Knee Replacement Surgery

Knee replacement surgery, also known as knee arthroplasty, is a widely performed procedure designed to relieve chronic pain and restore mobility in individuals with severe knee joint damage. It involves replacing worn or damaged surfaces of the knee with an artificial implant, allowing for smoother movement and improved function.

This surgery is most commonly performed for people with advanced osteoarthritis, but it is also an option for those with rheumatoid arthritis, post-traumatic arthritis, or severe knee injuries that limit daily activities and do not respond to other treatments.

This guide will cover everything you need to know about knee replacement surgery, including:

• When knee replacement is needed and the conditions it treats.
• How the procedure is performed, and the different types of knee replacement.
• What to expect during recovery and how to achieve the best results.
• Potential risks and complications to consider.
• Answers to common patient questions about knee replacement surgery.

Whether you’re considering knee replacement for yourself or a loved one, this guide will help you make an informed decision about your treatment options.

Knee Joint Anatomy

The knee is the body’s largest joint and plays a vital role in movement, balance, and weight-bearing. It allows for bending, straightening, and rotation, making it essential for everyday activities like walking, climbing stairs, and sitting down.

The knee joint consists of:

• The lower end of the femur (thighbone), which forms the upper part of the joint.
• The upper end of the tibia (shinbone), which supports body weight.
• The patella (kneecap), a small, protective bone that helps improve knee function.

The knee joint is supported by articular cartilage for smooth movement, menisci for shock absorption, ligaments for stability, and thigh muscles for strength. The synovial membrane produces also fluid to reduce friction.

When these structures function properly, the knee moves effortlessly, but injury or disease can disrupt this balance, causing pain, stiffness, and reduced mobility.

When is Knee Replacement Needed?

Knee replacement surgery is recommended when knee pain and stiffness become severe enough to interfere with daily life. It is typically considered after other treatments, such as physiotherapy, medications, and lifestyle modifications, have failed to provide relief.

Common Conditions Leading to Knee Replacement

• Osteoarthritis: The most common reason for knee replacement. This age-related wear-and-tear condition causes the cartilage in the knee joint to break down, leading to pain, stiffness, and swelling.
• Rheumatoid arthritis: An autoimmune condition that causes chronic inflammation in the joints, leading to cartilage damage and joint deformity.
• Post-traumatic arthritis: Arthritis that develops after a knee injury, such as fractures or ligament damage, which can lead to joint instability and cartilage deterioration.
• Severe knee injuries: Injuries that cause irreversible damage to the joint, making knee replacement the best option for restoring function.

Signs That Knee Replacement May Be Necessary

• Severe knee pain that affects daily activities such as walking, climbing stairs, or getting in and out of chairs.
• Pain while resting, even at night.
• Stiffness and swelling that limits knee movement.
• Dependence on walking aids like a cane or walker due to knee instability.
• Failed response to other treatments, including physiotherapy, pain relief injections, or medications.

Knee replacement surgery is usually recommended for individuals over 50, but younger patients with significant joint damage may also be candidates. A thorough assessment by an orthopaedic specialist, including X-rays and physical exams, helps determine whether knee replacement is the best option.

How is Knee Replacement Surgery Performed?

Knee replacement surgery typically takes between one and two hours. The specific steps vary depending on whether a total or partial knee replacement is being performed, but the general process remains similar.

Pre-Surgery Preparation

Before surgery, patients undergo a thorough assessment, which may include:

• X-rays or MRI scans to evaluate the extent of joint damage.
• Blood tests and a general health check to ensure fitness for surgery.
• Preoperative physiotherapy to strengthen the knee and improve post-surgery recovery.

Patients are also given instructions on fasting before surgery and advised on any medications that may need to be stopped or adjusted.

The Knee Replacement Procedure

1. Anaesthesia – The procedure is performed under either general anaesthesia (where the patient is asleep) or spinal anaesthesia (where the patient remains awake but the lower body is numb).
2. Incision – The surgeon makes an incision at the front of the knee to access the joint. In minimally invasive surgery, this incision is smaller, leading to a quicker recovery.
3. Removing damaged bone and cartilage – The worn-out surfaces of the thigh bone (femur) and shin bone (tibia) are carefully removed using precision surgical instruments.
4. Implant placement – Artificial joint components made of metal and plastic are securely fixed to the bone using surgical cement or a press-fit technique that allows bone to grow onto the implant.
5. Resurfacing the kneecap – In some cases, the underside of the kneecap (patella) is replaced with a plastic component for smoother movement.
6. Testing and adjustments – The surgeon moves the knee joint to ensure proper alignment, stability, and range of motion.
7. Closing the incision – The incision is closed with stitches or surgical staples, and a sterile dressing is applied. The knee may be placed in a brace or bandage for support.

Types of Knee Replacement Surgery

There are different types of knee replacement surgery, depending on the severity of joint damage:

• Total knee replacement (TKR): The most common type, where both sides of the knee joint are replaced with artificial components.
• Partial knee replacement (PKR): Suitable for some patients with damage limited to one part of the knee. This approach preserves more natural bone and may lead to a quicker recovery.
• Minimally invasive knee replacement: Uses smaller incisions and less disruption to surrounding tissue, often leading to faster healing times.

