KNEE · TREATMENT DECISIONS
Total Knee vs Partial Knee Replacement
Understanding when a total knee replacement or unicompartmental knee arthroplasty (UKA) fits your joint.
Match the Replacement to the Arthritis
Knee replacement is considered when arthritis causes substantial pain and limits everyday life despite appropriate nonsurgical care. The choice between total knee replacement and unicompartmental knee arthroplasty (UKA, or partial replacement) depends on where the arthritis is, ligament function, alignment and motion.
[1][2]| Partial knee replacement · UKA | Total knee replacement · TKA | |
|---|---|---|
| What is replaced? | The worn surfaces in one compartment; more healthy joint surfaces and ligaments are preserved. | The main worn joint surfaces are resurfaced with implants; the kneecap surface may also be treated. |
| Typical fit | Advanced arthritis confined to one suitable compartment, with functional ligaments and acceptable motion and alignment. | More widespread arthritis or a knee whose instability, deformity or stiffness makes partial replacement unsuitable. |
| Potential advantage | Less extensive surgery and often a faster early recovery; some patients report a more natural-feeling knee. | Addresses disease across multiple compartments in one operation. |
| Main tradeoff | Arthritis can progress in the unreplaced compartments, potentially requiring further surgery. | More of the joint is resurfaced, and recovery can be more substantial. |
Who Is a Good Candidate for UKA?
Partial replacement is an option for a selected knee, not simply a smaller operation chosen on preference alone. Examination and weight-bearing X-rays help determine whether the remaining compartments and ligaments can support it. Inflammatory arthritis, marked stiffness or significant ligament dysfunction may make it unsuitable. Age by itself should not determine eligibility.
[1]What Does Long-term Evidence Show?
TOPKAT RANDOMIZED TRIAL · TEN YEARS
Both Options Can Work Well in the Right Knee.
The TOPKAT trial enrolled 528 patients with isolated medial-compartment arthritis who were suitable for either operation. At ten years, the groups had no clinically meaningful difference in their Oxford Knee Scores. Revision occurred in approximately 5% of each group when analyzed by the treatment patients were originally assigned.
This supports both approaches for appropriately selected patients treated by experienced surgeons. It does not mean UKA is appropriate for arthritis throughout the knee or that an individual patient’s revision risk is identical.
[3]Choosing Around Your Goals
Discuss walking, stairs, work and preferred recreation—not just the implant. Either operation requires recovery and carries risks including infection, blood clots, stiffness and persistent pain. Replacement can improve function without creating a completely normal knee, and high-impact activity is generally discouraged afterward.
[2]Questions to Bring to Your Visit
- Is my arthritis truly limited to one compartment?
- Are my ligaments and alignment suitable for a partial replacement?
- What might make you recommend a total replacement instead?
Sources & Further Reading
Evidence checked October 3, 2026. General education; recommendations depend on an individual evaluation.