Partial or total knee replacement depends on where the knee is worn

Partial replacement fits wear in one knee area

The other knee areas must still work well. Your ligaments must give enough support. Your leg also needs to sit straight above the knee.

Partial surgery keeps more bone and tissue. Some people had an easier early recovery. Other knee areas can still wear later.

One study compared people suited to either operation. At five years, both groups had similar soreness and movement. They also needed another operation at similar rates.

Total replacement covers the whole knee surface

Total surgery covers the whole knee surface. It can fit wear across several areas. More bone and tissue are changed.

At ten years, both groups still reported similar soreness and movement. Some people in each group needed another operation. Your result can't be known ahead.

Reports from many hospitals found total replacements lasted longer on average. The reports covered many surgeons and patients. Your knee still needs its own exam.

The worn area decides which operation may fit

Ask where wear shows on your X-ray. Have the surgeon check your ligaments too. Don't leave that check out.

Tell the surgeon which movements you miss. Include walking, stairs, sleep, and yard work. You'll keep the talk tied to your life.

Before the visit, note what still helps. Stop when soreness turns sharp or keeps growing. Gentle movement can limit stiffness.

Sources

1. TOPKAT randomised 528 patients with medial compartment knee osteoarthritis across 27 NHS hospitals to partial (unicompartmental) or total knee replacement. At 5 years there was no significant difference in mean Oxford Knee Score (difference 1.04, 95% CI -0.42 to 2.50), reoperation frequency was similar (22/245 partial vs 28/269 total) and revision rates were 10/245 versus 8/269.

   Beard DJ, Davies LJ, Cook JA, et al. — Total versus partial knee replacement in patients with medial compartment knee osteoarthritis: the TOPKAT RCT.. Health Technology Assessment, 2020. DOI: 10.3310/hta24200.

2. At 10 years, TOPKAT found no clinically meaningful difference between partial and total knee replacement in Oxford Knee Score (mean difference 0.27, 95% CI -1.59 to 2.13). Complications by treatment received were 53/245 (22%) for partial versus 74/270 (27%) for total; reoperations including revision were 9% in both arms; revisions were 15 (6%) versus 11 (4%). Partial replacement was more cost-effective, with lower healthcare costs (mean difference -GBP 731, 95% CI -1352 to -110).

   Beard DJ, Davies LJ, Cook JA, et al. — Assessing clinical and cost effectiveness of total versus partial knee replacement (TOPKAT): 10-year follow-up of a multicentre, randomised controlled trial.. The Lancet Rheumatology, 2026. DOI: 10.1016/S2665-9913(25)00250-4.

3. Pooled national registry data covering 299,291 total knee replacements across 14 registries give a 25-year all-cause survival of 82.3% (95% CI 81.3-83.2); pooled 25-year survival of unicompartmental knee replacements across four registries was 69.8% (67.6-72.1).

   Evans JT, Walker RW, Evans JP, et al. — How long does a knee replacement last? A systematic review and meta-analysis of case series and national registry reports with more than 15 years of follow-up.. The Lancet, 2019. DOI: 10.1016/S0140-6736(18)32531-5.