Hello!
Heterotopic ossification (HO) is the abnormal formation of true bone within extraskeletal soft tissue.
This can occur after trauma and surgery, discuss with your surgeon if you had any past surgery. It is more common after hip surgery.
Take care!
Heterotopic ossification (HO) is the process by which bone tissue forms outside of the skeleton.
See website below for complete information
http://en.wikipedia.org/wiki/Heterotopic_ossification