Recovery & Rehabilitation

Recovering from knee replacement surgery involves a combination of pain management, physiotherapy, and gradual return to daily activities. The speed of recovery varies between individuals, but most patients regain mobility and function within a few months.

Immediate Post-Surgery Recovery

• After surgery, patients are monitored in a recovery area while the anaesthesia wears off.
• Pain management begins immediately, often with a combination of medications and cold therapy to reduce swelling.
• Patients are encouraged to move their foot and ankle soon after surgery to promote blood circulation and prevent blood clots.
• In most cases, assisted walking begins on the same day or the next day with the help of a physiotherapist.

The First Few Weeks after Knee Replacement

• Patients typically stay in the hospital for one to three days, depending on their progress.
• Physiotherapy starts immediately, focusing on restoring knee flexibility and strength.
• A walker, crutches, or a cane may be needed temporarily for balance and support.
• Swelling and discomfort are normal but improve with medications, ice packs, and elevation of the leg.
• Regular wound care is required, and stitches or staples are usually removed after two to three weeks.

Returning to Daily Activities after Knee Replacement

• Most patients can walk without assistance within 4–6 weeks, depending on their progress.
• Driving is typically possible after 4–6 weeks, once mobility and reaction times improve.
• Low-impact activities like swimming, cycling, and walking are encouraged after 6–12 weeks.
• High-impact sports, running, and kneeling should be avoided unless advised otherwise by a doctor.

Long-Term Recovery & Implant Lifespan of Knee Replacement

• Full recovery, including regaining strength and flexibility, can take 3–6 months.
• The artificial knee implant typically lasts 15–20 years, depending on activity levels and implant type.
• Regular follow-up appointments are necessary to monitor knee function and detect any complications early.

Most patients experience significant pain relief and improved mobility, allowing them to return to an active lifestyle. However, adhering to physiotherapy and post-surgery care guidelines is essential for the best outcomes.

Risks & Potential Complications

Knee replacement surgery is generally safe and effective, but as with any procedure, there are potential risks. Most patients recover without complications, but it is important to be aware of possible issues and how they are managed.

Common Risks

• Infection – This can occur at the incision site or around the implant. Preventive antibiotics and sterile surgical techniques help reduce the risk.
• Blood clots – Deep vein thrombosis (DVT) or pulmonary embolism (PE) can develop after surgery. Blood thinners, compression stockings, and early movement help prevent these complications.
• Swelling and stiffness – Temporary stiffness is normal, but physiotherapy helps restore flexibility and function. Persistent stiffness may require additional treatment.

Less Common but Serious Complications

• Implant loosening or wear – Over time, the artificial joint may wear down or loosen, potentially requiring revision surgery.
• Nerve or blood vessel damage – Rarely, nearby nerves or blood vessels may be affected during surgery, causing weakness or numbness.
• Persistent pain – While most patients experience relief, a small number may continue to have discomfort due to scar tissue or nerve irritation.

How Risks Are Managed

At St John & St Elizabeth Hospital, we take proactive measures to minimise risks, including:

• Advanced surgical techniques that reduce trauma to surrounding tissues.
• Personalised pre-surgery assessments to identify and address individual risk factors.
• Enhanced recovery programmes with dedicated physiotherapy support.
• Regular follow-up care to monitor healing and detect complications early.

Being informed about potential risks helps patients make a confident and well-prepared decision about surgery.

Frequently Asked Questions about Knee Replacement Surgery

How long does knee replacement surgery take?

The procedure typically lasts one to two hours, depending on the complexity and whether a total or partial replacement is performed.

Is knee replacement surgery painful?

Pain is managed effectively with anaesthesia during surgery and medications afterward. Some discomfort is expected during recovery, but physiotherapy helps improve mobility and reduce stiffness.

How soon can I walk after knee replacement?

Most patients start assisted walking on the same day or the next day with the help of a physiotherapist. Walking independently is usually possible within four to six weeks.

How long does a knee replacement last?

Modern knee implants typically last 15–20 years, though this varies based on activity levels and implant type. Regular check-ups help monitor long-term function.

What are the alternatives to knee replacement?

Non-surgical treatments include physiotherapy, weight management, pain relief injections, and medications. If these no longer provide relief, surgery becomes the best option.

When can I return to normal activities after knee replacement surgery?

Recovery time varies, but most patients regain mobility in stages:

• Walking with assistance – Within a day or two after surgery.
• Walking without aids – Around 4 to 6 weeks.
• Driving – Usually after 4 to 6 weeks, depending on strength and reaction time.
• Low-impact activities (e.g., swimming, cycling) – After 6 to 12 weeks.
• Higher-impact activities (e.g., running, kneeling) – Often restricted or require surgeon approval.

Full recovery can take 3 to 6 months, with continued improvements up to a year. A structured rehabilitation plan helps restore strength and flexibility.