The Mythical Dwarves Flashcards
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
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)
Pseudochondroplasia
Less severe form of achondroplasia
AD, COMP gene
Rhizomelic limb shortening
Normal face
Cervical Instability
Odontoid hypoplasia
Scoliosis
Hip dysplasia
Windswept knees!
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
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
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
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
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
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
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
