CADS: Keeping Skiers on the Slopes
In the United States alone, there are reportedly more than 20,000 knee injuries each year which are attributed to Alpine skiing, sometimes to the point of having to resort to expensive surgery and extended periods of rehabilitation. However, skiers who have suffered knee injuries may still be able to take to the slopes with the aid of Constant-force Articulated Dynamic Struts (CADS).
Designed by Vail Valley resident, Walter Dandy, more than two decades ago, CADS makes use of a pelvic harness, rods and elasticized cords to transfer upper body weight to the ski boots – all of which are worn under ski pants. So when a skier bends his/her knees to assume a skiing position, the elastic bands are stretched, with the stretch being transmitted via the cords over the CADS pulleys to the pelvic harness, thereby reducing the skier’s effective body weight. This reduces the required quadriceps contraction strength, which in turn reduces compressive forces across the knee joint surfaces. A study carried out by the Steadman Clinic concluded that at 50 degrees of knee flexion, body weight is reduced by more than 22 percent for CADS users.
Walter Dandy explains that it’s like “sitting on a bedspring”. By pushing down on the ski and up on the skier, CADS does what muscles do, hence the skier doesn’t get tired and their knees don’t hurt. Dandy also reveals that he initially invented the CADS to alleviate thigh burn which he experienced as a vacation skier. Following a few days on the slopes one year, which left him with very tired legs, it occurred to him that skiers use muscle in a very unique way, keeping them in a state of constant tension. Realizing that a spring can mimic a muscle, the idea of the CADS was born – and the benefits to skiers with knee, foot, ankle, hip and back problems over the past 22 years have been enormous.