Pathophysiology
The exact mechanism of myositis ossificans is not clear. Inappropriate response of stem cells in the bone against the injury or inflammation causes inappropriate differentiation of fibroblasts into osteogenic cells. When a skeletal muscle is injured, inflammatory cytokines (Bone morphogenetic protein 2, Bone morphogenetic protein 4, and Transforming growth factor) are released. These cytokines stimulate the endothelial cells of the blood vessels to transform into mesenchymal stem cells. These mesenchymal stem cells then differentiate into chondrocytes, and osteoblasts, resulting in bone formation in soft tissues.The process of myositis ossificans can be divided into three stages: early, intermediate, and mature. The early phase occurs in the first four weeks of injury with inflammatory phase of bone formation. This is followed by intermediate phase of bone formation (four to eight weeks following injury) where calcification started to occur and is visible on X-rays. During the maturation phase, mature bone started to form. As the maturation continues, the bone will consolidate in the coming months and subsequently bone regression occurs. Diagnosis
Sonographic diagnosis
Calcification is typically depicted 2 weeks earlier by ultrasound (US) when compared to radiographs. The lesion develops in two distinct stages with different presentations at US. In the early stage, termed immature, it  depicts a non-specific soft tissue mass that ranges from a hypoechoic area with an outer sheet-like hyperechoic peripheral rim to a highly echogenic area with variable shadowing.
Olopatadine, sold under the brand name Opatanol among others, is a medication used to decrease the symptoms of allergic conjunctivitis and allergic rhinitis (hay fever). It is used as eye drops or as a nasal spray. The eye drops generally result in an improvement within half an hour.Common side effects include headache, sore throat, eye discomfort, change in taste. More significant side effects may include sleepiness. It is unclear if use during pregnancy or breastfeeding is safe. It is an antihistamine and mast cell stabilizer.Olopatadine was patented in 1986 and came into medical use in 1997. It is available as a generic medication. In 2017, it was the 270th most commonly prescribed medication in the United States, with more than one million prescriptions. Side effects
Some known side effects include headache (7% of occurrence), eye burning and/or stinging (5%), blurred vision, dry eyes, foreign body sensation, hyperemia, keratitis, eyelid edema, pruritus, asthenia, sore throat (pharyngitis), rhinitis, sinusitis, taste perversion, and vomiting. Chemistry
Synthesis
Pharmacology
Pharmacodynamics
Olopatadine acts as a selective antagonist of the histamine H1 receptor, thus stabilizing mast cells and inhibiting histamine release. History
Olopatadine was patented in 1986 by Kyowa Hakko Kogyo and came into medical use in 1997.In the United States, Pataday Twice Daily Relief was first approved by the FDA in 1996, under the name Patanol as a prescription drug and was indicated for the treatment of the signs and symptoms of allergic conjunctivitis (referring to ocular redness and itching due to allergies).