Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Paediatrics FCRS > Disproportionate Dwarfism > Flashcards

Disproportionate Dwarfism Flashcards

Achondroplasia Pseudoachondroplasia Multiple Epiphyseal Dysplasia Spondyloepiphyseal Dysplasia Diastrophic Dsyplasia Kneist's Dysplasia Metaphyseal Dysplasia

1
Q

What is achondroplasia?

A
  • The most common cause of disproportionate dwarfism
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the genetics of achondroplasia?

A
  • Autosomal dominant
  • caused by mutation of fibroblast growth factor receptor 3 (FGFR3) on chromosome 4P
  • changes lysine to argentine at position 380
  • sporadic mutation in >80% cases
    • Risk increases with advanced paternal age
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does this gene mutation cause?

A
  • Abnormal chondroid production by chondroblasts in the PROLIFERATIVE ZONE during enchondral bone formation at the physis
  • A quantative rather than qualitative cartilage defect
  • sporadic mutation in 80% cases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the conditions is achondroplasia associated with?

A
  • Lumbar stenosis
    • short pedicles
    • most likely to cause disability
  • Thoracolumbar kyphosis
    • may cause neurological symptoms
  • Foramen magnum and upper cervical stenosis
    • may cause periods of apnea
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is pseudoachondroplasia?

A
  • An autosmal dominant condition that is clinically similar to achondroplasia
  • caused by a defect in the Cartilage Oligomeric Matrix Protein (COMP) on chromosome 19
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How does pseudoachondroplasia differ form achondroplasia?

A

Pseusoachondroplasia has

  • Normal facies
  • associated with CERVICAL INSTABILITY due to ondontoid hypoplasia,
  • absence of spinal stenosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the symptoms of achondroplasia?

A
  • Normal IQ
  • Delayed motor milestones
  • Symptoms of spinal stenosis
    • pseudoclaudication and standing discomfort
    • Numbness and parathesia
    • Subjective weakness
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is this

A
  • A trident hand
  • Characterstic splaying of 2-4th digits along the ap axis in the plane of the palmwith relatively normal positioning of thumb and little finger
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the physical feature of Achondroplasia?

A
  • Classic RHIZOMELIC dwarfism
    • humerus and femurs shorter than forearms and tibia
      • adult height 50 inches
      • NORMAL trunk
  • Facial features
    • frontal bosssing
    • button noses
    • small nasal bridges
  • Hands
    • TRIDENT- inabilty to approixmate extended middle and ring fingers
    • Bowed legs
    • radial head subluxation
    • muscular hypotonia
  • spine
    • thoracolumbar kyphosis
    • excessive lordosis- short predicles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the X-ray appearance of pelvis in achondroplasia ?

A
  • Pelvis
    • champagne glass pelvis - wider than deep, flattened acetabulum, square iliac wings
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is this?

A
  • Posterior Vertebral Scalloping
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is seen on the spinal radiographs?

A
  • short pedicles with decreased interpedicular distance form L1-S1
  • T12/L1 vertebral wedging
  • posterior spine scalloping
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the tx for spinal kyphosis?

A

non op bracing operative- anterior strut corpectomy and post fusion if kyphosis >60 degrees

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

When in MRi useful in achondroplasia?

A
  • to evaluate Cervical stenosis
  • suspected foramen magnum stenosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the tx of spinal kyphosis in achondroplasia?

A

non operative

  • bracing
  • first line in mild curves

Surgery

  • Anterior strut corpectomy and posterior fusion
    • when kyphosis >60o by 5 yrs
    • bracing failed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the tx for foramen magnum stenosis in achondroplasia?

A

Surgery

  • Urgent decompression
  • when cord compression is present
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the tx for lumbar stenosis in achondroplasia?

A

Non operative

  • Weight loss, physical therapy, corticosteriod injections

Surgery

  • mutlilevel LAMINECTOMY and fusion
  • w spinal stenosis w severe symptoms
  • non op mx failed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the tx for short stature in achondroplasia?

A

Surgery

  • Limb lengthening thru metaphyseal corticotomy- controversial due to high risk of complications
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the tx for genu varum in achondroplasia?

A

Surgery

  • Tibial osteotomies or hemiepiphysiodesis
    • symptoms are severe
    • non op modalities have failed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is Multiple epiphyseal dysplasia (MEN)?

A
  • a form of dwarfism characterized by Irregular, delayed ossification at multiple epiphyses
  • caused by failure of formation of secondary ossification centre ( epiphysis)
21
Q

Describe the genetics of Multiple epiphyseal dysplasia?

