Skeletal dysplasias and dwarfism can be caused by over 200 genetic disorders that result in abnormal bone growth. There are two main types: dysplasias with generalized skeletal abnormalities and dysostoses with abnormalities of single or multiple bones. Achondroplasia, the most common type of dwarfism, is caused by a mutation that slows endochondral bone growth. It is characterized by frontal bossing, midface hypoplasia, rhizomelic shortening of the limbs, trident hands, genu varum, and normal intelligence. Assessment involves examining for disproportion, general examination including radiographs to evaluate for complications like foramen magnum stenosis. Treatment focuses on managing complications through surgery or other

1. Skeletal dysplasias and dwarfism
Dr G Praveen Kumar Reddy

2. Introduction
• Bone dysplasias ( Dwarfism)
• Greek word – Dys- disordered
Plasia – development
• Shortening of the growing bones in different
proportions due to multiple gene defects
• >200 disorders, abnormal growth of bones
and cartilage
• Height less than 147cms, <3rd percentile

3. Dysplasia
• Disorders with generalized
abnormality of the skeleton.
• Phenotype continues to
evolve throughout the life.
Dysostosis
• Disorders with
abnormality of a single or
multiple bones.
• Phenotypically remains
static throughout the life.

4. Nomenclature and Classification
• Sir Thomas Fairbank was among the first to
try to classify the skeletal dysplasias, in his
Atlas of General Affections of the Skeleton.
• In Dynamic Classification of Bone Dysplasias,
Rubin further refined the classification
schemes, grouping the dysplasias according to
the anatomic distribution of bone changes

6. Assessment I
Disproportion
Assessment III
Radiology
Assessment II
General
Examination

7. Assessment I - Disproportion
• Upper/lower segment ratio
– 1.7 newborn
– 1.0 ages 2-8yrs
– 0.95 adult
• Sitting height: ascertains trunkal shortening
• Limb lengths:
– Rhizomelia (humerus & femur)
– Mesomelia (radius, ulna, tibia & fibula)
– Acromelia (Hands & feet)
• Body asymmetry
• Spine: assess for scoliosis, kyphosis & lordosis

8. Assessment II – General Examination
• General examination:
– facial features,
– hair quality,
– dental health,
– nails
• Systemic features:
– renal problems,
– cardiac abnormalities
• Developmental history
• Family history
• Ethnicity
• Joint pain

9. Assessment III - Radiology
• Antenatal: Ultrasonography
• Postnatal:
• AP & lateral skull to include atlas & axis
• AP chest
• AP pelvis
• X ray DL spine –AP and Lat
• AP one lower limb
• AP one upper limb
• PA one hand (usually left for bone age
assessment)

10. Dwarfism
Proportionate Disproportionate
Symmetrical decrease
in both trunk & limb
Short trunk
variety
Short limb
variety
Rhizomelia
(Proximal part)
Mesomelia
(Middle part)
Acromelia
(Distal part)
Micromelia
(entire limb)

11. • Proportionate-
symmetric decrease in both trunk and limb length.
• Examples
– Constitutional
– Familial
– Endocrinopathies
– mucopolysaccharidoses

12. Disproportionate dwarfism
• Short-trunk variety
(e.g., Kniest syndrome–spondyloepiphyseal)
• Short-limb variety
(e.g., achondroplasia, diastrophic dysplasia)

14. Source
• chondro = of cartilage
• osteo = of bone
• spondylo = of the vertebrae

18. • 1 in 30,000 to 1 in 50,000
• Most common type of dwarfism.
• Autosomal dominant disorder
• 75-80% patients have de novo mutation.
• Gain-of-function mutation in the gene for FGFR3
slows endochondral growth
• paternal age----- chances of achondroplasia

19. • Limit endochondral bone formation in the
proliferative zone of the physis.
• Intramembranous and periosteal ossification
processes are normal

20. frontal bossing and midface hypoplasia

21. Abnormal growth of the skull and facial bones results in:
1. Midface hypoplasia
2. A small cranial base
3. Small cranial foramina.
*The mid face hypoplasia causes :
1. Dental crowding-Maxillary hypoplasia
2. Obstructive apnea-
3. Otitis media-eustachian tubes may not function normally
4. Flat nose at bridge
*Narrowing of the jugular foramina is believed to increase
intracranial venous pressure and thereby to cause hydrocephalus.

