Knee injuries are a fact of life in any sport but over the past 30-35 years serious knee sprains, usually involving the anterior cruciate ligament (ACL), have become an inherent risk of modern Alpine skiing, with more than 70,000 sustained each year by skiers.
The ACL is located near the centre of the knee and helps to maintain proper alignment of the load-bearing surfaces.
- Injury to the ACL can result in an unstable knee, which may lead to expensive surgery or a lengthy period of rehabilitation.
- Events leading up to the ACL injury are subtle, giving the skier little or no warning of impending injury.
The Phantom Foot ACL
One common ACL injury scenario has been termed the Phantom Foot because it involves the tail of the ski, a lever which points in a direction opposite that of the foot. Phantom Foot injuries can occur when the tail of the downhill ski, in combination with the stiff back of the ski boot, acts as a lever to apply a unique combination of twisting and bending loads to the knee.
RECOGNISING POTENTIALLY DANGEROUS SITUATIONS
Three types of situations can lead to the Phantom Foot syndrome:
- Attempting to get up while still moving after a fall
- Attempting a recovery from an off-balance position
- Attempting to sit down after losing control
Six elements define the Phantom foot profile:
- Uphill arm back
- Skier off-balance to the rear
- Hips below the knees
- Uphill ski unweighted
- Weight on the inside edge of downhill ski tail
- Upper body generally facing downhill ski
Response to prevent injury if these elements occur:
- Arms forward
- Feet together
- Hands over skis
This action aims to:
- Reposition the downhill thigh in line with the downhill ski in order to reduce twisting loads on the knee
- Reposition the uphill ski so that it is available for weight transfer
- Put the skier in a good position for either a recovery or a controlled fall (bail-out)
CORRECTING POOR TECHNIQUE
It may also be possible to help reduce the risk of serious knee sprains by paying closer attention to skiing technique. Several elements of the Phantom Foot profile can be considered bad habits. Uphill arm back, off-balance to the rear, and hips below the knees, are not part of normal skiing technique.
If you do sustain a snow sports injury please do not leave it a long time before getting it checked out. Every year in early summer or even later we see people who sustained an injury skiing and just hoped it would get better. Some of these injuries are serious and require surgery.