hello and welcome to your online lecture for the anatomy of the knee and by the knee joint what i'm referring to is the tibial femoral joint uh and i'm not referring to the patellofemoral joint so we will have two separate anatomy videos to watch we will have the anatomy of the knee joint or the tibial femoral joint and then there will be a separate online lecture for the anatomy of the patellofemoral joint so if it seems like i skipped through patellofemoral it's okay because we're going to get that in its own separate lecture i happen to treat the joints separately because they are completely different structures the tibial femoral joint represents the articulation between the tibia and the femur right and then the patellofemoral joint represents the relationship of the patella with the femur and so they're different in the way that they behave arthrokinematically right okay so let's start with the video um and in this video what we're going to see is a dislocated patella right the problem is is how long does it take for someone to recognize that this athlete is down on the ground and actually needs help right now simple extension of the knee probably would solve the athlete's problem but there's an inherent reality in this as athletic trainers if you're learning nothing from this video is that we should always be observative of our student athletes right we're about 10 seconds into the injury and yet that athlete doesn't have help quite yet now when we look at how the athlete or the patient actually injured him or herself we can certainly see that it's a non-contact injury right which brings up the other point of this lecture a lot of the knee injuries that happen within the actual tibial femoral joint will be non-contact injuries in other words no one will be around the student athlete when this injury actually happens typically it's a landing mechanism but in this case it's a pivoting cutting kind of mechanism so we have to make sure that we are always observing uh our student athletes when they're on the field or on the court or in practice or competition so unlike the ankle joint which we know that the ankle joint is one of the most commonly reported injuries across all sports in the united states when we look at the ankle or the knee epidemiology what we know is that among college professional high school sports or youth sports we know that the knee is the most common injury that you will encounter in the high school setting so if you are an aspiring high school athletic trainer most often what you're going to see come into your clinic most often are going to be knee pathologies i've listed and ordered the most common types of knee injuries that occur at the high school level and then this again is is reported by the united states statistics so this is an evidence-based statistic so the most common injury reported among high school student athletes is going to be the mcl or medial collateral ligament followed secondarily by the patella or patellar tendon or tendonitis tendonitis and then look at what we get next the third type of pathology that reports to the clinic is going to be acls so we can see that acls even though they get a lot of notoriety although they're way newsworthy right so and so in in the nfl just returned what two weeks ago what happened we had three or four acl injuries in the first week of returning to play right so it gets a lot of notoriety but we can see that it's probably not the most common knee pathology that we're actually going to interact with or see granted it is one of the injuries that will take a longer time and take up chunks of our times as athletic trainers as you rehab them we also know i'm assuming you all know that girls are most likely to injure their acl when compared to their male counterparts and there is a ton of research to suggest several different factors both intrinsically and extrinsically so uh extrinsically the the link or rise in acl injuries when compared to their milk counterparts females have weaker hamstrings females tend to land in ingenu valgus right and then intrinsically what we know about females is that during menstruation in particular there's increase in laxity which increases their risk of acl injury so we have two different things we have this increase in in knee injuries among high school athletes but then we also know just in general across sports across levels of sports that girls or females are more apt to injure their acl when we compare them to their male counterpart so let's take a look at this video [Music] wow so if we could look at that and we could call that what mechanism of injury do you think is happening right here what's that mechanism of injury i hope that you all said a genuverus right i'm hoping that's what you all said uh so let's play it one more time right here genuverus injury which means the lcl is going to be injured right so quick so subtle those of you working football those of you that will go on to work football something so quick that happened in less than a second's time right you're gonna have to be able to figure out what the mechanism of injury was because that was so quick we hope that his athletic trainers were looking at them but if not they would have to figure that out they would do a varus stress test right all right let's move on to anatomy now that we've talked about epidemiology and um the risk of injury to the knee joint in specific populations now we're diving deep into the anatomy and i really hope that this is a a true review for all of you guys there are two anatomical structures that we're going to talk about today as it relates to the knee joint itself now in the upper right hand corner we have the top part of the femur and we really won't talk about that until we get to the hip so just disregard it well then the most important one of the most important anatomical structures to