22. Narrowing of the foramen magnum often causes compression of the
brainstem at the craniocervical junction in approximately 10% of
patients and results in an increased frequency of :
1. Hypotonia
2. Quadriparesis
3. Failure to thrive
4. Central apnea
5. Sudden death.
Between 3% and 7% of patients die unexpected during their first year of
life because of brainstem compression (central apnea) or obstructive
apnea.

23. Height
132 cm for men
122 cm for women

24. trunk length is within the lower range of normal

25. Decreased arm span and standing
height—Rhizomelic shortening

26. fingertips usually reach only to the
tops of the greater trochanters

27. trident hand
Starfish hand
flexion contracture of the elbows

28. Kyphosis at the DL junction Lumbar lordosis increases

29. Other medical complications include:
1. Obesity
2. Lumbar spinal stenosis that worsens with age,
3. Genu varum.

30. Intelligence is normal

31. • The overall functional health score is not
dramatically lower.
• Life expectancy is not significantly diminished
• Ligamentous laxity is common at the knees
and ankles

32. • Delayed motor development.
1. Hypotonia
2. Hyper-extensible joints (although the elbows
have limited extension and rotation).
3. Mechanical difficulty balancing their large
heads.
4. Less commonly, foramen magnum stenosis with
brainstem compression.

33. • The signs that are most predictive of severe
stenosis of the foramen magnum, which
requires surgery, are the presence of
– clonus or hyperreflexia, and
– central hypopnea,
revealed by sleep study

34. • The diagnosis of achondroplasia is usually confirmed by
radiographic findings.
• The features of achondroplasia cannot be detected by
prenatal ultrasonography before 24 week’s gestation.
• DNA testing can be performed when both of the
parents are affected and ambiguous cases but is
usually not necessary for the diagnosis to be made.

35. • double homozygous--stillborn or die
shortly after birth.
• Prenatal diagnosis before 20 weeks of
gestation is available only by molecular
testing of fetal DNA.

36. • Short tubular long bones, with a relative increase in
bony diameter & density.
• Metaphyses - widened & flared,
• Epiphyses - uninvolved.
• Growth plates - U or V shaped (best seen at distal
femur).
• Metacarpal, metatarsal, & phalangeal bones - short &
thick.
• Widened proximal femoral metaphyses, short femoral
necks - abnormalities in longitudinal growth.

37. • Ossification of proximal femoral epiphysis is delayed to
more than 1 year of age.
• Greater trochanter is normal in size as formed by
periosteal ossification - decrease in articulotrochanteric
distance.
• True coxa vara is absent, but overgrowth of greater
trochanter - appearance of varus.
• Cervical instability-not usually seen in this

39. Frontal bossing
Mid face hypoplasia
Thoracolumbar kyphosis with
narrow lumbar spinal canal
Trident configuration of hands
Genu Varum

40. Antero-posterior radiograph
showing V shaped distal
femoral physis
Radial head dislocation
Lateral radiograph showing
posterior scalloping
of vertebral bodies
& shortened pedicles

41. short & broad iliac wings,
champagne glass shaped pelvic inlet,
flat acetabula

42. decreasing interpedicular distance in distal lumbar spine

43. MRI of a child with achondroplasia shows
stenosis at the foramen magnum

44. • Treatment of the complications of achondroplasia.
• During infancy and early childhood, patients must be
monitored for :
- Chronic otitis media
- Hydrocephalus
- Brainstem compression
- Obstructive apnea and treated as necessary.

45. • If stenosis is suspected, sleep studies should
be used for evaluating brain stem functions
• If the diagnosis of foramen magnum stenosis
is made and the clinical picture persists
decompression of the brain stem

46. • Early hearing screening
• Obstructive sleep apnea –adenotonsillectomy or
more advanced procedures to enlarge the airway.
• Clinical hydrocephalus--ventriculoperitoneal shunt

47. • During later childhood and through early adulthood, patients
must be monitored for symptomatic :
- Spinal stenosis
- Genu varum
- Obesity.
- Dental complications
- Chronic otitis media and treated as necessary.
• Treatment of the spinal stenosis usually requires surgical
decompression and stabilization of the spine.

