1) Heterotopic ossification is the formation of bone in soft tissues where bone is not normally present, usually occurring after injury or surgery. 2) It has three stages - early inflammatory phase with swelling, intermediate consolidation phase with calcification visible on x-rays, and late maturation phase where the bone hardens. 3) Risk factors include trauma, surgery, burns, and genetic conditions. It most commonly occurs around the elbow and hip. 4) Excision surgery aims to remove the ectopic bone, with different approaches depending on the location. Prophylaxis with indomethacin or radiation can decrease rates of recurrence after hip surgery.

1. HETEROTROPIC OSSIFICATION
Dr.Ponnilavan

2. Definition:
Heterotropic ossification – formation of mature cellular bone in
non – osseous tissue or presence of bone formation at a place
where it should not be present[ heterotopic] that is usually soft
tissue.

3. HETEROTOPIC OSSIFICATION
• HO – 1st described in 1883 by Riedel.
• HO may be traumatic or non-traumatic
• Types of HO:
- HO per se / Myositis ossificans circumscripta
- Traumatic HO/ Myositis ossificans traumatica
- Neurogenic HO

4. • Causes?? Evolution of disease :
- It has early, intermediate and late presentations and pts may
present anytime during the disease evolution.
- Fever, swelling, erythema and joint stiffness typically seen in
early HO may mimic the presentation of cellulitis, osteomyelitis
or thrombophlebitis
Idiopathic
Tetanus
Hemophilia
DISH

5. • MRI –
- T1 – isointense to hyperintense
- T2 – intermediate to high signal
These features though suggestive of HO may be confused with
focal myositis so confirmation comes only when the lesion
matures with time.

6. PATHOGENESIS
• Early disease[ inflammatory phase]:
- Early there is swelling & pain similar to an infection or soft tissue
aggressive tumor
- Radiographs??
- Usg – hypoechoic mass with central reflective core is seen that may
have a lamellar hyperreflectivity at the periphery of the mass
- CT scan ??
Radiographs are normal or show a soft tissue density
CT scan reveals enlarged m/s group with normal attenuation

7. • INTERMEDIATE STAGE [ CONSOLIDATION STAGE ]:
- Clinically ?
- Radiographs shows dotted veil calcificaton confusing with
rhabdomyosarcoma or synovial sarcoma
- There may be continuous or discontinuous peripheral
calcification.

8. • The lesion becomes clinically firm with constant pain
• There may b limitation of movements at adjacent joints if the lesion
is large
• CT SCAN is a better modality & reveals zonal phenomenon with rim
of calcification of varying thickness at periphery while central area
similar to m/s
• MRI – more non specific with variable signal at the center &
decreased signal intensity at periphery on all pulses
• d/d – calcific tendinitis- if mass is small as in tendinitis the mass is
small with asso.calcification

9. • Late stage [ maturation phase]
• Mass – bony hard & easily discernable from its surrounding
tissue.
• Pain reduces dramatically but the swelling & deformity is
concern for most pts
• Mass may mere with adjacent bone resembling
osteochondroma

10. • Movts at the asso. Jts may be limited in a large mass.
• pattern of mineralization --periphery -more mature than
central region that is still evolving [ zonation phenonmenon]

11. • This helps in differentiating it from extraskeletal osteosarcoma
• Os- hav immature periphery mature dense calcification
centrally
• d/d – osteomyelitis, osteochondroma,osteosarcoma,myositis,
pentazosine induced myopathy,hematoma formation,
intramuscular parasitic cysts, rhabdomyosarcoma,synovial
sarcoma

12. Rx
• Early stage ?
• Prognosis is good & the lesion usually does not recur after sx
excision if performed adequately

13. Traumatic HO/ myositis ossificans traumatica .
• m/c form
• Can occur after any type of musculoskeletal trauma
- characterized by
heterotopic calcification & ossification in muscle tissue.
Injury is an important factor in its pathogenesis.
Usually there is a h/o severe single injury.
It is only seen in children with # or d/l of elbow. In our
country, usually the patient has taken massage treatment.

