Knee Ligament Injuries with Skiing

With the Winter Olympics to inspire us, it’s time to get ready for the next Aussie ski season. Fantastic amazing scenery, loads of fun, lots of adrenaline, heaps of speed – and unfortunately, lots of knee injuries.

Every year there we see a steady stream of injuries from skiing that involve knee ligaments. Here’s an easy-to-understand explanation of why the knee can be a problem area for skiers, and a run-down of the common ligaments that are injured. We’ll just stick to ligaments for now, as cartilage & bone injuries are another story that we’ll look at separately.

Knee injuries account for about 1/3 of all skiing injuries, and the majority of these are related to ligament damage. Ligaments are like pieces of rope that cross over joints to hold the bones together in the right place.

As you can see in the diagram there are 4 main ligaments in the knee, one on each side (the medial and lateral collateral ligaments) and 2 that form a cross through the middle of the knee (the anterior and posterior cruciate ligaments).

Different ways of falling and twisting the knee predispose injuries to different ligaments, and more than one ligament may be injured in a single fall. As treatment varies with the degree of ligament damage, we use a system for grading the severity of injury;

  • Grade 1 – minor injury with no laxity (excess movement). Less than 30% of ligament fibres torn. Usually accompanied by mild swelling and pain.
  • Grade 2 – moderate injury with some laxity (excess movement) but still a firm “end feel” (a nice solid block that limits the movement). Between 30-80% of fibres torn. There will be significant swelling and pain, and specialized management is very important to ensure strong and durable healing.
  • Grade 3 – severe injury or rupture. Excessive laxity with no real end feel – effectively the joint will just keep moving the more you push it. 80% – 100% of fibres torn, which effectively means that the ligament has completely ruptured and does not hold the joint in position any more. Usually marked swelling and pain, although complete ruptures may present more as pronounced instability rather than pain as the 2 torn ends of the ligament are not joined any more and therefore do not get stressed with tension in the ligament.  These injuries may require surgical reconstruction.

Most Grade 1 & 2 ligament injuries respond well with physio and a full recovery is often made. Grade 3 injuries may require further investigation with medical imaging like an MRI and an orthopaedic review.  These injuries are associated with an increased risk of damage to other structures like bone and cartilage.

Signs of knee ligament can include:

  • Swelling, especially if this occurs rapidly eg within a few hours. Aggressive swelling, i.e. a large amount within 1-2 hours, strongly suggests bleeding into the joint, which should be investigated & treated as soon as possible.
  • The knee does not seem to be aligned in its normal position
  • You hear a “popping” sound or similar during your fall
  • You are unable to take at least a moderate amount of weight through your knee due to pain &/or instability (the feeling your knee will give way)
  • You aren’t able to fully straighten your knee
  • There is sharp localised tenderness over 1 or 2 areas of your knee

If you have any of these signs then you should ‘call the POLICE’ straightaway.  POLICE is an acronym for Protection, Optimal Loading, Ice, Compression & Elevation.  The Protection and Optimal Loading component has replaced the R for Rest and indicates a need see a physio or doctor ASAP. Getting treatment as early as possible is enormously beneficial in preventing secondary problems such as excessive swelling, muscle tightness, hypoxic injury from increased pressure through the knee, and muscle wasting due to reduced knee function.

The 2 most common knee ligament injuries are to the medial collateral ligament (MCL) & the anterior cruciate ligament (ACL). These are described in more detail below.  Please remember that this info is general advice only – please see your physio for an individual assessment and advice about your knee.

Medial Collateral Ligament (MCL) Injuries

This is the most common ski injury & accounts for around 25% of all injuries. It is often associated with the snow-plough position (ie skis tails wider apart & pointed inwards at the tips) so is common in beginner skiers. It can also be caused by “catching an edge” as you start to go faster.

The mechanism of injury is a “valgus” force, which is where the foot moves outwards compared with the knee. This can be the result of a fall, the skis crossing, or the snowplough stance widening.

