From the Sidelines · First Tracks
I keep hearing about skiers tearing their ACL. Why does it happen, and can I actually lower my odds?
Most ski ACL tears happen without any collision at all. Here's the split-second pattern behind them, and what actually lowers your odds.
Straight answer: Most skiers tear the ACL without ever colliding with anyone. It usually happens in a split second when you lean back, your ski catches or keeps sliding, and your knee twists under your weight. You cannot make the risk zero, but you can lower it - with stronger legs, better habits on the slope, and bindings that are set correctly.
The question
"I ski a few weekends a year and I love it, but a friend tore her ACL last season just falling on an easy run. How does that even happen, and is there anything I can do about it?"
What the ACL does
The ACL is a short, strong ligament in the center of the knee. It keeps your shin bone from sliding too far forward and helps control twisting. Skiing puts it in a tough spot: your foot is locked into a stiff boot, your boot is locked to a long ski, and that ski can act like a long lever on your knee.
How the tear usually happens
Two patterns cover a lot of ski injuries.
The first is the backward fall. You get in the back seat, weight over your heels, and the inside edge of a ski catches. Your body keeps rotating while your foot stays put, and the knee twists inward.
The second is the awkward landing or recovery. You land off balance, mostly on one leg with the knee caving in, or you try to stand up while you are still sliding instead of letting the fall happen.
Fatigue makes both patterns more likely. That is why the classic story is the last run of the day, on a run that should have been easy.
What actually helps lower your odds
Get your legs ready before the season. Strong hamstrings, glutes, and quads help keep the knee lined up when you get thrown off balance. Single-leg strength and balance work matter - skiing is mostly done one leg at a time.
Stay out of the back seat. Keep your shins in contact with the front of your boots and your weight centered. Lessons are not just for beginners. One lesson focused on stance can undo the leaning-back habit that puts the ACL at risk.
Have your bindings checked each season. Bindings are designed to release before forces get too high, but only if the settings match your weight, height, boot, and skiing level. Rental gear counts too.
Know when to stop. Take breaks, and if your legs are spent, call it a day. Technique falls apart when you are tired.
Let the fall happen. Trying to muscle your way back upright while sliding often twists the knee more than the fall itself.
When to get checked
Get checked if you hear or feel a pop, the knee swells quickly within a few hours, it feels unstable or gives way, or you cannot fully straighten it. Those signs do not prove an ACL tear, but they are reasons not to ski again until someone examines the knee and, if needed, gets imaging.
The takeaway
Skiers tear ACLs when a locked-in foot, a long ski, and a backward or twisting fall line up at the wrong moment. Strong legs, a centered stance, correctly set bindings, and stopping before you are exhausted will not guarantee a safe season - but together, they are the most honest way to lower your odds.
Have a ski question you'd like covered in a future post? Send it to Ask Dr. G. Reader questions shape what I write next.
For education only - not medical advice.
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