48. • Obesity-more common than in the general
population.
– followed up using
• triceps skinfold thickness
• weight/height squared
• Weight control measures should be instituted
when these values exceed 95% of those for the
general population

49. • Both growth hormone therapy and surgical
lengthening of the lower legs have been
promoted for treatment of the short stature.
• Both therapies remain controversial.

50. • Four per million- one of the more common skeletal
dysplasias
• First described in 1959 by Maroteaux and Lamy as a
form of SED.
• Mutation in COMP
• Premature death of physeal chondrocytes results in
decreased linear growth
• Late-onset physical findings and milder spinal
involvement-distinct from SED

51. • Growth tapers- falls to less than the fifth
percentile by the age of 2 years
• This pattern of progressive involvement is
typical of storage disorders, which is
essentially the nature of this condition.
• Usually, the diagnosis is made by the age of 2
to 4 years.

52. • skull and facies in pseudoachondroplasia are
normal
• Rhizomelic shortening- both the epiphyses
and metaphyses are involved
• Platyspondyly-spine involved
• Ligamentous laxity
• Knees are most commonly in excessive valgus
or windswept

53. • waddling gait-hips are dysplastic
• hands are not trident-shaped
• The mean adult height is 119 cm
• normal intelligence, and a normal life
expectancy
• Normal interpedicular distance in LS

54. head and trunk are
normal
rhizomelic shortening
hands and feet are short
and broad

56. platyspondyly with
anterior beaking

57. Normal
interpedicular
distance in lumbar
spine

58. Deformation and delay in the ossification of the epiphyses

59. Epiphyseal flattening and windswept deformity in knee
metaphyses are broad, irregular at the ends, and flared at the edges

61. • Characterized by disproportionate dwarfism with
progressive involvement of the spine and epiphyses
of the long bones.
• There are two major types of SED.
– The congenita type is detectable at birth
– tarda type manifests later in childhood

62. Spondyloepiphyseal Dysplasia
Congenita
• Obvious short-trunk dwarfism and variable degrees
of coxa vara, accompanied by abnormal epiphyses
and vertebral flattening
• Autosomal dominant
• Chromosome 12
• Defect in type II collagen(mutation in COL2A1 gene)
• Femoral heads are not apparent on radiographs
until the patient is approximately 5 years of age

64. • Face is taut and the mouth small
• Cleft palate
• The trunk and extremities are shortened
• Pectus carinatum
• many similarities to Morquio syndrome, but
an absence of visceral involvement

65. • The degree of hip varus has been felt to be the
best marker for the severity of the disease.
• Foot –equinovarus
• Retinal detachment is frequent and is reported
to occur especially during the adolescent
growth spurt
• Adult height varies from 90 to 125 cm.

66. 12-year-old boy is with his
14-year-old brother
extreme spinal shortening,
increased lumbar lordosis,
hip flexion contracture

67. Bulbous and pear-shaped
vertebrae at birth
severe platyspondyly with thin
intervertebral disc spaces
Essential radiographic features

68. Scoliosis, with a sharp
apex concentrated
over a limited number
of vertebrae, is
characteristic of
spondyloepiphyseal
dysplasia congenita.

69. severe coxa vara, with delayed ossification of the
capital femoral epiphyses

70. horizontal roofs of acetabula and short and broad iliac wings;
delay in the ossification of the heads of femur

71. large and dolicocephalic skull
relatively short femurs and small
epiphyses with secondary
metaphyseal irregularity

72. Spondyloepiphyseal Dysplasia Tarda
• Later age at diagnosis and milder features(clinical
attention when the child is approximately 4 years
old, at the earliest)
• Autosomal recessive or X-linked recessive
• The spine and only the larger joints are affected.
• Height is affected only minimally
• Adult height may be 152 cm or more
• Armspan is significantly longer than height

73. • The condition may be first diagnosed as
bilateral Perthes syndrome
• SED involvement is symmetric, whereas in
bilateral Legg-Calvé-Perthes disease
involvement is discordant, with one hip more
radiographically affected than the other
• Coxa magna

74. Platyspondyly with
heaped-up or hump-shaped
appearance on the posterior
two-thirds of end-plates

75. Typical mild
flattening of the
vertebral
bodies, but no
scoliosis.

76. Bilateral flattened femoral heads, short necks and
premature degenerative changes

77. • 2 types
– Conradi-Hünermann syndrome- XR-normal life
expectancy(arylsulfatase E (ARSE) gene mutation)
– Autosomal recessive- fatal during the first year of
life, rhizomelic form.

