Originally Posted by Garrett
Originally Posted by jdistefa
the 'inward twisting' component of the injury mechanism - from the rut/bump picking up and redirecting the ski very rapidly - probably overwhelms the capacity of any mechanical binding to react in enough time to protect the knee.
Lastly, IMO there's some woefully ignorant crap on this thread re. biomechanics, physics, injury mechanisms, and equipment.
And what are your particular qualifications in mechanical design and multibody dynamics that led you to the conjecture above?
FWIW, the conjecture present in that first statement comes dangerously close (if I'm being polite) to what you are complaining about in the latter. The statement you made is suspect until proven otherwise with analysis, and it wouldn't be a simple analysis. I'll leave that up to people designing bindings for a living. I just enjoy the fruits of their work.
I made a post earlier using "twist" with scare quotes, and Jim responded with a rant about how wrong I am using twist without any such scare quotes. The level of discourse here is certainly pretty low; I'll agree with you on that.
I edited my post several times to tone down my response. Don't bother pretending to be polite .
If you read my post, I did say probably overwhelms the capacity of the binding. There are very few certainties with this stuff given the variables involved. Rick's design is based on good bench science and a very solid understanding of the typical injury mechanisms involved. How well the design works in the real world will require data collection of a type that will probably not be done (open to hear from Rick on this point) - hence my earlier comment about efficacy vs. effectiveness.
The example I cited is rare, and tends to occur among elite skiers at high speeds. Once you treat (well, not you) a few of these guys/gals and review their videos, it's painfully obvious re. what happened to their knee. As Rick referred to, the typical combination of loading that ruptures the ACL is a triad of backward position, valgus stress, and internal rotation. What I (and others) believe happens in these specific cases is a very sudden and large internal rotation load on top of some degree of rearward position and valgus knee stress from the act of skiing (i.e. angulation). Essentially these athletes give themselves their own 'pivot shift' maneuver (I'll leave that up to you to google). There just isn't good clinical 'science' on this stuff, but there is expert opinion (and experience) which has some value IMO.
If I recall, you were the same guy that was pontificating about F1 vs. World Cup medical coverage. Carry on .
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