A diagnosis can be made based on the description of the fall, and physical examination. There is usually at least some swelling in the knee, the inside of the knee may be tender to touch, it is often hard to fully straighten or bend the knee or take weight on it, and a positive valgus stress test (moving the lower leg outwards relative to the knee reproduces pain)

The degree of movement and the “end feel” (ie how the ligament feels at the end of it’s stretched position) helps indicate the degree of injury, although often a full test is impossible initially due to acute pain.

Treatment includes techniques to reduce inflammation as quickly as possible, movements to restore full movement, graded exercises to maintain and restore muscle strength, and proprioception exercises to restore your full balance and reactive agility to your whole lower body. These will be tailored later in your program to be specific to skiing & any other type of exercise you wish to return to.

Combining this end-stage retraining with specific strengthening is vital to ensure a full recovery and to reduce the risk of re-injury. Most MCL injuries do not need further investigation (x-ray, MRI) or orthopaedic referral, however if your physio is concerned about the extent of injury further investigation can be arranged.

Anterior Cruciate Ligament (ACL) Injuries

ACL injuries account for about 15% of skiing injuries. These are significant knee injuries as they can result in an unstable knee that may require surgical repair (a “knee reconstruction”), and also because a fall that is bad enough to produce an ACL injury can often injure other ligaments, bone or cartilage.

ACL injuries mainly occur when the tibia (shin bone) is sheared forwards from underneath the femur (thigh bone), or when the knee is hyperextended (over straightened).  There are a number of mechanisms of ACL injury that are unique to skiing and have very descriptive names like “The Phantom Foot”, “The Boot Induced” and “The Power Out” mechanisms.

This mechanism occurs when the tail of the downhill ski (the “phantom foot”), in combination with the stiff back of a ski boot, acts as a lever to apply a unique combination of twisting and bending force across the knee joint. Video analysis of more than 14,000 skiing injuries has identified a typical profile that characterizes this mechanism of injury.  When all six elements of the phantom foot profile are present, injury to the ACL of the downhill leg is extremely likely.  Situations that can predispose to this scenario developing are:

  • Attempting to get up whilst still moving after a fall
  • Attempting a recovery from an off-balance position
  • Attempting to sit down after losing control

There are 2 classic things that people report with ACL injuries. The first is hearing a “pop” during the fall (this may sometimes also be loud enough to be heard by other people nearby), and the second is a large swelling that appears rapidly (within 1-2 hours). This type of swelling is called a haemarthrosis, which means bleeding directly into the joint.

Other common things that people report after an ACL injury are moderate to severe pain (interestingly, sometimes complete ACL ruptures are not very painful because the 2 torn ends have no tension through them), inability to put weight through the knee, instability and feeling like the knee may give way underneath them, and loss of range of movement.

Assessment in the clinic includes a thorough history and then several specific tests to check for the integrity of the ACL.  The physio will give you help to reduce swelling, restore range and maintain/improve quads muscle function, which is extremely beneficial.

Partial tears of the ACL are treated in similar ways to partial tears of other ligaments, however some complete tears may require surgical repair.  This depends on your age and the level at which you want to participate in pivot sports such as skiing. If you undergo a surgical ACL repair then physio is vital for progressing back to full function and minimising the risk of future problems. Depending on the surgery performed, any associated injuries, and your individual recovery pattern, return to full sporting activity is usually around 9 to 12 months and you may require a brace to help support your knee when skiing.

So, now you have a little background on the common ligament injuries encountered when skiing. Remember, if you have a knee injury that limits your weightbearing or movement, produces some swelling or any feeling of instability, you should be assessed by a physio as soon as possible. This is important, not just for a speedy recovery from this injury, but is also vital for preventing secondary problems or other injuries in the future due to incomplete recovery. But most of all, so you can enjoy your time on the slopes