Blog · 2026-09-29

Partial Knee Replacement: Who Qualifies and How It Compares

PUBLISHED 2026-09-29 · Op. Dr. Serdar Karaman, Orthopedics & Traumatology · Live Taller Now

In short: a partial knee replacement, or unicompartmental knee arthroplasty, replaces only the worn part of the knee, most often the inner side. It suits people whose arthritis is confined to one compartment and whose ligaments are intact. Recovery is usually faster and the knee often feels more natural, but joint registries report a higher revision rate than for total knee replacement.

What a partial knee replacement is

The knee has three compartments: the inner (medial), the outer (lateral) and the one behind the kneecap. In many people with osteoarthritis, the damage is concentrated in one of them, usually the medial side, which is common in bow-legged knees. A partial knee replacement resurfaces only that compartment with metal and plastic components and leaves the healthy cartilage, the other compartments and the cruciate ligaments in place. A total knee replacement, by contrast, resurfaces the whole joint.

Who qualifies

Careful selection is the single biggest factor in how well a partial knee does. Surgeons look for a specific pattern on examination and imaging, usually standing X-rays and sometimes stress views or an MRI.

• Arthritis limited to one compartment, with the others healthy or nearly so.
• An intact anterior cruciate ligament and a stable knee.
• A deformity that corrects, rather than a fixed, severe bow or knock.
• Good range of movement before surgery.
• Osteoarthritis rather than inflammatory arthritis, such as rheumatoid arthritis, which affects the whole joint.

Estimates vary, but only a minority of people needing knee replacement meet these criteria.

The advantages

Because less tissue is removed and the ligaments are kept, partial knee replacement typically involves a smaller incision, less blood loss and a shorter hospital stay. Recovery is usually quicker than after a total knee, which we describe in knee replacement recovery time. Many patients also say the knee feels more like their own, with better bending and more natural movement on stairs and slopes.

The trade-offs

National joint registries consistently show that partial knees are revised more often than total knees over ten years or more. Part of the reason is that arthritis can progress in the untouched compartments; part is that converting a partial to a total is relatively straightforward, so surgeons may choose to revise sooner. Results are also closely linked to surgeon experience: centres that perform partial knees regularly report better survival than those that do them occasionally. Robotic assistance is increasingly used to position partial knee components precisely, which we cover in robotic knee replacement.

Partial or total: how the decision is made

The choice should come from your X-rays and examination, not from a preference for a smaller operation. If you meet the criteria, a partial knee offers a faster, more natural-feeling recovery with a higher chance of a later revision. If arthritis is spread across the joint or the ligaments are damaged, a total knee is the more reliable option. For long-term survival figures, see how long a knee replacement lasts, and for candidacy reviews, our knee replacement in Turkey page.

Frequently asked questions