Joint Replacement
Surgical replacement of a damaged hip or knee joint with an artificial one.
Last revised
Key takeaways
- Most common: hip and knee replacement
- Prehabilitation: exercise before surgery can help recovery
- Most useful single change: Do prescribed exercises before surgery, not only after.
- Commonest mistake: Delaying so long that muscle loss makes recovery harder.
- See a doctor if any of the signs under "When to get help" below apply to you.
Why it matters
Outcomes are strongly influenced by preparation and rehabilitation, which are the parts patients can actually affect.
The numbers, in one place
| Measure | Figure |
|---|---|
| Most common | hip and knee replacement |
| Prehabilitation | exercise before surgery can help recovery |
| Hospital stay | often short; some people go home the same day |
| Rehabilitation | physical therapy continues for months, not weeks |
| Implant longevity | most last many years; revision surgery is possible |
What helps
- Do prescribed exercises before surgery, not only after
- Stop smoking before surgery; it reduces wound complications
- Arrange home support and equipment in advance
- Follow the physical therapy program fully, including when it is dull
What to avoid
- Delaying so long that muscle loss makes recovery harder
- Stopping rehabilitation when pain settles
- Ignoring signs of infection around the wound
In depth
Joint replacement, also called arthroplasty, removes the damaged surfaces of a joint and replaces them with implants made of metal, plastic or ceramic. In a total knee replacement, the ends of the thigh bone and shin bone are resurfaced, and the back of the kneecap may be too. In a total hip replacement, the ball at the top of the thigh bone and the socket in the pelvis are both replaced. Partial replacements, which resurface only one part of the knee, are an option for some people.
The most common reason for joint replacement is severe osteoarthritis that continues to cause significant pain and limit daily life despite exercise, weight management, pain relief and other treatments. Other reasons include inflammatory arthritis, fractures and loss of blood supply to the hip bone. The decision is usually based on how much the joint affects your life rather than how it looks on an X-ray.
For most people, hip and knee replacements reliably reduce pain and improve function. Recovery is gradual. Knee replacements often take longer to feel fully natural than hips, and some people continue to notice stiffness or occasional aching. Your effort before and after surgery, especially exercise and physical therapy, has a large influence on how well the new joint works.
Signs and symptoms
- Joint pain that limits walking, stairs or sleep despite other treatments
- Pain at rest or at night that is hard to control
- Stiffness that makes daily tasks such as putting on socks difficult
- A joint that has become visibly deformed or unstable
- Steady decline in function over months despite treatment
Causes and risk factors
- Advanced osteoarthritis of the hip or knee
- Joint damage from rheumatoid arthritis or other inflammatory arthritis
- A hip fracture, particularly in older adults
- Loss of blood supply to the hip bone, called osteonecrosis
- Previous injury that has led to severe joint wear
How it is checked
An orthopedic surgeon assesses your symptoms, how they affect your life, what treatments you have already tried and your general health. They examine the joint for movement, stability and alignment and review X-rays to see the extent of damage. Together you weigh the likely benefits against the risks, which depend partly on your age, weight and other conditions.
Before surgery you will have a preoperative assessment, which may include blood tests, an ECG, a review of your medicines and checks for infections such as dental or urinary infections that need treating first. People with diabetes may need their blood sugar brought under better control, and smokers are strongly encouraged to quit. These steps reduce the risk of complications.
Related topics
- Rehabilitation After Surgery: What Published Guidance Supports (Rehabilitation)
- Bone Health in Women: What the Evidence Actually Says (Women's Health)
- Hormone Replacement Therapy: Sorting the Evidence From the Noise (Thyroid and Hormones)
- The Evidence on Back Pain in Older Adults, Without the Hype (Back and Posture)
Where to go next
- Joint Replacement: The Practical To-Do List
- Myths About Joint Replacement, Checked Against the Guidance
- Bone and Joint: The Complete Guide
- Tendon Problems: What the Evidence Actually Says
- What the Guidance Really Says About Vitamin D and Bone
When to get help
Contact your surgeon urgently or go to the emergency room for increasing pain, redness, heat or drainage around the wound, fever, or a sudden inability to bear weight — joint infection needs immediate assessment. Call 911 for chest pain or sudden shortness of breath, and seek same-day care for calf pain and swelling, which can indicate a blood clot.
Where this comes from
- National Institute of Arthritis and Musculoskeletal and Skin Diseases — Joint Replacement Surgery
- MedlinePlus — Hip Joint Replacement
How this page was put together
Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarized or generalized beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to your doctor, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 911.