Improper care of a thigh contusion leading to incomplete absorption of the hematoma can produce formations similar to a cartilage or bone. this process is known as:

Myositis ossificans traumatica (MOT) is an inflammatory process of muscle in its early stage. There is heterotrophic growth of bone in muscle and other soft tissues previously exposed to trauma and hematoma. Common examples are Horse Riders Bone and Infantrymen's drill bone on the deltoid. The commonly involved muscles are quadriceps femoris, brachialis anticus, adductor muscles of the thigh and deltoid muscle. It usually occurs in adolescents and adults.

just here for the other one bc they put up with u