What is Osteoarthritis?
Osteoarthritis is a whole-joint condition in which cartilage gradually breaks down, bone underneath changes, and the joint lining becomes mildly inflamed. It most often affects knees, hips, hands, and the spine, causing pain that worsens with use, stiffness lasting under 30 minutes after rest, and reduced range of motion. Exercise and weight management are first-line treatments.
Key takeaways
- Osteoarthritis is not simply wear and tear; it involves active changes in cartilage, bone, and the joint lining.
- Morning stiffness usually lasts less than 30 minutes, which helps distinguish it from inflammatory arthritis.
- Exercise is a first-line treatment, not something to avoid — appropriate loading helps rather than harms.
- X-ray findings correlate poorly with symptoms; imaging is not needed to start treatment in typical cases.
- Joint replacement is highly effective for advanced hip and knee disease when other measures no longer work.
Overview
Osteoarthritis is the most common joint disease in the world and a leading cause of disability in older adults. For decades it was described as simple mechanical wear, but that picture is outdated. What actually happens is an active process involving the whole joint: the smooth cartilage that caps the bone ends softens and thins, the bone beneath it thickens and forms spurs, the joint lining produces low-grade inflammation, and surrounding muscles and ligaments adapt. The result is pain with use, stiffness after inactivity, and gradual loss of function.
It is not an inevitable part of ageing, and it is not untreatable. The strongest evidence supports exercise therapy and weight management as the foundation of care — a message that surprises people who assume a painful joint should be rested. Medication, injections, braces, and eventually joint replacement all have a place, but the interventions with the most consistent benefit are the ones the person does themselves, supported by a physical therapist.
What Osteoarthritis is
Cartilage is a smooth, slippery tissue with no blood supply and very limited capacity to repair itself. In osteoarthritis its matrix breaks down faster than it is rebuilt, so the surface becomes rough and thin. Bone responds by remodelling — becoming denser just beneath the cartilage and growing bony outgrowths called osteophytes at the joint margins. The synovial lining releases inflammatory mediators, contributing to pain and swelling.
The joints most often affected are those that bear load or are heavily used: knees, hips, the base of the thumb, the small finger joints, and the spine. Hand osteoarthritis produces the characteristic bony enlargements known as Heberden and Bouchard nodes. Unlike rheumatoid arthritis, osteoarthritis is not symmetrical by nature and does not cause systemic illness.
Common symptoms
Symptoms build slowly over months to years and follow a use-related pattern.
- Joint pain that worsens with activity and eases with rest — the defining pattern
- Stiffness after sitting or on waking, typically lasting under 30 minutes
- Reduced range of motion in the affected joint
- Grating, clicking, or crackling with movement (crepitus)
- Bony enlargement around finger joints or knees
- Mild swelling, sometimes with a small joint effusion
- Weakness in muscles around the joint, especially the quadriceps in knee osteoarthritis
Less common symptoms
- Pain at night in advanced disease, disrupting sleep
- A sensation of the joint giving way or buckling
- Joint locking or catching — may suggest a loose fragment or meniscal tear
- Visible deformity or angulation in advanced knee disease
Risk factors
- Age — cartilage repair capacity declines and cumulative load increases over decades
- Excess body weight — each pound of body weight multiplies force through the knee, and fat tissue also contributes inflammatory signals
- Previous joint injury — ligament tears, meniscal injury, or fracture through a joint substantially raise later risk
- Repetitive occupational loading — kneeling, squatting, and heavy lifting are associated with knee and hip disease
- Female sex — particularly for hand and knee osteoarthritis after menopause
- Genetics — family clustering is well documented, especially for hand disease
- Muscle weakness around the joint — reduces shock absorption and joint control
- Joint malalignment or developmental hip abnormalities — concentrate load on a small area
Causes
Osteoarthritis develops when the mechanical load on a joint exceeds the ability of its tissues to maintain and repair themselves. That imbalance can come from higher load — obesity, injury, malalignment, repetitive occupational stress — or from reduced repair capacity related to age, genetics, and metabolic factors. Low-grade systemic inflammation associated with obesity and metabolic syndrome appears to contribute independently of mechanical load, which is why weight loss helps even in non-weight-bearing joints like the hands.
Post-traumatic osteoarthritis deserves separate mention. An anterior cruciate ligament tear or meniscal injury in a young athlete markedly raises the risk of knee osteoarthritis decades later, regardless of whether it was surgically repaired.
How it is diagnosed
In typical cases the diagnosis is clinical, based on age, symptom pattern, and examination, without needing imaging.
| Test or assessment | What it looks at |
|---|---|
| Clinical assessment | Age over 45 with activity-related joint pain and morning stiffness under 30 minutes is often sufficient for a working diagnosis in the knee or hip. |
| X-ray | Shows joint space narrowing, osteophytes, subchondral sclerosis, and cysts. Findings correlate poorly with symptoms, so imaging is used when the picture is unclear or surgery is being considered. |
| Blood tests | Not used to diagnose osteoarthritis but are helpful to exclude inflammatory arthritis when there is prolonged morning stiffness, multiple swollen joints, or systemic symptoms. |
| MRI | Reserved for suspected mechanical problems such as meniscal tears or for unexplained pain; it is not needed for routine diagnosis and often shows incidental changes. |
| Joint fluid analysis | Used when infection, gout, or pseudogout needs to be excluded — particularly with a hot, acutely swollen joint. |
Treatment overview
Treatment is layered, starting with self-management and exercise and adding medication or procedures as needed. The categories below describe available approaches; specific choices and any dosing are set by your clinician.