14. • Clinical Features
• Rapid enlargement and severe pain are
the cardinal
• symptoms usually 1 or 2 weeks following
trauma.
In our country after trauma or injury, the
bonesetter/quack massages the injured
part daily, often vigorously. This leads to
calcification.
• Patient usually presents with stiff painful
joint.
• h/o injury 1 to 2 weeks back.
• Patient may come even months after the
injury.

15. • O/E:
-palpable swelling.
-Mass is initially ill defined, then becomes better circumscribed.
The part becomes grossly swollen.
-lesion - self-limited and usually matures into a hard
mass, or it may totally regress.
-Most common location is the post-traumatic elbow

16. myositis ossificans is
• diaphyseal , lying parallel to surface of bone &
often separated from it by a distinct lucent area
in which cortex & periosteum have abn’l
appearance
Osteogenic sarcoma is likely to show some
evidence of involvement of the cortex &
periosteum, & it is metaphyseal .
• Occasionally, the differentiation is difficult &
even the histologic ex. may be misinterpreted
Differential
Diagnosis
Myositis ossificans
must be
distinguished
from calcifying
hematoma,
interstitial
calcinosis, and
osteogenic
sarcoma.

17. • Treatment
• Rest of the affected part during the period while the
process is active is the basic principle of Rx.
-Aspirin is known to inhibit calcification.
-Passive movts & vigorous exercises must be stopped.
No massage.
Very gentle exercises must be started.
Surgery is contraindicated during the period when calcification matures.
Usually it takes more than 8 months one
ossification to mature and if it interferes with function, it may be excised

18. 43% rate of HO
in operatively
treated fracture
–d/l
half of these
requiring sx
intervention.
was asso. with
clinically
relevant
motion
deficits
20 % of 130 elbow HOForuria et al
Shukla et
al

19. Risk Factors for Developing Heterotopic
Ossification about the Elbow
Trauma
■ Open elbow D/L requiring extensive or
multiple débridements
■ Elbow D/L asso with # that require ORIF
■ Radial head # treated with surgery > 24
hrs after injury
Surgery :
■ Distal biceps tendon repair
■ Repeated procedures with improper
exposure in first 2 wks
■ CNS injury
■ Traumatic brain injury
■ Elbow trauma + traumatic brain injury
Burns
■ 3rd-degree burns over 20% of
TBA
■ 3rd-degree burns over elbow
■ Long periods of bed
confinement
Genetic Conditions
■FOP
■ H/O heterotopic bone
formation

20. Location of Heterotopic Ossification Related to
Associated Pathological Process
• Traumatic
• ■ Most often posterolateral elbow
• ■ Bone bridge between lateral humeral condyle and posterolateral
olecranon
• ■ Bone may fill olecranon fossa
• ■ Anterolateral compartment second most common location
• ■ Bone may extend from distal humerus to radius and ulna at level
of bicipital tuberosity
• ■ Coronoid frequently enlarged, blocking elbow flexion

21. • Burn-Related
• ■ Most often posteromedial
• ■ Cubital tunnel often obliterated
• ■ Ulnar nerve may be completely encased in bone
• Neurogenic
• ■ M/C anteriorly in flexor muscles or posteriorly in extensors
• ■ Ossification tends to occur within the muscle and follow a single
plane
• ■ Forearm and proximal radioulnar joint also may be involved

22. EXCISION OF HETEROTOPIC OSSIFICATION
• Usually a posterior skin incision is made, and subcutaneous
dissection is carried laterally or medially depending on the
location of the heterotopic ossification. Care must be taken to
identify and protect the ulnar nerve.

23. • POSTEROLATERAL EXCISION
• ■ For posterolateral resection, retract the triceps mechanism
medially without disturbing its insertion and expose the ectopic
bone subperiosteally. Resect the central portion of the bony bridge.
• ■ Flex the elbow and remove the attachments of the ectopic bone
to the humerus and olecranon. Anterior capsular release is not
necessary.
• ■ Excise any ectopic bone in the olecranon fossa to reduce
olecranon impingement

24. • MEDIAL EXCISION
• ■ When the posterior ectopic bone extends to the medial aspect of
the elbow, ulnar nerve transposition is necessary.
• ■ Identify the ulnar nerve, which may be completely surrounded by
bone.
• ■ Expose the triceps expansion and incise it distal to its insertion.
• ■ Expose the ectopic bone subperiosteally and resect it.
• ■ If the ectopic bone interferes with ulnar nerve function,
decompress the nerve or transfer it anteriorly if necessary.

