YKC’s Nick London and Dave Duffy have been researching whether the lack of an anterior cruciate ligament causes problems for partial knee replacement patients. The key finding? The Persona Partial Knee implant functions at least as well in patients with an ACL-deficient knee, as for those with an intact ACL.
Even if you’ve never had an issue with your ACL, you’ve probably heard plenty about it. It’s the ligament that athletes often rupture, and reconstruction surgery can often keep them on the sidelines for many months.
A deficient ACL (that is, an ACL that doesn’t work as well as it should) won’t be able to stabilise your knee. You’ll typically find the knee gives way when you attempt to twist or turn. But because not every patient is suitable for ACL reconstruction surgery, and because not all of us need to be able to perform at elite athlete level, there are plenty of people who are getting on with life without a fully functioning ACL.
But what happens when those people develop osteoarthritis?
Osteoarthritis and the ACL
A knee replacement is never the first course of action for someone with osteoarthritis (that is, wear and tear of the knee joint), but it may well be the recommended option once non-surgical alternatives have been exhausted. There are two general types of knee replacement: a partial and total. Which is appropriate depends on how many compartments of the knee have suffered damage. Find more about knee replacements here.
Partial knee replacements have many benefits over their total counterparts, but there’s long been a question over their suitability for patients with ACL-deficient knees.
The question stems from studies of a particular type of partial knee implant that uses a mobile bearing. There are three component parts to a knee implant. In a mobile bearing implant one of those parts is free to move and slide as part of the design. In a fixed bearing implant all parts are locked. Surgeons are recommended to use mobile bearing implants only in patients with intact ACLs because without the ligament there’s an increased risk of dislocating the implant bearing.
Fixed bearing implants offer numerous advantages over their mobile counterparts and YKC’s (and many others’) long-held view is that, generally speaking, they are the better option. According to most joint registries, for example, they have a longer life expectancy. But are they the better option for ACL-deficient patients too?
At least as effective in the ACL-deficient knee
To find out, we’ve been following a cohort of 229 consecutive patients who have had a partial knee replacement using the Persona Partial Knee (PPK) fixed bearing implant. ‘Consecutive’ means that, beyond the requirement that they should all have had a partial knee replacement using the PPK implant, there was no additional selection or sifting of the patient group. Around 10% of the cohort have ACL-deficient knees.
Our evidence, which is based on functional outcomes (that is, how well the knee performs) and patient satisfaction data at one and two years after surgery, shows that the knee replacement results in “excellent functional outcomes”, and that the PPK is at least as effective in the ACL-deficient knee as for those patients with intact ACLs.
You may find the use of “at least” a little strange. That’s because, on average, the PPK performed even better in those with a deficient ACL as those with an intact one. We can’t really explain that other than to say that perhaps the expectations of those specific patients were not as high and therefore they reported even greater satisfaction than others. This is, we should stress, just conjecture.
Can you have a partial knee replacement if you don’t have an ACL?
Our evidence suggests that you can. We believe that, with the fixed bearing PPK implant, ACL-deficient patients are not functionally disadvantaged compared with those who have an intact ACL. As patients reach five and ten years with the implant, the study will continue to review them to confirm this remains the case.
Read the abstract here: https://www.isakos.com/GlobalLink/Abstract/4449
Feel as though your knee may give way? It could be an ACL injury
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What’s the difference between a total & partial knee replacement? And is either right for you?
What Is Osteoarthritis?
What does osteoarthritis look like? What are the symptoms? And short of surgery, how do you treat it?
Here are some of our knee specialists’ most frequently asked questions for some of our most common procedures