Study of 392 ACL injured out of 1817 skiers suggests which parameters could be considered to reduce the likelihood of ACL injury in rec skiers

[Rich_Ease_3051]

Changing Ski Type Reduces ACL Risk | Orthopedics This Week

Changing Ski Type Reduces ACL Risk

ryortho.com

Impact of ski geometry data and standing height ratio on the ACL injury risk and its use for prevention in recreational skiers | British Journal of Sports Medicine

Conclusion Reduced ski length, narrower ski tip width, lower rear standing height and a lower standing height ratio (ie, rear component of the ski binding is more elevated compared with the front component) were associated with a reduced likelihood for ACL injury. When buying or renting skis, these parameters could be considered to reduce the likelihood of ACL injury in recreational skiers.

 

[Philpug]

Conclusion Reduced ski length, narrower ski tip width, lower rear standing height and a lower standing height ratio (ie, rear component of the ski binding is more elevated compared with the front component) were associated with a reduced likelihood for ACL injury.

This is not new information This was addressed more than a decade ago by Volkl with women's skis and thier Biologic ski/binding combined that had more taper in the tail and the binding moved back and with a negative delta. All because women are more susceptible to knee injuries than men.

When buying or renting skis, these parameters could be considered to reduce the likelihood of ACL injury in recreational skiers.

I would be interested in hearing the percentage of knee injuries with recreational skis where the skier had marked down Type III verses II or I.

 

[Rich_Ease_3051]

This is not new information This was addressed more than a decade ago by Volkl with women's skis and thier Biologic ski/binding combined that had more taper in the tail and the binding moved back and with a negative delta. All because women are more susceptible to knee injuries than men.

I would be interested in hearing the percentage of knee injuries with recreational skis where the skier had marked down Type III verses II or I.

Maybe someone with a spare 33 pounds can download it for us. I think people who work in academia (I dont') can also request the data.

Do you have theory why a wider ski tip would more likely cause an ACL injury than a narrow one?

 

[neonorchid]

This is not new information This was addressed more than a decade ago by Volkl with women's skis and thier Biologic ski/binding combined that had more taper in the tail and the binding moved back and with a negative delta. All because women are more susceptible to knee injuries than men.

I would be interested in hearing the percentage of knee injuries with recreational skis where the skier had marked down Type III verses II or I.

So, not so much waist width but the amount of taper/sidecut, i.e., a straighter ski shape, and a low stack/low ramp binding such as Look Pivot and '23 Salomon Strive for those of us not wild about going to the high stack height, greater ramp angle, heavy'ish new '23 Tyrollia Protecter on their ≥ 95mm waist skis?

Maybe someone with a spare 33 pounds can download it for us. I think people who work in academia (I dont') can also request the data.

View attachment 174954


Do you have theory why a wider ski tip would more likely cause an ACL injury than a narrow one?

I think Wide Shovel is in reference to a highly tapered deep sidecut ski where the waist is significantly narrower than the shovel (effective edge contact point) , i.e. skinny frontside carver, locking into a turn, not easy to release.

 

[Rich_Ease_3051]

I think Wide Shovel is in reference to a highly tapered deep sidecut ski where the waist is significantly narrower than the shovel (effective edge contact point) , i.e. skinny frontside carver, locking into a turn, not easy to release.

I'm not sure about that. I mean I understand that a deeper sidecut can cause a ski to be locky/harder to release, that then leads to accident that causes ACL injury.

But if deeper sidecut were more likely to cause ACL, they would have said deeper sidecut, not wider tip.

 

[Philpug]

I think a negative (or at least zero) delta helps mitigate and also upward release from the toe. But again this is not new information, but in a performance aspect, for most, a positive delta is better. It shows tha, in many applications, we are willing to sacrifice safety for performance.

 

[EricG]

Curious to see how many assumptions are going to be extrapolated based on the brief conclusion. Not to mention the rehash of old stuff.

 

[Rich_Ease_3051]

Curious to see how many assumptions are going to be extrapolated based on the brief conclusion. Not to mention the rehash of old stuff.