the tibial femoral joint is the distal portion of the femur so to orient your you guys this is the lateral epicondyle we have the medial epicondyle and then right here we have the adductor tubercle and it is the distal attachment site to all of our adductor muscles right which will become important in the hip and then more distally we have the lateral condyle which is the largest portion of the femur and the medial condyle right and each of these anatomical structures will articulate right distally with the the tibia right what we also know at the femur in particular is that the epicondyles on each side serve as proximal attachment sites for our collateral ligaments right so that lateral collateral ligament is going to attach to the lateral epicondyle and that um medial collateral ligament is going to attach proximally to the medial epicondyle right and so they be serve as important attachment sites for the major ligamentous stabilizers of the actual knee itself distally we know that the condyles like i said are the largest roundest portion of the distal portion of the femur and their major role is kind of twofold it's to articulate with the tibia right um uh by moving or gliding or rolling across those menisci but then last but definitely not least what we know about the condyles is that they are rich or covered in hyaline cartilage and so the major component here is anytime there's a tear or a break to that hyaline cartilage then we expose the bone and we increase the risk of developing osteoarthritis in that knee so again those condyles major role is to articulate with the tibia to create knee movement osteokinematic movement but then they also howls are covered in this thick hyaline cartilage and that hyaline cartilage the job of that highlighting cartilage is to protect the femur the actual femur the bone itself from injury as we move to to the tibia we can kind of see a beautiful picture of the tibial um femoral joint here so we can see that tibial femoral joint here and one of the questions that i always get asked is hey dr cosby is the fibula a part of the tibial femoral joint and the correct answer is no because what we know about the fibula is that it does not in any way articulate with the femur directly right indirectly we know that the lcl has a distal attachment to that fibular head and and so indirectly is there some relationship to the femur yes but is there a direct articulation where the femur is um articulating with the fibula the answer is no guys so we have to keep that in mind so when we're talking about the tibial femoral joint what we're really talking about are these two two bones here and to me that makes perfect sense what we know about the femur is it's the largest bone in the body and then what we know about the tibia is it's the largest bone in the the lower limb right and so those two bones the femur and the tibula tibia articulate right uh and when they articulate uh and when they move arthrokinematically they produce gross movements about the knee or osteokinematic motions at the knee and those osteokinematic motions at the knee are knee flexion their knee extension and internal external rotation now some some may say uh dr cosby is uh valgus and varus in osteokinematic motion i would argue that you some could say that it is a subtle um osteokinematic motion for sure but the four that occur at the knee are knee knee extension and flexion and then tibial internal axonal rotation are the major osteokinematic motions that are going to occur at the tibial femoral joint now as we look at the anatomy of the tibial femoral joint the patella again rests and articulate with the femur so we're going to talk about it in its own online lecture so we're going to ignore that for now and we need to think about the most important anatomical landmarks on the tibia the first one is the tibial tuberosity which is the most anterior uh superior portion of the tibia its major attachment uh anatomical structure is going to be uh via the what good the patellar ligament right that patella ligament is going to have a distal attachment to the tibial tuberosity and then we have medial um and lateral tibial plateaus now on the medial side uh we know that the um the sergeant muscles attach right here right so that sartorius that semitendinosus and that gracilis are all going to come down and attach on that medial right that medial tibial plateau and then last but not least is gertie's tubercle and i like to look at gertie's tubercle on this anatomical specimen the it ban has a distal attachment to the actual tibia itself and that is called gertie's tubercle and it sits right here and you can't see that right that's way unsatisfactory but if we look down here at the knee joint um what we'll see is that it band comes down to attach on to the anterior lateral portion of the tibia um on an anatomical structure called gerdy's tubercle so gertie's tubercle receives that distal attachment of the iliotibial band right so bony wise we have the tibial tuberosity certainly have the patella we have the medial plateau tibial plateau and the lateral tibial plateau on the medial side we have the sergeant muscles distally coming down to attach there so we have sartorius we have gracilis and we have semitendinosus coming down and in lab i'm assuming that you saw that it creates the goose's foot or the three different attachment sites as we move forward now we begin to talk about the muscles of of the thigh and the knee um and so anteriorly we know what we have there we have the the quadriceps and muscles right and in whole if we wanted to look at the quadriceps we could the vastus lateralis the rectus femoris and the vastus medialis and as a whole concentrically they're going to contract to cause what knee extension right and then in addition to the anterior quad muscles uh we also have the sartorius which comes down