Osteoarthritis

Osteoarthritis is the most common form of arthritis, and a leading cause of joint pain and disability worldwide. It is a degenerative joint condition in which the smooth cartilage that cushions and protects the ends of bones gradually breaks down over time. As this cartilage wears away, the bones within the joint begin to rub against one another, causing pain, stiffness, swelling and a progressive loss of movement. The knees, hips, spine and hands are most commonly affected, though osteoarthritis can develop in almost any joint in the body.

While osteoarthritis is often described simply as “wear and tear,” this undersells what is actually a complex process affecting the whole joint — not just the cartilage, but also the underlying bone, the joint lining, and the surrounding ligaments and muscles. It is also far more common than many people realise: most adults will show some evidence of osteoarthritis on imaging by their 60s or 70s, though not everyone with these changes experiences significant symptoms.

Types of Osteoarthritis

Osteoarthritis is generally classified according to its underlying cause, and separately described by which joint is affected — both of which can influence the most suitable approach to treatment.

• Primary Osteoarthritis: The most common form, arising from the gradual, age-related wear of cartilage without any other clearly identifiable underlying cause. Typically develops from the late 40s onward, most often affecting the knees, hips, hands and spine.
• Secondary Osteoarthritis: Develops as a result of an identifiable underlying cause, such as a previous joint injury or fracture, joint deformity present from birth, another inflammatory joint condition, or a metabolic disorder affecting the joints. Can occur at a younger age than primary osteoarthritis.
• Knee Osteoarthritis: One of the most common and disabling forms, affecting the weight-bearing knee joint and often significantly impacting walking, climbing stairs, and standing from a seated position.
• Hip Osteoarthritis: Affects the hip joint, another major weight-bearing joint, often causing groin, thigh or buttock pain and a noticeable limp or reduced walking distance as the condition progresses.
• Hand and Finger Osteoarthritis: Commonly affects the base of the thumb and the small joints of the fingers, causing pain, stiffness and the characteristic bony enlargements sometimes seen at the finger joints.
• Spinal Osteoarthritis: Affects the small joints of the spine, which can contribute to back or neck pain and stiffness, and in some cases, nerve compression if bone spurs narrow the space around spinal nerves.

How Osteoarthritis Develops

Osteoarthritis develops through a gradual breakdown of the whole joint, not simply the cartilage in isolation:

• Cartilage breakdown: The smooth, slippery cartilage that normally allows bones to glide against each other with minimal friction gradually thins, roughens and wears away, reducing its ability to cushion and protect the joint.
• Bone-on-bone friction: As cartilage loss progresses, the underlying bones increasingly come into direct contact with one another, causing pain, and in some cases the bone surfaces themselves begin to change shape.
• Bone spur formation: The body's attempt to repair and stabilise the affected joint can lead to the formation of bony outgrowths, known as osteophytes or bone spurs, around the joint margins.
• Joint lining inflammation: The thin membrane lining the joint (the synovium) can become mildly inflamed and thickened, contributing to swelling and stiffness, particularly after periods of rest.
• Weakening of supporting structures: The ligaments and muscles that stabilise and support the joint can weaken over time, both contributing to and resulting from the joint changes of osteoarthritis, and further affecting joint stability and function.

This combination of changes explains why osteoarthritis produces more than just pain — it can also cause visible joint enlargement, reduced range of motion, and a sensation of grinding or catching within the joint during movement.

Symptoms of Osteoarthritis

Osteoarthritis symptoms typically develop gradually over months to years and tend to worsen slowly over time, although the pace and severity can vary considerably between individuals and between different joints.

• Joint pain that worsens with activity and typically improves with rest, particularly in the earlier stages
• Stiffness, especially first thing in the morning or after periods of inactivity, that usually eases within around 30 minutes of movement
• A grating, crackling or grinding sensation (crepitus) during joint movement
• Swelling and tenderness around the affected joint
• Loss of flexibility or a reduced range of motion in the joint
• Visible bony enlargement around the joint, particularly noticeable in the fingers
• A feeling of joint instability, or the joint giving way, particularly in the knee
• Muscle weakness around the affected joint, often from reduced use over time
• As the condition progresses: pain that also occurs at rest or disturbs sleep, and increasing difficulty with everyday tasks such as walking, climbing stairs, or gripping objects

Because these symptoms usually develop slowly, many people initially dismiss them as a normal part of ageing — but early recognition and management can meaningfully slow the impact of the condition on daily life.

