Why can it take months for a bone to heal?

Answer 1

Because a bone in your body is very rough and hard, the bone's healing time depends on the size of the damage, if the bone is completely snapped then it will take longer then a cut because it is bigger damage whereas a cut can seal itself.

The skin as such is made up out of organic soft material where cells can multiply very fast given the right conditions.

Our bone structure is made up out of specialized cells that absorbs a lot of calcium (and other components) that hardens them over time.

A bone heals quite quick though as in having or getting the cells needed in order to "glue" it back together again. This happens much at the same rate as skin cells would heal up.

It is the process of hardening and strengthening this freshly formed new material that is responsible for the long time it takes.

A broken bone will rarely break at the same place again after it is healed though. The fracture actually make the bone structure stronger where it happened due to "scar tissue" or extra bone material being deposited in and around the fracture.

Skin with scar tissue does not experience this effect and will be weaker for a really long time afterwards, often through life, although not much weaker.

Answer 2

because it needs to reform itself