Submitted by Toast1185 t3_ybyeyq in askscience
spicemyrice t1_itkcajs wrote
There are a couple of factors that can increase ACL injuries.
- Hormones. This mostly applies to female athletes but certain points of a female’s menstrual cycle makes her more prone to injuries. The hormones basically tell the body to “loosen up” in prep for potential birth and this instability increases risk of injury.
- Previous history of injury to that knee/leg, not just ACL injuries but ANY injury. Re-injury is far more common. Any previous meniscus tears, medial/lateral collateral ligament tears, etc, will weaken that area. This area will always be the weakest link and first to go, especially in contact sports. This is why appropriate rehab and adequate time off will greatly reduce chances of re-injury. It takes about a year to fully rehab an ACL injury and reduce risk of re-injury. Unfortunately athletes are not always provided this time off.
- Mechanism of injury. ACL injuries occur when there is stress on the knee joint, usually because there is a fixed point and another force that creates knee torsion. An example of an external force is when a football player is tackled; the foot is the fixed point to the ground and the tackle creates the knee torsion. This can also occur without an external force like a tackle. An athlete is also prone to ACL injury when she/he quickly changes direction (ie: cutting); the foot planted is the fixed point and the change of direction creates torsion. This can also occur if a basketball player jumps for a shot and lands awkwardly, which can also create the same knee torsion with a fixed foot. My guess is your football player was quickly changing directions when his injury occurred. He could’ve had other previous injuries that might’ve contributed to his risk of re-injury, but a professional level athletes body is asked to do a LOT more than the average person and at higher speeds, which already puts him at risk for ACL injury even if he didn’t have a previous history.
To answer your question on prevention, it would greatly reduce an athletes chances of ACL injury if he/she has a good strength and conditioning coach that focuses on strength, balance and engaging the correct muscles during agility drills. Have you ever lifted something heavy without using your legs/core and then regretted it? You can likely still lift it but your back will just hate you for the next few days. Same concept with athletes, except they are in a much faster paced environment and need to react much more quickly. They don’t have time to think “oh yes need to lift with my legs not my back” - it should be drilled into them like second nature to use correct musculature during their movements. Sounds easy, but it’s not. Our bodies are smart and will adapt/compensate to do the movement but over time, repetitive incorrect movements will result in pain and injury. In addition, fatigue throughout the course of a game will also contribute to more mistakes/injuries. An athlete needs to be conditioned not just to barely make it through the game but be at 100% throughout the entirety. Sport performance coaching is a lot more nuanced than one would think but a good training program/coach will make a big difference to the athlete.
AquaDoctor t1_itkfo8g wrote
While you are correct that hormonal changes have been found to have an effect in ligament strength, you are confusing normal estrogen and progesterone fluctuations with the hormone called Relaxin. Relaxin prepares the body for birth by loosening things up. But that’s only weeks before birth. Not during normal cycles. Do a google on that and you’ll learn more.
To your point though, female soccer players have the highest incidence of ACL tear in noncontact sports. For many reasons neuromuscular control, hormonal changes, and anatomical differences between male and female knees. There are specific physical therapy programs designed to help decrease injury in female athletes.
Jetztinberlin t1_itkwu4w wrote
Female anatomy teacher and hypermobility sufferer here: Sadly, that's untrue. Relaxin not only starts as early as 6 weeks into pregnancy, but is also regularly elevated in the luteal (post-ovulatory) phase of a regular menstrual cycle, which not coincidentally is when women are statistically more likely to suffer joint injuries.
booky456 t1_itkhpbt wrote
I wrote a section in my dissertation about female football players and the relation to hormones and acl injuries! It’s fun seeing stuff you actually know about on the internet.
Jetztinberlin t1_itphuca wrote
You're correct, and it is so frustrating that an actual orthopedist, if their claim is true, is actively uninformed about half the world's issues with cyclical joint instability. Something something medical misogyny :(
AquaDoctor t1_itvtokx wrote
Thanks for pointing that out. I didnt realize how early in pregnancy the Relaxin was released. However, I did do some research on the levels and while it does exist during a normal menstrual cycle, it is about 50 times higher during pregnancy. All the research I found recently in response to your post pointed me toward Estrogen being the main culprit in ligament laxity. But again, always open to new info so I love the questions your post raises.
Your claim regarding medical misogyny seems extraordinary however. Do you really feel that I hate women because of my post? I hope not.
Jetztinberlin t1_itvvce8 wrote
I appreciate your taking your own advice and researching to better educate yourself! It's always heartening to see that. No, unfortunately medical misogyny is a far larger issue than your comment, and I meant it more in the widespread sense of "here's someone who really should know this, as a professional regarding a common situation that could affect all their female patients / half the world's population, and yet they don't, very possibly through no fault of their own but because this very basic stuff about female anatomy isn't considered important enough to be taught." Medical misogyny is a pretty common catchphrase for a lot of these issues, whether it's failing to address how teaching male anatomy as the default does a disservice to women, to how much longer it can take women to get diagnosed correctly, etc.
FYI wrt relaxin, yes, sure, lower in the luteal phase than during pregnancy, but yes, still present sufficiently to increase joint issues! (As someone with hypermobility disorder I can validate this personally to boot!) IIRC oestrogen increases expression of relaxin, so they're not unrelated. You might enjoy this writeup: https://www.frontiersin.org/articles/10.3389/fendo.2022.827512/full .
AquaDoctor t1_iu0qdcu wrote
That article review link you sent was interesting. "...the premise of this review is based entirely on inductive reasoning. Additionally, consideration of lower-level of evidence literature and inconclusive literature was necessary."
Here's a group that seems to focus on this issue specifically:
https://www.hypermobility.org/hormones-and-hypermobility
"...studies have not demonstrated a clear relationship between the level of relaxin and the degree of laxity. Other factors must be involved."
Seems like a lot more research is warranted. But it could be very interesting.
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