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Flashcards in The Mythical Dwarves Deck (10):
1

Achondroplasia

AD, but 80% spontataneous, FGFR3
Proliferative zone

Quantitative defect
Normal cartilage

Defect in enchondral ossification, mainly affecting metaphysis
? advanced paternal age

Features

Disproportionate dwarfism
Rhizomelic limb shortening (normal trunk)
Frontal bosing, saddle nose
Normal intelligence and life expectancy

Delayed motor

Radial head dislocation
Wide pelvis ‘Champagne glass pelvis’
Spine

Foramen Magnum constriction can be a cause of sudden death. Presents as apnea, OSA, delayed motor development. Recommended screening is with
MRI early in infancy
Hyperlordosis: worsened by flexion contractures of the hips
Spinal stenosis: Short pedicles with decreasing interpedicular distance from L1-L5. Adolescent or early adult symptomatic stenosis. Tx with decompression. In adolescents, fusion is necessary due to high rates of post-laminectomy kyphosis. In adults, wide laminectomy is necessary (2 levels up and down).
Thoracolumbar kyphosis: Common in infants when they begin to sit due to hypotonia. Usually resolves in early childhood. Recommended bracing for curves >30 degrees and surgical correction (fusion) for curves >50 degrees.

Genu Varum:

Excessively long fibulas, varus can be at proximal tibia or distal femur. Symptomatic deformity or varus thrust are indications for correction.
Osteotomy or eiphysiodesis

Hand: Trident hand (larger gap between D3 and D4). No treatment necessary

2

Hypochondroplasia

Similar to Achondroplasia but less severe
Not diagnosed until 2-3 years of age
Disproportionate dwarfism
Normal intelligence
Rhizomelic limb shortening, but head not affected and spine less affected than achondroplasia
Spine

Hyperlordosis
No spinal stenosis

Genu Varum (less severe)

3

Pseudochondroplasia

Less severe form of achondroplasia
AD, COMP gene
Rhizomelic limb shortening
Normal face
Cervical Instability

Odontoid hypoplasia

Scoliosis
Hip dysplasia
Windswept knees!

4

Diastropic Dwarfism

Most Severe short-limed dwarfism
AR Sulfate transport gene (DTDST)

Defect in chondrogenesis

Spine

Cervical kyphosis:

High risk of quadriplegia
Fuse early

Thoracolumbar kyphoscoliosis
Spina bifida
Atlantoaxial Instability

Severe joint contractures:

Dislocated hips
Knee flexion contractures may require release or osteotomy
Severe clubfoot: May try casting to initiate treatment, usually require surgical release

Cleft Palate (60%)
Cauliflower ears
Coxa Vara
"Hitchhikers thumb": Abduction deformity at 1st MCP joint

5

Spondyloepiphyseal dysplasia

Disproportionate Dwarfism

Short trunk

Spine and hips primarily involved
Congenital = AD, dx at birth
Tarda = XR, dx at school age
Type II collagen formation
Cleft palate, small mouth
Equinovarus feet
Respiratory problems
Retinal detachment (optho exam)
Sensorineural hearing loss
Spine

Atlantoaxial instabilty: Odontoid hypoplasia. Typically require fusion at early age.
Sharp curve scoliosis

Coxa Vara:

May develop pseudarthrosis due to varus femoral neck. Valgus osteotomy often required at young age. High risk of hip OA.

Genu valgum
Distal tibia valgus

6

Kniest Syndrome

AD
Type 2 collagen
Short TRUNK dwarfism
Midface hypoplasia
Cleft Palate/lip
Odontoid hypoplasia
Dumbell Femurs
Retinal detachment
Respiratory problems
Frequent otitis media and hearing loss
Joint contractures, malalignment
Early hip OA

7

Cleidocranial dysplasia

Proportionate dwafism
Autosomal dominant

TF for osteoblast differentiation

Defect in flatbone formation (skull, clavicles, pelvis)
Slightly shortened stature
Absent clavicles
Wide pubic symphisis
Coxa vara
Large skulls with widened, largely patent fontanelles
Wormian bones
 
Coxa vara - may need valgus osteotomy
Scoliosis - may need treatment

8

Mutiple ephiphyseal dysplasia

Disorder of the enchondral ossificaiton
Only moderate growth stunting  (5 feet tall)
AD, Type 2 Collagen
Three types:

Severe: Late appearance of all ephiphyses, deformed fingers and toes
Moderate: Mainly affects hips, mild deformity of fingers and toes
Localized: Only affects hips

Classic involvement of proximal femoral epiphysis: Late appearance, fragmentation

Femoral head wide and flat
May have coxa vara
Acetabular changes (cysts)
Early OA - early THA

Can be difficult to differentiate from LCP - anytime you have bilateral LCP must think of MED, can differentiate based on acetabular involvement (more involvement in MED than LCP)
R/O spondyloepiphyseal dysplasia based on normal vertebral bodies

9

Larsens Syndrome

Rare
AD or AR
Prominent forehead, flat nose bridge
Significant ligamentous laxity - differentiate from arthrogryposis
Multiple dislocations at birth

radial head
Hips dislocated - require open reduction
Knee dislocations - usually respond to serial casting

Clubfeet or Pes Equinovalgus

May require surgery for significant equinus

Spine

Atlantoaxial instability possible
Kyphoscoliosis possible

10

Morqouio

Atlantoaxial instability

Odontoid hypoplasia

Thoracolumbar kyphosis
Coxa valga

May involve Proximal femoral epiphysis

Genu valgum
Pes planovalgus
Corneal opacity

Lysosomal storage diseases

Dx: Urine analysis
Type 1: Hurler
Type 2:
Type 3:
Type 4: Morquio
All are AR except Hunters (X-linked)
General Features

Proportionate short stature
Stiff joints
Acetabular dysplasia
Oval vertebral bodies

Most common: Morquio’s
Hurler’s may need early BMT