or rises proximally off of that anterior superior iliac spine right it comes down and has an attachment on to that what the medial tibial plateau so we have um the four quad muscles which i didn't talk about the vastus intermedius because it's deep right super deep to the rectus fem so if we're orienting ourselves here that rectus fam has been transected and reflected back and now we can see the vastus intermedius right all four of the quad muscles come down approximately or come down from a proximal orientation to a distal orientation and by way of the quadriceps tendon right have a superior attachment to the superior pull of the patella right but as a whole the anterior muscles of the knee concentrically contract to control the extension and then they are going to slow down the rate at which we would flex the knee or slow down um knee flexion and the posterior aspect of the knee we have the hamstring muscle group i hope you guys all know these by now but on the uh lateral side of the knee joint we have the the biceps femoris and remember i hope in gross anatomy you saw that there was a long head which had an attachment to the ischial tuberosity but then we also had a short head right which had a direct attachment to the femur so we have the biceps fem which proximally has an attachment to the ischial tuberosity and then comes down distally to attach to the fibular head and then on the medial side we have the muscles of the semitendinosus and membranosis and the way that we can tell which is which is by looking at the long tendon right so this is going to be our semitendinosus and then we have the symbiome membranosis here the all three of those muscles biceps femoris long head and the semis all come up and attach proximally to the what the ischial tuberosity and then distally like i said that biceps fem is going to come down and have an attachment to the fibular head semitendinosus is going to come down and have an attachment to the medial tibial flare right and so these muscles together concentrically contract to do what hopefully you all say consensually contract to create knee flexion and then they slow down the rate at which the move is go the knee is going to move into knee extension now the peasant serene as you guys know it or i call it this the sergeant muscles remember they're all going to attach to that medial tibial flare so they're going to attach right here and i love to kind of look at them as as a group what we know about them so we let's just practice this so we have sartorius tendon we have the gracilis tendon and then we have the tendon of the the semitendinosus all coming down to have that medial attachment to the medial tibial plateau and we can see this down here this was a a dissection that i did with a student you can actually see them on a cadaver and they are just beautiful right they are independent tendons um as they come off of their attachment sites proximally but essentially once they attach to that medial tibial plateau they become kind of one tint in the structure and remember just deep to those tendons there's a bursa so we have a peasant serene bursa because of the friction that occurs across these tendons and the medial tibial plateau so what we know about the pes and serene is that when the foot is planted on the ground you ready for that the pes and serene is going to basically externally rotate the femur on a fixed tibia okay so if you could stand up and do that and imagine that right so if i'm standing up which i'm actually doing right now and my foot is on the ground when i go to externally rotate the femur on that fixed tibia the peasant serene is driving that right when however i am sitting on a table and my foot is suspended in the air the peasant serene is going to pull the tibia into internal rotation that makes sense right if you're thinking about that essentially it's going to do the opposite um of what it did on the ground itself okay so practice that stand up because it becomes important for us to understand this as we progress to the next slide which is the screw home mechanism so the screw hole mechanism is an important concept for all knee injuries in particular the acl so the screw hole mechanism represents the point at which the medial and lateral condyles are locked in a close packed position on the knee so let's think about this um from an arthrokinematic perspective remember we define arthrokinematics as small movements between two bones which create what osteokinematic motion or gross movement right so in this particular case what we are saying is as the femur moves on the tibia in a closed kinetic chain right because the femur's moving on the tibia which means the tibia is stationary it represents the point at which that knee is going to be locked in a full extension right in other words it represents the point at which the the medial and lateral condyles are locked on that tibia in a knee extended position right now can this happen in the open kinetic chain heck yes right it represent the point at which the tibial condyles are locked right think about that the tibia is moving getting into extension so now it's locked on on the femur so we can look at it both ways but i really like to look at the screw hole mechanism from a closed kinetic chain position because that's most often where knee injuries are going to happen so i'm going to define it one more time the screw hole mechanism represents the point in time in which the medial and lateral condyles are locked in a closed position on the tibia the powerpoint says knee joint because that's what your textbook says but on the tibia right so let's think about that if you are standing right now do it with me guys if you are standing right now bend your knee just a little bit and then move into extension now imagine as you're moving into extension that femur right those condyles are rolling over