Partial knee replacement

Who is suitable?

A partial knee replacement can be a good option when arthritis is limited to one compartment of the knee, most often the inner (medial) side, the knee ligaments are healthy and the knee bends and straightens well. I assess this with an examination and standing X-rays, and sometimes further X-rays or an MRI scan.

Partial or total knee replacement?

National guidance recommends that people with arthritis in the inner part of the knee are offered the choice of a partial or a total knee replacement. A large UK trial (TOPKAT) found that patients did as well after a partial as after a total knee replacement at five years. A review of studies published in the BMJ found lower risks of complications, such as blood clots, heart attack, stroke and deep infection, after a partial than after a total knee replacement.

• Advantages: recovery is often quicker, the knee often feels more natural, and serious complications in the first months are less common.
• Trade-off: partial replacements are more likely to need further surgery later. If needed, a partial replacement can usually be converted to a total one.

How long does a partial knee replacement last?

For most partial knee replacements, I use the ZUK implant, one of the best-performing partial knees in the UK National Joint Registry, with one of the longest track records. Registry figures show that 91 in 100 of these partial knee replacements last more than 15 years after surgery, and many last longer. This compares with 95 in 100 for the total knee replacements I use. However, individual factors, such as your age and activity level, can affect this significantly.

Robotic assistance

Where it is suitable, I can perform a partial knee replacement with Mako robotic assistance, which helps position the implant precisely.

Risks

Risks are similar to those of a total knee replacement, including infection, blood clots, stiffness and ongoing pain. Arthritis can also progress in the rest of the knee, which may lead to a total knee replacement in the future.

Costs and insurance

I am recognised by Bupa, AXA Health, Aviva, Vitality, Aetna and Healix. Please check your policy and ask your insurer for a pre-authorisation number before your first appointment. If you are paying for yourself, Nuffield Health Ipswich will give you a fixed-price package after your consultation. See fees and insurance.

Written and reviewed by Mr Krishna Boddu FRCS (Tr & Orth), consultant orthopaedic surgeon, GMC 5206961. Last reviewed: 1 November 2026.

Sources

• NICE guideline NG157: Joint replacement (primary): hip, knee and shoulder (2020)
• Beard DJ et al. The clinical and cost-effectiveness of total versus partial knee replacement in patients with medial compartment osteoarthritis (TOPKAT): 5-year outcomes of a randomised controlled trial. Lancet 2019;394:746–56.
• Wilson HA et al. Patient relevant outcomes of unicompartmental versus total knee replacement: systematic review and meta-analysis. BMJ 2019;364:l352.
• Liddle AD et al. Adverse outcomes after total and unicompartmental knee replacement in 101,330 matched patients: a study of data from the National Joint Registry for England and Wales. Lancet 2014;384:1437–45.
• National Joint Registry annual reports: implant survival
• Gill JR, Nicolai P. Clinical results and 12-year survivorship of the Physica ZUK unicompartmental knee replacement. Knee 2019;26:750–8.