Knee osteoarthritis (OA) is a very common, long-term condition where the knee joint changes gradually over time. It’s sometimes called “wear and tear,” but it’s more accurate to think of it as a whole-joint condition. OA can involve the cartilage (the smooth covering on the ends of the bones), the bone underneath, the joint lining, and the muscles and ligaments that support the knee. These changes can contribute to pain, stiffness, swelling, and reduced confidence with movement.
Cartilage acts like a smooth, low-friction surface and helps the knee share load. With OA, cartilage may become thinner or rougher, and the joint can develop small bony changes (often called bone spurs). Importantly, knee OA is not a straight line to worsening disability. Symptoms commonly flare and settle, and many people stay active and independent for years with the right approach.
Physiotherapy plays a key role because it targets the things that most strongly influence day-to-day symptoms and function: strength, joint load, movement habits, fitness, and confidence. Evidence-based care focuses on education plus a tailored exercise program, helping you build stronger supportive muscles, improve tolerance to activity, and manage flare-ups. Even when X-rays show arthritis changes, people can still make meaningful improvements in pain and function through consistent rehab.
The main message: knee OA is common, but it’s also very manageable. With physiotherapy-led guidance, most people can keep moving, stay involved in the activities they value, and feel more in control of their knee symptoms.
Key Facts
- X-rays can show osteoarthritis changes even when someone has little or no pain. Research has found that only 15% of people with X-ray knee OA changes were actually symptomatic. 🔗
- In Australia, osteoarthritis is the most common type of arthritis. National survey data also suggests that about 2.1 million Australians (around 8 in every 100 people) report living with arthritis, showing how many people are affected by arthritis-related conditions overall. 🔗
- First-line care for symptomatic knee OA includes patient education and physical therapy. Doing both supervised and home exercises work best. 🔗
Risk Factors
- Age over 45, as knee OA becomes more common with increasing age.
- Previous knee injuries (meniscus, ACL, fractures) that change mechanics or contribute to long-term weakness.
- Higher body weight, which increases compressive load on the knee during daily activity.
- Family history of osteoarthritis, suggesting genetic predisposition.
- Female sex, particularly after menopause, where risk is higher.
- Occupations or lifestyles involving repetitive knee loading (frequent kneeling, lifting, stairs, heavy manual work).
- Low physical activity and reduced lower limb strength over time, reducing joint load tolerance.
Symptoms
- Knee pain, typically worse with weight-bearing activities such as walking, standing, hills and stairs, and often worse at the end of the day.
- Morning stiffness or stiffness after sitting for a while, usually easing after gentle movement.
- Swelling or a feeling of fullness in the knee, sometimes worse after a flare-up or a more active day.
- Reduced range of motion, making it harder to fully bend or straighten the knee.
- Grinding or crunching sensations (crepitus) during knee movement.
- Muscle weakness, especially the quadriceps, often due to pain-related reduced activity and inhibition.
- Episodes of flare-ups where pain and stiffness increase for days to weeks, then settle again.
Aggravating Factors
- Prolonged standing or long walks, especially on hard surfaces.
- Climbing or descending stairs, hills, and getting up from low chairs.
- Kneeling, squatting, lunging, or repeated bending and straightening of the knee.
- High-load days with more lifting, carrying, or repeated household tasks.
- Long periods of sitting followed by standing, especially during flare-ups.
- Cold mornings or inactivity periods, which can increase perceived stiffness for some people.
Causes
Knee osteoarthritis (OA) usually develops from a mix of normal joint changes over time and how well the knee can tolerate the loads we put through it. The encouraging part is that many of the key drivers of symptoms are modifiable, and the knee can become stronger and more resilient with the right plan.
How load plays a role
Your knee is built to handle big forces. Even walking puts several times your body weight through the joint, and stairs or hills increase that further. When activity or training load goes up faster than your knee is currently conditioned for, symptoms can flare. With gradual progress, your knee’s tolerance can improve.
Age-related changes
As we get older, joint tissues can become a bit less resilient. That doesn’t mean pain is inevitable. It just means the knee may need more consistent strength and conditioning to stay comfortable and cope with busy periods.
Previous injury
Past knee injuries (like ligament injuries, fractures, or meniscus problems) can increase the chance of OA later on, especially if they affect how the knee moves or lead to ongoing weakness. The good news is that targeted rehab can improve strength, movement control, and confidence.
