Osteogenesis Imperfecta : Mnemonic

Synonym: Brittle Bone Disease

Incidence: 1 in 20,000

Gene defect: Col1A1 (17q) and Col1A2 (7q)

Mnemonic: Remember “one” for “bone”. Collagen one is the main composition of bone. OI is a disorder of bone. Hence, the defect is is in Col1.

Features

Mnemonic: BLOOD

  1. Blue sclera
  2. Otosclerosis (SNHL)
  3. Osseous fragility
  4. Dentinogenesis imperfecta
Sillence TypeInheritanceFeaturesMnemonicCollagen
IADBlue sclera, Otosclerosis; Osseous fragility (variable) – mildBlONormal quality; Insufficient quantity
IIAD, ARLethal perinatalLPoor quantity and quality
IIIAROsseous fragility (moderate to severe) – progressive deformingOCollagen poorly formed; normal quantity
IVADOsseous fragility, Dentinogenesis imperfecta – deforming with normal scleraODSufficient quantity but poor quality

Treatment

Mnemonic: BDSM

1. Basilar invagination: Bone resection via transoral approach

2. Deformities: Realignment osteotomy with rod fixation (Sofield-Miller procedure)

3. Scoliosis: Operate when curves >45 degrees in mild forms and >35 degrees in severe forms

4. Multiple fractures:

  • Prevention: Bracing and Bisphosphonate
  • <2 years old: Conservative
  • >2 years old: Telescoping rods (Duval)

Reference:

  1. General Orthopaedics and Basic Science edited by Nikolaos K. Paschos, George Bentley
  2. Sillence DO, Senn A, Danks DM. Genetic heterogeneity in osteogenesis imperfecta. J Med Genet. 1979;16:101โ€“116.


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