14599 Partial Knee Replacement

Overview

A partial knee replacement is an operation that replaces only the worn or damaged part of the knee joint, not the whole knee. It is sometimes called a unicompartmental knee replacement. The surgeon puts smooth metal and plastic parts into the affected area and keeps as much of your healthy knee tissue as possible. It is used when arthritis or wear is limited to one section of the knee.

Partial knee replacement is less common than total knee replacement. It is an option for a selected group of people whose knee wear is limited to one area.

It mostly affects adults with osteoarthritis in one part of the knee, often middle-aged or older adults. It can sometimes be considered in younger, active people after a knee injury, but it is not usually done in growing children.

Symptoms

Common symptoms

• Knee pain, often on one side of the knee
• Stiffness after sitting or resting
• Swelling after activity
• Grinding, catching, or a feeling of roughness in the knee
• Pain when going up or down stairs or getting up from a chair
• Difficulty walking longer distances
• The knee sometimes feeling weak or giving way

Symptoms in children

• Knee pain in children has many causes and is checked differently.
• Partial knee replacement is very rarely, if ever, done in growing children because their bones are still developing.

Symptoms in older adults

• Osteoarthritis is more common with age, so older adults are more likely to be considered for this operation.
• Older adults may also have muscle weakness, balance problems, or other health conditions that affect recovery planning.

Causes

Main causes

• Wear-and-tear arthritis limited to one part of the knee
• Past knee injury that damaged one side of the joint
• Uneven loading across the knee over time

Risk factors

• Older age
• Being overweight, which puts more load on the knee
• Family history of knee arthritis
• Previous knee injury or knee surgery
• Heavy or repetitive knee loading from work or sport
• Leg alignment that puts extra stress on one side of the knee

When to see a doctor

See a doctor urgently if:

• After surgery, seek same-day medical advice for fever, chills, or a wound that is more red, hot, swollen, or leaking pus.
• Seek same-day advice for new calf pain or swelling, or knee pain and swelling that get much worse.
• Seek same-day advice if you cannot keep fluids down or feel dehydrated.

Book a routine appointment if:

• Knee pain or stiffness that persists for several weeks or keeps coming back
• Knee symptoms that affect sleep, walking, work, or daily activities
• Swelling or pain that is not improving with rest and simple self-care
• You are considering knee replacement surgery or want to discuss options

Diagnosis

A clinician will ask about your knee pain, how it affects walking and daily life, and what treatments you have tried. They will examine your knee and may review imaging. You may then be referred to an orthopaedic surgeon, a doctor who specialises in bone and joint surgery.

Tests that may be done

• X-rays to show joint damage and alignment
• MRI scans in some cases to look at soft tissues and the extent of wear
• Blood tests if infection or another condition is suspected
• A joint fluid sample in some cases to check for infection or gout

What to expect at your appointment

You may have a pre-operative assessment to check your general health and plan your recovery. The surgeon will discuss whether a partial or total knee replacement is more suitable, along with the risks, benefits, and expected recovery. Bring your questions and, if you wish, a family member or friend.

Treatment

Treatment usually starts with non-surgical options. If these do not control your symptoms and the wear is limited to one part of the knee, surgery may be discussed.

Self-care at home

• Stay active within comfort and follow advice from a physiotherapist or clinician.
• Keep to a healthy weight to reduce load on the knee.
• Use a walking stick or other aid if it helps you move more comfortably.
• Use ice and elevation for swelling if advised.
• After surgery, follow your surgical team's plan for wound care, exercise, and returning to activity.

Medical treatments

Your clinician may suggest pain relief, physiotherapy, weight management, walking aids, and sometimes injections. They will explain the benefits and risks. No medicine can rebuild worn cartilage, and treatment is focused on managing pain and helping you stay active.

When is surgery considered?

A partial knee replacement may be offered when arthritis is limited to one part of the knee, the knee ligaments are stable, and symptoms seriously affect daily life despite other treatments. The surgeon will check whether it is suitable for you. It is not right for everyone, and some people need a total knee replacement instead.

Living with this condition

After surgery, you may need help at home for a while. You will likely use a walking aid, do daily exercises, and care for your wound. Swelling and stiffness are common during recovery. Follow your team's advice about work, driving, travel, and when to increase activity.

Lifestyle tips

• Build leg strength gradually as guided by your physiotherapist.
• Choose low-impact activity such as walking, swimming, or cycling when cleared.
• Avoid twisting movements and falls, especially early in recovery.
• Pace yourself and rest when your knee swells or feels sore.
• Keep a healthy weight to reduce strain on the knee.
• Get enough sleep and ask for help when you need it.

Diet and exercise

Eat balanced meals with enough protein and fibre, and drink enough fluids. Exercise as advised by your physiotherapist to strengthen the muscles around the knee. Avoid smoking or seek help to stop, as smoking can slow healing.

Mental health and emotional wellbeing

Recovery can be frustrating, and it is normal to feel anxious or low at times. Talk to your care team if these feelings are affecting you. If you feel you may harm yourself or are in crisis, contact your local emergency number or a crisis support service immediately.

Prevention

Not all knee arthritis can be prevented. Keeping a healthy weight, staying active, strengthening leg muscles, and avoiding knee injuries may lower the risk of knee problems and may help delay the need for surgery.

Vaccines

There is no vaccine that prevents knee arthritis or the need for a partial knee replacement.

Screening programmes

There is no routine screening test for needing a partial knee replacement. See a clinician if you have ongoing knee pain, stiffness, or swelling.

Complications

If left untreated

• Pain and stiffness may get worse over time
• Muscles around the knee may become weaker
• Walking, stairs, and daily activities may become harder
• Balance problems and falls may become more likely
• Sleep, mood, and general activity levels may be affected

Long-term outlook

For suitable people, a partial knee replacement can reduce pain and improve knee function. Recovery takes time and effort, and some people later need more surgery. Your care team will support you through recovery and help you set realistic goals.

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