Fat Skis are driving a Rise in the Incidence and Severity of Knee Injuries?

This question comes as the result of yesterday's conversation with the manager at Cripple Creek/Aspen Highlands. he clearly knows his stuff and is also an active and longtime member of the RF valley's skiing community including backcountry/race instructor. Per friends at the Aspen Valley Hospital there has been a huge surge in tibia/plateau fractures that the Orthos think is directly related to fatter skis. The racing community takes this very seriously and the kids are not allowed to use or freeski on anything greater than 90 mm.
As someone who really likes his 110 Nordica Enforcers and medical curiosity, I did a literature search and came up with this:
https://pmc.ncbi.nlm.nih.gov/articles/PMC7739600/
The variables are going to be very difficult to control for, but to some extent physics is physics. My take is hard snow and fat skis are an especially bad combination. Most of us that have a quiver will opt for something smaller anyway by necessity and fun factor. Snow is going to change the physics dramatically and decrease the load on the knee. In theory, binding stack height will also contribute as it acts like a lever multiplier.
The question is complicated and I am curious what the Maggot collective thinks, especially those in the industry.

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Originally Posted by redeyeballs

This question comes as the result of yesterday's conversation with the manager at Cripple Creek/Aspen Highlands. he clearly knows his stuff and is also an active and longtime member of the RF valley's skiing community including backcountry/race instructor. Per friends at the Aspen Valley Hospital there has been a huge surge in tibia/plateau fractures that the Orthos think is directly related to fatter skis. The racing community takes this very seriously and the kids are not allowed to use or freeski on anything greater than 90 mm. As someone who really likes his 110 Nordica Enforcers and medical curiosity, I did a literature search and came up with this: https://pmc.ncbi.nlm.nih.gov/articles/PMC7739600/ The variables are going to be very difficult to control for, but to some extent physics is physics. My take is hard snow and fat skis are an especially bad combination. Most of us that have a quiver will opt for something smaller anyway by necessity and fun factor. Snow is going to change the physics dramatically and decrease the load on the knee. In theory, binding stack height will also contribute as it acts like a lever multiplier. The question is complicated and I am curious what the Maggot collective thinks, especially those in the industry.

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i think this is probably true, but the freeride bases flat style might mitigate the issue somewhat. Theres no doubt the loading on the medial condyles, and imbalance between lateral and medial condyles, is worse with wider skis. My SO is an ortho surgery resident, been trying to get her to do some research on this for a couple years...

I think you have to talk about how many mm underfoot cuz everyone has a different idea what fat is also Fatski have been around for long time

What about all these people skiing touring bindings in bounds? I feel like that's a more recent development than fat skis.

What about all these people skiing touring bindings in bounds? I feel like that's a more recent development than fat skis.

How is a tib fib fracture a knee injury?


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Originally Posted by bodywhomper

How is a tib fib fracture a knee injury?


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Tibial plateau = joint surface in the knee.



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Fat was defined as anything greater than 90mm. The point about touring bindings is a good one. Folks who also tour are probably skiing faster and velocity is yet another force multiplier. Euros don't really love fat skis so I wonder if their incidence is lower.

I remember when a Tua sumo was called fat cuz it was > 70mm and then the width's just kept going up year after year which is why i suggest quoting in MMs for touring 100-110 is still nimble enough, more than that is kinda fat and a lot to carry, I would call 120 or more definatley Fat and I have some 135 underfoot that are super fat

/shrug. I blew my knee on eighty-four underfoot metal laminates in the forest. The title of this thread is off. Skis are wider and more people are skiing these days. Of course injuries have gone up. /end? PS— tell your coach who is limiting his athletes’ ski widths that he’s a moron.

Isn't a tibial plateau fracture usually associated with impact? I'm no scientist, but I don't see how ski width would affect that.

I recall that there is a relation between the release characteristics of pin bindings (rotational release at the heel iso at the toe as with alpine bindings) and tib/fib fractures.
This has been discussed here before, potentially in relation to the knee binding.

