19- Disorders of Growth/Development

Question 1

What is dysplasia?

Answer 1

a condition affecting growth or development in which the primary defect is intrinsic to the affected tissue

Question 2

What is dysostosis?

Answer 2

condition of abnormal cartilage ossification or bone remodeling. Usually only a single bone or group of bone involved

Question 3

What is dystrophy?

Answer 3

condition resulting from defective or faulty nutrition, broadly constructed to include nourishment of tissue by all essential substances including those normally manufactured by body itself

Question 4

What are the 2 extrinsic factors that can affect fetal cartilage?

Answer 4

hormonal abnormalilites, metabolic disturbances

Question 5

At what height is dwarfism in males and females?

Answer 5

Males < 58in, Females < third percentile for age

Question 6

What is proportionate dwarfism?

Answer 6

short stature where BOTH trunk and extremities are EQUALLY affected

Question 7

What is disproportionate dwarfism?

Answer 7

extremities are relatively affected more or less than trunk

Question 8

What is rhizomelia?

Answer 8

proximal segments are disproportionately shorter than middle and distal segments

Question 9

What is mesomelia?

Answer 9

middle segments are disproportionately shorter than proximal and distal segments

Question 10

What is acromelia?

Answer 10

distal segments are disproportionately shorter than proximal segments

Question 11

What is micromelia?

Answer 11

shortness of limb

Question 12

What would happen if there are problems with intramembranous ossification?

Answer 12

Abnormalities seen in patients with cleidocranial dysplasis
I) Cranial facial abnormalities
II) no clavicle

Question 13

What is the etiology of DMD?

Answer 13

disruption of muscle cell membrane physiology which results in abnormal muscle function

Question 14

What is the predominant ECM component of bone, tendon and ligament?

Answer 14

type I

Question 15

What is the morphology of collagen?

Answer 15

triple helix

Question 16

What are the genetic defects to cause osteogenesis imperfecta?

Answer 16

transcription, translation, hydroxylation, glycosylation, cross linking, extracellular transport, cleavage of procollagen

Question 17

What are the etiologies of short stature?

Answer 17

A)Malnutrition
B) endocrinopathy
C) Skeletal dysplasia
D) Constitutional short stature

Question 18

Why is family Hx important for pt’s with skeletal dysplasias?

Answer 18

Many skeletal dysplation are caused by genetic mutation transmitted by mendelian patterns of inheritance

Question 19

What is the incidence of achondroplasia?

Answer 19

A) 1.5 per 10,000 live birth

B) Most common form of dwarfism

Question 20

What are the physical characteristics of achondroplasia?

Answer 20

avg height of 48 in, short extremities but normal size trunk because of FGFR3 active mutation which stunts endochondral ossification, trident hands, bowlegs common, large head, hyperlordosis

Question 21

What is the trident hand of achondroplasia?

Answer 21

in full extension the bases of the digits can touch but the distal tips cannot

Question 22

Why do achondroplasia pt’s have a waddling gait?

Answer 22

) Being bow legged (genu varum)

II)Loss of full hip extension

Question 23

What are the Sx of spinal stenosis?

Answer 23

A)low back pain,
B) lower extremity paresthesias,
C)weakness,
D) neurogenic claudication (leg pain).

Question 24

What shows on the radiographs of the long bones of achondroplasia?

Answer 24

short, metaphyseal flaring, prominent muscle insertion sites, distal femoral physis has a characteristic inverted V appearance, long fibula, broad pelvis, shortening of the base of the skull

Question 25

Why ican surgery be a way to treat spinal stenosis in achondroplasia pts?

Answer 25

Surgical spinal decompression with laminectomy with or without spinal fusion is often necessary for symptomatic relief

Question 26

How can surgery treat some achondroplasia pt's knee pain?

Answer 26

I)bony realignment procedures (osteotomies) | II)growth plate arrest (epiphyseodeses)

Question 27

What is the cause of DMD?

Answer 27

A)X-linked recessive disorder B)characterized by progressive loss of muscle function C) replacement of normal muscle by fibrous and fatty tissue.

Question 28

Why do muscle cells die in DMD pt's?

Answer 28

lack of dystrophin results in: I)cell membrane fragility II)leakage of intracellular contents into the ECM (clinically manifest by increased serum creatine kinase levels) III)decreased synthesis of dystrophin-associated proteins

Question 29

What is dystrophin?

