let's look at the pattern of movement through the concept of convex and concave um the convex concave movement pattern is really the combination of osteokinematics and arthrokinematics all together so um let's demonstrate this with our own hands uh let's make a fist with our right hand and our left hand is trying to cover uh our um our right hand so our right hand with the fists um the the surface here uh represent uh the convex surface whereas our left hand kind of cover the right hand this is a concave um surface um what we can expect is when uh we're moving the convex uh bone uh you you can see that the convex surface going to move into the opposite direction to the bone that we want to do for example here um this person is trying to raise up their arm um by uh by raise up their arm you can see the clavicle U the other side of the clavicle kind of go in the same directions as this person is trying to rise up on their arm however if we look closer to the Joint surface between the clavicle and the sternum because of the joint um surface is convex you can see when this person is trying to uh raise up the clavicle the head of the clavicle actually goes down it is the opposite directions to the bone that um is trying to to do and you can see that this is a combination of Osteo kinematics movement and arinc movement right here so what happened when a con he bone is moving on the convex bone the example here is uh this person is trying to move their knee this is the knee movement this is the femur bone this is the tibia bone right here okay so when we when we move our concave bone it actually the whole movement kind of move into the same direction as the bone goes so example here if we're trying to flex or to bend the knee the the the tiia is trying to move in this direction and you know uh the because the joint surface is concave it actually go to the same direction as uh this person's trying to bend the need and same thing happen when this person is trying to extend the neede you can see that it goes in the same direction as the bone segment is trying to go there's one interesting example in our human body which is the thumb carbo a coup of joint CMC joint CMC joint is a saddle joint if you see because the shape of it looks like a a saddle I see this as a prle uh potato chips so you can see that um to one surface is convex and the other surface is concave so this th thumb CMC actually has concave sorry concave moving on convex and convex moving on concave movement um so um there are a different type of movement that we need to know uh and then we call the kinematic chains roughly we can we categorize them as open chain uh movement versus closed chain movement and open open chain movement is the distal segment is moving while the proximal segment is uh fixed in the uh example here this person is trying to rise up um the legs right so in this sense the distal segment is moving while um the proximal segment is fixed and the Clos chain is the opposite so the Clos chain is the the thisto segment is fixed and then um all other proximal um proximal uh segments are moving so in the in the example here this person is trying to stand up the distal um segment is fixed and then um the hip and the knee these are the proximal segments are moving same thing when this person is trying to sit down is also a Clos chin uh movement because this toe U segment is fixed why do we know this why do we need to know this because it is uh we use this as a training protocol a lot in our uh practice uh for open chain uh we can use it we often use it to enhance the muscle strength uh and range of motion to a specific muscle group and you can see uh when a person uh performs a closed chain movement it require multiple joints acting all at the same time all together so it requires a lot of co- contraction and coordination among these uh uh joints so depending on the purpose of our treatment uh you we can choose whether we want to do a close chain movement versus an open chain movement I try to uh categorize open chain movement to uh close chain movement so that we have a a better understanding here so for an open chain movement um number of the joint axis um is uh uh one primary you can argue that well a lot of joint is moving yes but um the key movement for open chin uh in our example to uh raise up the leg is actually the hip or the knee right um so that's one primary uh um um joint AIS well um the Clos chain movement the example that we had before was uh trying to uh stand up um so there are multiple joint access is actually um happening at the same time right and not to mention the joint segments involving um to uh the open chain is one stationary and the other are Mobile versus when uh in the close chain movement all uh uh sorry both stationary and uh a mobile segment are moving um at the same time right so um this is really important that we know that the muscle that's that's involved in open chain movement versus a closed chain movement are very different so for open chain movement it's actually the one specific muscle group that is doing there's um there may be some co- construction but not as much as um the close Shain movement because you know uh the body needs to coordinate multiple joint at the same time multiple groups of muscle are actually Contracting at the same time so there's a lot of co- contractions going on in the closed chain movement um now so there is a um a confusion concept vers uh to the open chain closed chain um it is related to The Joint surface concy The Joint Surface concluye by how well the joint surface match to each other uh when uh a joint is conuent we call it a uh this joint is at a close pack position this is when the two bones are um um close to each other very tight and this is also um the position that the joint capsule or The Joint ligaments are uh really uh tight so take the example here when uh this person is uh bending uh the knee uh so when when they bend the knee the the surrounding ligament is being stretched right so when it's at the close pack position this is when the ligament is at a really tight position because of this um the close pack position um can be easily hurt because everything is you know the tension uh is high right so um but also this is also a position that after a person's injury uh we may uh be request by the um surgeon to put the The Joint in a close packed position for example um the close pack pos position for the uh m mCP joint is when the mCP is in a flexion uh about 90° this is the position that we have challenging or we have difficulty to abduct or UCT the fingers right and this is also U the position that the surrounding ligament around the mCP joint is been um um stretched um after injury uh a lot of time we uh are required to position the mCP in into a flexion position because we want to preserve the length of the ligament so that um when they are uh free to move um they have the ability to bend their mcps to uh the degree that we position them so for example if we don't position on the mCP inflection let's say um a little bit um flection or fully extend when they're trying to move the ligaments actually shorten because you know we put it into a a period of time not moving right then this person may lose the range of motion because of how we position the mCP joint uh when they're in the immobilization phase so um the opposite way is when the The Joint surface does not match to each other perfectly and this is when uh the joint is at the uh open packed position and we clinically we call it a resting position position because it's not as tight so it's relatively comfortable compared to the close pack position so uh this is because the capsule and the ligament are lose in in in this position right um after the injury very easily we want to avoid pain right so um The Joint uh will be likely to put into a open pack position like we discussed earlier that this may result in shorten of the ligament then the person may lose the range of motion right um if we look at the knee joint right here sometimes um we need the ligament to be tight right so we may position the knee into extension on purpose because we want the ligament to be tight but in hand we want the hand to have full range of motion then we would uh um try to position the hand join in the uh close pack position so that being said communication is key here we have to communicate with the team here on how and what position to uh maintain or to immobilize after an injury so some technique that uh we can use uh clinically uh because our knowledge um in uh osteokinematics and arthro kinematics is really important and combined with the concave convex principles we can actually facilitate a typical or a normal joint motion uh using our knowledge here when the joint motion is not typical or is damaged then we need to perform some technique uh called Joint mobilization technique to realign the joint or to facilitate the range of motion in a way so sometimes we may apply a compression force where um the two Force um you know um are toward to each other or we may need to uh separate the The Joint what e uh or enlarge the joint space right there by uh applying a tensil uh traction um to the the joint and then we can use some mobilization technique by applying uh force opposite Force to each bone to create this kind of she sheer force to realign um The Joint um surface sometimes we may uh apply the bending Force bending force is that one side is doing uh a movement where the other side is being stretched right um occasionally very occasionally I may apply a torsion Force to to manipulate the joint uh the the the picture right here this therapist um is holding the ankle and the knee but her focus is actually the hip um by holding uh the knee and an ankle she's applying the rotation Force to the hip um sometimes we uh apply this technique just to uh realign or to relax the muscle when we need to