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What is Myositis ossificans is? and explain in detail?
ANSWER: (D) Post traumatic ossificationREF: Apley 8th ed page 571, Tachdjian's Orthopaedics 3rd ed page 2168MYOSITIS OSSIFICANS/ HETROTROPIC OSSIFICATION:It is hetrotopic calcification and ossification in muscle tissue. The name is a misnomer as there is no myositis (inflammation of muscle)Etiology:Post traumatic ossificationSurgical traumaMicrotrauma & overuse injury (soleus muscle)Massage & vigorous passive stretchingPathogenesis: The bone formation in muscle represents metaplasia of fibroblast at the site of injury. Trauma leads to periosteal elevation followed by subperiosteal hematoma formation followed by subperiosteal ossification. It has 4 microscopic zones (Ackerman Zonation). Centre zone of undifferentiated, highly active mitotic cells and outermost zone of well differentiated bone cells surrounded by fibrous tissueClinical features:Mostly asymptomaticOthers presents with tenderness, palpable swelling, painful range of movement, stiffness and increased warmth.Imaging:Initial radiographs are normalDotted veil/cotton wool appearance in radiograph after 10 days to 4 weeksPeripheral opacification and central lucency is seenCT is better than X rayTreatment:Watchful inactivityPhysical therapy should be discontinuedLow dose irradiation and IndomethacinSurgical excision not done untill 1-2 years after acute phase of disease.