hello this is Dr Gay from forsake MRI and this is a video about the anterior crocheted ligament this first patient has a normal ACL and the second one I will show has a torn ACL and this is one of our most common injuries we see in the knee often requiring surgery because of the instability and so this is the normal patient you can see the femur coming down here it ends at the level of the knee joint which is right here and Below we see the tibia to the left is the front of the knee we see the kneecap or the patella and the ACL is right in the middle of the knee joint and here it is we see the acell coming off the back of the femur coming down obliquely this dark band is the intercrusted ligament or ACL and attaches to the front of the tibia and the ACL keeps the tibia from shifting forward so if the ACL tries to go forward this is almost already taut right now if it goes any further forward this will become completely taut and stop the anterior motion of the tibia when this tears or ruptures the tibia can drift forward which we call anterior tibial translation now the PCO goes the opposite direction these are right next to each other making a sort of an X the ACL this way PCL this way and the PCL this is the opposite keeps the tibia from going backwards if it shifts backward this becomes taut it stops it and this ACL is a little bit smaller more wispy than the PCL it can tear more easily so this is the normal ACL this is a coronal view the normal ACL this is the middle of the knee this is called the intercondylar notch of the femur and this vertical band here this is the ACL going vertically here is the PCL next to it and here they are the ACL vertically here's the PCL next to it it's dark band and they're within the Intercontinental notch in the central part of the knee now we're going to find the patient who has the ACL tear and here it is so this patient has a torn a interior cruciated ligament this is the ACL coming down here normally we see a nice dark band like the last patient in this patient we see this fog this poor poorly defined region of intermediate signal intensity and if we look more closely in the window we see a little curve linear band here this is the ACL that's torn and folded forward upon itself we can see something else back here this is the PCL that goes the opposite direction remember PCL looks pristine and the ACL is a Lacks completely torn folded anteriorly upon itself and there's some ill-defined signal in here now on this View we see another thing here this is the lateral femoral condyle normally it's nice and round and smooth we see a little divot here this is where the tibia has impacted we see the marrow edema back here So the patient's knee would probably flexed a little bit and this bone way back here slipped over here hit right here and impacted this bone causing it to be cupped like this and then it jumped back to normal position so a long distance this went and had a significant injury of both of these bones and if we go to the opposite side of the knee this is the medial side we see another bone bruise back here bone contusions or bruises look bright so this bone here also moved forward and impacted and came back but there's no corresponding bruise over here so this is a torn or ruptured into cruciated ligament we see the ACL completely torn we see evidence that this bone shifted really far forward and packed it and came back to position rupturing that ACL we also see that the PCL is intact we can also see this on one more sequence here this is called the coronal View and on the coronal view we see the vertical band here is not well defined it's just intermediate and Signal there's gray we don't see the nice dark band and this one this fluid sensitive normally we see a really well-defined black band and instead we see this intermediate fog and the little brightness here which is abnormal this is the PCL the next one that looks just perfectly fine again that ACL is completely torn and one last little bit of anatomy this is the lateral collateral ligament lateral collateral ligament complex right here is the fibular collateral ligament it is thick and intermediate in Signal this is partially torn or sprained I'm off here on the lateral side and the medial side the medial collateral ligament is intact thank you very much