Knee osteoarthritis

Why does knee osteoarthritis develop?

Osteoarthritis develops through a combination of cartilage loss, changes in the underlying bone and the joint’s response to loading. It may affect the inner, outer or kneecap compartment, or more than one part of the knee.

• Increasing age and inherited susceptibility
• Previous meniscal, ligament or bone injury
• Previous knee surgery or fracture
• Leg alignment and the way load passes through the joint
• Muscle weakness and reduced conditioning
• Higher body weight, which can increase joint loading
• Inflammatory disease, previous infection or other causes of secondary arthritis

What symptoms can it cause?

Symptoms often fluctuate, with better and worse periods, and may progress gradually.

• Pain during walking, standing, stairs or rising from a chair
• Stiffness after rest and reduced movement
• Swelling or a feeling of fullness in the knee
• Grinding, clicking or crepitus
• A bow-legged or knock-kneed change in alignment
• Giving way or reduced confidence in the knee
• Night pain and reduced ability to work, exercise or manage everyday activities

Assessment and X-ray findings

Examination includes walking pattern, alignment, swelling, tenderness, movement, strength and ligament stability. The hip, back, circulation and nerves may also be assessed when another source of symptoms is possible.

Weight-bearing X-rays usually provide the most useful imaging. They may include front, side and kneecap views. MRI is not routinely required when the clinical picture and X-rays already demonstrate osteoarthritis.

• Narrowing or loss of the joint space
• Osteophytes, sometimes called bone spurs
• Hardening of the bone beneath the joint surface (sclerosis)
• Small cysts within the bone
• Change in alignment or shape of the joint

Treatment without surgery

Treatment is individual and aims to reduce symptoms, maintain movement and support the activities that matter to you. Core management includes information, therapeutic exercise and support with weight management where appropriate.

• Activity modification and pacing
• Strength, mobility and aerobic exercise, often supported by physiotherapy
• Weight optimisation where relevant
• Pain relief or anti-inflammatory medication when medically suitable
• A walking stick, brace or other aid in selected cases
• A knee injection when appropriate for a defined purpose
• Continuing without surgery while symptoms remain manageable

When might surgery be considered?

Surgery may be considered when pain, stiffness or reduced function substantially affects quality of life and appropriate non-operative care is no longer providing acceptable relief.

The choice between a total or partial knee replacement depends on the pattern of arthritis, ligament function, alignment and individual circumstances. The decision is shared and is not based on an X-ray alone.

• The severity and pattern of symptoms
• Clinical examination and weight-bearing imaging
• Expected benefits and limitations of each option
• General health and opportunities to optimise risk
• Your priorities and willingness to undertake rehabilitation
• The alternatives and the option to delay or decline surgery