Modeling Forces on the Anterior Cruciate Knee Ligament During Backward Falls While Skiing

Abstract

In recent years a dramatic increase has been observed in isolated anterior cruciate knee ligament (ACL) lesions and in knee sprains where the principle injury has been to the ACL. Traditional mechanisms for this type of injury are not, in general, consistent with the type of fall nor do they explain why there should be such an increase in ACL injuries. One new mechanism that has been proposed is the boot-induced anterior drawer. In a fall involving this mechanism, a skier is off-balance posteriorly such that loads are applied to the tail of the ski tending to push it forward and rotate the tip down. The loads are transmitted to the skier through the boot which pushes the tibia anteriorly relative to the femur, thus stressing the ACL. In this work, the loads on the ACL have been modeled during a boot-induced anterior drawer incident. These loads have been shown to increase in the impact phase with increased slope and in the impact and rotation phases with increased boot stiffness in backward lean.

An approach to generate noncontact ACL-injury prone situations on a computer using kinematic data of non-injury situations and Monte Carlo simulation

“…In the simulated injury prone landings, the skier got into a backward leaning position and landed asymmetrically on one ski tail with extended hips and knees (Table 1). The description of the obtained injury prone landings is consistent with other studies, where the same characteristics were observed (Bally et al 1989;Bere et al 2011;Heinrich et al 2014).…”

Anterior knee laxity in skiers before and after racing

“…It involves the application of an active anterior drawer applied by the posterior shell of the ski boot along with powerful quadriceps contraction [1,4,5]. This repeated anterior drawer force on the proximal tibia is produced by tremendous quadriceps contraction.…”

Anterior Cruciate Ligament Forces in Alpine Skiing

“…The incidence of anterior cruciate ligament (ACL) injuries in Alpine skiing has increased in the past 2 decades (Bechtel, Ellman, & Jordon, 1984;Feagin et al, 1987;Hauser & Schaff, 1987;Howe & Johnson, 1982;Johnson, Ettlinger, & Shealy, 1991;McConkey, 1986). This increase has been associated at least partly with changes in the design of ski boots and the design and release settings of bindings (Bally, Boreiko, Bonjour, & Brown, 1989;Figueras et al, 1987;Johnson, Ettlinger, Campbell, & Pope, 1980;Johnson, Ettlinger, & Shealy, 1989;Johnson et al, 1991). For example, the ski boots have become higher and stiffer in the past years, thus increasing the potential for transmitting forces directly from the skis to the knee joints (Bechtel et al, 1984;Ettlinger, 1986;Hauser & Schaff, 1987;Johnson et al, 1991).…”

“…tries to recover from this fallen-back position (Bally et al, 1989;Figueras et al, 1987). In this situation, the bindings typically do not release, and the skiers report a "snap" or "pop" in their knees, either as they are forced into a hyperflexed knee joint position or as they try to recover from the hyperflexed knee joint position by contracting the knee extensor muscles powerfully (Figueras et al, 1987).…”

“…Although isolated ACL injuries in Alpine skiing have been described in the literature (Ekeland & Thoresen, 1987;Shino, Horibe, Nagano, & Ono, 1987), the precise loading conditions and the mechanisms associated with this injury have not been studied using experimental data of t.he condition of interest. It has been speculated that the ski boot pushing forward on the tibia may preload the ACL (Bally et al, 1989). This preload coupled with a violent contraction of the quadriceps muscle group to maintain balance is believed to be instrumental to the tearing of the ACL (Feagin et al, 1987;McConkey, 1986McConkey, , 1987.…”