Myositis ossificans

Definition , Types ,Pathophysiology , clinical presentation ,Investigations , Differences between myositis ossificans and osteosarcoma , Management.

1. Dr. Prasanth

2. MYO-MUSCLE , OSSIFY-CALCIFY/BONE FORMATION It is also known as post traumatic ossification / sterners tumor

3. DEFINITION Bony formation with in a muscle secondary to blunt trauma Essentially metaplasia of the intramuscular connective tissue resulting in extra osseous bone formation

4. TYPES 1. NON HEREDITARY MYOSITIS OSSIFICANS 2. MYOSITIS OSSIFICANS PROGRESSIVA (“ FIBRODYSPLASIA OSSIFICANS PROGRESSIVE”)

5. NON HEREDITARY MYOSITIS OSSIFICANS Conditions occur in children(due to periosteum is loosely attached around bones) and in young active males due to trauma to the muscle and soft tissues(hematoma in muscles), massage following fracture can aggrevate. Muscles usually involved- QUADRICEPS -BRACHIALIS -GLUTEAL MUSCLES -DELTOID Other sites:erector spinae & pectoralis muscles.

6. PATHOPHYSIOLOGY BMP(bone morphogenetic proteins) stimulate primitive stem cells in soft tissues to form osteoblasts Organization of haematoma Fibroblastic hypoplasia Osteoid formation

7. CLINICAL PRESENTATION Pain , Tender swelling and decrease ROM(extra- articular Ankylosis) usually occurring with in days of injury. Sometimes painless enlargening mass that occurs usually after an injury. It is a self limiting problem.

8. INVESTIGATIONS X-RAYS Mineralization occurs about 3wks after injury. Peripheral bone formation with central lucent area may appear as “ DOTTED VEL PATTERN” MRI with gadolinium Rim enhancement is seen with in the first 3 weeks CT scan Mineralization progresses to form Zoning pattern( “EGG SHELL calcification”) it is mineralized at the periphery from lamellar bone and lucency from center from immature tissue. Increased ESR and Serum alkaline phosphatase

9. DIFFERENCES MYOSITIS OSSIFICANS 1. Calcification occur Centripetally to centre (EGG SHELL calcification) 2. As time goes on pain decreases 3. Calcification occurs in association with bone Diaphysis. OSTEOSARCOMA 1. Calcification occur Centrifugally to periphery 2. As time goes on pain increases 3. Calcification occurs in association with bone metaphysis.

10. TREATMENT REST and Observation. Activity modification. Physical therapy to maintain the active range of motion (NO Passive range of motion, they may stimulate ossification reaction and lead to recurrence ) Limb should be rested with the knee in extension/ Elbow in 90degrees of flexion, until local reaction has subsided. Avoid heat and massage. Prophylaxis: NSAIDS and low dose radiation.

11. Surgical Treatment Don’t excise it in early stages because this will lead to recurrence. Size of mass usually decreases after 1 yr , so follow up X-rays needed. Surgery indicated if lesion is mature (may take upto 1 yr ) Active-margins of the bone mass are fluffy X-Ray Mature- Trabeculated with well defined margin

12. DIFFERENTIAL DIAGNOSIS PAROSTEAL OSTEOSARCOMA. Soft tissue Sarcoma including malignant fibrous histiocytoma . Synovial sarcoma.

13. MYOSITIS 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

14. Chromosome 2q23-24 Heterozygous mutation in the glycine-serine Incidence – 1 in 2 million. Age- Avg. 5yrs (Foetus - 25 yrs ) Their offspring have a 50% probability of inheriting the condition. Painful lumps and stiffness in the adjoining joint, lumps decreases in a few weeks ,but joint mobility reduction persists.

15. Exacerbating factors for ossifications at new sites -Minor trauma -Venepuncture -Biopsy of lumps -IM injections -Dental treatments -Excision of masses

16. Most common sites -Sternocleidomastoid, Paraspinal muscles, Masticatory muscles, shoulder and Pelvic girdle muscles. Spared muscles -Abdominal muscles, Extra ocular muscles Muscles of facial expression, Diaphragm, Larynx and Tongue muscles. Ossification progresses from proximal to distal and cranial to caudal.

17. Clinical Features Digits: short hallux in valgus w ith synostosis short thumbs and clinodactyly. Fibrous tissues: swelling in aponeurosis, fasciae and tendons- ossification in muscles and fibrous tissues. Most prominent in the neck dorsal trunk and proximal extremities KYPHOSCOLIOLIS: restricted shoulder and pelvic girdle movements.

18. Investigations Hemogram, ESR , s.Ca ECG findings may be abnormal. Spirometry: restrictive pattern, reflective of chest wall involvement.

19. Plain radiography of FOP Short metacarpals and metatarsals. Phalangeal synostosis. Vertebral fusions, vertebral abnormalities ,Pedicle thickening. Thick , short femoral neck. Variations in bone maturation sequence. Increased incidence of enchondromas .

20. Treatment Once diagnosis is established ,usually clinically any surgical Biopsy is contraindicated in FOP. No established medical therapy exists. Pain medications. Supportive measures- gentle occupation and physical therapy

21. Early Diagnosis The mainstay of diagnosis 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.

22. Prevention is better!! Avoid falling 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.

23. thank you