25. • ANTERIOR EXCISION
• ■ If anterior excision is necessary, elevate the origins of the brachioradialis
and brachialis muscles from the lateral supracondylar ridge to expose the
ectopic bone.
• ■ Identify the radial nerve and retract it laterally.
• ■ Resect the bone subperiosteally.
• CLOSURE
• ■ Deflate the tourniquet and obtain hemostasis before routine layered
closure over a suction drain. Do not close the capsule. Apply a soft dressing
that will allow immediate postoperative range of motion.

26. THA
High risk for HO
male
hypertrophic OA
and h/o of HO or
posttraumatic
arthritis with
hypertrophic
osteophytosis
Moderate risk is
associated with
ankylosing
spondylitis,
DISH, Paget
disease, &
unilateral
hypertrophic
osteoarthritis
According to Iorio
and Healy

27. THA HO
Anterior and
anterolateral
approaches
transtrochanteric
or posterior
approaches
higher risk of
heterotopic
ossification
VS

28. After Kocher-
Langenbeck
approach
25%
14-50%
After
ilioinguinal
approach
rare

29. indomethacin (25
mg three times a
day for 4 to 6
weeks)
occasionally
radiation therapy
with a one-time
dose of in patients
in whom
indomethacin is
contraindicated
700 cGy
KOCHER-LANGENBECK
APPROACH
or

30. THA HO
Calcification can be seen radiographically the 3rd or 4thwk; however,
the bone does not mature fully for 1 to 2 years.
classification of Brooker et al. is useful in describing the extent of
bone formation:
• Grade I: islands of bone within soft tissues
• Grade II: bone spurs from the proximal femur or pelvis with at least
1 cm between opposing bone surfaces
• Grade III: bone spurs from the proximal femur or pelvis with less
than 1 cm between opposing bone surfaces
• Grade IV: ankylosis

31. Brooker grade IV heterotopic ossification occurred
despite postoperative irradiation.

32. THA HO
prevalence of
HO: 2% to
90%
Mostly HO: asymptomatic
Brooker grade III or grade IV
:restricted ROM & pain.
Marked limitation of motion
or bony ankylosis is
uncommon,
but significant loss of
function - 10% pts

33. Controversy on prophylaxis
• Multiple authors have found indomethacin to be effective in
decreasing significant HO after acetabular fracture surgery,
although this has been called into question by others who
found indomethacin to be ineffective in their prospective
series.
• Low-dose irradiation has been shown to be effective in
decreasing the incidence of significant heterotopic ossification,
and an additive effect has been noted when the two regimens
were combined.

34. • Radiation exposure is limited to the soft tissues immediately
around the hip joint, and ingrowth surfaces must be
appropriately shielded
• Hedley et al. reported no clinical evidence of loosening,
subsidence, or radiolucent lines around cementless prostheses
after irradiation

35. • Kennedy et al. also reported no increase in radiolucent lines
and no revisions for aseptic loosening in a group of cementless
total hip arthroplasties treated with radiation prophylaxis
• Delayed union or nonunion of trochanteric osteotomy is a
potential problem with radiation therapy. Malignant
transformation after radiation has not been reported with
dosages currently recommended for prophylaxis.

36. • NSAIDs have been shown to reduce the formation of heterotopic bone in
many studies.
• Historically, nonselective cyclooxygenase-1 (COX-1) and cyclooxygenase-2
(COX-2) inhibitors for 6 weeks have been recommended, although courses
of administration of 7 days have been reported as successful.
• Compliance is limited by medical contraindications to the drug and by
patient intolerance.
• Cella et al. found that 37% of patients were unable to complete a course of
treatment with indomethacin.
• More recently, a meta-analysis by Xue et al. of four randomized trials
comparing selective COX-2 inhibitors with nonselective COX-1 inhibitors
showed no difference in efficacy in preventing heterotopic ossification.

