Partial vs total knee replacement

The knee joint is really made up of three separate compartments: the medial (inner), lateral (outer), and patellofemoral (behind the kneecap). Arthritis can affect all three, or it can be concentrated in just one — most often the medial compartment. This distinction is the whole basis for the partial-vs-total decision.

A partial knee replacement resurfaces only the damaged compartment, leaving the healthy bone, cartilage and ligaments in the rest of the knee untouched. Because less of the joint is altered, some patients experience a more natural-feeling knee afterward, a smaller incision, and often a somewhat faster early recovery than with a total replacement.

It isn't right for everyone. A good candidate typically has arthritis clearly confined to one compartment, intact ligaments (especially the ACL), reasonable knee alignment, and no significant inflammatory arthritis such as rheumatoid arthritis. Surgeons assess this carefully with imaging and examination before recommending it.

A total knee replacement resurfaces all three compartments. It's the right choice when arthritis has spread across the joint, when ligament support is compromised, or when significant deformity or instability is present. It remains the more commonly performed of the two procedures, and it has a long track record of reliable, durable outcomes.

• Recovery: partial replacement recovery is often somewhat quicker in the early weeks, though both procedures follow a broadly similar overall timeline. See our realistic recovery timeline for what to expect either way.
• Feel: many partial-replacement patients describe the knee as feeling closer to "their own," since healthy compartments and ligaments are preserved.
• Durability and revision risk: historically, some registry data has suggested a somewhat higher rate of eventual revision surgery for partial replacements compared with total replacements, partly because arthritis can progress in the untreated compartments over time. This gap has narrowed with modern implants and patient selection, and it's a reasonable factor to discuss directly with your surgeon relative to your age and activity level.
• If a partial fails or arthritis progresses: a partial replacement can generally be converted to a total replacement later, which is one reason some surgeons see it as a reasonable first step for younger, active patients with single-compartment disease.

Your surgeon will base this recommendation on your X-rays (and sometimes an MRI), a physical exam of your ligaments and alignment, and your own goals and activity level. It's a genuinely collaborative decision — there's rarely only one correct answer, and a good surgeon will walk you through why they're recommending one option over the other for your specific knee.

If you're still weighing whether either surgery is the right step at all, our articles on signs you might need a knee replacement and non-surgical treatments worth trying first are good starting points.

Partial and total knee replacement aren't a "better vs worse" choice — they're different tools suited to different patterns of arthritis. The right one depends on exactly where your damage is, how strong your ligaments are, and what you want your knee to do for you over the years ahead.