What is the underlying cause for this fracture?
Findings are typical of a bisphosphonate related fracture.
What is the difference between a stress fracture and insufficiency fracture?
Stress fracture is abnormal stress on normal bone. Insufficiency fracture is normal stress on abnormal bone.
What other imaging study is required?
Contralateral femur +/- OPG. There are often insufficiency fractures affecting the contralateral leg, and bisphosphonates can results in mandibular osteonecrosis.
Right femur chalk stick fracture.