Skiing and ACL Injuries - part 1
ACL Injuries are the most common injury that put alpine skiers in the hospital. They can be life-changing, they’re brutal to rehab and can truly be a depressing and career-ending injury.
In this article, we are going to cover:
What is an ACL injury?
How do ACL injuries happen?
How do I know if I have an ACL injury?
Why are they so common in downhill skiing?
In Part 2, we will cover:
What to do if you think you have an ACL injury
How do I know I have an ACL injury?
Do I need surgery to fix my ACL?
Will I have knee pain forever after hurting my ACL?
Can I still ski after I tear my ACL?
In part 3, we will cover:
How to prevent alpine skiing ACL injuries
Training in preparation for the ski season
Training during the ski season
What is an ACL, anyways?
The ACL is shorthand for the Anterior Cruciate Ligament. Ligaments attach bones to each other and limit unwanted movement. The ACL is one of the most important ligaments that stabilize your knee, attaching your shin bone (tibia) to your thigh bone (femur). The primary job of the ACL is to prevent anterior translation of the tibia on the femur. (Huh?) In other words, it keeps your shin bone from moving forward underneath your thigh bone. (Fun fact: ligaments also help us with our ‘joint position sense’, also known as proprioception).
The ligaments are what are known as ‘passive stabilizers’ of your joints. They don’t actively contract or control movement like your muscles do. Instead, they pretty much work just by being there and waiting until they’re needed (at least when it comes to joint stability).
Most of the time, our ligaments are some of the most reliable structures in the body. They save us from ourselves all the time and keep us moving!
When they are injured though, they like to let us know about it.
What does it mean if the ACL is injured?
Ligament injuries are known as SPRAINS and come in levels, known as ‘GRADES’, each more severe than the one before.
GRADE 1 SPRAIN: some mild stress on the ligament causing irritation.
This level of injury is almost never diagnosed in the ACL. This is because the ACL is so strong that most of the time it can handle the twists and stresses we through at it.
The most common ligament to be sprained is the ATFL (anterior talofibular ligament) aka an Ankle Sprain
Not usually associated with swelling or bruising
Despite the lack of ligament damage, this injury can be extremely painful and still requires proper rehab
GRADE 2 SprAIN: some stretching and possible tearing of the ligament
ACL injuries usually fall somewhere between Grade 2 and 3. This is because Grade 2 is very broad, and covers everything from mild tearing up to just shy of complete tearing
Often extremely painful
Associated with joint swelling, bruising and range of motion limitations
GRADE 3 SPRAIN: complete tearing/rupturing of the ligament.
ACL ruptures are the most common reason a skier will end up in the hospital
Grade 3 Sprains are often accompanied by severe swelling and bruising
Surprisingly, a full ACL tear is not always associated with extreme pain, at least not immediately. This is because the nerves that sense pain are also ruptured, so the knee can no longer send the pain messages back to the brain. The pain usually takes anywhere from minutes to hours to develop, and in some cases, never truly comes.
Complications: it is important to note that a severe ACL injury is often accompanied by damage to other structures in the knee. The most common grouping is known as the ‘terrible triad’ and includes the ACL, MCL (medial collateral ligament), and the medial meniscus.
How do ACL injuries happen?
Injuries happen when the forces applied exceed the body’s ability to resist them. In the case of a ligament, those injuries typically have specific patterns. We typically see ACL injuries with either a straight leg landing (for example landing a jump with stiff knees while in the backseat on your skis) or with a paired twisting and forward force (like trying to get up on your skis, but catching the tail end and torquing your knee).
Here is an example of pro skier Landon Gardner (Team USA) tearing his ACL landing a freestyle jump in 2009: https://www.youtube.com/watch?v=XguonAtk3C8&ab_channel=LandonGardner (while this is not a graphic video, it might not be the most pleasant to watch).
For skiing specifically, there are two primary injury mechanisms:
The Phantom Foot mechanism
The Boot-induced mechanism
1) The Phanton Foot mechanism happens when a skier is either trying to get up from a seated position, or they are off-balanced and fall backwards. Often the skier will place all of their weight on a single leg with weight on the inside edge of their downhill leg. The other ski basically either floats in the air or (worse) catches the ground, but the downhill leg keeps going. The ACL is unable to manage the force and snaps under the tension.
2) The Boot-induced mechanism happens when a skier is again off balance when landing with their legs straight. The landing forces the shinbone up and forward relative to the thigh bone and again overloads the ACL.
Ski-Knee.com has some great graphics on these mechanisms:
Why are ACL injuries so common with skiing?
There are many reasons why injuries happen.
In the case of skiing, the forces, the gear, and the terrain are have a large impact on the nature of the injury.
THE GEAR:
Most gear advancements have decreased skiing injuries. Improvements in ski, boot, and helmet technology have all decreased injury rates since skiing inception. However, better gear also means fast skiers and faster skiers means higher forces… which we already know is a risk for more serious injury.
Skis themselves also change the way our legs function. They limit our rotational movement through the hips (because your can’t exactly twist your skis in any direction without consequences) and essentially eliminate motion in the ankle. When we cannot perform rotation in the hips, and can’t use our ankles in rull range of motion, the only joint left to take responsibility is the knee. The knee is what is known as a hinge joint. It is great at bending forward and back. It is not so great at rotation or side bending (the two primary forces involved in ACL tears).
THE FORCES:
Any time we add in a tool, we increase the amount of force we dealing with. Try throwing a hockey puck as hard as you can slap shot it. Not going to happen. Any time we add in a form of transportation that lets us move faster than we can run (skis, bikes, skates, cars) we start exposing ourselves to forces and speeds that are much more dangerous than we can typically produce with our own power.
This is one of the reasons why skiing injuries can be so devastating. When you are moving at higher speeds, even a small mistake can lead to some pretty frustrating consequences.
THE TERRAIN:
Skiers encounter all sorts of terrain and snow conditions. The nature of the sport takes advantage of gravity while sliding along on a slippery surface. Gravity tends not to care if you are ready for it or not, so often ACL injuries involve unprepared landing or falls.
Snow conditions can also be a fracture, when one ski hits a patch of wet and heavy snow, causing it to trail behind, and putting some crazy forces through the knee.
At the end of the day, the last thing I want you to be thinking about is your ACL. Instead, I want you to be recounting the best stories from the day with your buddy over a beer or a good whiskey. The last thing I want is for you to be scrambling to make an appointment with me on Monday morning. If you DO think you have an ACL injury… well that is what Part 2 is for. (Stay tuned).
Author: Dr Mark Murdoch, Chiropractor and Co-Founder at Base Camp Sport and Spine in Vernon, BC.
Mark Murdoch is a Doctor of Chiropractic with a Master’s Degree in Sports Medicine.
Contact: drmurdoch@basecampclinic.com
Instagram: Base.Camp.Doc
Disclaimer: This blog is intended for general informational purposes only and is not intended for the delivery of medical advice. No doctor/patient relationship is formed. The use of information on this blog or materials linked from this blog is at the user's own risk. The content of this blog and website is not intended to be a substitute for medical advice.