Didn't Aspen get fat skis 25 years ago like the rest of us? What you are claiming makes no sense in relation to the past couple decades - and I feel sorry for the race kids, that's a ridiculous rule.Injuries prolly increased due to a couple things, like the use of pin bindings on fat skis inbounds. Also the level of skiing getting really high, and the nhigher it gets the room for error is small. Monkey-see-monkey-do is pushing people that have questionable talent and they are getting cooked. No kids, a double or triple backflip is not something to try because you saw somebody do it on Insta. Or maybe it's 50+ skiers who are out of shape trying to ski like they are 35 and are getting hurt.Sure fat skis prolly put more torque on knees but I don't see a huge amount of injuries because they came out. Get out of the backseat and keep your fat skis!

THis exactly ^^ fat ski have been around for a VERY long time and I see lots of people on tech bindings at the local hill probaly cuz the only local ski store sells both BC and alpine and they did not get the memo Tech was designed when the average ski was 67mm underfoot so I do think TECH is very possibly well past the design parameters and that would be a worthy discussion

Correlation =\= causation

i see significantly more skiers of lower skill off piste in expert+ terrain over the past 10 years, and think the combination of more skiers traveling to ski (ie ikon pass) and getting in over their head at bigger mountains is a significant driver here.

The loading scenario they applied to the knee in the experiment may have been problematic.

The vertical component of the ground reaction force can't be more than vertical load applied to the ski, in steady state.

But they talk about applying forces equal to 1.5x or 2x body weight on a ski angled 25 degrees from flat (not exactly clear from their description). In a steady state turn at 25 degrees inclination, the MAXIMUM force that could be applied would be 1.1x vertical load, anything higher would mean the vertical component of the ground reaction for would be greater than the vertical load applied, which can't happen in steady state.

If they did get to 1.5x or 2x loading in the test, that means they applied unnatural side loading to the knee in the test - possibly up to 3.5x what could be applied to a ski inclined 25 degrees.

To achieve a 2x ground reaction force in steady state would actually require a ski inclination more like 60 degrees, and at that inclination, much more of the loading is acting in-line with the leg, instead of side loading the knee.

I don’t really buy fatter skis causing any significantly higher forces on knees from a mechanical standpoint either. I’m with Marshal, much more likely that more people skiing than ever before, often on terrain that they probably shouldn’t, is causing a rise in one injuries. Modern fat rockered skis may also enable people to feel more confident/ski runs they maybe shouldn’t be, or push themselves harder. I know that’s true for me too, bigger fatter skis push me to ski harder in soft snow. There’s also the element of using fat pow skis that are great in the morning, but do probably become more of an injury liability in the afternoon when things get chopped and bumped out


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Originally Posted by Marshal Olson

Correlation =\= causation

i see significantly more skiers of lower skill off piste in expert+ terrain over the past 10 years, and think the combination of more skiers traveling to ski (ie ikon pass) and getting in over their head at bigger mountains is a significant driver here.

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It feels a bit like saying that because there are more injuries on full suspension bikes than hardtails, full suspension bikes are more likely to cause injuries.

I don’t really buy fatter skis causing any significantly higher forces on knees from a mechanical standpoint either. I’m with Marshal, much more likely that more people skiing than ever before, often on terrain that they probably shouldn’t, is causing a rise in one injuries. Modern fat rockered skis may also enable people to feel more confident/ski runs they maybe shouldn’t be, or push themselves harder. I know that’s true for me too, bigger fatter skis push me to ski harder in soft snow. There’s also the element of using fat pow skis that are great in the morning, but do probably become more of an injury liability in the afternoon when things get chopped and bumped out of

The study didn’t come to the conclusion that this thread’s title implies.

Fat skis, like snowboards, make it much easier to be a bad skier. Long, skinny non-rockered skis required skill and balance because they did not work unless your weight followed the tips of the skis. Fat rockered skis and snowboards now allow you to smear in any direction with some semblance of control. Skiing powder and crud used to have a learning curve but fat skis now allow intermediates to charge 3D snow at high speed and make it down the hill while being significantly imprecise with thier turns. Fat skis are much harder to carve with on hard snow but that does not matter because most skiers do not do that since it is no longer necessary. Compared to the old skinny waisted skis fat rockered skis are like training wheels. We now have more marginally skilled skiers going faster on all types of snow and terrain, which I suspect leads to different types of injuries since the forces are sideways more of the time. I love my fat skis but they have changed the game in almost every way, including the type of injuries occurring.

I remember buying some Rossi Big Bangs when they first came out. 74mm underfoot and were considered FAT. Now one of my DDs is 115.