Genetics (ACL)

[Meconium]

Seems some people just pop while others hammer awkwardly in the back seat for a lifetime.

Anyone ever hear of a healthy ACL strength evaluation or study? Be cool if you could actually get a minor acl surgery "beef-up" before the fact.

[Vinman]

Seems some people just pop while others hammer awkwardly in the back seat for a lifetime.

Anyone ever hear of a healthy ACL strength evaluation or study? Be cool if you could actually get a minor acl surgery "beef-up" before the fact.

The estimated strength of an intact ACL is ~2160 N. PT graft is ~2950N, HS graft ~4500 N to failure. (source:
http://www.orthoassociates.com/ACL_grafts.htm) Thses number are probably estimates done during cadaver testing. Some of these numbers are also from studies that are close to 10 years old so there maybe better data out there also.

As far as mechanics go it is actually tougher to tear your ACL than you think. Everything has to be "perfect" for it to happen. many factors come into play, such as strength, fatigue, snow conditions, equipment, anatomy, mechanics, experience, etc the list is huge. I looked for some numbers on the forces generated during skiing but couldn't find much doing a quick search. i'm sure the numbers are out there I just couldn't find them quickly.

[Arnold Babar]

What does N stand for? Also, as far as genetics go, some people are predisposed to having a "narrow notch", where the ACL is seated. I guess those w/ narrow notches are more prone to injury because of the pinch factor. I don't really know, just something my doc told me. Vinaman? He also widened my notch a bit when doing the graft.

[L7]

N is newtons of force I believe. I recently heard of the narrow notch as well but am not that clear on how much it would predispose someone. I think the far more over riding factor would be muscle balance and adquate hamstring strength to protect the ACL. I think the predominant predisposition is skiing tends towards building much more quad strength than hamstring and specific hamstring exercises have to be don to offset this. I also believe the nature of skiing (high hard boots strapped to 180cms of composites) puts extra pressure on the hamstings for the job of protecting the ACL.

My experience is the doctor will often seek out the surgical solution (widening the notch) but give short shrift to other solutions such as proper muscle balance.

[Yeti]

N = Newtons, a unit of force equal to one kilogram-meter per second squared.

That orthoassocs site linked to above is my knee doc, as it happens.

[Vinman]

I guess those w/ narrow notches are more prone to injury because of the pinch factor.

Exactly the reason. During some motions of the knee the ACL can get kind of stretched over the edge of the notch if it is too narrow kind of a fulcrum effect like when breaking a large stick.

L7 is correct about skiing building quad strength and the hams getting no love so to speak. That is another factor that contribute. Later today I try to do some more research on forces involved in skiing. Really there are so many factors that come into play during skiing, quad/ham ratios, narrow notches, binding set up, poor form, fatigue the list is endless.

[Tyrone Shoelaces]

The estimated strength of an intact ACL is ~2160 N. PT graft is ~2950N, HS graft ~4500 N to failure. (source:
http://www.orthoassociates.com/ACL_grafts.htm)

YES! My new ACL is stronger! I knew it!! Dammit...I really am going to take that hammer to my other knee now so it can have a stronger ACL too! Do I really need the hammer? Will they do the surgery if I just ask them too? Why go through life with a weak-ass limp natural ACL when you can have one that's nearly twice the strength?!

[Tyrone Shoelaces]

do I really need to put a winky in that thread?

How do the numbers from a cadaver operation stack up? I'm assuming they're closer in strength to a 'regular' acl?

[Viva]

Also, as far as genetics go, some people are predisposed to having a "narrow notch", where the ACL is seated. .

An then there are some women predisposed to having a "narrow notch". That, my friends, is a woman to be desired.

[scoober]

Those tensile force numbers should be taken with a grain of salt, especially for the hamstring graft. Those numbers are generated by testing the graft in a purely tensile failure (ie. pulling it in direct tension). So, of course a hammy graft that is doubled over on itself (ie. one long ligament strip folded over on itself to make two strips in tension) is going to be stronger in pure tension than a natve ACL or a patellar graft that is a single ligament strip.

However, when you position your knee in the situation that causes ACL tears, do you think the ACL is in pure tension? There are all sorts of force vectors going on in there that can't be accounted for in lab tests. So it is questionable that in an ACL event that you are really getting the benefit of the full 4500N in tension that the hamstring has been tested to. It is more reasonable to think that one strand is seeing the brunt of the force and the other is kind of just hanging out.

As for genetics, I've heard a little about the notch issue. I have also read quite a while ago that females are sort of predisposed to ACL injuries because the way their pelvis aligns their femurs and therefore stresses the knee joint. This may have been disproven since.

[Tyrone Shoelaces]

Dammit Scoober.....ruining my fantasy with your "science" and your "logic".

[scoober]

Dammit Scoober.....ruining my fantasy with your "science" and your "logic".

Dude, with two hammy strips "rated" at 2250N each in there you have double the ligaments and each is still rated higher than the native. So blow that other knee and get your self quadruple ACL reinforced!

