common knee injuries (unhappy triad)

[MudPhud20XX]

Kaplan anatomy says they are:
1. Tibial (medial) collateral lig
2. Medial meniscus
3. ACL

FA 2012 says:
1. Medial collateral lig
2. Lateral (not medial) meniscus
3. ACL

So between medial vs lateral meniscus which one is it?

FA says specifically "not medial," I'm not sure why though.

Kaplan also explains that medial meniscus is firmly attached to the tibial (medial) collateral lig. Therefore, it is less mobile and is more frequently injured than the lateral meniscus, which is directly contradicting to FA.

Can anyone help me out?
Many thanks in advance.

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[CherryRedDracul]

Ah yes, this is often debated.

The "classic unhappy triad" described by O'Donoghue is ACL, MCL, and medial meniscus. However, further research showed that it was the lateral meniscus that gets injured more commonly than the medial meniscus; think of the injury as an acute valgus stress (e.g., getting tackled in the side of the leg) where the lateral meniscus is getting crushed underneath. Yet in chronic ACL insufficiency, the medial meniscus gets damaged because of inadequate stabilization by the ACL.

All in all:
- "Classic" unhappy triad: ACL, MCL, medial meniscus
- What more commonly occurs in acute injury: ACL, MCL, lateral meniscus
- Chronic ACL insufficiency: weakened ACL --> medial meniscus damage

 

[MudPhud20XX]

Ah yes, this is often debated.

The "classic unhappy triad" described by O'Donoghue is ACL, MCL, and medial meniscus. However, further research showed that it was the lateral meniscus that gets injured more commonly than the medial meniscus; think of the injury as an acute valgus stress (e.g., getting tackled in the side of the leg) where the lateral meniscus is getting crushed underneath. Yet in chronic ACL insufficiency, the medial meniscus gets damaged because of inadequate stabilization by the ACL.

All in all:
- "classic" unhappy triad: ACL, MCL, medial meniscus
- what more commonly occurs in acute injury: ACL, MCL, lateral meniscus
- Chronic ACL insufficiency: weakened ACL --> medial meniscus damage

Thank you so much for the explanation!

 

[AnonymousD.O.]

Thank you so much for the explanation!

Perfect explanation, this is for sure the real deal, at least based off my professors.....BUT, is this was is in USMLE world? I think as of now I would answer on the USMLE as ACL, MCL and Lateral Meniscus. Has anybody done this question on USMLE world and got something different in the explanation? I'm pretty sure in FA 2013/2014 has it as the Lateral Meniscus as well

 

[THH]

COMLEX at least is still asking it both ways. So be sure to read the question and ID whether they are asking for the classic triad specifically or just the most likely triad of injuries in the patient.

 

[dyspareunia]

Ah yes, this is often debated.

The "classic unhappy triad" described by O'Donoghue is ACL, MCL, and medial meniscus. However, further research showed that it was the lateral meniscus that gets injured more commonly than the medial meniscus; think of the injury as an acute valgus stress (e.g., getting tackled in the side of the leg) where the lateral meniscus is getting crushed underneath. Yet in chronic ACL insufficiency, the medial meniscus gets damaged because of inadequate stabilization by the ACL.

All in all:
- "Classic" unhappy triad: ACL, MCL, medial meniscus
- What more commonly occurs in acute injury: ACL, MCL, lateral meniscus
- Chronic ACL insufficiency: weakened ACL --> medial meniscus damage

I thought the MCL is more commonly injured because it is less mobile (than the LCL).. not because of inadequate stabilization.

Can't remember the details, but it's something to do with the menisci...?

 

[CherryRedDracul]

I thought the MCL is more commonly injured because it is less mobile (than the LCL).. not because of inadequate stabilization.

Can't remember the details, but it's something to do with the menisci...?

As far as I know, the MCL is more commonly injured simply because the insult is more like to be direct to the lateral side of the knee than to its medial side. Maybe the fact that the LCL is not attached to any menisci might make it less vulnerable to injury, but I really don't know.

Funny thing (well, not so funny) is that my friend took a blow to the lateral side of his right knee due to a tackle gone wrong while we were playing soccer 3 weeks ago. We had to carry him off the field because his knee was buckling inward when he tried to walk. Without an MSK exam, I was positive his MCL was screwed and it was possible his ACL was injured as well.

He goes to the doc and reports to me that he has a full ACL tear. Not really a surprise but I didn't expect it to be that bad. But then he tells me that it was his LCL that was torn, not his MCL. I had to ask him to repeat what he told me so I'd know I wasn't just hearing things. Confirmed that he was diagnosed with an LCL tear. Go figure. 😕

 

[dyspareunia]

As far as I know, the MCL is more commonly injured simply because the insult is more like to be direct to the lateral side of the knee than to its medial side. Maybe the fact that the LCL is not attached to any menisci might make it less vulnerable to injury, but I really don't know.

Funny thing (well, not so funny) is that my friend took a blow to the lateral side of his right knee due to a tackle gone wrong while we were playing soccer 3 weeks ago. We had to carry him off the field because his knee was buckling inward when he tried to walk. Without an MSK exam, I was positive his MCL was screwed and it was possible his ACL was injured as well.

He goes to the doc and reports to me that he has a full ACL tear. Not really a surprise but I didn't expect it to be that bad. But then he tells me that it was his LCL that was torn, not his MCL. I had to ask him to repeat what he told me so I'd know I wasn't just hearing things. Confirmed that he was diagnosed with an LCL tear. Go figure. 😕

Yeah it has something to do with the fact that the LCL isn't attached to the meniscus, but the MCL is. Also something to do with how the menisci aren't very mobile. Can't remember the details, but it was emphasized in our anatomy class.
Google didn't yield anything. Oh well.

 

[AnonymousD.O.]

Yeah it has something to do with the fact that the LCL isn't attached to the meniscus, but the MCL is. Also something to do with how the menisci aren't very mobile. Can't remember the details, but it was emphasized in our anatomy class.
Google didn't yield anything. Oh well.

If you think about the mechanism of the injury, (i.e. classically a football player getting a helmet to the side of his knee) it is the MCL that gets torn as the knee buckles inward.

 

[acciddropping]

Ah yes, this is often debated.

The "classic unhappy triad" described by O'Donoghue is ACL, MCL, and medial meniscus. However, further research showed that it was the lateral meniscus that gets injured more commonly than the medial meniscus; think of the injury as an acute valgus stress (e.g., getting tackled in the side of the leg) where the lateral meniscus is getting crushed underneath. Yet in chronic ACL insufficiency, the medial meniscus gets damaged because of inadequate stabilization by the ACL.

All in all:
- "Classic" unhappy triad: ACL, MCL, medial meniscus
- What more commonly occurs in acute injury: ACL, MCL, lateral meniscus
- Chronic ACL insufficiency: weakened ACL --> medial meniscus damage

Hey do you have an explanation for "Chronic ACL insufficiency: weakened ACL --> medial meniscus damage"?