This document discusses myositis ossificans, a condition where bone forms in muscle tissue or other soft tissues. It presents two main types - non-hereditary myositis ossificans, which usually occurs after trauma in adolescents and young adults, and myositis ossificans progressiva (also called fibrodysplasia ossificans progressiva or stone man syndrome), a rare genetic disorder where muscle and connective tissues are gradually replaced by bone. The document outlines the etiology, clinical features, diagnosis, histopathology, and treatment of both conditions. Surgical excision may be indicated if the condition causes intolerable pain, neurological compression, or limited range of motion.

1. MYOSITIS OSSIFICANS
PRESENTED BY: DR. BIPUL BORTHAKUR
PROFESSOR, Dept of Orthpaedics,SMCH

2. INTRODUCTION
• Acquired development of non neoplastic heterotopic ossification
within soft tissues
• Most often in response to localized trauma
• Although the process most commonly develops within skeletal
muscle, the term itself is a misnomer, because nonmuscular tissue
may be involved, and inflammation is rare.
• Adolescents & young adults, predominantly men, are affected
most frequently, although it has been reported in infancy as well

3. ETIOLOGY
• PRECIPITATING FACTORS –
• Single or repetitive trauma (70%)
• Severe thermal injury
• Post-traumatic paraplegia
• Brain injury
• Orthopaedic operations – THR

4. GENETIC & DEVELOPMENTAL FORMS –
• Fibrodysplasia ossificans progressiva
• Progressive osseous heteroplasia
• Pseudomalignant heterotopic ossification
• Albright hereditary osteodystrophy
• Parosteal fasciitis

5. TYPES-
• 1. NON HEREDITARY MYOSITIS OSSIFICANS
• 2.MYOSITIS OSSIFICANS PROGRESSIVA
(“FIBRODYSPLASIA OSSIFICANS PROGRESSIVE”)

6. NON HEREDITARY MYOSITIS OSSIFICANS-
• 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 this condition
• Muscles usually involved are -
• Quadriceps
• Brachialis
• Gluteal muscles
• Deltoid

7. MYOSITIS OSSIFICANS PROGRESSIVA-
• Also called Fibrodysplasia ossificans progressiva OR STONE
MAN SYNDROME
• Autosomal dominant connective tissue disorder
• Muscle tissue and connective tissue –tendons & lig.gradually
replaced by bone (ossified), extra-skeletal or heterotopic bone
that constrains movement
• No cure
• Usualy die early - malnutrition & recurrent infections

8. • Painful lumps and stiffness in the adjoining joint.
• Lumps decrease in a few weeks, but joint mobility reduction persists
EXACERBATING FACTORS FOR OSSIFICATIONS AT NEW
SITES ARE-
• Minor trauma
• Venipuncture
• Biopsy of lumps
• IM injections,
• Dental treatments
• Ossification progresses from proximal to distal and cranial to caudal.

9. CLINICAL FEATURES-
Digits:
• Short hallux in valgus with synostosis short thumbs
• Clinodactyly
• Fibrous Tissues:
• Swelling in aponeurosis, fasciae, and tendons
• Ossification in muscles and fibrous tissue
• Most prominent in the neck, dorsal trunk and proximal extremities
• The sternocleidomastoid muscle is commonly affected
• Kyphoscoliosis

10. Myositiss Ossificans Progressiva- (left) Dorsal view of patient
(upper) B/L clindodactyly of 5th finger of hands (below) B/L
short hallux valgus of feet

11. Xray showing B/L short hallux valgus

12. PATHOPHYSIOLOGY OF MO-

13. HISTOPATHOLOGY-
• Four distinct zones:
• 1. Central undifferentiated zone- Mitotically active
• 2. Surrounding zone of immature osteoidformation – Less active
• 3. Zone with new bone – Osteoblast & fibroustissue with trabecular
organization
• 4. Peripheral zone of fibrous tissue
• At least 10 days are required following onset of symptoms for these zones
to become apparent.

15. Myositis Ossificans- Histopathology

16. CLINICAL FEATURES-
• Typically begin approximately 1 to 3 weeks after an injury
• Localized pain and a palpable mass.
• Increased warmth, swelling
• Progressive loss of ROM - Hallmark sign
• Low-grade fever
• Mildly elevated ESR

17. DIAGNOSIS-
RADIOGRAPHIC FEATURES-
• Early plain radiograph-
• Non calcified mass in the soft tissues
• Within 2 to 4 weeks after the injury –
• Floccular calcifications begin to appear within the mass
• If the cambium layer of the periosteum was involved in the
initial injury, a periosteal reaction of the underlying bone
• Over a 6 to 8 wk period - serial x-rays at 1 to 2 wk intervals
show-
• Peripheral osseous maturation of the lesion
• Central lucent zone and a lucent line separating it from the
underlying cortex , distinguishing from an extraosseous
sarcoma
• After5 to 6 months - mature bone is evident, and the lesion

18. MYOSITIS OSSIFICANS- A. Knee B. Elbow

20. FIBRODYSPLASIA OSSIFICANS PROGRESSIVA

21. • CT scan –
• Delineats the zonal maturation and cortical separation when the
diagnosis is unclear
• Other imaging modalities –
• Bone scintigraphy
• Ultrasound
• MRI
• Leukocyte scanning, and angiography, particularly in early lesions or in
difficult cases

22. CT scan shows Egg shell calcification

23. DIFFERENTIAL DIAGNOSIS-
• Parosteal Osteosarcoma
• Soft tissue Sarcoma including malignant fibrous
histiocytoma
• Synovial sarcoma

24. TREATMENT-
• As the calcifications will typically resolve after a period of time,
non-surgical treatment is encouraged.
• Affected limb should be immobilized with bed rest, ice therapy,
and elevation of the affected limb.
• Range of motion exercise can be introduced as long as the range
of motion is not painful.
• For those who had total hip replacement postoperative single
low-dose radiation with 3 weeks of oral indomethacin regimen
will be preventive.

25. INDICATION OF SURGICAL EXCISION –
• Intolerable pain
• Compression of the neurovascular structures
• Limitation of the range of motion of the joint which
affects the activities of daily living.

26. Chapter 6, Verse 6
bandhuraatmaatmanastasya yenaatmaivaatmanaa jitah |
anaatmanastu shatrutve vartetaatmaiva shatruvath ||
For a person who has conquered his lower self by the divine self,
his own self acts as his best friend. But for that person who has not
conquered his lower self, his own self acts as his worst enemy.
Thanks