Pediatrics Section 4: Metabolic disease/Arthritides

Question 1

Rickets

Answer 1

• Deficiency of Calcium –> poorly defined zone of provisional calcification
• Enlarged zone of hypertrophy
• Short stature, varus angulated limbs, bone pain
• Physeal cupping/widening
• Looser lines
• Rachitic rosary

Question 2

Osteogenesis Imperfecta

Answer 2

• Defect in type I collagen (glycine substitution) - COLIA2 gene
• Scoliosis, tooth defects, hearing defects
• Blue sclera
• Basilar invagination –> myelopathy, apnea, altered conciousness, ataxia
• Bone does not remodel –> wormian bone –> fragile/brittle bone
• Tx
  
  • Brace early
  • <2 yo same as normal children
  • >2 yo telescoping IM rods
  • Bisphosphonates –> may lead to banding in the metaphysis with high dose longer term use
• 90% fit into type I or IV
  
  • I - blue sclera, hearing loss
  • IV - normal sclera, normal hearing
    
    • A - tooth involvment
    • B - no tooth involvment

Question 3

Idiopathic Juvenile Osteoporosis

Answer 3

• Self limiting –> resolves within 2-4 years
• Appears between 8-14 years
• Osteopenia, growth arrest, bone pain

Question 4

Osteopetrosis

Answer 4

• Failure of osteoclastic resorption –> dense bone (“marble bone”)
• Thymus defect most likely
• Loss of medullary canal –> anemia
• Optic and occulomotor nerve encroachment –> possible blindness
• Rugger jersy spine
• Erlynmeyer flask deformity
• Tx with bone marrow transplant may work

Question 5

Infantile Cortical Hyperostosis

Caffey Disease

Answer 5

• 0-9 months
• Follows febrile illness
• Soft tissue swelling
• Cortical thickening - Jaw and ulna MC
• Benign and self limited
• R/o trauma by single bone involvment

Question 6

Marfan Syndrome

Answer 6

• Fibrillin-1 (FBN1) gen defect
• Autosomal dominant
• Arachnodactyly, dural ectasia
• Acetabular protrusio
• SUPERIOR lens dislocation
• Bracing ineffective

Question 7

Elher-Danlos Syndrome

Answer 7

• Defect in collagen V
• Autosomal dominant
• Hyperextensibility of skin (“cigarrette paper skin”)
• Joint hypermobility and dislocation - Beighton-Horan scale
• Kyphoscoliosis

Question 8

Homocystinuria

Answer 8

• Insufficient cystathionine B-synthase enzyme –> error of methionine metabolism –> increased homocysteine
• Autosomal recessive
• Marfanoid habitus (except stiff joints)
• INFERIOR lens dislocation
• DX with homocysteine in the urine
• TX with Vitamin B6 and diet poor in methionine

Question 9

Juvenile Idiopathic Arthritis

Answer 9

• Persistent, non-infectious arthritis lasting 6 weeks to 3 months
• Typically before age 4 years
• Knee, hand, wrist MC
• DX must have one of the following
  
  1. • RF - only 15% are positive
  2. Irridicyclitis –> biannual slit lamp exam
  3. Cervical spine involvment –> kyphosis, facet ankylosis, AA instability
  4. Pericarditis
  5. Tenosynovitis
  6. Intermittent fever
  7. Morning stiffness

Question 10

Alkalosing Spondylitis

Answer 10

• Adolescent boys
• Asymmetric lower extremity arthritis (large joint: ankle/knee)
• Hip/back pain come later
• Limitation of chest wall expansion - more sensetive that HLA-B27
• + HLA-B27 - however it is + in 8% of normal white americans and 95% of Reiter syndrome patients
• Symetric sacroilliac errosions
• Bamboo spine
• Tx with NSAIDS and PT