Carpal Bones Ossification : Mnemonic

Roughly one center appears per year from the age of 1 year to 7 years, anti-clockwise in right hand and clock-wise in left hand looking from the anterior surface, i.e. from ulnar side to radial side. Pisiform, being a sesamoid bone it gets left behind and only develops years later.

  1. capitate: 1-3 months
  2. hamate: 2-4 months
  3. triquetrum: 2-3 years
  4. lunate: 2-4 years
  5. scaphoid: 4-6 years
  6. trapezium: 4-6 years
  7. trapezoid: 4-6 years
  8. pisiform: 8-12 years

Wrist Trauma Radiographic Evaluation - Hand - Orthobullets

Also it’s nice to know the appearance of ossification center of:

  1. Distal radius: 1 year
  2. Distal ulna: 4-5 years

A simple way to remember ossification centers of carpal bones [top left]. X-ray 1-Child 2-3 y. Capitate (>2 m) and Hamate (>3 m) have appeared, but triquetral has not appeared (<3 y). Lower end of radius has appeared (>2 y). X-ray 2-Child 3-4 y. All findings same as in 1, but additionally triquetral has appeared (>3 y). Lunate not appeared (<4 y). X-ray 3-Child 6 y. Findings same as in x-ray 2, but additionally Lunate has appeared (>4 y), and also trapezoid (>5 y). Lower end of ulna also appeared (>6 y). Scaphoid and trapezium should have appeared by now normally, but this X-ray shows a variation. X-ray 4-child 6-12 y. All carpals have appeared except pisiform (<12 y). Lower end of ulna has appeared (>6y). X-ray 5-child 12-16 y. Pisiform has appeared (>12 y); head of 1st metacarpal not united (<16 y). 

If that didn’t work for you, try this mnemonic

Camera Has Three Lens, So Take Three Photos.

  1. Capitate
  2. Hamate
  3. Triquetral
  4. Lunate
  5. Scaphoid
  6. Trapezium
  7. Trapezoid
  8. Pisiform
Carpal bone fractures

Also, if you’ve been having hard time remembering if the location of trapezium and trapezoid, just remember that the trapeziUM is towards thUMb and trapezoID is insIDe.

It can be a bit daunting to remember this, specially because different books mention different timelines.

If you were like me, getting confused with the volume overload, forget everything else. Just remember this one image. Thank me later!


Hope that mnemonic helped. Got a better mnemonic for the same? Let us know in the comments below.
Also check out these medical mnemonics.

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