why do knee ligament injuries don’t heal by itself? eli5
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Ligaments and tendons are tough and have very little blood flow. This means they heal slowly. A ligament also functions to hold a joint in place or to limit movement. If a ligament tears or is severed, it has no chance of healing to the point that it can sustain nominal loads unless the injured tissue is surgically relocated to maximize the chance that it heals according to its nominal anatomy.
Ligaments don’t have alot of blood vessels that limits the amount of nutrients it can get to heal. But given a long enough timeframe they will heal on their own, however outside of mild damage people are likely to injure it again prior to completion of the healing process which leads to assistance being needed as it’s just a big QOL boost.
Ligaments and tendons are tough and have very little blood flow. This means they heal slowly. A ligament also functions to hold a joint in place or to limit movement. If a ligament tears or is severed, it has no chance of healing to the point that it can sustain nominal loads unless the injured tissue is surgically relocated to maximize the chance that it heals according to its nominal anatomy.
Ligaments don’t have alot of blood vessels that limits the amount of nutrients it can get to heal. But given a long enough timeframe they will heal on their own, however outside of mild damage people are likely to injure it again prior to completion of the healing process which leads to assistance being needed as it’s just a big QOL boost.
Ligaments and tendons are tough and have very little blood flow. This means they heal slowly. A ligament also functions to hold a joint in place or to limit movement. If a ligament tears or is severed, it has no chance of healing to the point that it can sustain nominal loads unless the injured tissue is surgically relocated to maximize the chance that it heals according to its nominal anatomy.
Ligaments don’t have alot of blood vessels that limits the amount of nutrients it can get to heal. But given a long enough timeframe they will heal on their own, however outside of mild damage people are likely to injure it again prior to completion of the healing process which leads to assistance being needed as it’s just a big QOL boost.
It depends a bit which knee ligament and how many were injured at a time (there are four). For the anterior and posterior cruciate ligaments (ACL and PCL), the ends of the ligaments typically aren’t touching each other after they’re torn, so there is no way for them to heal back together. Google some MRI images of torn ACLs. And even if they’re close enough together that some healing occurs, the repair is weak and the ligament is elongated and unable to perform its usual task.
For the medial collateral ligament (MCL), *if* this is the only ligament torn, it can heal well, even with complete tears, if the person has their knee immobilized in a specific way. The lateral collateral ligament (LCL) does not heal well on its own, even with immobilization.
As others have said, ligaments have poor blood supplies, but actually not terrible. After you tear your ACL, even in the absence of other injuries happening at the same time, your knee will fill with blood. That blood is coming from the torn ends of the ligament. It takes an hour or two to accumulate, sometimes more, but it does happen.
It depends a bit which knee ligament and how many were injured at a time (there are four). For the anterior and posterior cruciate ligaments (ACL and PCL), the ends of the ligaments typically aren’t touching each other after they’re torn, so there is no way for them to heal back together. Google some MRI images of torn ACLs. And even if they’re close enough together that some healing occurs, the repair is weak and the ligament is elongated and unable to perform its usual task.
For the medial collateral ligament (MCL), *if* this is the only ligament torn, it can heal well, even with complete tears, if the person has their knee immobilized in a specific way. The lateral collateral ligament (LCL) does not heal well on its own, even with immobilization.
As others have said, ligaments have poor blood supplies, but actually not terrible. After you tear your ACL, even in the absence of other injuries happening at the same time, your knee will fill with blood. That blood is coming from the torn ends of the ligament. It takes an hour or two to accumulate, sometimes more, but it does happen.
It depends a bit which knee ligament and how many were injured at a time (there are four). For the anterior and posterior cruciate ligaments (ACL and PCL), the ends of the ligaments typically aren’t touching each other after they’re torn, so there is no way for them to heal back together. Google some MRI images of torn ACLs. And even if they’re close enough together that some healing occurs, the repair is weak and the ligament is elongated and unable to perform its usual task.
For the medial collateral ligament (MCL), *if* this is the only ligament torn, it can heal well, even with complete tears, if the person has their knee immobilized in a specific way. The lateral collateral ligament (LCL) does not heal well on its own, even with immobilization.
As others have said, ligaments have poor blood supplies, but actually not terrible. After you tear your ACL, even in the absence of other injuries happening at the same time, your knee will fill with blood. That blood is coming from the torn ends of the ligament. It takes an hour or two to accumulate, sometimes more, but it does happen.
Lack of vasculature in the tissue. For example the meniscus has 3 zones defined by blood supply mostly.
outer meniscus: has blood vessels, tears to this can be sewn and heal entirely.
Middle meniscus: diffuse blood supply, i.e no blood specific vessels but blood gets there from the surrounding outer meniscus through diffusion, usually this can also be sewn but takes longer to heal and may not always heal.
Inner meniscus is basically just cartilage with no blood flow and if a tear occurs here in the white zone then it basically needs to be resected/debrided so that it doesn’t cause further irritation and damage in the knee.
So whether something can heal is mostly decided by whether blood can get there and carry nutrients/oxygen to it.
Another similar example is the scaphoid bone in the wrist. It has poor blood circulation and usually fractures to this bone taken long while to heal if at all due to the lack of direct blood flow.
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