Is there a disease where the bones are very strong?

Dense but not strong: Osteopetrosis known as marble bone disease, is an extremely rare inherited disorder whereby the bones harden, becoming denser. These dense bones result from defective osteoclasts and overgrowth of bone. The bones become thick and sclerotic, but their increased size does not improve their strength. I.

No: There is no disease that causes strong bones. Some people have genetically stronger bones. Others develop stronger bones by maintaining stronger muscles over a long period of time. One study showed a significant increase in the size and bone density of the dominant arm in professional tennis players.