What is a knee replacement?

Knee replacement, also called knee arthroplasty, is an operation that replaces worn joint surfaces with artificial components. It is usually considered when knee arthritis causes ongoing pain, stiffness, and loss of function that no longer settles with non-surgical care.

Some people need a partial knee replacement, while others need a total knee replacement. The decision depends on how much of the joint is affected, your symptoms, your imaging findings, and how much your knee problem is limiting walking, stairs, work, sleep, exercise, or day-to-day life.

If you are exploring treatment options, it also helps to read about knee pain, osteoarthritis, and post-operative physiotherapy so you know what recovery usually involves.

• Persistent knee pain with walking, stairs, or standing
• Morning stiffness or loss of knee movement
• Swelling, grinding, or knee deformity
• Reduced confidence with daily activity or exercise
• Pain that no longer responds well to simpler treatment

When is a knee replacement considered?

A knee replacement is usually considered when knee joint damage is advanced and symptoms remain severe despite good non-surgical care. That often includes activity modification, strengthening, weight management where relevant, pain relief strategies, and guided rehabilitation. The AAOS knee replacement guide explains that surgery is commonly considered when pain and function loss remain significant despite these steps.

What causes the knee joint to wear down?

The most common reason is osteoarthritis. However, other causes can also contribute to joint deterioration and the need for surgery.

• Osteoarthritis: gradual cartilage wear and joint change over time
• Previous injury: meniscus, ligament, fracture, or cartilage damage
• Inflammatory arthritis: such as rheumatoid arthritis
• Past surgery: earlier procedures may alter joint mechanics
• Muscle weakness: lower limb weakness can increase knee load
• Body weight load: extra load can aggravate an already sore joint

What symptoms can lead to knee replacement?

Most people report a steady pattern of pain, stiffness, swelling, and reduced tolerance for walking or stairs. Some also notice their knee becoming bowed, knocked, or harder to fully straighten. These changes can make work, sport, shopping, and family activities much harder than they used to be.

How is severe knee arthritis diagnosed?

A physiotherapist, GP, or orthopaedic surgeon will assess your symptoms, walking pattern, joint movement, swelling, strength, and function. X-rays often show the degree of joint wear. In some cases, extra imaging is used if your clinician wants to assess other structures or rule out another source of pain.

How can physiotherapy help before and after knee replacement?

Pre-operative physiotherapy

Pre-operative physiotherapy aims to improve your knee movement, walking pattern, and leg strength before surgery. This preparation is often called prehabilitation. It can also help you learn how to use crutches, practise key exercises, and set realistic recovery goals.

You may benefit from a tailored program that works on quadriceps strength, hip control, calf strength, swelling management, and knee extension. Good preparation can make the early post-operative phase feel more manageable.

Post-operative physiotherapy

After surgery, physiotherapy focuses on restoring knee extension and flexion, improving walking, reducing swelling, rebuilding strength, and helping you return to daily tasks safely. Many people also need help with stairs, balance, confidence, pacing, and progressing from basic exercises to more functional loading.

Your physiotherapist may guide you through:

• pain and swelling management
• walking retraining and gait aids
• knee range of motion work
• quadriceps, hamstring, calf, hip, and gluteal strengthening
• balance and proprioception drills
• sit-to-stand, stair, squat, and step progressions
• return-to-activity planning for work, exercise, and recreation

If you are recovering from surgery, guided physiotherapy and staged knee treatment may help you move more confidently and build function progressively.

What activities can you do after a knee replacement?

Most people return to walking, stairs, driving, shopping, gardening, and many lower-impact forms of exercise. Swimming, cycling, gym-based strengthening, and golf are often more suitable than repetitive high-impact activity. Your surgeon and physiotherapist will guide you based on your recovery, goals, and any precautions.

If arthritis is affecting both knees or you are not yet ready for surgery, a structured program such as the GLA:D® Australia Program may also help some people manage symptoms and improve confidence with movement.

Related articles

1. Knee Arthritis – Learn more about knee osteoarthritis symptoms, causes, and management options.
2. Post-Operative Physiotherapy – Find out how rehab can support your recovery after surgery.
3. Knee Pain – Explore common causes of knee pain and when to seek help.
4. Osteoarthritis – Read about joint wear, stiffness, and practical treatment strategies.
5. Rheumatoid Arthritis – Understand how inflammatory arthritis can affect joint health.
6. Knee Arthroscopy – Compare another common knee surgery pathway.
7. Patellofemoral Pain Syndrome – Learn about another frequent source of knee pain.
8. Knee Sports Injury – See common sports-related knee problems and recovery options.

Knee replacement FAQs

How long does recovery take after a knee replacement?

Recovery varies. Many people improve steadily over the first 6 to 12 weeks, but strength, confidence, and higher-level function often continue to improve for several months.

Is physiotherapy important after knee replacement?

Yes. Physiotherapy usually focuses on walking, swelling control, range of motion, strength, and safe progression back to daily tasks and exercise.

Can I walk straight after knee replacement surgery?

Many people start standing and walking early after surgery with guidance from the hospital team. The exact timing depends on your surgeon’s protocol and your medical progress.

Will I be able to bend my knee normally again?

Most people regain enough movement for day-to-day tasks such as sitting, walking, and stairs. However, the final range can vary based on your pre-operative movement, swelling, scar tissue, and rehab progress.

What sports can I do after a knee replacement?

Lower-impact activities such as walking, cycling, swimming, and golf are often more suitable. Your surgeon and physiotherapist can guide what fits your recovery and goals.

Do I always need surgery for knee arthritis?

No. Many people first try exercise-based care, physiotherapy, load management, and other non-surgical strategies. Surgery is usually considered when those options no longer provide enough relief or function.

What to do next

If knee arthritis is making walking, stairs, work, or exercise harder, a physiotherapist can assess your strength, movement, swelling, and function, then help you decide on the next step. That may include pre-operative preparation, post-operative rehabilitation, or a non-surgical management plan.

If you have already had surgery, early guided rehabilitation may help you regain movement, build strength, and return to activity more smoothly.

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References

1. American Academy of Orthopaedic Surgeons. Total Knee Replacement. OrthoInfo. Accessed March 14, 2026.
2. Konnyu KJ, Thoma LM, Cao W, et al. Prehabilitation for Total Knee or Total Hip Arthroplasty: A Systematic Review. Am J Phys Med Rehabil. 2023;102(1):1-10. doi:10.1097/PHM.0000000000002006
3. Konnyu KJ, Thoma LM, Cao W, et al. Rehabilitation for Total Knee Arthroplasty: A Systematic Review. Am J Phys Med Rehabil. 2023;102(2):139-160. doi:10.1097/PHM.0000000000002008
4. Bravi M, Di Bari M, Pillastrini P, et al. Supervised versus unsupervised rehabilitation following total knee arthroplasty: A systematic review and meta-analysis. Arch Orthop Trauma Surg. 2023;143(8):4577-4587. doi:10.1007/s00402-022-04696-5