Body weight and overall health
Carrying more body weight can increase the compressive load through the knee. If weight change is a goal, even small changes can help symptoms—but it’s not about blame. Many active, motivated people still get knee pain. Physio can help you stay moving safely while you work on broader health goals.
Strength and movement control
The muscles around the knee and hip (especially the quadriceps and glutes) act like shock absorbers. When they’re weaker or not coordinating well, the knee can feel more sore or unstable. This is a big reason exercise therapy is one of the most effective treatments for knee OA.
Flare-ups are normal
OA isn’t a straight path downhill. Symptoms often come in waves—better weeks and flare weeks. Rehab focuses on building capacity so flare-ups happen less often, feel less intense, and you feel more confident with walking, stairs, and everyday life.
How Is It Diagnosed?
Knee osteoarthritis is usually diagnosed using a combination of symptoms, clinical examination, and sometimes imaging. A physiotherapist will ask about your pain pattern, stiffness behaviour, functional limits, flare triggers, and your goals (walking, work demands, sport, caring responsibilities). They will also assess strength and movement.
Clinical assessment often includes:
1) Observation and functional testing: walking, sit-to-stand, stairs, squats, and single-leg control if appropriate, to understand how the knee loads and where movement strategies can be improved.
2) Range of motion: checking how well the knee bends and straightens, and whether stiffness is joint-based or muscle-based.
3) Strength testing: particularly quadriceps and hip strength, because strength is strongly linked to function and confidence in knee OA.
4) Joint irritability: swelling, warmth, and how the knee responds over the next day after activity. This helps guide a safe exercise dose.
Imaging is not always necessary to start treatment. Many people can begin a physiotherapy program based on symptoms and function. If imaging is used, it should help guide decisions, not replace clinical reasoning. Australian guidance emphasises high-value care, where education and exercise are core, even when imaging shows OA changes.
Investigations & Imaging
- X-ray (plain radiograph)
- Commonly used to confirm OA changes such as joint space narrowing, osteophytes (bone spurs), and bony changes. X-ray severity does not perfectly match pain severity, so it should be interpreted alongside symptoms and function.
- MRI (Magnetic Resonance Imaging)
- Not routinely required for typical knee OA. MRI may be used if there is suspicion of another condition (for example an acute meniscus tear pattern) or if symptoms are atypical. MRI can show cartilage, meniscus, bone marrow changes, and synovitis.
- Ultrasound
- May be used to assess joint effusion (fluid) or guide injections, but it is not the standard test to grade knee OA.
Grading / Classification
- Kellgren-Lawrence Grade 0
- No radiographic signs of osteoarthritis.
- Kellgren-Lawrence Grade 1
- Doubtful joint space narrowing and possible small osteophytes.
- Kellgren-Lawrence Grade 2
- Definite osteophytes and possible joint space narrowing.
- Kellgren-Lawrence Grade 3
- Multiple osteophytes, definite joint space narrowing, possible bone deformity.
- Kellgren-Lawrence Grade 4
- Large osteophytes, marked joint space narrowing, definite bone deformity.
Physiotherapy Management
Physiotherapy is one of the most effective, evidence-based treatments for knee osteoarthritis in Australia. Current guidance highlights education and exercise as the foundation of care, not something you only try after medications. The goal is to help you reduce pain, feel more confident with walking and stairs, build strength, and stay active with fewer flare-ups.
Your physiotherapist will tailor a plan to your symptoms and what you want to get back to. The best programs are practical and progressive: you start with a safe baseline you can repeat, then gradually increase strength and activity so your knee becomes more resilient and better at handling load over time.
Some people choose a structured group-based option (such as programs offered in many Australian clinics), while others prefer one-to-one sessions. Either way, the approach is similar: targeted strengthening, balance and movement control, and clear education to support long-term self-management.
Exercise
Knee osteoarthritis physiotherapy exercises are chosen to make daily tasks easier, not just to “work the knee”. The strongest evidence supports exercise therapy for improving pain and function in knee OA. Your physiotherapist will dose exercise based on your symptoms and will often start with movements you can do confidently, then build toward the tasks that currently hurt (stairs, squats, longer walks).
Quadriceps strengthening: The quadriceps are key for knee stability and shock absorption. In knee OA, quadriceps weakness is common and can increase pain sensitivity and functional difficulty. Physiotherapy often includes progressive strength work such as sit-to-stand variations, step-ups, leg press, knee extension patterns, and isometrics during flare-ups. The focus is not just strength once, but strength endurance so the knee does not collapse late in the day.