the tibia in such a way until they get to a knee lock position now the screw hole mechanism is extremely important and here's why there are several reasons but the major reason is because what we see a lot in knee injuries most of you some of you have had knee injuries in this group is that one of the things that gets lost after a knee injury is their ability to get into a knee extended or a knee lock position following surgery right now think about it from this perspective the screw hole mechanism represents the ability of that femur in a closed kinetic chain to lock into position on the tibia if i have a knee injury and i can't get into full extension can i can i maximize my screw hole mechanism the answer is no so it's one of the reasons as clinicians we try our best to get our patients full in the extension the other part that we're not talking about here with the screw hole mechanism is just as important as it is for us to get into full extension the screw hole mechanism also represents our ability to unlock the knee joint to move from an extended position move those condyles from a locked position to an unlocked position to allow our knee to flex right so we have two key components we have the locking mechanism of the screw hole mechanism and but then we also have the unlocking mechanism the ability to move from an extended position to a knee flexed position now i've been talking a whole bunch and i think that you guys probably want to see what that actually looks like right so i'm going to show you a youtube video because i think they do it better than i could ever do it you guys uh this group did it so well that i don't think it can be redone what we are going to look at now is this what happens in the screw home mechanism when we are in a standing position so this bone right here is going to be femur this bone right here is going to be tibia and look at what happens in the screw hole mechanism so when the knee is extended do you see that the femur rotates medially to lock to unlock it it's going to rotate externally let's see it one more time as i move into an extended position femur there it rotates medially do you see that to get the knee in a locked position to unlock i now have to externally rotate you see it and then the knee opens up in the flexion let me say that one more time in a closed kinetic chain position arthrokinematically to move from a knee flexed position to a knee extended position that femur rolls rolls rolls on the tibia and when we get to end range extension we'll internally rotate if i want to unlock my knee joint and move into flexion that femur is going to externally rotate or spin externally on the tibia and then start to roll or glide back now let's take a look at this screw hole mechanism still close kinetic chain from an anterior view i think it'll help as well so here we are moving into extension i'm going to immediately rotate that femur externally rotate to open it up right once again i'm moving into extension internally rotate to lock see it unlock accidentally rotate and now the knee flex take a look at this from an open kinetic chain perspective and know that the tibia is now going to be moving so when we move into extension the tibia is going to externally rotate and then internally rotate to open up the knee so opposite that of femur extension externally rotate to lock the knee moving into flexion unlocking internally rotate to unlock the knee so you all can see that this is a complex movement right you have to consider whether or not the patient is in the closed kinetic chain if they're in the open kinetic chain i think how i want to kind of finish the screw hole mechanism is just to say that it is a critical mechanism that plays an important kind of role in terminal knee extension the the knees ability to get into a their most its most stable position right uh and so that becomes an important concept when we think about the knee joint in general we know that it's a hinge joint right where most of the movement that occurs across the knee joint is going to be knee flexion and extension so you can see how the screw hole mechanism the ability to get into full extension the ability to unlock and get into knee flexion is extremely important um kinematic phenomenon of the knee joint right finally i want to talk about the unlocking of the knee because it's the unlocking of the knee that probably is most important with the screw hole mechanism so let's talk about a muscle you guys i think you know a little well which is the pop lydias so what we know about the the popliteus uh in essence is that it has the proximal attachment to the lateral condyle of the femur right and then it comes down and has has an attachment to to the tibia right and what we also know about the popliteus which is extremely important is that in the open kinetic chain it's what's responsible for unlocking the knee joint does that make sense guys it's what's responsible you're tracking for causing the tibia to rotate to unlock the knee or move the knee into a knee flexed position likewise in a closed kinetic chain it's our external rotators at the hip that are going to be responsible for the unlocking or the external rotation of the femur to unlock the knee to move it into knee flexion right i've spent a lot of time here on the screw hole mechanism so i'm hoping that you're understanding that it's an extremely important mechanism for for the knee right it's major role is to make sure that knee gets into terminal extension right that that knee joint is extremely stable right and so we have to make sure that we maximize that that we get full knee extension regarding the popliteus it is a major unlocker of the knee when the knee is in an open kinetic chain it's a major unlocker of the knee um specifically right if we're thinking about that as the knee is in full extension and we need to move it