78. Conradi-Hünermann syndrome
• Short stature,
• dry and scaly skin,
• occasional heart defects, and
• cataracts
• Congenital vertebral anomalies - scoliosis or
kyphosis
• normal life spans

80. Rhizomelic form(AR)
• In the rhizomelic type, Cataracts tend to be bilateral
and symmetric. In the X-linked dominant type, they are
usually asymmetric and often unilateral
• lack of cataracts is characteristic of the autosomal
dominant form of chondrodysplasia punctata.
• Die in infancy of respiratory complications

81. • Hallmark of the disease is the presence of multiple punctate
opacities(non specific) in the unossified cartilage at the ends
of the long bones, the tarsals, the pelvis, and the vertebrae.
• Early diagnosis is important because the characteristic
punctate calcifications disappear within the first year of life
• Peculiar appearance of a duplicate calcaneus (also in
thanatophoric dysplasia)

84. • Defect in COL2A1 gene
• Characterized by
– Dwarfism
– Progressive joint stiffness and contractures
– Retinal detachment
– Cleft palate, midface hypoplasia
– hearing loss
– Kyphoscoliosis is a hallmark of the disease.

85. • Autosomal dominant: detected at birth
• a disorganized physeal growth plate; soft,
crumbly cartilage with a “Swiss cheese”
appearance
• Rhizomelic involvement

86. • presence of enlarged cartilaginous epiphyses
and sclerosis within the epiphysis differentiates
Kniest dysplasia from SED congenita.
• Kniest dysplasia resembles Morquio syndrome
radiographically, however, two conditions can be
distinguished by laboratory testing of the urine

89. • Failure of normal mineralization of the zone of
provisional calcification that leads to widened
physes and enlarged knobby metaphyses
• Epiphyses are spared, and thus arthritis rarely
develops

91. McKusick-type
• cartilage-hair hypoplasia
• Increased risk of viral infection especially
Varicella zoster
• Hirschsprung disease, intestinal
malabsorption, and megacolon may also
develop
• Increased risk of malignancy, such as
lymphoma, sarcoma, and skin cancer
• Life expectancy is decreased

92. light, sparse hair,
disproportionate short stature
pectus excavatum
varus deformities of the LL
increased lumbar lordosis
flexion contractures of the
elbows

93. • more shortening and less
varus of the long bones
than is seen in the Schmid
type
• metaphyseal involvement
is more evenly distributed
• Mild coxa vara,
• bowing of the femurs and
tibias with metaphyseal
expansion, and
• irregular zones of
provisional calcification

94. Schmid-type
• Autosomal dominant
• Mutations in type X collagen
• D/D - nutritional and vitamin D resistant rickets
normal serum chemistry values.
• Presents with
– leg pains
– varus knees and ankles
– short stature
– waddling gait

96. Jansen type
• Defect in the receptor for parathyroid
hormone and parathyroid hormone-related
protein(PTRP)
• may have hypercalcemia
• more severe metaphyseal changes

97. • AD inheritance
• heterogeneous disorder
– Mutations in the gene for COMP on chromosome 19
– COL9A2 mutations
– matrilin-3 mutations
• intracytoplasmic inclusions similar to
pseudoachondroplasia

98. • produces symptoms mainly in those bones
with significant load bearing
• Historically
– Ribbing dysplasia--mild type
– Fairbank dysplasia--more severe type

99. • Patients typically present later in childhood
– Joint pain in the lower extremities,
– Decreased range of motion,
– Gait disturbance, or
– Angular deformities of the knees
– Flexion contractures of knees or elbows
– Somewhat short stature, ranging from 145 to 170 cm
• The face and spine are normal.
• There is no visceral involvement.

