Teresa L. Schuemann, PT, SCS, ATC, CSCS
Each year thousands of people suffer injury to their knees. Many of these individuals are skiers who have a tear of the Anterior Cruciate Ligament. The injury rate for ACL sprains has been estimated to have tripled since the late 1970's, while the incidence of practically every other ski injury has declined as a result of equipment changes/design. Preliminary reports show another increase of ACL injury incidence as the popularity of shaped skis continues to grow. These reports do not blame the ski for the injury, only the fact that the skier is skiing more vertical feet and more difficult terrain with these skis.
After much study of the mechanism of injury of those skiers who suffer an ACL sprain, there have been common behaviors identified that result in the injury mentioned. Dr. Robert Johnson, Dr. Jasper Shealy, and Carl Ettlinger of Vermont have completed an extensive research project to study and identify these behaviors. As a result of this study they have designed an "ACL Awareness" program to attempt to teach individuals to recognize and routinely correct high-risk skiing behaviors in an attempt to decrease the likelihood of knee injury.
The most common mechanism of ACL injury while skiing is named the "Phantom Foot Syndrome". This profile includes several elements that produce the twisting and bending forces at the knee necessary to tear the ACL. This phenomenon is named as such because it involves the tail end of the downhill ski that the skier does not even perceive as being on the ground, thus a "phantom foot" is the resulting cause of the injury. The "at risk" skier becomes off balance to the rear and has allowed the uphill arm to drop back. The skier will then unweight the uphill ski placing all of his/her weight on the inside edge of the downhill ski. If the hips now fall below the level of the knees and the upper body is turned to face the downhill ski; ALL of the forces necessary to injure the downhill leg, specifically the ACL are present and injury is imminent.
The first step to avoid this injury is to recognize these elements and the necessity for all of these elements to be present for the injury to occur. By recognizing the danger of this scenario, the skier can develop a strategy and quickly implement it in order avoid injury to the ACL. There are likely MANY initial strategies that will work. One initial strategy that I encourage is to keep:
" your arms forward,
" your skis together,
" your hands over your skis.
This plan will keep your uphill arm from dropping back, your skis equally weighted and your upper body facing correctly. Four of the six elements will be changed, greatly reducing the risk of ACL injury. In addition to reducing the dangerous elements, it will place the "at risk" skier into a good position for either a recovery or a controlled bailout.
If you review the six elements of the "Phantom Foot syndrome", you will recognize that some of the elements are just plain bad habits or poor technique with downhill skiing. Many ski instructors spend a good deal of time to correct poor technique such as your uphill arm falling back, loosing your balance to the rear and allowing your hips to fall below your knees. Routinely correcting your technique by keeping your arms forward, keeping your hips above your knees and maintaining good balance and control will reduce your risk of injury and improve your overall skiing in general. However, even with the best of intentions and instruction, one can find him/herself rapidly in trouble and a well understood/practiced initial strategy as described above will change the elements of the Phantom foot syndrome and decrease injury risk.
In addition to the techniques described above, avoidance of some specific high-risk behaviors will also prove beneficial to reducing injury occurrence. Injury often happens when an out of control skier attempts to get up from a fall before they have fully stopped falling and sliding. You do not want to straighten your legs when you fall. You should keep your knees flexed until you have fully stopped sliding. You do not want to want to attempt to get up until you have stopped sliding and you should not land on your hand. Keeping your arms up and forward, your knees bent, hip-checking the hill and not attempting recovery until you have stopped sliding are all ways to avoid injury once you have lost control. This procedure of a controlled fall or bail out should be implemented when a fall is imminent. It may not ensure that no injury will occur, but it will decrease the risk of a severe injury and specifically a knee sprain.
In summary, a skier should remember to routinely correct their skiing technique, avoid high-risk behavior, recognize potentially dangerous situations and respond quickly and effectively to correct the dangerous situation. The skier is able to do these things with good and well-tuned equipment, a tuned and well-conditioned body and a practiced initial strategy if skiing goes awry. In addition to these principles, I encourage people to ski in control and at their ability level. Take an inventory of your body and call it a day when you are fatigued. Finally, do not become a victim to the rule of 3's. This rule is skiing on your third day in a row, after 3:00 p.m. and over 3000 vertical meters (10,000 vertical feet). Many injuries occur in this situation with fatigue of legs and general body likely the culprit. It may be a good time to call it a day before all three of these conditions are completed and enjoy that evening as well as the rest of the ski vacation and/or season.
Teresa L. Schuemann, PT, SCS, ATC regularly includes ACL Prevention Strategies in her fall program for former ACL patients, the ski club and other interested parties in her local community. Please feel free to contact her with comment and/or questions at click here
References
1. Johnson R, Shealy R, and Ettlinger C. ACL Awareness. Video and Booklet.
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