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Myositis ossificans
Myositis ossificans is the formation of bone within muscle tissue or within the soft tissues. It is usually caused by injury but can also occur spontaneously. There are two main types - myositis ossificans circumscripta which occurs as a localized mass in response to injury, and fibrodysplasia ossificans progressiva which is a rare inherited condition causing progressive heterotopic ossification throughout the body that is ultimately disabling. Diagnosis is based on clinical features and radiographic findings of ossification, and treatment focuses on prevention of further ossification through avoiding re-injury and surgical procedures when possible.
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Myositis ossificans
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- 2. extra-osseous non neoplasticgrowth of new bone Misnomer Heterotopic ossification not always inflammatory within extra-skeletal soft tissues – mainly in connective tissue than muscle
- 3. Ectopic Calcification ?!! Depositionof radio dense Calcium Phosphate Difference in mineral phase No true bone matrix is formed Eg:- Hyper/Hypoparathyroidism, Renal failure, Following TB, Calcific Supraspinatus Tendinopathy, Scleroderma, Dermatomyositis
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- 5. Types Myositis ossificans circumscripta/traumatica fibrodysplasia ossificans progressiva (FOP)
- 6. Myositis ossificans circumscripta /traumatica Inresponse to soft tissue injury:- blunt trauma, stab wound, fracture/dislocation, surgical incision (THR) Systemic Conditions:- Head injury,Spinal cord injury Tetanus, Burns
- 7. Without known injury:- Nondocumentedtrauma, Repeated small mechanical injuries(blunt trauma in horse riders) Nonmechanical injuries caused by ischemia or inflammation. Increased risk in patients with Diffuse Idiopathic Skeletal Hyperostosis (DISH) and Paget’s Disease
- 8. Pathophysiology BMP stimulate primitivestem cells in soft tissues to form osteoblasts Organization of Haematoma Fibroblastic hypoplasia Osteoid formation
- 9. Radiographic evidence in6-8 weeks The lesion begins to calcify at the periphery and works toward the center (Reverse in Osteosarcoma)
- 10. Histopath- 4 distinctzones: the central undifferentiated zone- mitotically active the surrounding zone of immature osteoid formation – less active zone with new bone – osteoblast & fibrous tissue with trabecular organization Peripheral zone of fibrous tissue At least 10 days are required following onset of symptoms for these zones to become apparent.
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- 17. most commonly inthe second and third decade Areas commonly affected - elbow, thigh, buttocks, shoulder and calf ., erector spinae, pectoralis muscles (Quadriceps and brachialis - most affected.) Majority –asymptomatic; may cause pain/ loss of ROM
- 18. presents as arapid enlargement and significant pain one to two weeks after injury. Swelling and warmth at the site Hypercalcemia- contributing factor Increased ESR and serum alkaline phosphatase.
- 19. Treatment Watchful inactivity Rest andgentle stretching. Surgery if persistent pain – excised in toto in mature cases Risk of recurrence + If left alone, the mass will shrink in size
- 20. Treatment should not continueto play sports or use the affected muscle. Avoid Heat and massage. Reinjury to the same area, returning to activity too early, or initial passive forceful stretching can lengthen recovery. Prophylaxis: NSAIDS(Indomethacin), low dose radiation
- 21. Heterotopic Ossification Osteosarcoma Site:Diaphysis Metaphysis Peripheral rimming Ossification center (can mimic necrotic tr) to periphery Improvement in pain over Pain worsens with time and rest time Biopsy:Zone phenomenon Undiff tissue- viable muscle fibres similar to central intact cortex zone
- 22. Myositis Ossificans Progressiva/ Fibrodysplasia Ossificans Progressiva rare autosomal dominant disorder skeletal malformation and progressive, disabling heterotopic osteogenesis. fibrosing and ossification of muscle, tendon and ligaments of multiple sites often in the upper extremities and back that is disabling and ultimately fatal
- 23. Nine-year-old Mexican girlwith Fibrodysplasia Ossificans Progressiva (FOP).
- 26. Chromosome 2q23-24 Heterozygous mutation(617G®R206H) in the glycine-serine (GS) domain of the Activin A receptor type I (ACVR1) gene, a bone morphogenic protein (BMP) type I receptor Incidence 1in 2 million Age: Average 5 yrs (Fetus-25 yrs) Their offspring have a 50% probability of inheriting the condition.
- 27. painful lumps andstiffness in the adjoining joint. Lumps decrease in a few weeks, but joint mobility reduction persists. Exacerbating factors for ossifications at new sites minor trauma, venipuncture, biopsy of lumps, IM injections, dental treatments, and excision of masses.
- 28. Most common sites:-sternocleidomastoid, paraspinal muscles, the masticatory muscles, shoulder and pelvic girdle muscles. Spared are the abdominal muscles, extraocular muscles, muscles of facial expression, diaphragm, larynx and tongue muscles. Ossification progresses from proximal to distal and cranial to caudal.
- 29. C/F Digits: Short halluxin valgus with synostosis short thumbs , Clinodactyly Fibrous Tissues: Swelling in aponeuroses, fasciae, and tendons- ossification in muscles and fibrous tissues, most prominent in the neck dorsal trunk and proximal extremities (The sternocleidomastoid muscle is commonly affected.) Kyphoscoliosis: Restricted shoulder and pelvic girdle movements
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- 32. Lab Hemogram, ESR, S.Ca,P:- WNL ECG findings may be abnormal spirometry :-restrictive pattern, reflective of chest wall involvement.
- 33. Plain radiography ofFOP Short metacarpals and metatarsals Phalangeal synostosis (eg, monophalangeal great toe) Vertebral fusions, vertebral anomalies (i.e., small bodies), pedicle thickening Thick, short femoral neck Variations in bone maturation sequence Increased incidence of enchondromas
- 34. Treatment Once diagnosis isestablished, usually clinically, any surgical biopsy is contraindicated in FOP. No established medical therapy exists. Pain medications supportive measures -gentle occupational and/or physical therapy.
- 35. Prevention is better!! avoidfalling or getting bruises avoid IM injections since these can cause bone to grow. Never stretch their joints outside of their normal ROM. Flare-ups can occur spontaneously, even perfect preventive care cannot guarantee the absence of bone growths.
- 36. The mainstay ofdiagnosis is bilateral great toe anomaly present from birth, reported in 79 to 100% of patients microdactyly of both halluces due to a single phalanx in valgus position The finding of congenital hallux valgus must raise the possibility of FOP so that management should be early and adequate.
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