37. • In light of a more favorable gastrointestinal safety profile for
the COX-2 inhibitors, they were recommended for heterotopic
ossification.
• Similar to irradiation, NSAIDs have been shown to diminish
bone ingrowth into porous implants; however, no method
exists to shield the implant, in contrast to radiation treatment

38. • An operation to remove heterotopic bone rarely is indicated because pain
usually is not severe, and excision of established heterotopic bone is a difficult
procedure.
• Extensile exposure is required, and the ectopic bone obscures normal
landmarks.
• The abnormal bone is not easily shelled out of the surrounding soft tissues.
• Substantial blood loss can be anticipated.
• Radiation and NSAIDs have been used successfully to prevent recurrence.
Decreased technetium bone scan activity indicates that the heterotopic bone is
mature and that excision can take place safely.
• Range of motion should improve with excision, but pain may not be reliably
alleviated.

39. After shoulder arthroplasty
• Bridging heterotopic bone of glenohumeral jt or glenoacromial
space can occur in extreme situations.
• No correlation is evident, however, b/w HO and the
development of shoulder pain.
• Low grade HO, is present early in postop period, is
nonprogressive, and does not adversely affect clinical results
10% to
45% -HO
Risk factors:
Male gender
& OA

40. After total ankle arthroplasty
freq. HO (42%
to 82%)
HO pts had limited
dorsiflexion and
plantar flexion and
lower (AOFAS)
• Male
• limited preop
ROM
• previous
heterotopic
bone
formation,
• posttraumatic
OA,
• ankylosing
spondylitis
• infection

41. After total ankle arthroplasty

42. Classification of Heterotopic Ossification After
Total Ankle Arthroplasty
• CLASS CRITERIA
• 0 No HO
• I Islands of bone within the soft tissue around the ankle
• II Bone spurs from the tibia or talus, reducing the posterior joint
space by < 50%
• III Bone spurs from the tibia or talus, reducing the posterior joint
space by ≥ 50%
• IV Bridging bone continuous between the tibia & the talus

43. After total ankle arthroplasty
Currently, NSAIDs
most freq. used method for prophylaxis .
• Do not routinely administer NSAIDs before total ankle
arthroplasty, but prophylactic therapies (e.g., NSAIDs,
radiation) may be used in patients who require
excision of symptomatic HO.
• Noting the lack of strong asso. b/w HO &
postoperative ankle pain & functional limitation, Choi
and Lee cautioned against attributing these symptoms
to HO in posterior ankle when considering its excision.
Meticulous
soft tissue
dissection,
adequate
implant size
&
shortened
operative
time.
To reduce
risk of HO

44. CASE SCENARIO
• Three years after total knee arthroplasty, a 66-year-old male
patient presents with right knee stiffness and swelling for 6
months after being struck in the anterior thigh by a baseball.
Range of active motion is 10 to 40 degrees.??

50. Fibrodysplasia ossificans progressiva (FPP, Stone
Man Disease/ Munchmeyer’s disease/MOP]
• Rare progressive disease
• It involves the ACVR1 gene (activin A type I receptor gene, a BMP
type-1 receptor).
• hallmark characteristics:
- progressive heterotopic ossification (muscles, fascia, tendons,
ligaments and joint capsules)
- congenital malformation of the great toe (hallux valgus, malformed
first metatarsal and monophalangism)
• BMP4, which contributes to the formation of the skeleton in the
normal embryo, is implicated in this disease.

51. muscles of
face, larynges,
tongues and
diaphragm -
spared.
Characteristically muscles
involved are those of the
hand and back, then the
shoulder
muscles and hips

52. • . Probably excessive proliferation
• of collagenoblast sets the pace. The collagen accepts
• calcium a salt, i.e. dystrophic calcification occurs. This is
• followed by metaplasia of collagenoblasts into osteoblast
• and chondroblast which eventually transform into
• mature bone. It progresses along with muscle sheaths and

53. • Treatment:
-bisphosphonates- limited success
-Low frequency radiotherapy and immunomodulators
- Gamma interferon

54. FOP
malformed great toesfrozen" spine with complete loss of motion
exostosis and heterotopic
ossification around the knee.

55. heterotopic ossification around the left hip.
ossification of soft tissues and paraspinal ligaments
and fusion of the vertebral bodies give rise to a
“bamboo spine” appearance

56. Summary
• Heterotropic ossification – formation of mature cellular bone
in non – osseous tissue
THANK U
SOURCE-
CAMPBELL
KULKARNI