What is a partial (unicompartmental) knee replacement?

Firstly, one must understand a little bit of nomenclature for the knee.  There are 3 compartments or "areas" where we look for arthritis.  These are called the "medial," "lateral" and "patellofemoral" compartments.  If only one compartment has arthritis or loss of cartilage, then there are surgeries designed to partially replace the injured part of the knee.  This is how we come up with the term "partial" knee replacement.
Picture
The three compartments of the knee. If only one has disease, a partial (unicompartmental) knee replacement may be for you

Am I a candidate for partial knee replacement?

That's a tough question to answer without seeing you!  Every patient is different.  Our surgeons follow recommendations of the best data available.  Generally speaking, an age between 45-65 is an ideal range, with isolated arthritis to only one part of the knee.  In Atlanta, we have noticed a severe problem with patients having partial knee replacements while they have arthritis in more than one compartment.  Arguments are that new implants can "accomodate" arthritis in other parts of the knee are false.  Studies like this have been performed by manufacturers and have lead to increased amount of surgeons doing knee replacements in patients who likely are not candidates.  Our surgeons do not go by trends, we go by data.  We always have an MRI to prove the arthritis is located to one compartment. 
Surgical Indications

Age 45-65
Excellent bone quality
Isolated Arthritis to a single compartment
Failure of conservative management
No contracture (knee can't get fully straight)
No history of rheumatoid arthritis
Must have ACL/PCL intact
Intact lateral meniscus with no tears
No arthritis under the knee cap

What is the difference between a total knee and a partial knee replacement?

The main differences between the two is that a partial knee replacement only replaces one compartment of the knee while a total knee replacement resurfaces all 3 compartments.  Below we have pictures and a pros/cons for each device as well as pictures to help you learn the difference!

Partial Knee Replacement

Pros
Slightly smaller incision
Slightly faster rehab
Theoretically less pain after procedure
More "normal" knee motion

Cons
Shorter lifespan than full knee replacement
Very specific indications (reason to do)
Higher failure rate than total knee at 10 years


Picture
A well placed partial knee replacement due to arthritis on the inside portion of the knee.

Total Knee Replacement

Pros
Longer lifespan of implants in all studies
Used when partial knee replacement fails
More reproducible results
Less likely to need revision

Cons
Slightly longer recovery
Less "normal" feeling
More rehabilitation usually required


Picture
A well placed knee replacement performed for a patient with arthritis in all 3 compartments of the knee.

Are you ready for a partial knee replacement?

Give us a call today if you are interested in seeing if you are a candidate for a partial knee replacement!   You can always fill out our survey and we'll get back to you within 1-2 business days!
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