100. • may be easily confused with those of bilateral Perthes
disease
• In Perthes disease, usually one hip is involved before
the other, so that each hip is in a different stage of the
disease
Metaphyseal cysts are seen in Perthes disease, but not
in MED
• MED is distinguished from SED by the absence of
severe vertebral changes

101. • In the growing patient,the epiphyses are
fragmented and small in size
• In adulthood, major joints develop premature
osteoarthritis
• Femoral condyles are flattened
• Double-layered patella in the lateral view
• hatchet head of humerus

103. Multiple epiphyseal dysplasia. Radiographs of the hip (A), left knee
(B,C), left foot and ankle (D,E), and left wrist (F) show lack of epiphyseal
ossification centers with punctate calcifications in the knee.

104. Multiple epiphyseal dysplasia in an adolescent. AP and lateral radiographs of
the knee (A,B) and ankle (C,D) showing irregular epiphysis with joint deformities.

115. Thanatophoric dysplasia.

116. • most numerous, disparate, and severe skeletal abnormalities
• Diastrophic-distorted
• rhizomelic shortening
• autosomal recessive and is extremely rare
• Lack of sulfation of glycosaminoglycans (GAGs) in articular
cartilage renders the cartilage vulnerable to early degeneration
• Intelligence is normal.
• double-layered manubrium, which is specific to this dysplasia

117. prominent cheeks,
circumoral fullness,
equinovarus feet,
valgus knees with flexion contracture,
abducted or hitchhiker thumbs

118. Cervical kyphosis

121. Cleidocranial dysostosis
• Disorder in which the bones formed by
intramembranous ossification (primarily the
clavicles,cranium, and pelvis) are abnormal
• Autosomal dominant
• Chromosome 6
• Identified within the first 2 years of life

122. • Elfin faces (the skull is wider than normal, but
the face appears small )
• most common defect is U/L or B/L loss of the
lateral end of the clavicle, with failure of
development of the middle third of the
clavicle second in frequency
• second metacarpal is unusually long

127. enlarged cranium,
widened sutures, and
a persistent anterior fontanel

128. symphysis pubis is widened and vertical hypoplastic iliac wing

130. CLEIDOCRANIAL DYSPLASIA.

132. short, horizontally running rib with widening of
the costochondral connections.

138. • osteoclast defect
• Three clinical presentations of osteopetrosis
– infantile or autosomal recessive form
– adult form or autosomal dominant form
( Albers-Schönberg Disease = Marble Bone
Disease(type 2 variety)
– An intermediate clinical type

139. Autosomal Recessive Osteopetrosis
• Infantile autosomal recessive osteopetrosis is the more severe
form that tends to present earlier. Hence, it is referred to as
"infantile" and "malignant“, compared to the autosomal
dominant osteopetrosis.
• The natural history of the condition means that by age 6, 70% of
the affected will die.
• Most of the remainder have a very poor quality of life with death
resulting by the age of ≈ 10.

140. Clinical Features
• Those who survive childbirth present with :
• failure to thrive
• cranial nerve entrapment
• optic nerve compression and blindness,
• facial nerve dysfunction, and
• sensorineural deafness
• snuffling (nasal sinus architecture abnormalities)
• hypercalcaemia
• pancytopenia (anemia, leukopenia and thrombocytopenia)
• hepatosplenomegaly (extramedullary haemopoesis)

141. • infections of the bones or mandibles
• intracerebral hemorrhage (thrombocytopenia)
• Lymphadenopathy
• A prominent forehead and broad upper skull with
hypertelorism
• One of the commonest presentations is ocular disturbance:
failure to establish fixation, nystagmus or strabismus.
(Searching nystagmus )

143. Lateral radiograph of the skull reveals diffuse thickening of the calvarium, most
significant in the region of the occiput. The partially visualized upper cervical
vertebrae and maxilla are also dense and thickened.

144. Severe bilateral optic canal narrowing (arrows) in a 4-yr-old patient with
complete loss of vision in the left eye and 20/80 visual acuity in the right eye.

145. Axial T2-weighted FSE image shows optic canal stenosis and optic nerve atrophy

146. Autosomal dominant osteopetrosis
• less severe than its autosomal recessive mate.
• "benign" or "adult" since patients survive into
adulthood.
• 50% patients are asymptomatic
• Recurrent fractures
• Mild anemia
• Rarely cranial nerve palsy
.