A
  • Autosomal Dominant
  • Defect in cartilage oligomeric matrix protein (COMP) on chromosome 19- most common & severe form
  • mutations in COL9A1, COL9A2, COL9A3
    • codes for type IX collagen
    • causes Type 2 collagen dysfunction because of type IX collagen acts as a link protein for type 2 collagen

***NB MEN in white COLLars**

22
Q

What are the symptoms of pts with Multiple epiphyseal dysplasia?

A
  • short limbed dwarfism
  • Joint pain
  • Often don’t manifest until ages 5-14 yrs
  • waddling gait

Signs

  • joint deformities from joint incongruity
    • Valgus knee common
    • early OA
  • Joint contractures common
  • spine usually normal
23
Q

What is seen on pelvic radiographs with Multiple epiphyseal dysplasia?

A
  • Bilateral epiphyseal defects
    • may mimic Legg-calves perthes
    • difference in Multiple epiphyseal dysplasia is hips are simultaneous and bilateral
24
Q

What is seen in knee xrays w Multiple epiphyseal dysplasia?

A
  • Valgus knee
  • tibial “slant sign”
  • Double layer patella
25
Q

What is seen in hand and foot xrays in Multiple epiphyseal dysplasia?

A

Hand

  • short, shunted/broad metacarpals
  • hyperextensible fingers

Foot

  • Short metatarsals
26
Q

What is the tx of Multiple epiphyseal dysplasia?

A

Non operative

  • NSAIDS and PT
    • early OA

Sugery

  • Corrective osteotomy or hemiepiphysiodesis
    • progressive genu valgum
  • Total hip replacement
    • severe arthritis
    • joint incongruity may lead to early arthritis & often requires THR early on in life
27
Q

What is spondyloepiphyseal Dsyplasia

A
  • A form of short- trunk dwarfism caused by a defect in the secondary ossification centre (epiphysis)
28
Q

What is the epidemiology of spondyloepiphyseal Dsyplasia?

A
  • 1 per 100,000 live births
  • risk factors
    • advanced Paternal age
    • familial inheritance
29
Q

what is the pathophysiology of spondyloepiphyseal Dsyplasia?

A
  • Caused by abnormal synthesis of TYPE 2 collagen
  • primarily affects the Vertebra and epiphysis of bone
30
Q

Describe the genetics of spondyloepiphyseal Dsyplasia?

A
  • Autosomal Dominant - SED congenita
  • X linked recessive - SED tarda
  • random mutation 50% cases
  • Mutations
    • ​COL2A1 on chromosome 12
31
Q

Name the assocaited conditions of spondyloepiphyseal Dsyplasia

A
  • atlantoaxial instability
  • Frequent cause of myelopathy in spondyloepiphyseal Dsyplasia congenita
  • nephrotic syndome (SED Tarda)
32
Q

What is the classificaiton of spondyloepiphyseal Dsyplasia?

A
  • SED congentia
    • Autosomal Dominant
    • More Severe than tardia
  • SED tarda
    • ​X linked recessive
    • **clinically less severe **
    • doesn;t have lower extremity angular deformities that are present in congenita form
33
Q

What are the symptoms of a pt with spondyloepiphyseal Dsyplasia?

A
  • Cervical myopathy
    • due to atlantoaxial instability
  • respiratory Difficulty
    • respiratory insufficiency 2ary to thoracic dysplasia
  • Problems with vision
    • due to myopia or retinal detatchment
  • Hip pain
    • ​due to coxa vara
  • decreased walking distance
    • due to poor muscular endurance adn skeletal deformities
34
Q

What are the signs of spondyloepiphyseal Dsyplasia?

A
  • Short stature
  • Flattened Facies
  • Kyphoscoliosis
  • Lumbar lordosis
  • coxa vara
  • genu valgum
  • Wadlling gait
  • reduced rom of hips
35
Q

What is seen in xrays of c psine in spondyloepiphyseal Dsyplasia?

A
  • Upper cervical spine instability
    • odontoid hyperplasia or os odontoideum
36
Q

What is seen on thoracolumbar spine xrays in spondyloepiphyseal Dsyplasia?

A
  • Platspondyly
    • flattening of vertebral bodies in lumbar spine
  • incomplete fusion of spinal ossification centres
  • end plate irregularities and narrowed intervertebral disc spaces
  • kyphoscoliosis
  • excessive lumbar lordosis
37
Q

What is the tx of spondyloepiphyseal Dsyplasia?

