Why would the ligaments of the knee not give way before the bone breaks?
My blame list: 1) The bindings, they simply are not as good as they could be. 2) Unusual ski position circumstance, even with bindings that dont work as well as they could, they do work at least most of the time, otherwise we would all have broken legs, so something as far as the ski/user position, occured that put uncommon stresses to the system. 3) Stiff boots, in the past even if your bindings did not release your boot had enough give so that there would not be any concentrated pressure on your legs to tear or break anything. 4) Skier's bones, I think that if a biopsy were done with the bones from those who have had the breaks, we may find that for whatever reason these skiers bones were not as strong as they could be at that point in time....or that they had been compromised previously, and all they needed was an extra push to fail.
WC skiers fall at 70mph with heavy 200+cm skis and DINs of 14+ and leg breaks are not the norm (torn connective tissue is); leads me to believe that they have strong bones, nutrition and training increases the resilience and density of bones. Our victims may have all the skills of a WC racer but due to age, conditioning, or a maybe medication they are taking, their bones may be slightly compromised, enough to result in a break, even before the ligaments give.