Hip and glute strengthening: Hip strength affects how load travels through the knee, especially during stairs and walking. Weak gluteals can increase knee stress and reduce confidence. A physiotherapist may include gluteus medius and gluteus maximus strengthening and progress these into functional tasks like step-down control and split-squat patterns.
Balance and neuromuscular control: Many knee OA presentations include reduced balance and reduced control with direction changes or uneven surfaces. Neuromuscular training improves confidence and movement efficiency, and is a major feature of programs like GLA:D®.
Aerobic conditioning: Walking, cycling, and aquatic exercise can improve overall fitness and help manage symptoms. Your physio may help you find a walking dose that improves capacity without triggering a multi-day flare.
Flexibility and range: Gentle mobility work can help stiffness and improve movement confidence. This is most useful when paired with strengthening, because stronger muscles help the knee use its available range safely.
Activity Modification
Activity modification for knee OA is about smart pacing, not avoidance. Many people get trapped in a boom-bust cycle: doing too much on good days, then flaring and resting for days. Physiotherapy breaks this cycle by setting a stable baseline and progressing gradually.
Stairs and hills: If stairs are your biggest trigger, your physio may temporarily reduce stair volume, change technique (use the railing, slow tempo, split tasks), and build the strength required to tolerate stairs again.
Walking plans: Your physio may prescribe shorter, more frequent walks rather than long walks that cause next-day swelling. A common strategy is increasing weekly walking load in small, predictable steps so the knee adapts.
Flares: During flare-ups, your physiotherapist may reduce compressive load temporarily, use pain-calming strength options (isometrics, partial range), and then return you to normal training once irritability settles.
Manual Therapy
Manual therapy can be useful for knee OA when pain and stiffness are limiting movement. A physiotherapist may use joint mobilisation, soft tissue techniques, and stretching to improve comfort and range, particularly during a flare-up or when stiffness is preventing exercise progress.
Manual therapy is best viewed as an adjunct. It can reduce symptoms and help you move better, but long-term improvements usually come from exercise therapy, education, and load progression. The aim is to use hands-on treatment to help you do your knee OA exercises more comfortably and consistently.
Postural Retraining
Postural retraining for knee OA often focuses on the way you use your knee during daily tasks rather than “standing posture” alone. Small technique changes can reduce joint stress and help you stay active.
Your physiotherapist may coach you on sit-to-stand technique, stair pacing, squat depth selection, and walking strategy. For example, using the hips more effectively during sit-to-stand can reduce knee load and improve confidence. If you have a limp due to pain, gait retraining can help reduce compensations that overload other joints.
Bracing & Taping
Bracing and taping can help some people with knee OA by reducing pain during walking and stairs. An unloader brace may be considered if one side of the knee joint is more affected, and simple supportive sleeves can help with warmth and proprioception.
Your physiotherapist can advise whether bracing is likely to benefit you and how to use it strategically, for example during longer walks or more demanding days. Bracing works best when paired with strengthening, because stronger muscles provide the main long-term support.
Heat & Ice
Heat and ice can be used to manage symptoms in knee OA, especially during flare-ups. Heat may reduce the feeling of stiffness before movement. Ice can reduce pain after a more active day when the knee feels hot or swollen.
These strategies are best used to support your physiotherapy plan. If you rely on heat or ice daily without improving function, it often means your exercise dose or activity plan needs adjusting.
Education
Education is a key part of managing knee osteoarthritis. It helps you understand that OA isn’t simply “bone on bone,” that pain doesn’t always mean damage, and that your knee can become stronger and more load-tolerant with the right plan.
A physiotherapist can guide you through what to expect, how flare-ups work, and how to use pacing so you can stay active safely. Education is also very practical, working out strategies for things like stairs at work, building up walking without triggering a multi-day flare, and progressing strength exercises with confidence.
Other
Hydrotherapy: Exercising in water can reduce joint load while still building strength and fitness. This is especially helpful for people with high pain levels during weight-bearing exercise or those returning after a long period of reduced activity.
Assistive devices: In more symptomatic phases, a walking stick, trekking poles, or temporary gait aid can reduce pain and help you keep moving while strength improves. Your physiotherapist can ensure the device is fitted correctly and used effectively.
