What is a Partial Knee Replacement?

A partial knee replacement (PKR), also called a unicompartmental knee replacement, is an operation where only the damaged part of the knee joint is replaced with an artificial implant.

Unlike a total knee replacement, which replaces the whole joint, a partial knee replacement preserves as much of your natural bone, cartilage, and ligaments as possible. This can lead to a knee that feels more “natural” after recovery.

Why is it Done?

Partial knee replacement may be recommended when:

• Arthritis or damage is limited to one part of the knee (usually the inner side, less often the outer or under the kneecap).
• The rest of the knee joint is healthy and stable.
• Pain and stiffness are not controlled with medications, injections, or physiotherapy.
• You have knee pain that affects daily activities, such as walking or climbing stairs.

It is often considered in younger, more active patients or those wishing to keep as much of their natural knee as possible.

Benefits of Partial Knee Replacement

• Smaller incision compared to total knee replacement.
• Less pain and faster recovery after surgery.
• More natural knee movement, as ligaments and cartilage are preserved.
• Shorter hospital stay and quicker return to normal life.
• Easier to revise to a total knee replacement later if needed.

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What Happens During Surgery?

• Surgery is performed under general or spinal anesthesia.
• The surgeon makes a small incision over the knee.
• Only the damaged compartment of the knee is cleaned out.
• An artificial implant (made of metal and medical grade polyethylene) is fitted onto the prepared bone surface.
• The rest of the knee joint, including the healthy cartilage and ligaments, is left intact.
• The wound is closed with sutures or staples, and a dressing is applied.

The operation usually takes 1–1.5 hours.

Recovery and Rehabilitation

In the hospital:

• You will be encouraged to walk (with help) the same day.
• Pain medication and blood clot prevention will be given.
• Physiotherapy starts early to help regain strength and movement.

At home:

• Keep the leg elevated to reduce swelling.
• Use walking aids (crutches, cane) for a short time.
• Follow a personalised physiotherapy programme to restore strength and motion.

Typical recovery timeline:

• Walking without aids: 2–3 weeks.
• Driving: usually after 3–4 weeks (when safe).
• Return to work and daily activities: 4–6 weeks.
• Return to sports or higher activity: 3–6 months.

Risks and Complications

Partial knee replacement is safe, but possible risks include:

• Infection.
• Blood clots in the leg.
• Nerve or blood vessel injury (rare).
• Stiffness or ongoing pain.
• Implant wear or loosening over time.

Prognosis

• Most patients experience excellent pain relief and return to normal activities within weeks.
• Many people say the knee feels more “natural” than after a total knee replacement.
• They find it easier to return to some of their favourite activities like tennis, golf etc compared to a total knee replacement.

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