A
  • mutlidisciplinary rehabilitation
    • all pts to maintain and improve function
    • PT/OT/ortho ( bracing), respiratory, ophalamolgist

Surgery

  • Posterior atlantoaxial fusion ( post instrumentation)
    • atlantoaxial instability >8mm
    • myelopathy
  • Posterior thoracolumbar instrumentation
    • spinal scoliosis >50o
    • distraction spinal rods- ypunger pts
    • post instrumented fusion older pts
  • Valgus intertroachanteric ostoetomy
    • Coxa vara <110 o
    • progressive coxa vara
    • symptomatic hip arthritis
38
Q

What are the complications of spondyloepiphyseal Dsyplasia?

A
  • Cervical spine instability
  • Spinal deformity
    • including scoliosis, kyphosis, lordosis
  • Ocular abnormalities
  • Hip deformities
  • Degenerative Joint disease
39
Q

What is Diastrophic dysplasia?

A
  • A form of short limb dwarfism
  • caused by failure of formation of secondary ossification centre (epiphysis)
  • associated with progressive deformity
40
Q

What is the epidemiology of Diastrophic dysplasia?

A
  • More common in Finland
  • Rare rest of world
41
Q

What is the genetics of Diastrophic dysplasia?

A
  • Autosomal Recessive
  • **Mutation of DTDST gene **(SLC26A2) on chromosome 5q
    • encodes for sulphate transporter protein
    • Mutation is present in 1 in 70 Finnish citizens
    • leads to undersulfation of catilage proteoglycan
    • abnormalities in the hydraulic properties of cartilage= why cartilagneous structures affected -ears, trachea and ligaments
42
Q

what are the signs of a child with diastrophic dysplasia?

A
  • Short stature- twisted dwarf
    • rhizomelic shortening
  • `cleft palate- 60%
  • Cauliflower ears 80%
  • Poorly developed UE
  • Hitchhikers thumb
  • thoracolumbar scoliosis
  • Severe cervical kyphosis
  • hip and knee contractures
  • Genu Valgum
  • Skewfoot ( serpentine or z foot)
    • tarsometatarsal adductus & valgus hindfoot
  • Rigid clubfoot- equinocavovarus
43
Q

What is the tx of dystrophic dysplasia?

A

Non operative

  • Observation and supportive tx
    • most pts
    • cauloflower ears respond to compressive bandages
    • cervical kyphosis frequently resolves spontaneously

Surgery

  • Occipital-Cervical fusion
    • Atlantoaxial instability w neuro symptoms
    • risk of quadariplegia is concern
  • Post cervical fusion
    • Cervical kyphosis that doesn’t resolve spontaneously
  • Thoracolumbar fusion
    • kyphoscoliosis of thoracolumbar spine
    • if progressive may require ASF/PSF
  • Soft tissue surgical release
    • rigid clubfoot
    • severe joint contractures hip/knee
  • Osteotomies for correction
    • for progressive valgus deformity of lower extremities ( w dislocated patella)
  • Total joint arthroplasty
    • end stage arthritis
44
Q

Define Kniest’s Dysplasia?

A
  • Form of disproportinate dwarfism
  • Autosomal Dominant
  • defects leads to abnormal Type 2 collagen
45
Q

What is Kniest’s dysplasia associated with?

A
  • respiratory problems
  • cleft palate
  • Retinal detachment/ myopia
  • otitis media w hearing loss
46
Q

Describe the features of Kniest’s dysplasia?

A
  • Disproportinate short-trunk dwarfism
  • Joint stiffness/ contractures
  • dumbell shaped femora
  • Hypoplastic pelvis and spine
  • scoliosis and kyphosis
  • cleft lip
47
Q

What is seen on xrays in Kniest’s dysplasia?

A
  • Osteopenia
  • Dumbell femora
48
Q

What is the tx of Kniest’s dysplasia

myopia, joint contractures, joint degeneration?

A
  • Myopia= ophthalmolgic consultattion
  • Joint contractures- early PT
  • Hip degenertaive arthritis= joint reconstruction
49
Q

What is metaphyseal chondrodysplasia?

A
  • Short limbed disproportinate dwarfism
  • Involves the proliferative and hypertrophic zones of the physis
  • 3 types
    • Jansen’s
      • ​AD, defect in parathyroid hormone related peptide receptor
      • Low IQ, wide eyes, monkey like stance
      • osteobulbous metaphyseal expansion of long bones
    • Schmid
      • ​AD , defect in type X collagen
      • xs lumbar lordosis, severe thigh/leg bowing genu varum, wrist swelling
    • Mckusicks
      • ​AR seen in amish pop and in Finland
      • cartilage hair dysplasia, atlantoaxial instability, ankle deformity due to fibular overgrowth, immuno def and increased risk of malignancy

Paediatrics FCRS (27 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions