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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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11
Q

What is this?

A
  • Posterior Vertebral Scalloping
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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
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13
Q

What is the tx for spinal kyphosis?

A

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

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14
Q

When in MRi useful in achondroplasia?

A
  • to evaluate Cervical stenosis
  • suspected foramen magnum stenosis
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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
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16
Q

What is the tx for foramen magnum stenosis in achondroplasia?

A

Surgery

  • Urgent decompression
  • when cord compression is present
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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
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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
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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
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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)

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