@ SkiMagoJazz & The Dad: I answered your good question, definitively.
Regarding Phantom Foot and Slip Catch events (cause of approx 70% of all skiing-ACL injuries):
No 'ordinary' binding ( 'ordinary' = only lateral toe and forward heel release ) reads or reacts to the (lateral) abduction forces that enter the ski-human-system directly under the tibia which abduction forces arise during Phantom Foot or Slip Catch injury-producing-mechanisms — AND which abduction forces acting at the distal-end of the tibia ACT OVER THE LENGTH OF THE TIBIA to generate massive vaglus torque ( in structural engineering this same effect on columns is called 'lateral overturning moment' — utilized in earthquake design of building structures — but orthopedists call the same thing 'valgus torque'), which valgus torque generates massive strain across the ACL (at the intersection of the column and beam ... that's the point in a structure were buildings fail during the lateral shaking from earthquakes). In other words, the abduction force enters the ski-human system directly under the tibia, thereby generating zero torque around ("about") the tibia ( because Torque = force times distance, whereby an abduction force that enters the ski-human-system directly under the tibia thereby has a lateral-distance of zero (a lateral-lever arm of zero), therefore if the abduction force is 10 or 100,000, torque around ("about") the tibia will always be zero. ( T = f x d; and where d = 0, then T always = 0 ). 'Ordinary' bindings (with only lateral toe and forward heel release) have a pivot that deals with lateral loads that is located under (or nearly under) the tibia: therefore, under the condition when an abduction force enters the system — an 'ordinary binding' also 'has' ('supplies') no lateral lever arm with which it can read or react to the abduction force that is applied at the center of its 'ordinary pivot' that's also located directly under the tibia. No 'ordinary binding' can release in the presence of an abduction force.
Regarding BIAD events (cause of approx 10% to 15% of all skiing-ACL injuries):
(Pls see description of 'BIAD', above): Only bindings that offer pure vertical toe release will respond ('read' and 'react') to BIAD-induced loading. Presently, there are no toes on the market (anywhere in the world) that provide pure vertical toe release. Many years ago, there were many bindings that provided pure vertical release at the toe of the boot: these included but are not limited to: Geze SE3 (the only independently adjustable vertical toe release — so it provided some degree of retention ... but not enough for most advanced skiers, thus it failed to be viable), Spademan, Cubco, Burt, Besser, Moog, Eckyl, Americana, Calspan, Sundial, Inertia-B, Revolution-X, Weinmann, Gertsch, and several others. All of those bindings suffered from massive pre-release and were totally non-viable in the real world of skiing.
NO 'ORDINARY' BINDINGS WITH ONLY LATERAL TOE AND FORWARD HEEL RELEASE CAN PROVIDE ANY MITIGATION OF SKIING ACL INJURIES.
For example, if, with an 'ordinary binding', you set the lateral toe and forward heel release ( DIN ) as low as 3.0 — then find yourself in a Phantom Foot or Slip Catch situation, your 'ordinary binding' feels nothing that will cause lateral toe release or forward heel release ... there will be NO release ... but the abduction-component of the Phantom foot or Slip Catch mechanism will act over the LENGTH OF YOUR TIBIA to impart a massive valgus torque that can take your ACL well past its elastic limit.
(( "Height" in the DIN-charts ONLY serves as a 'correction' for people who are overweight — and has NOTHING to do with the above noted effects of tibia length; HOWEVER, the total distance from the snow surface to the center of the knee does have a direct effect on valgus torque, and this effect is 'dealt with' by all bindings that have lateral HEEL release. ))
((( All alpine ski bindings, including all with lateral heel release, must (by definition of what an 'alpine ski binding' is according to the international standard for alpine ski bindings, ISO 9462) meet the minimum international standards — ISO 9462, 9465 & 11087 AND must meet 'standard industry practice' for anti-pre-release and durability. )))
Edited by Richard Howell - 10/4/12 at 10:02am