- Intramembranous ossification involves mesenchymal cells differentiating directly into osteoblasts and forming bone, while endochondral ossification involves cartilage models that are later replaced by bone. - Dysplasias of ossification can involve failures in resorption and remodeling of primary spongiosa (endochondral) or intramembranous bone, leading to accumulation of unresorbed cartilage or bone. - Metabolic bone diseases like renal osteodystrophy involve abnormalities of calcium and phosphate metabolism from chronic kidney disease, leading to osteomalacia, secondary hyperparathyroidism, and bone lesions.

1. By Dr Sachin

2.  Intramembranous Ossification:
Mesenchymal cells within embryonic connective
tissue
Proliferates
Early Mesenchymal condensations
Differentiate directly
Osteoblasts

3. Mesenchymal Condensation
Cartilage Anlage (Model)
Bone Collar
Mesenchymal Cells Differentiate Into
Prechondroblasts And Chondroblasts & Later In To
Chondrocytes
Calcification Of Bone Collar – Osteoclasts & Blood
Vessels, Enter Primary Ossification Center

4. Osteoclast Invasion And Wave Of Resorbing
Activity
Removal Of Calcified Cartilage
Woven Bone- The Primary Spongiosa
Further Remodeling -Woven Bone And The
Cartilaginous Remnants
Replaced With Lamellar Bone
The Mature Trabecular Bone- Secondary
Spongiosum

5. Growth in Bone Shape and Diameter
(Modeling)
During Longitudinal Growth Of A Long Bone,
Continuous Resorption By Osteoclasts Beneath
Periosteum
Progressively Destroys Lower Part Of Metaphysis
Transforming It Into Diaphysis

6.  Dysplasias
Osteopetrosis
Pyknodysostosis
Craniotubular dysplasias
Craniotubular hyperostoses
 Metabolic
Renal osteodystrophy
 Poisoning
 Chronic hypervitaminosis A
 Idiopathic
Caffey's diesase (infantile cortical hyperostosis)
Idiopathic hypercalcemia of infancy
Lead
Fluorosis
Hypervitaminosis D

7. Dysplasias Of Endochondral Ossification
(Primary Spongiosa)
Failure In Resorption & Remodeling Of Primary
Immature Spongiosa By Osteoclasts
Accumulation Of Calcified Cartilage Matrix Packing The
Medullary Cavity
- Osteopetrosis
- Pyknodysostosis
Target sites: tubular & flat bones, vertebrae, skull
base, ethmoids, ends of clavicle

8.  Defective Carbonic anhydrase function
 Lack of alkaline environment for osteoclast
function
 Defective osteoclast function
Types
 Infantile autosomal recessive osteopetrosis
 Benign adult autosomal dominant osteopetrosis

9.  Failure to thrive
 Cranial nerve entrapment (Optic nerve)
 Snuffling (nasal sinus architecture abnormalities)
 Hypercalcaemia
 Pancytopaenia (anaemia, leukopaenia and/or
thrombocytopaenia)
 Hepatosplenomegaly (extramedullary haemopoesis)
 Intracerebral haemorrhage (thrombocytopaenia)
 Lymphadenopathy
 Premature senile facies

11.  Mandible : triangular opacity representing calcification
within the secondary condylar cartilage ossification center
 Paranasal sinuses : poorly pneumatized (ethmoid sinuses
least severely affected)
 Hypertelorism
 Calvarium : high-attenuation inner table, a broad, low-
attenuation diploic space, and a less high-attenuation
outer table
 “Hair-on-end" appearance : increased haematopoietic
activity

12. Osteosclerosis in superior
and inferior portions of the
vertebral bodies -'sandwich'
appearance

14.  A lysosomal disorder due to genetic deficiency in
Cathepsin K
 Short stature particularly limbs
 Delayed closure of cranial sutures
 Frontal and occipital bossing
 Nasal beaking
 Obtuse mandibular gonial angle with relative
prognathism
 Segmentation defects

17.  Errors in resorption & remodeling of secondary
spongiosa, focal densities / striations
◦ Focal densities / striations
◦ Enostosis
◦ Osteopoikilosis
◦ Osteopathia striata

18.  Dysplasias Of Intramembranous Ossification
◦ Target sites: flat bones, calvaria, bones of upper face, tympanic
parts of temporal bone, vomer, medial pterygoid
◦ Progressive diaphyseal dysplasia
◦ Hereditary multiple diaphyseal sclerosis (Ribbing disease)
◦ Hyperostosis corticalis generalisata
 Van Buchem disease
 Sclerosteosis (Truswell-Hansen disease)
 Worth disease
 Nakamura disease
◦ Diaphyseal dysplasia with anemia
◦ Oculodento-osseous dysplasia
◦ Trichodento-osseous dysplasia
◦ Kenny-Caffey syndrome