Risk Factors for Osteoarthritis

Several factors are known to increase the likelihood of developing osteoarthritis:

• Age: Risk increases progressively with age, as cartilage naturally becomes less resilient and joints accumulate wear over a lifetime of use.
• Sex: Women are more likely to develop osteoarthritis than men, particularly after menopause, and tend to experience more severe symptoms in certain joints such as the hands and knees.
• Excess body weight: Additional weight places extra mechanical stress on weight-bearing joints such as the knees and hips, and excess fat tissue can also release inflammatory substances that affect joint health.
• Previous joint injury: A prior fracture, ligament tear or other significant joint injury — even one that occurred many years earlier and healed well — increases the long-term risk of osteoarthritis in that joint.
• Repetitive joint stress: Occupations or activities that involve repetitive joint loading, heavy lifting, or frequent kneeling and squatting can accelerate joint wear over time.
• Genetics: A family history of osteoarthritis increases individual risk, reflecting an inherited tendency towards cartilage or joint structural characteristics.
• Joint deformity or misalignment: Structural abnormalities present from birth, or those that develop over time, can lead to uneven distribution of load across a joint, accelerating localised cartilage wear.
• Other joint or metabolic conditions: Conditions such as gout, rheumatoid arthritis or diabetes can increase the risk of developing secondary osteoarthritis.

Possible Complications of Osteoarthritis

Without appropriate management, osteoarthritis can progressively affect not just the joint itself, but overall function, independence and wellbeing:

• Chronic pain: Ongoing joint pain can become a persistent, wearing feature of daily life, and may become more difficult to manage the longer it goes untreated.
• Reduced mobility and disability: Progressive joint damage can make walking, climbing stairs, and other everyday activities increasingly difficult, sometimes leading to significant loss of independence.
• Joint deformity: Advanced osteoarthritis can lead to visible changes in joint shape and alignment, such as bowing of the legs in advanced knee osteoarthritis.
• Muscle weakness and imbalance: Reduced use of a painful joint often leads to weakening of the surrounding muscles, which can further destabilise the joint and worsen symptoms.
• Increased fall risk: Joint instability, reduced strength, and altered walking patterns associated with osteoarthritis, particularly of the hip or knee, can increase the risk of falls, especially in older adults.
• Impact on mental health: Chronic pain and reduced mobility are associated with a higher risk of low mood, anxiety and social isolation, particularly when the condition significantly limits daily activities.
• Need for joint replacement: In more advanced cases where conservative treatment no longer provides adequate relief, joint replacement surgery may become necessary to restore function and relieve pain.

How Osteoarthritis Is Diagnosed

Osteoarthritis is generally diagnosed through a combination of clinical assessment and imaging, with additional tests sometimes used to rule out other types of joint disease.

• Clinical History and Physical Examination: A discussion of your symptoms, their pattern and impact on daily activities, followed by an examination of the affected joint for tenderness, swelling, reduced range of motion, and crepitus (a grating sensation) on movement.
• X-ray: The primary imaging test for osteoarthritis, showing characteristic features such as narrowing of the joint space (reflecting cartilage loss), bone spurs, and changes in the underlying bone.
• MRI (Magnetic Resonance Imaging): Not routinely required, but may be used in certain cases to assess cartilage, ligaments and other soft tissue structures in more detail, or to investigate symptoms that don't fully match the X-ray findings.
• Joint Fluid Analysis: In some cases, a sample of fluid may be withdrawn from the joint and analysed to help distinguish osteoarthritis from other causes of joint pain and swelling, such as gout or infection.
• Blood Tests: Not used to diagnose osteoarthritis directly, but may be performed to rule out other forms of arthritis, such as rheumatoid arthritis, which can present with somewhat similar symptoms.

Living Well with Osteoarthritis: Self-Management

Alongside medical treatment, day-to-day self-management plays a significant role in how well osteoarthritis is controlled and how much it affects your quality of life.

Staying as physically active as your joints comfortably allow — rather than avoiding movement altogether — helps maintain muscle strength, joint flexibility and overall function; low-impact activities such as swimming, cycling and walking are generally well tolerated. Pacing activities across the day, alternating periods of activity with rest, and using joint-protection techniques (such as using larger joints to carry loads, or using assistive devices for heavier tasks) can help manage symptoms without becoming overly restrictive.

Applying heat before activity can help ease stiffness, while cold packs after activity can help reduce swelling and discomfort. Because osteoarthritis is a long-term condition, maintaining regular follow-up with your care team allows your treatment plan to be adjusted as your symptoms and needs change over time.

How to Reduce Your Risk of Osteoarthritis

While some risk factors for osteoarthritis, such as age, sex and genetics, cannot be changed, several measures can meaningfully reduce your risk or slow its progression:

• Maintain a healthy weight: Reducing excess weight lowers the mechanical load placed on weight-bearing joints such as the hips, knees and feet.
• Stay physically active: Regular, joint-friendly exercise helps maintain cartilage health, joint flexibility, and the muscle strength that supports and protects your joints.
• Avoid joint injuries: Warm up before sport, use proper technique and footwear, and take care to avoid high-impact injuries, since joint trauma earlier in life significantly raises long-term osteoarthritis risk.
• Maintain muscle strength: Strong muscles around a joint help absorb and distribute load more evenly, reducing wear on the joint surfaces themselves.
• Practise good posture and body mechanics: Using correct lifting technique and posture during daily activities and at work reduces unnecessary strain on your joints.
• Eat a well-balanced diet: A healthy, balanced diet supports a healthy body weight and provides the nutrients needed for overall joint and bone health.
• Manage related health conditions: Good control of conditions such as diabetes and gout may help reduce the risk of secondary osteoarthritis.