Myositis ossificans comprises two syndromes characterized by heterotopic ossification (calcification) of muscle.
Classification
In the first, and by far most common type, nonhereditary myositis ossificans (commonly referred to simply as "myositis ossificans", as in the remainder of this article), calcifications occur at the site of injured muscle, most commonly in the arms or in the quadriceps of the thighs. [Source: Wikipedia 
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