In general, there is a legal principal that you must accept your victim as he is. If he has weak bones, that does not reduce Was-Mart's liability in the slightest.
If this were not the case, there would be extensive and very intrusive checking into the background of every plaintiff in the country.
How would you like it if you were injured in a car accident and your entire life back to the age of 2 or 3 were fair game for some insurance company lawyer and investigator?
“If he has weak bones”
It probably because he was and is on a prescription (i.e. inherently dangerous) drug.
People think “prescription” means strong when it actually means inherently dangerous or addictive.