Two types of ligament injuries common in skiing are both isolated anterior cruciate (ACL) and medial collateral (MCL), frequently in combination with ACL. Based on research related both to ligament injury mechanics and two-mode release binding function, the purpose of this paper was to critically assess the ability of two-mode release bindings to prevent combined MCL/ACL injuries. Making this assessment entailed several steps. First the loads typically transmitted by the knee during falls in which combined injury occurred were determined. Because more than one load was transmitted, the next step was to discern which of the loads was more damaging. Finally, heel-toe type bindings were evaluated for their potential to release in response to damaging loads.
The conclusions from these steps were that combined MCL/ACL injuries typically occur in forward-twisting-type falls where the primary loads are external axial and valgus moments at the knee. Of these two loads, an external axial moment is more damaging than a valgus moment both to the MCL when the joint is intact and to the ACL when the MCL is damaged. Heel-toe type bindings offer release sensitivity to this moment. Because bindings offer the release sensitivity to protect against many combined MCL/ACL injuries, the release level of the toepiece in twist is an important factor in the prevention of these injuries.