INTRO TO DYSPLASIA - Logan Class of December 2011



INTRO TO DYSPLASIA

KNOW INTIMATELY KNOW DEFINITIONS

Achondroplasia Hurler’s Syndrome

Cleidocranial Dysplasia Morquio’s Syndrome

Cranyosynostosis Infantile Cortical Hyperostosis

Marfan’s Syndrome Progressive Diaphyseal Dysplasia

Spondyloepiphyseal Dysplasia Pyknoysotosis

Osteogenesis Imperfecta Chondrodysplasia Punctata

Melorheostosis Dysplasia Epiphysealis Hemimelica

Osteopetrosis

Osteopoikylosis

ACHNODROPLASIA

80% spontaneous mutation

Trunk, spine and cord length are normal

Hyperlordosis w/ protruding abdomen = rolling gait and big butt

Achondroplastic Dwarf – most common form of Dwarfism

*autosomal dominant disturbance in epiphyseal chondroblastic growth and maturation

1. Pelvis

a. Pelvic bowl antiversion

b. Champagne Glass Pelvis (not much vertical dimension)

c. Remnant of Triradiate cartilage

d. Pelvis (and scapula) have squared off appearance

i. horizonal roof of acetabulum

ii. flatter crest

e. Mature pelvis

i. inferior and superior pubic ramus are small

ii. big obturator foramen

iii. excessive thickening of Y Cartilage

f. Femur

i. Short

ii. Premature DJD at head = hip replacement and wheelchair

iii. Mechanical forces usually cause bowing at proximal end

iv. at skeletal maturity – valgus or varus femoral angle

v. vara is the only one you can diagnose at any age

2. Scalloping of vertebral bodies

a. Dural Ectasia – invagination of lumbar bodies due to CSF pulsations

b. Not an exclusive feature, but common

3. Upper extremities

a. Short arm and forearm compared to age matched peers (humerus more)

b. Rhizomelia = short root

c. Width is w/in normal range although shape may be unusual

i. Splayed bone ends

ii. Metaphyseal cupping

d. Enchondral issues

e. Elbow deformities w/ limit of supination and extension

f. Tubular bones or hands and feet are short and thick

4. Medial borders of pedicle

a. Our pedicles get farther apart from side to side as they descend due to lumbosacral enlargement of the spinal cord

b. Most serious complication –

i. Central Canal Stenosis = canal gets smaller

ii. Pedicles will get closer together medially

5. Trident hand

a. widening of space b/t 3rd and 4th digits

b. fingers are the same length

6. Bullet Nose Vertebra

a. Growth ring - easiest to see in lumbars

b. Produces vertically short vertebrae, especially anteriorly

c. Results in angular kyphosis at thoracolumbar junction

7. Skull

a. Foramen Magnum

i. Most frequent cause of lethal complication harming newborns

ii. Fetus – amaturation

1. slow on growth chart

2. check amniotic fluid, ultrasound more

iii. C-section preferred

iv. More suspect to injury as they grow

v. MRI measures cord and shows physiology of cord

b. Brachycephaly

i. Large cranium

ii. Short in AP dimension

c. Basilar impression

8. 4 Clincal Syndromes

a. Nerve root compression, via disc herniation and osteophyte formation

b. Transverse myelophathy gradually induced by severe kyphosis

c. Acute traumatic transverse myelopathy w/ sudden paraplegia

d. Intermittent claudication of cauda equina, possibly due to ischemia. Symptoms suggesting vascular disease of lower extremities associated w/ activiy

CLEIDOCRANIAL DYSPLASIA / DISOSTOSIS

Uncommon, congenital and extremely varied presentation

Mutation on chromosome 6

*faulty ossification of intramembranous and enchondral bone

1. Classic Presentation

a. Funnel chest: Bell’s out from top to bottom

b. Clavicular Hypoplasia or agenesis

i. often may be missing a part of clavicle

ii. sternocleidomastoid?

