investigations. Revision surgery is appropriate only in selected cases, following careful planning.