The Skiing ACL

Many healthcare professionals believe that tearing your ACL is a binary event. You’ve either done it or you haven’t. But thanks to the improving quality of MRIs, we can categorically say this is false. There is a Spectrum of Injury, from mild to moderate to severe. This spectrum of damage aligns very closely with the ability of the ACL to heal. A minimally damaged ACL will likely heal on its own without much treatment, but a severely damaged ACL has less chance to heal and may require surgery.

Spectrum Of ACL Tears

A 3mm slice MRI, ideally a double oblique view, is necessary to get a good picture of the MRI. In the absence of MRI, some ways exist to tell what type of ACL tear has occurred.

  1. The level of force of injury. A high-speed, high-force, high-impact injury is more likely to result in a profoundly damaged ACL with a poor chance of healing.
  2. The amount of swelling and pain. A minorly damaged ACL will usually not bleed and swell grossly, and pain may be minimal.
  3. The level of function. People with minorly damaged ACLs are more likely to continue with their game/days skiing and still be able to continue with their activities.

It is often said that skiing is the No. 1 sport for ACL injury, and most of the skiing ACLs happen in relatively low-force, twisting falls. We see them every day in our ski clinics, catching an edge at low speed, bindings not releasing, and the torsion of the long lever arm of the ski translates up to the ACL, causing it to tear/pop. In higher-speed falls, the ski tends to release, preventing the twisting force from transferring to the knee.

Leading ACL researcher and doctor Tom Cross estimates that around 80% of skiing ACLs are this type of ‘low force’ injury, and they invariably have an excellent chance of healing. Of course, high-force ACL tears, such as high-speed falls, hitting trees, landing from big jumps, etc., may have a lower chance of healing.  On the sporting field, ACLs are often damaged in high-force falls, sprinting or landing from jumps, which results in more profoundly injured ACLs. Tom Cross is preparing to publish a paper on the skiing ACL and his ACL tear type classification. A full explanation of the different tear types is not possible in this brief blog, but some details are shown in the medical images below.

Type 1 ACL Injury
Type 2 ACL Injury
Type 3 ACL Injury

If you have sustained a ski injury and think it may be an ACL. The tells are:

  • Feeling or hearing a ‘pop’ at the time of injury
  • A sense of instability or wobbliness in the knee during weight-bearing
  • Some swelling and pain (this can be variable but usually present to some extent)
  • Inability to straighten or bend the knee deeply

You’ll need to present to a physiotherapist specialising in the knee and ACL as soon as possible and be fitted with a brace that reduces knee flexion. Straightening the knee may lessen the chance of achieving a heal. An MRI can often be arranged on return home, and all precautions should be taken to prevent DVTs on the journey home.

Niseko Physio