mindmap - congenital MSK patho

congenital MSK pathology

MSK congenital Pathology

• Osteogenesis Imperfecta
  • group of hereditary disorders caused by defective synthesis of type 1 collagen
  • extraskeletal manifestations
  • skeletal manifestations
    • too little bone
    • extreme skeletal fragility
    • 4 major subtypes
      • type 1
        • mildest and most common
        • blue sclerae
          • due to decreased scleral collagen contents
        • early life fractures
        • kyphoscoliosis in 20%
        • variable degrees of bone fragility
        • moderate bone deformity
        • premature deafness
          • conduction defects in middle and innder ear bones
        • normal lifespan
        • dentogenesis imperfecta in type1B
          • small misshapen teeth
      • type 2
        • uniformly fatal pre-natal /
          post partum due to multiple fractures
      • type 3
        • wheelchair bound
        • nonambulatory
        • very common orthopedic surgical case
      • type 4
        • similar to type 1 - but with white sclerae
• Achondroplasia
  • major cause of dwarfism
  • underlying etiology
    • point mutation in fibroblast growth factor receptor 3 (FGFR3)
    • normal epiphyseal plate expansion suppressed and long bone growth suppressed
    • typically autosomal dominant
    • typically heterozygotes
      • if homozygous, die due to respiratory failure soon after birth
  • clinical features
    • marked disproportionate shortening of limb
    • bowing of legs
    • swayed back posture
    • 
    • tendency toward obesity
    • frequent ear infections
• Osteopetrosis
  • general characteristic
    • rare genetic disorder
    • reduced osteoclast-mediated bone resorption
    • defective bone remodelling
  • morphology
    • grossly dense, stone-like bone
  • clinical features
    • frequent fractures
    • cranial nerve entraapments
    • frequent infections due to insufficient bone marrow
    • hepatosplenomegaly due to expansive extramedullary hematopoiesis
  • bone marrow transplant promising cure