LOL. I'm guessing 3-4 pages of assumptions, with a smattering of:
- Take lessons, lessons, lessons and you likely won't get into accident
- Personal anecdote to debunk study conclusion (I ski with wide tip, positive delta binding, 188cm ski for 20 years and never had an ACL injury).
- Personal anecdote to debunk study conclusion (I ski with narrow tip, negative delta binding, 160cm ski and still had an ACL injury!).
- Know your limits
- Ignore study. It's not the ski. It's your technique. Book an instructor lesson immediately to refine you technique

 

[neonorchid]

I'm not sure about that. I mean I understand that a deeper sidecut can cause a ski to be locky/harder to release, that then leads to accident that causes ACL injury.

But if deeper sidecut were more likely to cause ACL, they would have said deeper sidecut, not wider tip.

Well, if that's the case, when was the last time you saw an Alpine Ski shapped like a Nordic Skate Ski?

I think a negative (or at least zero) delta helps mitigate and also upward release from the toe. But again this is not new information, but in a performance aspect, for most, a positive delta is better. It shows tha, in many applications, we are willing to sacrifice safety for performance.

I can't imagine skiing a negative ramp angle, wouldn't that put one on their heels and in the backseat more prone to phantom fall catch release something or another mechanism to ACL injury?

Curious to see how many assumptions are going to be extrapolated based on the brief conclusion. Not to mention the rehash of old stuff.

difficult to extrapolate with such a semantics issue, not clear on what the heck the author is talking about.

 

[KingGrump]

Relationship between side cut and ACL injuries had been documented fairly thoroughly over the years.

From what I understand. ACL injuries generally happened during rearward twisting falls. The incidents of ACL injuries increased significantly since the introduction of the "shape" skis. The skis can keep on carving through the turn injuring the knee in the process. The old straight ski will generally let go once input pressure is released.

I believe prior studies had also show a marked increases in ACL incidents surprisingly with so called expert skier. It was presumed that the "expert" skiers exasperate the issue by trying to save the fall.

The ramp angle aspect is new to me. Nevertheless, I strongly dislike bindings with zero or negative ramp angle. Not going there. My bindings are set several points over the standard DIN charts anyway. For me, retention is much more valued.

 

[Rich_Ease_3051]

Well, if that's the case, when was the last time you saw an Alpine Ski shapped like a Nordic Skate Ski?

I mean it could be powder skis (wide tip, wide underfoot) and all-mountain/frontside skis (wide tip, mid to low width underfoot) that's causing the ACL injuries.

 

[Philpug]

I can't imagine skiing a negative ramp angle, wouldn't that put one on their heels and in the backseat more prone to phantom fall catch release something or another mechanism to ACL injury?

I am not a fan of it either and cannot ski that way. As far putting less pressure on the knee, the negative delta will release easier in the rearward fall because it does not have to go from +4* to 0* to -4*.

 

[AlexisLD]

LOL. I'm guessing 3-4 pages of assumptions, with a smattering of:
- Take lessons, lessons, lessons and you likely won't get into accident
- Personal anecdote to debunk study conclusion (I ski with wide tip, positive delta binding, 188cm ski for 20 years and never had an ACL injury).
- Know your limits
- Ignore study. It's not the ski. It's your technique. Book an instructor lesson immediately to refine you technique

I mean, it is hard to say without looking at the full article (I also don't have access to it), but you clearly cut and pasted the parts that interest you! :-P

There is also that part in the abstract:
A total of 1817 recreational skiers participated in this study, of whom 392 (21.6%) sustained an ACL injury. Multiple logistic regression analysis indicates a higher age, a lower skill level and riskier behaviour as independent individual risk factors associated with an ACL injury.

