Total vs partial knee replacement
There are two ways to resurface an arthritic knee. A total knee replacement resurfaces the whole joint; a partial knee replacement resurfaces only the one worn part and leaves the rest alone. Neither is universally better. Which suits you depends on where the arthritis is and the state of the rest of your knee.
What's the difference?
Total knee replacement resurfaces all the worn surfaces of the knee with metal and plastic components. It's the more common operation and suits the widest range of knees, including arthritis affecting more than one part of the joint. More on knee replacement.
Partial (unicompartmental) knee replacement resurfaces only the single compartment that's worn out, most often the inner (medial) side, and leaves the healthy cartilage and the knee's own ligaments, including the anterior cruciate ligament, in place. Because most of the knee is untouched, it's a smaller operation.
Who is suitable for a partial knee?
A partial knee replacement is an option when the arthritis is confined to one compartment, the ligaments are intact, and the knee isn't badly deformed or stiff. If the arthritis is spread across the joint, the ligaments are damaged, or there's significant deformity, a total knee replacement is the better choice. Only some people are suitable, and an X-ray and an examination of the knee decide it. Dr Tsung will tell you which fits your knee.
The case for a partial knee
For the right knee, a partial replacement has real advantages. It's a smaller operation with less blood loss, recovery is often quicker, and because it keeps the knee's own ligaments and healthy cartilage, the knee can feel more natural to some people. Early complication rates tend to be lower than for a total knee replacement.
The trade-off
The main trade-off is the chance of needing further surgery. In large registry data, partial knee replacements are revised about twice as often as total knee replacements.¹ Trials tell a more favourable story: over ten years in TOPKAT, the largest randomised comparison of the two operations, partial and total knee replacement had similar reoperation and revision rates and similar overall results, with partial tending to have slightly fewer complications and slightly better quality of life at lower cost.²
The gap between the registry and trial findings comes down to selection and accuracy. A partial knee replacement is less forgiving of being done in the wrong knee or positioned imperfectly. Chosen for the right patient and placed accurately, it performs very well; outside that, it's more likely to need revision. When a partial knee does need redoing, it's usually converted to a total knee replacement, which generally works well. More on how long a knee replacement lasts.
Where precision comes in
Because a partial knee replacement is less forgiving of small errors in implant position, accuracy matters, and this is where robotic assistance may help most. Dr Tsung uses the Mako system to plan and place both partial and total knee replacements from a CT scan of your knee. More on robotic-assisted joint replacement.
Which is right for you?
It comes down to your knee, not a preference for one operation over the other. After an X-ray and examination, Dr Tsung will tell you whether you're suitable for a partial knee replacement and talk through the trade-offs honestly so you can decide together. For many knees a total knee replacement is the right answer; for a well-selected knee, a partial can be a very good one.
Common questions
Is a partial knee replacement better than a total?
Neither is better overall. A partial suits a knee with arthritis in only one compartment; a total suits the rest. The right operation is the one that matches your knee.
Will a partial knee feel more natural?
It can, for some people, because it keeps the knee's own ligaments and healthy cartilage. Individual results vary.
Does a partial knee wear out faster?
In registry data it's revised about twice as often as a total knee,¹ though in trials of well-selected patients the rates are similar.² Selection and accurate placement matter a great deal.
Can a partial knee be converted to a total later?
Yes. If a partial knee replacement wears out or fails, it's usually revised to a total knee replacement, which generally works well.
How do I know if I'm a candidate?
An X-ray and an examination of the knee will show whether the arthritis is confined to one compartment and the ligaments are intact. Dr Tsung will advise.
Speak to Dr Tsung
To discuss your options, you'll need a referral from your GP or another specialist. Call reception on (07) 5676 9930 to book your first appointment, or email hello@sgco.au. New patients can pre-register online before the visit; the form prepares your records and does not book an appointment. More on knee replacement and robotic-assisted joint replacement.
References
- Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). Hip, Knee & Shoulder Arthroplasty: 2025 Annual Report. Adelaide: AOA; 2025.
- 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. Lancet Rheumatology. 2025.