into a knee flex position okay so moving on let's talk about the ligamentous support of the knee because that's basically what it's it's known for uh in general we know that the knee is a joint capsule so the knee by the knee i'm talking about the femur and its articulation to the tibia we know that it's a joint capsule and so what we know about this is that this joint capsule uh this capsular structure kind of envelops all of the knee joint itself we also know that the knee is a synovial capsule so in other words it's surrounded by lots of articular structures it's surrounded by lots of fluid that that is allowed to sit in the knee joint and kind of cause joint nutrition right so we have the joint capsule which would represent the articulation between the femur and the tibia right a joint is where two bones come together but then we also have this synovial capsule this idea or this concept that there's a lot of fluid in the actual joint capsule which creates joint nutrition um about the actual knee joint itself and then we have these things called plica they're extremely rare as you get older most often they'll get absorbed by the body but we have plica in the knee though the plica in the knee as you can see here are located within the actual synovial uh membrane of the knee but the probably the most important plica of the knee is the medial patellar plica it's the one that we see most often cause a lot of medial patellofemoral knee pain so we'll talk a little bit more about that when we get to those pathologies but essentially it's it's soft it's pliant um and what we know happens is that it's going to snap over do you see that the lateral and medial condyles and so it can cause uh inflammation it can cause irritation about the knee joint but these again just provide more stability to the actual knee joint it itself the iliotibial band gets its own slide for many different reasons i happen to think that it's one of the most important anatomical structures to knee stability and to hip function but we'll get to hip function later the iliotibial band as we know distally is an extension of the tensor fasciae latae approximately right so approximately we have the tensor fasciae latae which is extremely muscular in nature and then essentially as we progress more distally it becomes the iliotibial band and we if you were in lab and you saw the the images then you know that the iliotibial band track which you can see here is a dense tissue like structure that is extremely tough right one of the things that i've been learning about as i continue to teach gross anatomy is that the deep fibers of the it ban attach to the joint capsule itself of the knee right and so this is kind of a cool thing to think about it attaches to the joint capsule of the knee and so it in and of itself provides stump some stability to the knee joint which is i think is awesome right in other words it's going to play a significant role in knee stability it becomes important then to make sure that when a patient has i t band syndrome for example that we also check the integrity or the stability of the knee joint as well because the it band does play a major role in providing stability to the knee joint what we also know about the knee joint is this so when the limb is in full extension so we see that here what we know is that the it band is then considered a knee extensor so in other words if i'm fully extended that it band is also contributing to knee extension the cool thing about the it band is that remember it moves or glides over that that epicondyle that lateral epicondyle of the knee so when the knee is actually flexed past 30 degrees it becomes guess what and a sister in deflection so we have this kind of multi-functional muscle or tendon working at the knee to provide stability when the knee is in extension to help with knee extension when the knees in at least 30 degrees of deflection it's assisting with flexion right so it tells you just how important um the it band is when we're talking about knee anatomy right we have to give it a little bit more credit than we have in the past okay so now we get to the tibial femoral joints and um we'll we'll we'll talk specifically about really ligamented structures so the first ligamentous structure that we have is the medial collateral ligament so we can see that here we can see its most superficial layer of the the mcl what we know about the mcl is that it's broken down into two layers you can see those there the deep layer and the superficial layer superficial layer is just that it's the most superficial layer a superficial layer is going to have a proximal attachment to that uh medial epicondyle and then come down onto the medial tibial plateau right and we're pretty we know the medial collateral ligament more than anything for for its superficial slips what is most important to us is this deep layer so you can see the deep layer here we can also see that the deep layer is attached to the medial meniscus so it has fibrous attachments to the medial meniscus right and to the actual tibia itself do you see it there so when i say that it's attached to the joint capsule you can kind of see that it has an attachment to the tibial plateau so it's injury to the mcl most often we're assessing the superficial layer but a lot of times if there's injury to the mcl we'll probably get some type of joint capsule and or a medial meniscal tear the major role of the medial collateral ligament is to prevent against massive amounts of knee valgus forces right because if we don't have this restraint then we'll injure our acl we'll injure our meniscus so it's the mcl which is the first line of defense if there's a massive valgus force at the knee right the first thing to go is going to be the mcl second thing to go is going to be the deep bundle of the mcl third thing to go would be meniscus and then last