When arthritis is confined to one part of the knee, you may not need the whole joint replaced — a smaller operation with a faster recovery, for the right knee.
What is partial knee replacement?
In a partial knee replacement — also called unicompartmental knee replacement — only the damaged compartment of the knee is resurfaced, most commonly the inner (medial) compartment. The healthy cartilage, bone, and ligaments in the rest of the knee are left alone, including the ACL.
Because less is removed, the incision is smaller than with a total knee replacement, and more of your natural knee is preserved.
Who is a candidate?
A partial knee replacement works when arthritis is confined to one compartment of the knee, the ligaments (especially the ACL) are intact, and the alignment of the leg is correctable. Significant deformity, arthritis in multiple compartments, or inflammatory arthritis usually point toward a total knee replacement instead.
Be direct about this: most knees with advanced arthritis need a total. Partial knee replacement is for a minority of patients — and proper selection is everything. The wrong patient with a partial knee is worse off than the right patient with a total.
Partial vs. total knee replacement
For the right candidate, a partial knee replacement has real upsides: it tends to feel more like a natural knee, recovery is typically faster, and less bone is removed — which matters if you ever need another operation down the road.
The trade-off is durability data. In joint registries, partial knee replacements show a slightly higher revision (re-operation) rate than total knees — though part of that reflects a lower threshold for revising them. And there is a well-established fallback: if arthritis later spreads to the rest of the knee, a partial can be converted to a total knee replacement. Neither option is universally better; the right choice depends on your knee.
Why precision matters here
Partial knee replacement is a technically demanding operation. The components are smaller, the margins for error in positioning are tighter, and getting the alignment and ligament balance right is what separates a great result from a mediocre one.
This is one reason Dr. Sloan uses the Stryker Mako robotic system for partial knee replacements. The evidence here is genuinely encouraging: a recent randomized trial comparing robotic-assisted to conventional partial knee replacement found meaningful differences in implant positioning — the kind of precision advantage that matters most when the target is small. As with all robotics research, longer-term patient outcomes are still being studied, and Dr. Sloan will tell you exactly where the evidence stands.
What to expect
- Before surgery: imaging to confirm the arthritis is confined to one compartment, medical clearance, and pre-operative education.
- Day of surgery: around 80% of Dr. Sloan’s primary joint replacement patients go home the same day.
- Recovery: often quicker than after a total knee replacement — many patients are walking with assistance the day of surgery — but it still takes weeks of dedicated rehabilitation.
Frequently asked questions
How long does a partial knee last?
A well-done partial knee replacement in the right patient can last many years, often a decade or more. Longevity depends on your activity level, weight, and how the rest of the knee holds up over time.
Will it feel more natural than a total knee replacement?
Many patients report that it does. Because your ACL and most of your natural knee are preserved, the joint often moves and feels closer to normal than a total knee replacement.
What if arthritis spreads to the rest of my knee?
That’s the known trade-off, and there is a standard answer: the partial can be converted to a total knee replacement. Conversion is a well-established procedure, and having had a partial first does not “use up” your options.
Am I a candidate if I’m young?
Possibly — in fact, younger, active patients with single-compartment arthritis are often the ideal candidates, partly because less bone is removed now, preserving more for the future. The evaluation is based on your knee, not your age.
Related podcast episodes
- Episode #5 — Who Needs a Partial Knee Replacement?
- Episode #53 — Are Robotics the Future of Joint Replacement? (Prof. Fares Haddad)
- Bonus — Is Partial Hip Replacement Like Partial Knee Replacement?
- Episode #41 — RACER Knee: Does Robotic Knee Replacement Actually Improve Outcomes?
Schedule a Consultation
Wondering if a partial knee replacement could work for you? Meet with Dr. Sloan for an evaluation.
Schedule an Appointment · or call 978-369-5391.