Multiple Epiphyseal Dysplasia (MED)

Topic updated on 02/01/14 3:36pm
  • A form of dwarfism characterized by irregular, delayed ossification at multiple epiphyses
    • spectrum of disorders with a spectrum of phenotypes
  • Epidemiology
    • location
      • caused by failure of formation of secondary ossification center (epiphysis).
  • Genetics
    • most commonly autosomal dominant
    • defect in COMP  (cartilage oligomeric matrix protein) gene on chromosome 19 (most common and most severe form)
    • mutations in COL9A1, COL9A2, COL9A3
      • codes for type IX collagen
      • causing type II collagen dysfunction because of type IX collagen acts as a link protein for type II collagen
  • Symptoms
    • short-limbed dwarfism
    • joint pain
    • often does not manifest until ages 5 to 14 yrs
    • waddling gait
  • Physical exam
    • joint deformities from joint incongruity
      • valgus knee deformity common
      • early OA
    • joint contractures common
    • spine is usually normal
  • Radiographs  
    • cervical spine
      • flexion-extension films may show instability of upper cervical spine
    • pelvis
      • may show bilateral epiphyseal defects   
        •  may mimic Leg-Calve-Perthes (difference is MED hips are simultaneous and bilateral)
    • knee
      • valgus knee
      • tibial "slant sign"
      • double layer patella  
    • hand
      • may show short, stunted metacarpals
      • hyperextensible fingers
    • foot
      • short metatarsals
  • Nonoperative
    • NSAIDS and therapy
      • indications
        • early OA
  • Operative
    • corrective osteotomy or hemiepiphysiodesis
      • indications
        • progressive genu valgum
    • total hip arthroplasty
      • indications
        • severe arthritis
          • joint incongruity may lead to early arthritis and often requires total joint replacement early on in life.


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Qbank (1 Questions)

(OBQ08.118) A 9-year-old boy presents for evaluation of shortened stature. He denies back or extremity pain. Physical exam is notable for a valgus left knee and a waddling gait. Radiographs of the pelvis, knees, and left hand are provided in figures A-C. Genetic testing reveals a mutation of the cartilage oligomeric matrix protein(COMP). What is the most likely diagnosis? Topic Review Topic
FIGURES: A   B   C      

1. Multiple epiphyseal dysplasia
2. Achondroplasia
3. Diastrophic dysplasia
4. Perthes disease
5. Metaphyseal chondrodysplasia



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