GLA:D® program participation: If available near you, GLA:D® provides a structured pathway with education and supervised exercise. Program evaluations have reported improvements in outcomes for people with knee OA.
Other Treatments
Weight management: Where relevant, even modest weight reduction can reduce load on the knee during walking and stairs. Physiotherapy can support this by keeping you active safely and building strength so movement feels more achievable.
Pain-relieving medication: Paracetamol and anti-inflammatory medication may be used in some cases under medical advice. Long-term medication plans should be discussed with your GP due to side effects and individual health factors.
Injections: Corticosteroid injections may offer short-term symptom relief for some people, particularly during inflammatory flare-ups. Other injections (such as hyaluronic acid) are sometimes used, but benefit varies. Injections are typically most useful when paired with physiotherapy, because stronger muscles and improved movement habits provide the long-term gains.
Multidisciplinary support: Some people benefit from coordinated care involving a GP, physiotherapist, dietitian, and specialist input depending on symptom severity and health context.
Surgery
Surgery is not the first step for knee osteoarthritis. Many people can manage symptoms well for years with physiotherapy-led exercise, education, and healthy load progression. Australian guidance focuses on high-value conservative care and supports shared decision-making when symptoms persist despite appropriate non-surgical management.
For more advanced cases where pain and function remain severely limited despite a thorough trial of conservative care, surgical options may be discussed with an orthopaedic specialist. The most common operation for end-stage knee OA is total knee replacement (arthroplasty). Knee replacement can be very effective for improving pain and function in appropriately selected people, but it is still major surgery and requires post-operative physiotherapy to regain mobility, strength, and confidence.
Prognosis & Return to Activity
Knee osteoarthritis can progress in terms of joint changes over time, but symptoms don’t always steadily get worse. Many people are able to return to activities they enjoy and make meaningful improvements in pain, strength, and function with the right mix of physiotherapy, education, and a gradual exercise plan. Strong evidence and clinical guidance support exercise as core care for knee OA because it can improve pain and function regardless of what an X-ray shows.
Your long-term outlook is influenced most by things you can control: sticking with strengthening, staying generally active, managing body weight if that’s relevant for you, and learning how to respond to flare-ups without stopping everything. Flare-ups are common and usually manageable with short-term adjustments rather than full rest.
In more advanced cases, symptoms may eventually lead to discussing surgical options, but many people can delay or avoid joint replacement by building knee capacity and following an effective long-term management plan.
Complications
- Increasing difficulty with walking distance, stairs, and daily tasks due to pain, stiffness, and reduced confidence if strength and activity decline.
- Recurrent flare-ups with swelling and stiffness when activity load exceeds tolerance without a graded plan.
- Quadriceps deconditioning and reduced balance if pain leads to long-term avoidance of movement, increasing fall risk in some older adults.
- Reduced participation in sport, work, and social activities, which can impact mental health and overall fitness.
Preventing Recurrence
- Maintain a consistent strengthening routine for quadriceps and hips. Knee OA flares are more common when strength and conditioning drop and load suddenly increases.
- Use pacing to avoid boom-bust cycles. Build walking and stair exposure gradually so the knee adapts without multi-day flare-ups.
- Keep moving during flare-ups using modified exercise (partial range strength, gentle cycling, hydrotherapy) rather than complete rest, with guidance from a physiotherapist.
- Optimise daily mechanics: improve sit-to-stand and stair technique, avoid rushing stairs when flared, and use a handrail or support strategically when needed.
- Manage body weight where relevant through sustainable lifestyle changes supported by ongoing activity and, if needed, dietitian input.
- If one knee side is consistently painful (for example inner knee), discuss bracing, footwear, and strength strategies with your physiotherapist to reduce uneven loading and recurrence.
When to See a Physio
- You have persistent knee pain and stiffness that is limiting walking, stairs, work, or sport for more than 2 to 4 weeks.
- You are having repeated flare-ups with swelling or reduced range of motion and want a plan to manage activity safely.
- You are reducing activity because of knee pain and feel your leg is getting weaker or less stable.
- You want guidance on a structured program such as GLA:D® or an individualised knee OA rehab plan.
- You are considering injections or surgery and want physiotherapy input to ensure conservative care has been optimised and to prepare for better outcomes.
- You have locking, significant instability, severe night pain, or rapidly worsening symptoms and need screening and possible medical referral.