I'm sure that the bone was stronger than it would have been if he had not
been weightlifting. It just wasn't strong enough for that load applied
in that particular fashion. The comminution (free piece)is
characteristic of higher energy injuries to the bone.

Bone is a complicated material which is polyphasic in nature and responds
differently to tension (weaker) than compression (stronger). The
mechanical properties do depend on the relative mineral composition (ie
collagen to mineral, plus lots of other substances). Osteoporotic bone
is weaker. Paradoxically, osteopetrotic bone can also be weaker because
the microstructrue is altered.

I'm sure that I could dig up a more detailed explanation from Norden and
Frankel if necessary.

In short, he overloaded the bone, even though it was strong, just not
strong enough!

Chris Hamilton, MD
University of Texas Medical Branch
Department of Orthopaedic Surgery