but not least is acl so we can see how there are these layers of protection on the medial aspect of of the knee next is the lateral collateral ligament the lateral collateral ligament unlike the mcl does not attach to the joint capsule itself or the meniscus so it does not have attachment to the tibia in any way shape or form it doesn't have an attachment to the lateral meniscus in fact it doesn't have two bundles it is just the lcl we know the lcl attaches to the lateral epicondyle of the femur and then comes down distally to attach to the fibula on the lateral side of the knee and its major role is to prevent varus most often in full knee extension but it can be preventative up to 30 degrees of knee flexion right so its major role is to prevent massive varus forces at the knee we can look at this we've looked at it in a gross anatomy a few gross anatomy cadavers and we've seen that this this ligament is very s very thin when you compare it to its medial counterpart the mcl but the the awesome thing about uh varus injuries is that they're rare when you compare them to mcl injuries right so if we're thinking about the way that god uniquely makes us and designs us right this is an example of this we don't need as thick of a ligament on the lateral side because we don't have as many various forces we go back to the mcl there are tons of blows to the outside of the knee creating valgus forces so we need a thicker uh redefined structure and so we have the mcl which is a thicker structure so these are things to think about as you um really truly think about the way that our body is designed okay next we have the anterior cruciate ligament probably everybody's favorite ligament in the knee certainly not mine it gets a lot of credit but i think there are other anatomical structures that are just as important within the actual knee joint itself so we have the um we have two bundles of the acl we have the anterior medial bundle and then we have the posterior lateral bundle um yes i did say that the acl is a two bundle ligament well you know about this um if we're looking at this from a knee perspective is that it's going to insert on the wall of the the lateral condyle um and then have insertions on to um i call it the intercondylar notch of of the tibia we know about the acl for comparing acl to pcl is that it's longer than its pcl counterpart and it makes sense right it has to be because it's the ligament in the knee it's going to allow us to rotate as much as we rotate so it's it's a longer ligamented structure when we compare it to guess what you got it yes when we compare it to our pcl counterpart so what is the role of the acl in in the knee joint uh it's fourfold believe it or not the first one the one that we know most often is and to prevent anterior translation of the tibia on the femur so that's number one right we i think that's the one we know uh it also uh helps with internal rotation and external rotation of the tibia on the femur so screw home mechanism and then believe it or not it also serves as um a stabilizer against um hyperextension of the tibial femoral joint right so we've got it prevents massive amounts of anterior translation it's going to prevent massive amounts of internal external rotation of the tibia and last but not least it's going to prevent hyperextension at the knee joint right so we can see that any injury to the acl and now we have increased anterior translation depending on the bundle that's torn we could have in increased internal and external rotation and last but not least we certainly could have an increase in hyperextension what am i saying that's a massively unstable knee joint right so this is why the acl gets much much notoriety because it plays so many roles in stability of the knee joint so as i mentioned or i alluded to there are two bundles to the acl and i think it's important for us to understand them um so when the knee is fully extended what we know about these bundles is that the posterior lateral bundle is going to be tight okay so posterior lateral bundle is going to be the tightest or um be taught right when the knee is fully flexed what we know about it is that the anterior medial bundle is going to be tightest and this is the cool thing as we move into a flex position you can see how in an extended position those ligaments are parallel right as we flex what we typically see is as that anterior medial bundle becomes tight in knee flexion it also does this thing like a wrapping around do you see that so you get a little bit of a ringing of of the acl injury or the acl which is why we see uh most injuries occurring in a knee flexed position number one that anterior medial bundle is tight but now not only that the two ligaments are kind of wrapped or rung around one another that's what the research tells us anyways so in a fully extended position that posterior lateral bundle is extremely tight but it's the knee flexed position where we start to see changes about the ligament number one the anterior medial bundle's tight not only is it tight but we also see the winding or the wrapping mechanism as a result of the tightness or the pulling on that anterior medial bundle it's why we see so many acl injuries happen with the knee flexion moment it's that winding upon of the two ligaments the brother to the acl is the posterior cruciate ligament interestingly enough it is 120 to 150 wider than the acl so far so good remember the acl is longer the pcl is wider and it's stronger it's more resilient does that make sense does this remind you of another relationship the mcl and the lcl yes okay what we know about the pcl is it it is the primary resistance resistant or resistor to posterior displacement of the tibia on the femur in other words it's going to prevent the tibia from moving posteriorly okay we also know that it assists the acl um in restraining the