MCL injury

[Michael Shilton]

Hi Stephen
I noticed in your live scan of the knee you mentioned any fluid in the deep MCL region near the meniscus represents an injury. I’ve attached some photos of a patient with an anechoic area in that region that I’d like your opinion on for my education. As it happens this is not the clinically painful area of the knee. He also has some less echogenic areas on the anterior distal margin of an otherwise healthy looking Patella tendon. Is this a common finding? Again this was not particular tender as is perhaps also not relevant clinically for this patient.
2 years ago MRI diagnosed superior lateral Hoffa’s impingement in this patient and, although I understand US is not the best modality, it does seem there is a hyperechoic area at his site of pain in this area not seen on the asymptomatic side. He also has fluid in the lateral gutter and some in the supra patella recess and under his ITB. I’ve added the pictures of these for interest but my main questions are regarding the MCL and patella tendon, thanks. Mike

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[Stephen Bird]

Hi Mike,

I am not particularly concerb=ned by these images.

There is a joint effusion and that would be my main diagnosis.

The bit of fluid adjacent to the proximal edge of the medial meniscus i think is just joint fluid as well.

The fluid I mentioned in the presentation is where there is fluid between the meniscus and the MCL. To describe it better imaging th meniscus is a triangle on the ultrasound. The base of the triangle is closest to the transducer and the apex of the triangle is deeper. Fluid between the flat part of the base of the triangle and the MCL is what I mentioned and this represents a menisco’capsular separation. I don’t this is the case here as the base f the triangle is nicely attached to the MCL.

The distal patella tendon is also fairly normal. I see what you mean that the very superficial fibres are slightly less echogenic but I would not make much of this.

I agree fat pad impingement is not often an ultrasound diagnosis but if the fat pad is more echogenic than the other side you can suggest the diagnosis.

Nice images Mike,

Steve

[Michael Shilton]

Great, thanks for the info Steve.

[Diane]

Hi Steve, is a more echogenic fat pad the only feature to suggest impingement? Would you ever see the fat pat actually protruding into the patellar tendon or anything wild like that? (Not sure if I’m “MSU”).

Thanks!

[Stephen Bird]

Hi Diane,

Yes this would be MSU I think !

Fat pad impingement is most commonly not diagnosable with ultrasound but rather MRI,

The impingement occurs under the acoustic shadow of the bony patella so hence we don’t see it well,

In some cases the impingement causes a large enough area of fat pad oedema that we see it protruding from beneath the patella as an echogenic blush in the fat pad.

Most cases I scan we have an MRI already performed and you can easily see the increased signal in the fat pad and then the ultrasound is normal. We sometimes are asked to inject the area and we simply guide the needle under the patella in the area where the MRI shows the abnormality.

I have never sen it protruding into the patellar tendon or anything cool like that.

Steve

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