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Author Topic: How many have had false positive ACL tears on MRI?  (Read 4981 times)

Offline BayBells

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How many have had false positive ACL tears on MRI?
« on: March 01, 2005, 01:05:32 AM »
Just curious about how often people have had MRI report say they have a torn ACL but physical evidence proves otherwise -- negative Lachman, negative draw test, etc.  Or, in cases of arthoscopy, proved there was not tear?  Thanks...

Offline lisa_elliott

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Re: How many have had false positive ACL tears on MRI?
« Reply #1 on: March 01, 2005, 03:29:15 AM »
I have never heard of one, and I spoke to my sergon about it and he has never had one and he has been reconstructing ACL's in Australia for over 15 years.
August, 2004: Netball Injury, complete ACL tear (right knee).
September, 2004: ACL reconstruction, hamstring graft
February, 2005: First Water Ski Racing Event. (Placed 3rd)
March, 2005: Second Water Ski Racing Event. (tore Medial Ligament)

Offline spartanpele

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Re: How many have had false positive ACL tears on MRI?
« Reply #2 on: March 01, 2005, 01:25:17 PM »
I've had one...and it was recently too. 

On Jan 4th I injured my knee playing indoor soccer.  A few days later my family doctor did the physical tests.  He said it seemed as though I might have a meniscus tear, but the ACL and other ligaments were fine.  He ordered an MRI to verify everything. 

The MRI came back as saying I had a complete ACL tear, plus a meniscus tear. I saw a physical therapist.  He did the physical tests and thought the ACL was fine.  I saw another doctor, he thought the ACL was intact. 

Finally I saw a very accomplished knee specialist/orthopedic surgeon.  He went through the physical tests, Lachemann, Drawer, Varus, Valgus, etc..and he thought I had a partial tear, not a complete tear.  He then showed me the MRI on the computer and played the different scans.  He told me that because of the angle of the scans, an ACL can appear to be torn, even though it isn't.  He's one of the best surgeons in the Midwest (US), and does all the main athletes for the colleges in the area, including some pro athletes...so I trust his opinion.

So yes...its possible that the MRI can be wrong.  Remember that its simply a radiologist looking at a computer screen, and the MRI is supposed to support a diagnosis.  Its the physical tests and signs that you will need to treat anyways...so the best rule of thumb is to always treat the symptoms...not the MRI. 

If your knee is giving out on you (mine never did after the injury), is weak, loose, then I'd lean towards an ACL tear unless you have meniscal tears too.  The meniscus could be causing the problem.  If your knee feels strong and doesn't feel loose or  gives out on you, then the MRI reading might be incorrect. 

If you're in doubt...get more then one doctor to run the physical tests again.  Its possible that you have a partial tear and not a complete tear.

Best of luck!!

Offline jb-knee-geek

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Re: How many have had false positive ACL tears on MRI?
« Reply #3 on: March 01, 2005, 02:26:55 PM »
He told me that because of the angle of the scans, an ACL can appear to be torn, even though it isn't.  He's one of the best surgeons in the Midwest (US), and does all the main athletes for the colleges in the area, including some pro athletes...so I trust his opinion.

I can only relate my personal experience, I've had 2 MRI scans, on 2 different machines, they both revealed torn ACL's. One MRI was misread by the radiologist and physician assistant. The surgeon's got it right in both cases. So, if you have the scan and can get a 2nd opinion, do it.

I think the differences in MRI images may be due to the quality of the machines. Newer 3D imaging machines in the hands of experienced radiologists and OS's was my best bet. In my case, the picture was worth more than a thousand words or physical tests.

There seems to be a million variables when dealing with knee injuries, thank goodness for boards like these.

My 2 cents.
torn RK ACL March 2001, surgery Aug. 14 2006, after 4 knee sprains since Oct. '05.  Allograft, ~40% medial meniscus removed, some wear in the trochlear groove. Everything else looks good.

Post-op diary: http://www.kneeguru.co.uk/KNEEtalk/index.php?topic=29749.

Offline spartanpele

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Re: How many have had false positive ACL tears on MRI?
« Reply #4 on: March 01, 2005, 05:37:50 PM »
Hey, just so people aren't confused on my MRI thoughts. 

If you had a severe knee injury and you felt a severe pop, and then the knee is very loose and unstable, ...then the odds are that you tore the ACL either fully or partially.  A good ortho surgeon or qualtiy physical trainer, etc.  will also be able to do physical tests (Lachemanns, Drawer, etc.) that will indicate a full or partial tear as well. 

An MRI will clearly show a complete rupture if everything is gone, especially if its right down the middle...however, when you get to the different types of partial tears, at angles, at the ends, it can be difficult to completely see it on the MRI scans. 

The machines used at my hospital were actually top of the line machines, including some newer experimental scans that aren't on the market yet (our hospital serves the university which has research grants and a relationship with manufacturers) that show even more complete images....Even so, the radiologist misread the scans because of the angles of the scans and the location of my acl tear.

Is it rare?..sure... but as I said, you have to look at more then just the MRI, you also have to go by the physical signs of swelling, tightness in the joint cavity, weakness, instability, giving out, etc, etc... 

And obviously...beyond the 2nd or 3rd opinion..if necessary, you can have additional MRI or CT scans, or go in arthroscopically and verify a tear as well.

I hope this clarifies things a bit better.  I was lucky...the radiologist who read the MRI said I had a complete tear and it turned out to be a partial tear.  But the odds may be against you depending on your symptoms.

Offline BayBells

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Re: How many have had false positive ACL tears on MRI?
« Reply #5 on: March 02, 2005, 05:40:11 AM »
Thanks for all of your responses. It turns out that my daughter's doctor (also a top-notch knee specialist) has ruled against the MRI as of this morning's appt.  His tests showed firm endpoints, slight laxity but not much more than her other knee, and equal stability for both knees. He's ordered 3 more weeks of PT - says it takes six weeks to heal micro tears of the ACL and that she's doing great - best case scenario -- keep the brace on, just run straight ahead and next week, she gets the KT-1000 test to confirm equal stability.  The grade 3 meniscus tear (per MRI report) is not an issue, "misread by radiologist."  SO, it appears that MRI's are not the final word.

p.s. should note that she had no "popping" sound, no bruising, and has never felt like her knee was going to give out or buckle.
all she felt was her knee cap slide out and then back in again - that caused her to fall down in the middle of a basketball game (HS varsity).  the point: all of her signs and symptoms pointed to one thing while the mri pointed to needing surgery due to a tear.

thanks again for your responses!!   :) 

Offline jb-knee-geek

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Re: How many have had false positive ACL tears on MRI?
« Reply #6 on: March 02, 2005, 03:04:17 PM »
not sure I understand you point as far as MRI goes. They provide a snapshot picture, the OS always has the final word. Sounds like the radiologist mis-read the meniscus problem, which is not uncommon.

I wouldn't take an ACL "micro-tear" lightly in an active athlete.  Probably don't require surgery, but, they need TLC, bracing may be an answer or at least better leg workouts.

The OS can tell, from the MRI, what level sprain. I, II, III.

check this for more details:

http://orthoassociates.com/knee_lig.htm

good luck
torn RK ACL March 2001, surgery Aug. 14 2006, after 4 knee sprains since Oct. '05.  Allograft, ~40% medial meniscus removed, some wear in the trochlear groove. Everything else looks good.

Post-op diary: http://www.kneeguru.co.uk/KNEEtalk/index.php?topic=29749.