Well, the Aussie ski season is well and truly here now. Fantastic amazing scenery, loads of fun, lots of adrenaline, heaps of speed – and unfortunately, lots of knee injuries.
Each year around this time we start getting a steady stream of injuries from skiing, with many of them being knee ligament problems. The information below gives you an easy-to-understand background of why the knee is a problem area for skiing, and a run-down of the common ligaments that are injured. We’ll just stick to ligaments for this post, as cartilage & bone injuries are another whole story that we may look at another time.
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 you to injure different ligaments, and more than one ligament may be injured in a single fall. Also, because treatment will vary depending on the degree of ligament damage, we use a system for grading the degree of injury;
- Grade 1 – minor sprain with no laxity (excess movement). Less than approx 30% of ligament fibres torn. Usually mild swelling and pain that often resolves in under a week.
- Grade 2 – moderate sprain with some laxity (excess movement) but still a firm “end feel” (a nice solid block that limits the movement). Approx 30-80% of fibres torn. There will be significant swelling and pain, and treatment is definitely required to ensure strong and durable healing.
- Grade 3 – severe sprain 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.
Most Grade 1 & 2 ligament injuries respond well to physio and a full recovery is made. Grade 3 injuries need full investigation (eg MRI, orthopaedic review) to determine not just the full extent of ligament damage but also the usual damage to other structures like cartilage that often accompany Grade 3 knee ligament injuries.
Signs that you have a significantly damaged a 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 a haemarthrosis (bleeding into the joint) and this should be investigated & treated ASAP.
- The knee does not seem to be aligned in it’s 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 (just feels like it 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 these signs then you should start RICE treatment straight away & go to see a physio or doctor ASAP. Getting treatment as early as possible is enormously beneficial to prevent secondary problems such as excessive swelling, muscle tightness, further injury due to more pressure through the knee, and muscle wasting due to reduced knee function.
As mentioned before you may injure more than 1 ligament in a single injury, &/or may injure other structures such as knee cartilage and bone. Below is a summary of the 2 most common knee ligament injuries – the medial collateral ligament (MCL) & the anterior cruciate ligament (ACL). Please remember that this info is for general advice only – please see your physio for an individual assessment of your knee.
Medial Collateral Ligament (MCL) Sprains
This is the commonest ski injury & accounts for around 25% of all ski injuries. It is often associated with the snow-plough position (ie skis wider apart & pointed inwards) & so is common in beginner skiers. It can also be caused by “catching an edge” as you start to go faster, so is also seen in intermediate skiers. The mechanism of injury is a “valgus” force which is where the lower leg is taken out to the side so your foot moves outwards compared to you knee. This can be associated with an outwards rotation of the ski as well, so the front of the ski moves outwards twisting the knee out with it. A diagnosis can be made based on the description of the fall (as above), and physical examination. There is usually at least some swelling in the knee, the inside of the knee will be tender to touch, it is often hard to fully straighten or bend the knee or take weight on it, and a valgus stress test whereby the lower leg is moved 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, joint mobilisations (movements) to restore full movement, graded exercises to maintain and restore muscle strength, and proprioception exercises to restore your full balance and reaction times to your knee. 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 proprioception retraining with specific strengthening is vital to ensure a full recovery and 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 will be arranged.
Anterior Cruciate Ligament (ACL) Sprains
ACL sprains account for about 15% of skiing injuries. They are one of the more serious knee injuries, partly because a full ACL rupture produces a very unstable knee that requires surgical repair (a “knee reconstruction”), and also because a fall that is bad enough to produce an ACL injury will often also injure other ligaments, bone or cartilage. ACL injuries mainly occur when the tibia (shin bone) is sheared forwards on the femur (thigh bone), or when the knee is hyperextended (instead of bending backwards the shin bone is rotated forwards). Because of the angle of the ski boot and the fact that the ankle is in a fixed position, if the back of the ski catches or hits first then the back of the ski boot drives the upper calf forwards, shearing the tibia forwards on the end of the thigh bone and damaging the ACL. The ACL also plays a role in controlling rotation of the knee so if this forward shearing is also associated by a rotation force then the ACL is very prone to injury. Hyperextension may occur if you catch an edge and the ski slows and changes direction and you effectively go forwards over towards the front of the ski. 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 aggressive 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 just 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. If an ACL injury is suspected then you will be referred for orthopaedic assessment and usually an MRI. The earlier this is done the better especially as associated cartilage injury is relatively common, however some current schools of thought advocate delaying surgical ACL repair until the acute inflammation has resolved. Either way, early physio to reduce swelling, restore range and maintain/improve quads muscle function are extremely beneficial. Partial tears of the ACL are treated in similar ways to partial tears of other ligaments, however complete tears routinely require surgical repair, especially if you plan to continue skiing and most other sports. Following surgical ACL repair 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 from 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. Basically if you have a knee injury that limits your weightbearing or movement, produces some swelling or any feelings of instability then you should be assessed by a physio as early as possible. This is important not just for a speedy recovery from this injury, but is also vital for preventing secondary problems and potentially more injuries in the future due to incomplete recovery. Enjoy your time on the slopes.
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