19.  Hyperirritability
 Soft tissue swelling
 Cortical thickening
 Bones commonly
affected mandible,
ribs, clavicle, ulna,
any long bone but not
spine

20. ◦ Predominantly endochondral disturbance
 Dysosteosclerosis
 Metaphyseal dysplasia (Pyle disease)
 Craniometaphyseal dysplasia
 Frontometaphyseal dysplasia
◦ Predominantly intramembranous defects
 Melorheostosis
 Craniodiaphyseal dysplasia
 Lenz-Majewski hyperostotic dwarfism
 Progressive diaphyseal dysplasia

21.  Diagnosed as an incidental finding
 Monostotic, Monomelic, Or Polyostotic
 Sclerotomal distribution
 Dripping wax appearance or flowing candle wax
appearance

24.  Renal osteodystrophy
 Chronic hypervitaminosis A
 Lead
 Fluorosis
 Hypervitaminosis D

25.  Myelosclerosis/ Myeloproliferative disorders
 Metabolic
◦ Renal osteodystrophy
 Poisoning
◦ Fluorosis
 Neoplastic
- Osteoblastic metastases : prostate and breasts
- Lymphoma.
 Mastocytosis :
 Paget's disease

26.  Group of diseases
 Too many of certain types of cells made
in the bone marrow
 Fibrosis of the bone marrow with
extramedullary hematopoiesis

27.  Chronic myeloproliferative diseases e.g. essential
thrombocytopenia and polycythemia vera and
chronic neutrophilic, eosinophilic, and myeloid
leukemia
 Acute myeloid leukemia & lymphocytic leukemia
 Hodgkin's disease & non-hodgkin's lymphoma

 Hairy cell leukemia
 Multiple myeloma

28.  Fatigue, Weight Loss
 Easy Bruising And Bleeding
 Fever, Night Sweats
 Splenomegaly
 Gout And Renal Colic Due
To Hyperuricemia

29. Replacement of the normal
marrow cavity with fibrous tissue
with no trabecular or cortical
disorganization

34. A superscan
appearance -
intense symmetric
activity in the
bones with
diminished renal
and soft tissue
activity on a Tc99m
diphosphonate
bone scan

36.  Musculoskeletal abnormalities secondary to
chronic renal failure, due to concurrent and
superimposed
 Osteomalacia (adults) / rickets (children)
 Secondary hyperparathyroidism (abnormal
calcium and phosphate metabolism)
◦ Bone resorption
◦ Osteosclerosis
◦ Soft tissue & vascular calcifications
◦ Brown tumours
 Aluminum intoxication

37.  Osteopaenia : Early, thinning of cortices
and trabeculae
 Salt and pepper skull
 Subperiosteal resorption : on radial aspects
of middle phalanges of index and long
fingers
 Rugger-jersey spine
 Demineralization
 Soft tissue calcification

38. Renal failure - phosphate retention
Subsequent hyperplasia of parathyroid gland chief
cells
Decrease in serum calcium and an increase in
serum parathyroid hormone
Acts on kidneys

39. Increased osteoclast
activity - release of calcium from bone
Osteoblasts form an increased amount
of osteoid in response
to bone resorption
Excess osteoid does not contain
hydroxyapatite but appears
opaque on radiographs - Rugger jersey
Spine

40. D/d
•Paget disease
(“picture frame”
vertebral body)
•Osteoporosis
•Metastatic lesions

42.  Fluorosis
- Endemic areas (asia - india and china; rajasthan
and gujarat, andhra, punjab, haryana, M.P. And
maharashtra,t.N.,W.B.,U.P.,Bihar and assam)
- Increased osteoclastic response
- Cortical thickening encroachment upon
medullary cavity, ossification of ligamentous
attachments

44.  Metastatic disease
◦ Prostatic carcinoma
◦ Breast cancer
◦ Transitional cell carcinoma (TCC)
◦ Multiple myeloma
◦ Lymphoma
◦ Carcinoid
◦ Medulloblastoma
◦ Neuroblastoma
◦ Mucinous adenocarcinoma of the
gastrointestinal tract: , e.G. Colon carcinoma
◦ Lymphoma

46.  Hypercalcaemia, and
increase in periosteal new
bone with cortical
thickening
 Pseudotumour cerebri
 D/D
Infantile cortical
hyperostosis : > 1yrs of age

47. Thank you