A previous paper by the same authors (The Impact of Ski Geometry Data and Standing Height on the Risk of Falling in Recreational Alpine Skiers) says that:
Burtscher et al. [6] found in an earlier study that younger age, alcohol consumption on the skiing day, poor skiing skills, soft snow conditions, higher altitudes and smoking are associated with falls in a cohort of 1607 recreational skiers and 373 recreational snowboarders. In a follow-up study by Philippe et al. [7], due to the introduction of short and shaped carving skis [...] soft snow conditions and a lower skill level were predictive for falls in carving skiers.

Even if the ski properties can be correlated to higher risk of falling, it remains that the effect of skill is much larger. E.g., for the low-skilled skiers in this study, about 13 didn't fall that day and 50 did fall. For the highly-skilled skiers in this study, 86 didn't fall and 50 did fall. This is a huge difference (4-5x more likely to fall). In comparison, the relativized ski length (an apparently important factor) of skiers who didn't experience a fall was 95.4+-3.6 while the one of skiers who did experience a fall was 93.1+-4.1. That is basically the same length (<2% with 4% standard deviation) and you have to work really hard to say that this is an important factor. Your methodology can be debated endlessly! There could also be correlations between the length of skis that you give to low-skilled skiers vs highly-skilled skiers. And in this case correlation would not necessarily mean causation.

Regarding low tip width, it makes sense to me. If this study is the same as the one that I can access the pdf, then it was performed in a European resort with basically only piste/carving skis. A wide tip width means a ski with a low taper (as they are all almost the same waist width and sidecut), which means that it engages more and more as you tip the ski (intentionally or not). This is hard to control for beginner skiers and can make you fall.

Point is, don't fall! Take lessons, ski on equipment that makes you comfortable, know yourself, get in shape, don't drink, don't ski powder, don't do anything risky, etc.

 

[AlexisLD]

I am not a fan of it either and cannot ski that way. As far putting less pressure on the knee, the negative delta will release easier in the rearward fall because it does not have to go from +4* to 0* to -4*.

I think the negative delta might also help you not reach your knee joint limit during a backward fall. I am not sure, but I could imagine that still having some range of motion (i.e., not having your thigh touch your calf) when your butt touches the snow might be a good thing. Maybe?

 

[Philpug]

Point is, don't fall!

I will disagree with this ... I have seen numerous, as in more than one case where a skier tried to stop a fall and tore their ACL. In some cases it is better not fight the fall and let it happen.

 

[Snowfan]

I rented 98 Stockli Stormrider's with Markers then skied a steep couloir and blew my ACL in a wet storm. THE INJURY WAS MY FAULT, not the wide to me ski, because I was skiing tentatively....without focus and deliberation. That equals improper muscle control. I was hesitant due to wet snow and steep rocky terrain.

Do not ski cautiously.

Focus and go for it then stop and rest. Do not be careful and hesitant....that is when you might get hurt. Stay forward and ski like you own it or pick another trail.

Just my opinion and has worked for 10 years with rebuilt knee.

 

[Philpug]

I think the negative delta might also help you not reach your knee joint limit during a backward fall. I am not sure, but I could imagine that still having some range of motion (i.e., not having your thigh touch your calf) when your butt touches the snow might be a good thing. Maybe?

Maybe ...maybe not. it still comes down to bindings only know the force put into them.

 

[Philpug]

It still comes down to bindings were designed and tested to protect bones and not ligaments.

 

[Rich_Ease_3051]

I mean, it is hard to say without looking at the full article (I also don't have access to it), but you clearly cut and pasted the parts that interest you! :-P

Yeah but it wasn't my conclusion. It was the authors' conclusion. I literally just copy pasted their conclusion.

Are you saying you disagree with their conclusion? Or that their conclusion is wrong? Or that the conclusion is incongruent with their findings?

Personally, I don't have an opinion on their conclusion. Neither for or against. Just want to see people's opinions about it.

 

[AlexisLD]

I will disagree with this ... I have seen numerous, as in more than one case where a skier tried to stop a fall and tore their ACL. In some cases it is better not fight the fall and let it happen.

If you try to stop a fall then you are falling.

You shouldn't reach that point. When you are falling let yourself fall. But don't start falling is even better.