Bone Age X-Ray
A bone age radiograph is a single posteroanterior view of the left hand and wrist. It assesses skeletal maturity by the appearance and fusion of ossification centres and growth plates, and compares it with the child's chronological age.
Ossification centres appear and mature in a predictable sequence. In the wrist:
- capitate and hamate: about 2 to 6 months
- triquetral: 2 to 3 years
- lunate: 3 to 4 years
- trapezium and trapezoid: 4 to 5 years
- scaphoid: 4 to 6 years
- pisiform: 8 to 12 years
The adductor sesamoid of the thumb appears at about 11 to 13 years in girls and 12 to 14 in boys (a marker of the pubertal growth spurt).
The epiphyses of the phalanges, metacarpals, radius and ulna fuse progressively between 13 to 15 years in girls and 15 to 17 years in boys.
Methods:
- the Greulich-Pyle atlas (matching the film to the closest reference image, the most widely used)
- the Tanner-Whitehouse scoring methods (scoring each of 13 to 20 bones for a maturity score)
- the Fels method
- automated software that analyses the image and gives a bone age and an estimated adult height
The dose is negligible (under 0.001 mSv).
Bone age is used with height, growth velocity, puberty stage and family heights to investigate growth and pubertal disorders. In children, bone age reflects biological maturity better than chronological age, and the difference determines remaining growth and timing of puberty.
It is also used for:
- adult height prediction (Bayley-Pinneau, Tanner-Whitehouse and Roche-Wainer-Thissen methods, with an error of about 5 to 6 cm)
- monitoring of treatment (puberty suppression for precocious puberty, growth hormone therapy, aromatase inhibitors)
- in some jurisdictions, age estimation in legal settings, which is not reliable
Indications.
- Short stature (to separate constitutional delay from pathological causes).
- Tall stature or rapid growth.
- Delayed puberty and precocious or early puberty.
- Suspected endocrine disease (hypothyroidism, growth hormone deficiency, congenital adrenal hyperplasia, Cushing syndrome, hyperthyroidism, hypogonadism).
- Chronic disease with poor growth (coeliac disease, inflammatory bowel disease, chronic kidney disease).
- Monitoring growth treatment.
- Planning timing of orthopaedic procedures that depend on growth (epiphysiodesis, scoliosis management).
- Age estimation when legally required and no records exist (with the limits of the method clearly stated).
Not for routine assessment of normal growth, or for children with an obvious normal growth pattern.
Contraindications and precautions.
- No absolute contraindication.
- Pregnancy: not relevant to the dose, but not usually required.
- The left hand is used by convention (the right if the left is deformed or injured, with a note).
- For legal age estimation, consent and ethical review apply, and radiographs are not taken solely for non-medical reasons in some countries.
Preparation and technique.
- The child sits with the left hand and forearm flat on the detector, palm down.
- The fingers are slightly apart, the thumb abducted at 30 degrees, and the middle finger in line with the forearm.
- The beam is centred on the capitate.
- Include the distal radius and ulna to the fingertips.
- Remove rings and bracelets.
