Bone age (radiograph)

The bone age radiograph of the hand and wrist is a commonly performed examination to determine the radiographic age of the patient via the assessment of growth centers.

Indications

Bone age radiographs may be indicated for both clinical and non-clinical purposes :

• for the investigation of
  • short stature / poor growth, e.g. constitutional delay
  • tall stature
  • early or late puberty
  • congenital adrenal hyperplasia
• non-clinical examples include age assessment for legal purposes immigration (e.g. refugee / asylum sekeers) and elite sports, although assessment of age purely based on x-rays is not recommended

Patient position

• patient is seated alongside the table
• the non-dominant hand is placed, palm down on the image receptor
• shoulder, elbow, and wrist should all be in the transverse plane, perpendicular to the central beam
• the hand and elbow should be at shoulder height which makes radius and ulna parallel (lowering the arm makes radius cross the ulna and thus relative shortening of radius)

NB: many departments will have a blanket rule of a left-hand radiograph for bone age, it is advisable to check the local protocols regarding this examination

Technical factors

• posteroanterior projection
• centering point
  • the mid-metacarpal region of the left hand 
• collimation
  • laterally to the skin margins
  • proximal to include 1/3 of the forearm
  • distal to the tips of the distal phalanges 
• orientation  
  • portrait
• detector size
  • 18 cm x 24 cm
• exposure
  • 50-60 kVp
  • 1-5 mAs
• SID
  • 100 cm
• grid
  • no

Image technical evaluation

Fifth finger is positioned PA, with no rotation as evidenced by the symmetric appearance of the concavities of the phalanges. Interphalangeal and metacarpophalangeal joint spaces of digits 2 to 5 appear open.

The concavity of the metacarpal shafts is equal .

Practical points

This is not a technically challenging radiograph, always ensure the fingers are equal distance apart and the detector is high enough to avoid overlap at the wrist.

Assessment is performed with a radiograph of the non-dominant hand with a single PA view that includes the distal radius and ulna and all the fingers. Appearances of the carpal bones, metacarpal, phalanges, radius and ulna are traditionally compared to standardized versions in atlases:

• Greulich & Pyle atlas presents a single standardized image for a range of ages of each gender 
• Tanner-Whitehouse method involves the scoring of each carpal bone, the radius and ulna leading to a total score, from which age can be estimated
• Gilsanz & Ratib atlas: a newer digital atlas which includes synthetic images