One of the common questions we are asked in snow sports injuries is, ‘What conditions cause the most injuries?’.
Many people assume that the soft Japanese powder will mean fewer injuries, which is correct for upper limb injuries such as wrist fractures and AC joints. However, as we specialise in soft tissue injuries rather than fractures, our clinics are always the busiest when it snows heavily.
Firstly, people are skiing more; secondly, beginner and intermediate skiers are often not used to the dry Japanese snow. The classic ‘Japow Knee’ occurs when the ski is caught in the soft snow and twists. If the rotation is not at the correct angle and force to release the ski, the force centres on the fulcrum to the lever – which, thanks to stiff ski boots, is not the ankle but the knee. This rotation often causes an ACL or MCL injury in the knee. This low-force japow knee seems to cause minorly injured ACLs, that are the most amenable to healing. Dr Tom Cross estimates that about 75% of low-force skiing ACL tears are healable if managed optimally early. The healing window seems to be as short as 15-20 days post-injury, after which the ligament stumps can involute, and all healing chance is lost.
So, what is the ‘ideal management’ of an acute skier’s ACL?
The first and most important is to avoid straightening the knee. The knee must be kept bent 24/7 to optimise the chance of healing. In our locations, we need to balance the pro-healing benefits of flexion with the risk of DVT during and after a long-haul flight. We do not restrict ice as it always provides comfort and pain relief. Still, we recommend avoiding anti-inflammatory medication and aspiration of the knee unless the swelling is gross and causing significant discomfort. We usually set knee braces at 30-90 degrees, have long discussions on DVT risk reduction, and encourage patients to facilitate Doppler ultrasound and MRI soon after returning home.
So, while Japow is a boon for the Japanese ski industry, it does come with an increased injury risk.