147. • X-ray findings
• Diffuse osteosclerosis: Bone-within-bone appearance
• Cortical thickening with medullary encroachment
• Erlenmeyer flask deformity = clublike long bones due to
lack of tubulization + flaring of ends
• "Sandwich" vertebrae = alternating sclerotic + radiolucent
transverse metaphyseal lines (phalanges, iliac bones)
indicate fluctuating course of disease

148. sandwich vertebrae /
rugger jersey appearance

149. increased density of osseous structures due to
accumulation of immature bone.
Generalized increased density of bones &
alternating areas of increased & decreased density
in metaphyses (bone-within-bone appearance).

150. Densely sclerotic bone with Erlenmeyer flask deformity of the femurs with
under-tubulularization (lack of trabeculation) block femoral meatphyses.

152. • Fractures are treated by conventional methods, but slow to heal
• Intraoperative fractures can occur because the osteopetrotic
bone is difficult to drill or ream
• Coxa vara is the most common orthopaedic deformity-valgus
proximal femoral osteotomy
• Cervical and lumbar spondylolysis are commonly seen

153. • Dwarfism
• Pectus excavatum
• short fingers from acro-osteolysis
• hypoplasia of the facial bones, causing dysmorphic facial
features.
• Radiographically, there is generalized osteosclerosis similar
to osteopetrosis, but with preservation of the medullary
canal of long bones.

154. • Dense vertebral bodies with characteristic
sparing of the transverse processes is seen.
• Because the medullary cavities are preserved, patients
with pyknodysostosis (unlike patients with
osteopetrosis) tend not to have concurrent anemia.
• On the other hand, as with osteopetrosis, the bones
are brittle and prone to recurrent fractures.

155. Left tibia and fibula show
hyperostosis with preservation of
medullary cavity. A subacute
fracture is noted in mid-diaphysis of
tibia.

158. Overproduction of Bone by Osteoblasts
• Melorheostosis
• Camurati-Engelmann disease
• Sclerosteosis

161. typically affects one limb or one side

163. Anteroposterior radiographs
demonstrate the classic dripping
candle wax appearance of cortical
and medullary hyperostosis involving
the lateral aspect of the femur

164. new periosteal and endosteal bone

167. • Hyperostosis within the medullary canal and the
diaphyseal region, and also in the skull
• Clinical features
– enlarged head,
– proptosis,
– thin limbs,
– weak proximal muscle sometimes resulting in a
waddling gait, and musculoskeletal pain
• Spontaneous improvement at puberty has been
described

169. Sclerosteosis
• Characterized by skeletal overgrowth,
particularly of the skull and of the mandible
• Sclerotic long bones and gigantism
• Bony syndactyly is a characteristic clinical
marker

170. • characterized by striationsn in the metaphyseal
regions of cancellous bone, with sclerosis of the
base and vault of the skull
• symmetric involvement
• striations are radiodense and parallel to the long
axis of the bone
• pathognomonic feature of osteopathia striata is
sclerosis of the skull base
• bone striations do not change with age
• no orthopaedic complications

174. Chondroectodermal dysplasia
• A/K/A Ellis-van Creveld syndrome
• AR
• Mutation in novel gene, EVC, on Chromososme 4
• Generalized defect of maturation of endochondral
ossification.
• Abnormalities in the
– Mouth
– Teeth(appear early and loose early)
– Limbs
– Heart (ASD/Single atrium)

175. • Sparse, absent, or fine textured hair
• Heart (ASD/Single atrium)
• Teeth(appear early and loose early)
• Acromesomelic limb shortening
• Nails are hypoplastic
• Hypospadias and epispadias
• normal spine

176. • chest is narrow
• ligaments are lax
• often significant genu valgum
• external rotation of the femur and internal
rotation of the tibia
• Postaxial polydactyly (quite common in the
hands)

177. characteristic pronounced
hypoplasia of the lateral
proximal tibial epiphysis
with marked genu valgus.

180. The carpal bones have delayed maturation but the
maturation of the phalanges is accelerated.