Answer 29

a cell membrane protein that stabilizes the muscle cell membrane and links the cytoskeleton to the ECM.

Question 30

What is the clinical presentation of DMD?

Answer 30

A)Normal skeletal muscle at birth B)Delayed walking, abnormal gait, and clumsiness C)Later stages include: walk with a wide based gait, inability to run or maneuver stairs in a reciprocal fashion D)Pseudohypertrophy of the calves by ages 3-4

Question 31

What are myopathies?

Answer 31

Myopathies are characterized by functional but not progressive abnormalities

Question 32

What are muscular dystrophies?

Answer 32

Muscular dystrophies are disorder of progressive muscle deterioration

Question 33

What is the presentation of DMD at birth?

Answer 33

I)Patients have normal skeletal muscle at birth, over time, this tissue is replaced with fibrofatty tissue II)Patients present well after birth III)Parents will report delayed walking, abnormal gait, and clumsiness

Question 34

What is the presentation of DMD at 18 mo?

Answer 34

Any boy who is unable to ambulate should be screened for Duchenne muscular dystrophy by measuring serum creatine kinase levels

Question 35

What is the presentation of DMD at 3-4 yrs?

Answer 35

I)By the age of 3-4 years, patients will demonstrate characteristic pseudohypertrophy of the calves which is caused by the replacement of muscle with fibrofatty tissue. II)Lumbar lordosis can also be quite pronounced III)The most characteristic clinical feature is Gower’s maneuver(Obj 31)

Question 36

What is the Growers maneuver?

Answer 36

I) patients will roll prone II)rise on all four limbs III) extend the lower extremities IV walk their hands along the floor and up their legs until they are standing upright

Question 37

How can corticosteroids treat DMD?

Answer 37

can improve muscle strength and reduce loss of strength over time

Question 38

What is a good way to prevent and preserve for Tx of DMD?

Answer 38

Musculoskeletal care like heel cord stretching, strengthening and bracing

Question 39

When does DMD pts lose the ability to walk?

Answer 39

2nd decade

Question 40

What indicated for any patient with Duchenne muscular dystrophy and a spinal curvature of greater than 20°?

Answer 40

Spinal fusion

Question 41

What is Osteogenesis imperfecta (OI)?

Answer 41

is a hereditary disorder of connective tissue caused by mutations in the gene for type I collagen

Question 42

What is mutated to cause OI?

Answer 42

I) Significant number of case also due to new genetic mutation C)OA results from mutation in the genes encoding type I collagen COL1A1 and COL1A2 I) Genes encode for the procollagen triple helix II) mutations affects the quality and quantity of the procollagen molecules a) which in turn affects the production of Type I collagen

Question 43

What is Type I OI?

Answer 43

the most common form and the mildest clinical manifestations I)Inheritance pattern is autosomal dominant II)Patients with type I OI have blue sclerae, exhbit long bone fractures after walking age, and have normal stature and life expectancy

Question 44

What is Type II OI?

Answer 44

the lethal form I)Autosomal recessive inheritance II)Affected individuals are stillborn or die within the first weeks of life, usually because of respiratory failure or intracranial hemorrhage III)Multiple rib and long bone fractures are seen and sclerae are blue

Question 45

What is Type III OI?

Answer 45

a severe non-lethal form I)Most cases are autosomal dominant II)Sclerae are of normal color but multiple fractures are seen at birth III)Stature is short and life expectancy is reduced with respiratory failure, intracranial hemorrhage and basilar invagination accounting for premature mortality

Question 46

What is Type IV OI?

Answer 46

the intermediate form, most rare I)Sclerae are normal, adult height is variably affected II)Abnormal dentition and bony fractures are common III)Life expectancy varies depending on severity of the disease

Question 47

How is OI managed?

Answer 47

A)Treatment remains primarily supportive, with an emphasis on injury and prevention and maximizing function B)Fracture treatment should be as minimally debilitating as possible C) Most treatment is by non surgical means because patient still has capacity to heal D)Use of braces, supportive devices, and physical therapy is encouraged during recovery, both for bony healing, and further injury prevention E) Surgical treatment reserved for patients over the age 5 F)Scoliosis is treated by surgical means I) arthrodesis for progressive spinal curves or curves greater than 40o