amount of external tibial rotation that a patient can actually go into right so here we're looking at the the pcl so major restraint in posterior displacement assist the acl in resisting external tibial rotation and it is the stronger of the two ligaments by far and the widest of the two ligaments by far okay the menisci here they are there are so many roles of the meniscus they're listed on this slide but let me just talk to you about them a little bit the number one role of the meniscus is to provide shock absorption so it's bullet point number three they reduce the amount of forces driving through to the actual femur itself so they are like to me they are like buffers they are cartilaginous structures which are comprised of millions of rings you can't see them but tiny rings or coils of cartilaginous structures and so those coils are capable of absorbing the shock and then transferring the shock to to the femur right or dampening the shock and transferring those forces to to the femur the other rule that they play in the knee is that they deepen the articulation in other words if we didn't have these femur or these menisci i think of them as suction cups if we don't have them then we just have a flat a flat structure of the tibia and a rounded structure of the femur and so then there's instability there these menisci literally act as suction cups kind of pulling that femur into the the tibial plateau so they are extremely important in deepening the articulation between the femur and the tibia itself we also know about them as you can see here they improve the lubrication um so in other words they create like an oil-like substance think back to remember i said that synovial joint where there's fluids within the actual capsule right they they improve the lubrication um of the articulating surfaces those articulating surfaces are the plateau of the tibia and the heads of the femurs or the condyle of the the femur they also increase passive joint stability again that's all about that suction suction cup and then the cool thing that i love the most is that as we move into extremes of flexion and extension because they have this cup like appearance they prevent extremes um of flexion and extension now are they the um the primary restraint to these movements absolutely not but they are a secondary restraint and extremely important in providing knee stability and last but not least they help um and serve as a proprioceptive organ so what i mean by that they are always providing um feedback to the knee regarding where it is in in space so let's talk about them a little bit more and if i'm spending a lot of time here then you certainly should know that they are extremely an important anatomical structures the menisci itself this should be a repeat they have a vascular and a vascular and a pink zone right um so what we know is the closer they are to the periphery the more vascular they are the more that they move towards away from the periphery uh the more we know that they are avascular and they're not receiving a lot of blood flow right and so we'll talk about what that means in the longer run um but for now we'll talk about it as it relates to anatomical um to to anatomy sorry so on the outside we have lots of receptors typically coming from the muscles that cross the joint and lots of arterial uh capillary blood flow and so this outside or the periphery part of the meniscus is going to be fed by those structures and then again as we move towards the midline we there's not there's no muscular structures here right so there isn't any secondary capillary arterial venous blood flow and so there's zero to little blood there are some research to suggest that in the middle there's this pink zone and if it's close enough to the actual red zone that it could feed off of the blood flow um and so we have to figure out kind of what what that looks like as we get to meniscal injuries in just a moment but these are the vascular zones and you need to know them for your exam okay so speaking of evidence-based practice um you are getting ready to enter into i think sensitivity and specificity and odds ratios and risk ratios this week and so this is kind of comes from that kind of literature what are the risk factors for meniscal tear so acute meniscal tears what we know is these are the top three so you're playing soccer or rugby high incidence of meniscal tears you've waited longer than 12 months to have an acl repaired as a result remember that acl prevents external internal rotation anterior translation hyperextension so because you wait so long the knee has been able to move and glide more and so it actually causes wearing down of the meniscus and then those patients that have greater than 25 bmi and that's weight right weight of the femur onto the tibial plateau causes acute injuries to the meniscus but then we have patients who also have what are called degenerative um meniscal injuries or pathologies which means they just happened over time wasn't an acute injury those most often are going to be males we know about males as they typically are more active more likely to take risk and so over time they suffer from degenerative meniscal injuries patients over the age of 60 that's just degeneration so those that work in kneeling and squatting uh fields would also suffer from that and those that um climb a lot of stairs throughout the day are at a higher higher risk for degenerative most often though unless you're going into physical therapy or physicians assistant school you're going to see meniscal injuries that are acute in nature okay now this is where we get deeper in this class so we have the ligament of risberg riceberg and and humphries what we know about the ligament ready of risberg see it there that little itty bitty guy okay so here is the ligament of risberg here is the ligament of of humphries and then here