iii. sloping, dropping shoulder appearance is accentuated by not

seeing the visual line crossing from right to left

2. Skull

a. Large head with small face due to underdeveloped facial bones

b. Sella Turcica different

c. Crowded maxilla

d. Cranial facial ratio

e. Occiput and Parietal suture line is not interdigitated

i. Islands of bone along one long suture

ii. Wormian Bones

iii. Not exclusive

f. Deformed and enlargedforamen magnum

g. Platybasia – developmental deformity of base of the skull in which the lower occiput is pushed by the upper cervical spine into the cranial fossa

3. Pubic Bone

a. Superior and inferior rami just end = missing pubic bone

b. Midline defect

c. Spina bifida occulta @ L5

d. Small pelvic bowl due to small and underdeveloped pelvis bones

e. Early coxa vara develops into coxa varus

4. Cleft palate present

a. Hair lip possible

b. Common abnormality

5. Spine

a. Delayed mineralization, biconvex vertebral bodies

b. Increased incidence of spondyloslysis in L spine

c. Hyperlordosis, excessive kyphosis ans scoliosis are secondary to neural arch defects and hemivertebrae.

6. Hands

a. Most marked changes

b. Creating an elongated digit

c. Distal phalanges are hypoplastic and often pointed

7. Clinically

a. Drooping shoulders

b. Shoulder hypermobility due to no clavicle or non-union

c. Scapula often small, winged or elevated

8. Other complications

a. Genua valga

b. Scoliosis

c. Pes planus

i. pes = distal segment of hind limb of vert. including tarsus + foot

ii. planus = skin disease

d. Sinus infection

e. Upper respiratory complications

f. Recurrent otitis media

MARFAN’S SYNDROME

Autosomal dominant – defect of fibrillin-1 gene on chromosome 15

Not rare, w/ majority having familial incidence

Average height = 72 inches

Easy for pt. To be in late teens/early 20’s before diagnosed

1. Typical presentation

a. Long, slender tubular bones

i. Longer duration of enchnodral bone growth compared to intramembranous

ii. Sparse soft tissue

iii. Muscular hypoplasia

iv. Scaricity of subcutaneous fat

v. Greater length than width (big and narrow)

vi. Leg length discrepancy

vii. Over 50% of cases have scoliosis

b. Ocular abnormalities

i. Over 50% of cases have ectopia lentis = dislocation of ocular lens

ii. Myopia

iii. Contracted pupils secondary to absence of dilator muscle of pupil

c. Facial features

i. Dolichocephaly – long head with cephalic index of less than 75

1. high, arched palate

2. prominent jaw

d. Thumb sign

i. Take thumb across palm and form a fist around it

ii. Will see distal phalanx on pinky side

iii. Due to ligamentous laxity and being too narrow/long metacarpal

e. Cardiovascular

i. 95% of discernible cause of death

ii. Atrial septal defect is most frequent congenital lesion (CT issue)

iii. Aneurismal dilation of aortic root

1. most typically seen

2. begins in 1st or 2nd decade of life

3. has abnormal connective tissue (failure to produce normal collagen)

a. superior portion of arch

b. too elastic

iv. Abnormal tunica media and cystic medial necrosis

v. Floppy valve syndrome – dilation of ascending aorta, along w/ abnormalities of valves leading to imcompetence and left sided insufficiency

f. Thoracic cage deformities

i. Chest has squared off appearance

ii. Pectus excavatum – posterior arches of ribs are fairly high due to depressed sternum

1. 30-40% have this

2. can be a solitary finding

iii. Pectus carinatum

iv. Thoracic scoliosis

2. Radiographic features

a. No osteoporosis in young

b. Axial bone mineral density is lower than normal in men and women

c. Cortices are thin and delicate trabecular pattern

d. Acetabular protrusion in 50%

e. Sever scoliosis or kyphoscoliosis

f. Spinal canal is widened in more than 50%

g. Posterior scalloping of vertebrae

h. Thinning of pedicles and lamina secondary to dural extasia

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