Exercise therapy
Strengthening, range-of-motion, and aerobic exercise have the strongest evidence of any osteoarthritis treatment. Supervised programs from a physical therapist outperform general advice.
Weight management
Weight loss of 5-10% meaningfully reduces knee pain and improves function, with greater loss producing greater benefit.
Education and self-management programs
Structured programs covering pacing, joint protection, and flare management improve confidence and reduce pain-related disability.
Topical and oral analgesic classes
Topical NSAIDs are often preferred for knee and hand osteoarthritis; oral NSAIDs and acetaminophen are used with attention to stomach, kidney, and cardiovascular risk. Duloxetine is an option for persistent pain.
Injection therapies
Corticosteroid injections can provide short-term relief during a flare. Evidence for hyaluronic acid is mixed, and platelet-rich plasma remains investigational.
Assistive devices and braces
Canes, offloading knee braces, thumb splints, and appropriate footwear reduce load and improve confidence in walking.
Joint replacement surgery
Hip and knee replacement are highly effective for advanced disease with persistent pain and functional limitation despite other measures.
Lifestyle considerations
- Move the joint regularly — inactivity stiffens joints and weakens the muscles that protect them.
- Build lower-limb strength, especially the quadriceps and hip muscles, two or three times a week.
- Choose low-impact aerobic activity such as walking, cycling, swimming, or water exercise.
- Aim for gradual weight loss if you carry excess weight; the knee experiences several times body weight during walking.
- Use heat before activity to loosen a stiff joint and cold afterward for a swollen one.
- Pace activity across the day rather than doing everything on a good day and paying for it afterward.
- Wear supportive, cushioned footwear and consider a cane in the hand opposite the affected leg.
- Be sceptical of supplements marketed for cartilage repair; evidence for glucosamine and chondroitin is weak and inconsistent.
Prevention
- Maintain a healthy body weight from midlife onward — the strongest modifiable protective factor.
- Strengthen the muscles around major joints, particularly the thighs and hips.
- Prevent and properly rehabilitate sports injuries, especially knee ligament and meniscal injuries.
- Use good technique and appropriate equipment for repetitive occupational tasks.
- Stay active — regular moderate exercise protects joints rather than wearing them out.
- Manage blood glucose, since diabetes is associated with more severe osteoarthritis.
Warning signs and when to get help
Signs that need emergency care
If you believe you are experiencing a medical emergency, call emergency services immediately (911 in the United States).
- A hot, red, severely swollen joint with fever or feeling generally unwell — possible joint infection requiring urgent care
- Sudden inability to bear weight after a fall, with deformity — possible fracture
- Sudden calf swelling, redness, and pain after joint surgery — possible blood clot
- New chest pain or breathlessness after joint surgery — call emergency services
Signs that warrant a prompt appointment
These are not emergencies, but they are worth a call to your clinician rather than a wait-and-see.
- A joint that locks, catches, or gives way unpredictably
- Morning stiffness lasting well over an hour, or several swollen joints — may suggest inflammatory arthritis instead
- Pain that now wakes you at night regularly
- Rapidly worsening pain or loss of function over weeks
- Stomach pain, black stools, or swelling after starting an anti-inflammatory medicine
Questions to ask a healthcare professional
Take these to your next appointment — or build an agenda with the Appointment Prep tool.
- Which joints are affected, and how advanced are the changes?
- Can you refer me to a physical therapist for a structured exercise program?
- What weight change would make a practical difference for my joints?
- Would a topical anti-inflammatory be safer for me than an oral one?
- What are the realistic benefits and risks of a steroid injection?
- At what point would joint replacement be worth considering?
- Which activities should I modify, and which should I keep doing?
- Are any of my other medicines affecting my joint pain or my options?
Frequently asked questions
Will exercise wear my joints out faster?
No. Appropriate exercise is one of the best-supported treatments for osteoarthritis. Cartilage depends on movement for nutrition, and stronger muscles reduce the load transmitted through the joint. Pain that settles within 24 hours of activity is acceptable; a physical therapist can help set the right level.
How is osteoarthritis different from rheumatoid arthritis?
Osteoarthritis is a mechanical and metabolic joint condition with use-related pain and brief morning stiffness. Rheumatoid arthritis is an autoimmune disease with prolonged morning stiffness, symmetrical small-joint swelling, and systemic symptoms, and it needs disease-modifying treatment early.
Do glucosamine and chondroitin supplements work?
The evidence is weak and inconsistent, with the largest trials showing little benefit over placebo. They are generally safe for most people, but they are not a substitute for exercise and weight management, and cost is worth weighing.
Does cracking my knuckles cause arthritis?
No. Studies have not found a link between habitual knuckle cracking and osteoarthritis of the hands. The sound comes from gas bubbles in joint fluid rather than from damage.
When should I consider a joint replacement?
Generally when pain and functional limitation persist despite exercise therapy, weight management, and medication, and when quality of life is meaningfully affected. It is a shared decision rather than something dictated by X-ray appearance alone.
Sources
- Arthritis Foundation — Patient education, exercise programs, and self-management
- NIAMS — Osteoarthritis — NIH overview of causes, diagnosis, and treatment
- CDC — Arthritis — US prevalence and physical activity guidance
- MedlinePlus — Osteoarthritis — Consumer summary and related topics
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