is the pcl so you can see that these ligaments split intentionally to surround the the pcl what we also know about the lateral meniscus is this here let's let's orient ourselves so this is the lateral side okay of the knee here is the cool thing the ligament of riskberg and humphries are what serve as the conduit for the lateral meniscus now why am i saying that what we see here is that the ligament of risberg and humphries have an attachment to the um the meniscus sorry i have to orient myself here to the lateral meniscus yes okay so what we know about this is the lateral meniscus attaches to the lateral aspect of the medial femoral condyle how does it do that how does a lateral structure attach to a medial structure medial structure it does that through the ligament of wristburg and humphries and you can see their attachments here right and as they get ready to come up and attach to that media that that lateral aspect of the medial femoral condyle so the ligament of risberg and humphries are important because they are what attach that lateral meniscus to the medial side of the knee they are the major stabilizing ligaments you can see that here of the lateral meniscus so they are what's responsible for not allowing the meniscus the lateral meniscus to move a crazy amount of time and then more importantly what they do is they kind of act as a sling around the pcl so you can see them bifurcating here to kind of sling around that acl and then their their major role is just like that with the pcl is to do what it is to um prevent um posterior translation in particular the ligament of risberg more so than the ligament of humphries in fact what we know about these these this ligament the ligament of wristburg is that when we have a pcl injury it sometimes has been mistaken as a ligament of rispercompress or ligament of wristburg injury because of where this ligament actually lies right so if we think about these ligaments they're important to stability of the knee to ensuring that the um lateral meniscus can move to attaching that lateral meniscus to the medial side of the knee and then to providing more support in hyper extension of the knee it's so then we have this um this transverse ligament the role of the transverse ligament is to connect guess what the lateral the lateral and the medial menisci right so its major role is to attach that lateral meniscus to the medial meniscus anteriorly and if that ligament gets injured then we can see how the two can move independently which wouldn't be a good thing so this is a transverse ligament major role is to connect the lateral and the medial menisci the posterior lateral corner of the knee is extremely important the posterior lateral corner of the knee most often gets injured in an acl injury and here's what we know about the posterior lateral corner of the knee the posterior lateral corner of the knee provides stability against varus so not only do we have that small fibular collateral or lcl ligament but we also now have the posterior lateral corner which is going to help it's going to provide stability against massive amounts of external tibial rotation so we have the pcl helping with external tip rotation the acl and now we have this posterior lateral corner and it's going to help protect the knee against anterior and posterior forces so what is the posterior lateral corner and what in the world is contained in the posterior lateral corner well i'm glad you asked so they are all highlighted here in this image but we have the lateral head of the gastroc we have the popliteus tendon the tendon of the poplidius we have the popliteus muscle we have the patellofibular ligaments we have the biceps fem we have the it bands and last but definitely not least we have the lcl all of these structures make up what is called the posterior lateral corner and we've talked about all of these structures independently minus this popliteal fibular ligament but all of these structures come together to create the posterior lateral corner and they help prevent against what the the varus forces about the knee they help prevent against extreme amounts of external tibia rotation and then last but not least they work together to prevent massive amounts of forces as it relates to anterior posterior forces about the knee so this is an important structure most often when we have an acl injury the posterior lateral corner gets injured as well and we'll talk about injury to this corner and what are the consequences for our patients when we get to injuries of the knee joint itself last but not least are the arcu is the arcuate ligament the arcuate ligament is going to assist the cruciate ligaments in controlling posterior lateral rotary instability so let's look at the arcuate ligament here do you see it there so here's pop lydia is to orient yourself this is the posterior aspect of the knee so we've got the poplidius and then right here we have the arcuate ligament so in essence it's going to assist particularly the posterior cruciate ligament um in controlling posterior lateral rotary instability what does that mean instability that happens um from a varus injury instability that happens from the knee gliding too far posterior right its major role as you can see is to assist that pcl so it's going to help prevent posterior translation of the tibia and massive amounts of valgus force at the knee and so what we know about the arcuate ligament in general is that if there's injury to this ligament you're going to see increased amounts of external rotation of the tibia on the femur which is a terrible thing to happen at the knee if we have massive amounts of external rotation tibial external rotation then we're at a high risk for osteoarthritis we're at an increased risk for injury to the acl that concludes the anatomy for the tibial femoral joint please let me know if you have any questions