<prompt> Myositis ossificans is?Worm calcificationCallus formationRegenerationPost traumatic ossification  <response>: ANSWER: D Post traumatic ossificationREF: Apley 8th ed page 571, Tachdjians 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 muscleEtiology:Post traumatic ossificationSurgical traumaMicrotrauma overuse injury soleus muscleMassage 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 veilcotton 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. 