[Vinman]

Scobber definitly has some good points that I had not thought of.

The females and hip anglulation (Q Angle) can sometimes come into play if it is excessive 18 deg +. If basically cause females to knock kneed if excessive placing a lot of stress on the medial part of the knee.

And as far as narrow notches go, they kind of go hand in hand with overall size of the individual, the smaller the person the smaller the notch and vice versa. This holds true alot but not in all cases.

One big area of research right now is in the area fo hormonal differences and the effect that estrogen has on ligament laxity. They are beining to make connections between estrogen/progesterone levels and incidence of ACL tears in females. The jury is still out on this one but stay tuned it is a hot topic right now.

[Viva]

One big area of research right now is in the area fo hormonal differences and the effect that estrogen has on ligament laxity. They are beining to make connections between estrogen/progesterone levels and incidence of ACL tears in females. The jury is still out on this one but stay tuned it is a hot topic right now.

Of the gonadal steroids, testosterone has been shown, in mice, to have the biggest affect on bone density, thickness, and shaft strength. Estrogen did little which may be why women have weaker bones than men. Don't know anout tendons and ligaments, though.

Surprisingly, genetics, at the level of the sex chromosomes, played no roll in this phemomenon.

[basom]

if your head is gigantic, people think you are on the juice. just ask stump, his is larger than barry bonds's, and his attitude is even more wretched. plus have you ever seen how stump deals with the media! guy is a class A jerkface.

[Vinman]

if your head is gigantic, people think you are on the juice. just ask stump, his is larger than barry bonds's, and his attitude is even more wretched. plus have you ever seen how stump deals with the media! guy is a class A jerkface.

That thing is HUGE, it can delflect pulses, and has its own weak gravitational field. He's got to be like the 9th wonder of the world or something.

[altagirl]

And as far as narrow notches go, they kind of go hand in hand with overall size of the individual, the smaller the person the smaller the notch and vice versa. This holds true alot but not in all cases.

I have the bad genetics (don't know that I qualify as a small person at 5'8" though.) My surgeon showed me the pics of how he drilled out some bone during my ACL recon because the narrow notch was rubbing on my ACL, caused extra wear and tear, and made it a matter of time before I tore both. So my new graft has a nice clean pathway now.

[Theodore]

I too am a recipient of this so called 'notchplasty'. As for the genetics, I'd think that your natural size would come into play a certain amount. As in are you naturally more muscular or naturally a bean pole. I have a cousin who is a PT and has done her ACL. Her doctor said she had loose joints.(or as she calls them, slutty joints) Not sure how true that could be, but it would make sense to me for it to be directly related to flexibility.

[altagirl]

I too am a recipient of this so called 'notchplasty'. As for the genetics, I'd think that your natural size would come into play a certain amount. As in are you naturally more muscular or naturally a bean pole. I have a cousin who is a PT and has done her ACL. Her doctor said she had loose joints.(or as she calls them, slutty joints) Not sure how true that could be, but it would make sense to me for it to be directly related to flexibility.

Heh. The joints I haven't screwed up yet tend to be over-flexible too. Which doesn't help, apparently.

[splat]

I saw the Line video on the Pivogee binding. They had a lab setup to demonstrate the releases of a traditional binding and the Pivogee in what was presumed the equivalent action of an ACL-snapping backfall twist. I don't know how accurate the simulation was, but the forces involved were snapping skis mounted with traditional bindings. Almost made me wonder why legs don't just rip off at the knees.

[Tyrone Shoelaces]

Almost made me wonder why legs don't just rip off at the knees.

It's the glue silly.

[Vinman]

I too am a recipient of this so called 'notchplasty'. As for the genetics, I'd think that your natural size would come into play a certain amount. As in are you naturally more muscular or naturally a bean pole. I have a cousin who is a PT and has done her ACL. Her doctor said she had loose joints.(or as she calls them, slutty joints) Not sure how true that could be, but it would make sense to me for it to be directly related to flexibility.

Basically everyone who has an ACL reconstruction gets a notch plasty. And as far as muscular flexibility and joint laxity go, I'm not sure the two are connected. I could be wrong on that though. But yes, some people are naturally more "loose" in their joints, the so called 'double jointed" ones. And by the way double jointed is a BS term, there is really no such thing.

[Arnold Babar]

Dammit Scoober.....ruining my fantasy with your "science" and your "logic".

He's just jelous cuz he has a patellar, hammys rule! I'm gonna have all my ligaments reconstructed, cuz rehab is so fun I wanna do some more.

[0BernhardFranz]

a study says they go to 30 % of that they get replaced by body autogenous cells maybe dr .stoneclinic. s pig ligament does 7800 N
don´t blow your lig to get a new in case that is what you meant
you can someday maybe grow acl some stuff is going on using a kind of mesh to build it on you can grow a whole meniscus already genetics can help the healing process in many ways
predispoition should exist