Department of Orthopaedic Surgery
Stellenbosch University
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Orthopod #43
Show notes - Determination of Skeletal Age

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Risser's Sign


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Learn how to determine skeltal age from physical examination and x rays.

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Measurement of skeletal age

You as a medical practitioner will often be asked to determine a patients bone age. The reason may be legal. Many countries punish a criminal act perpetrated by minor, often defined as under 18, less severely than his older peer. Fractures are often treated differently in the immature skeleton and when growth ceases also has an effect on spinal deformities such as scoliosis.
How do we determine how skeletally mature a child is?
There are many aspects to maturation. This includes the development of reproductive and secondary sexual characteristics, changes in muscle and fat mass and distribution, as well as changes in bone structure.

Normal Growth:

The age at which the growth spurt occurs varies greatly. Normal puberty has a 4 year variation in the age at which it takes place. Humans have two basic pubertal stages, consisting of adrenarche and gonadarche. Adrenache is when the adrenal cortex mature (at about 6 to 8 years) and, is the activation
of the ovary and testis with a dramatic increase in gonadal steroid production and reproductive capability. In girls, gonadarche is manifested by breast development and the onset of menstruation (menarche). Boys undergo testicular
enlargement and virilization.

Both growth hormone and the sex steroids, particularly estrogen, are necessary for the normal adolescent growth spurt.
In general girls are skeletally mature at 14 ½ years of age and boys at 16 ½

Skeletal Maturity

Growth usually ceases before the physes close. At the end of growth the physes may be open even though the individual has ceased growing.
While the patient is prepubital chronological age is a reasonable indicator of bone age. Patients from birth to age three or four years can be assumed to be growing very fast. After this until they hit the adolescent growth spurt, growth is much slower.
As the child approaches eight years of age, adrenarche provides some indication of impending puberty. As children approach the growth spurt, it is helpful to ask questions about the initiation of breast development or about rapid foot growth.
The first signs of puberty and the rapid growth spurt are initial breast development in girls and rapid foot growth in both boys and girls.
The rapid growth spurt occurs while the triradiate cartilages are still open. The triradiate cartilage closes at about age 12. For scoliosis, include the acetabulum on films taken for this reason. If there are concerns about the additional radiation, then a careful assessment of hand skeletal age should be obtained.

X Ray indicators of Skeletal Maturity

1: Ossification Centres about the elbow

Are useful in the younger prepubital child up until the age of 11 years. At this stage the child has not reached the prepubital growth spurt, and they are thus of limited use in determining the progression of a scoliotic curve. With injuries to the elbow however knowledge of the growth center here is essential in order to distinguish a fracture from an growth center.
With elbow injuries in children always x ray the normal side for comparison. Displacements or of the ossification centres / fractures can easily be missed if this is not done. The age of the child can also be determined by the ossification centers.
There are 6 ossification centers around the elbow joint. These ossification centers all appear at different ages and they all fuse to the adjacent bones at various ages. It is not clinically important to memorize the specific ages of when these ossification centers appear or fuse. However, it is clinically important to realize that the ossification centers always appear in a specific sequence.
The mnemonic of the order of appearance of the individual ossification centers is C-R-I-T-O-E: Capitellum, Radial head, Internal (medial) epicondyle, Trochlea, Olecranon, External (lateral) epicondyle. Remember that the anatomic position of the body places the upper extremities in external rotation (supination at the elbows) such that the antecubital fossa faces anteriorly. Thus, the external epicondyle is on the radial side of the elbow, while the internal epicondyle is on the ulnar side of the elbow. The ages at which these ossification centers appear are highly variable, but as a general guide, remember 1-3-5-7-9-11 years.

2: Risser’s Sign

The Risser sign, which is commonly used as a maturity indicator in scoliosis, is based on the radiographic excursion of iliac apophyseal ossification. The iliac apophysis typically starts ossifying at the anterior superior iliac spine and
then extends posteriorly toward the posterior superior iliac spine.

The axial skeleton matures a few years later than the limbs, and for scoliosis, the Risser sign is a useful method of bone age determination.
Skeletal age can be determined by the appearance of the iliac apophysis of the pelvis. The apophysis appears laterally on a pelvic x ray, and moves towards the spine as the patient approaches adulthood. Risser's sign is a measures the growth left in the spine - this may help to determine the potential for progression of scoliosis
Grading (based on iliac crest divided into 4 quadrants)

Risser's Sign

o Risser 1: 25% iliac apophysis ossification Anterior Superior iliac spine (anterolateral) Seen in prepuberty or early puberty.
o Risser 2: 50% iliac apophysis ossification Ossification extends halfway across iliac wing Seen immediately before or during growth spurt
o Risser 3: 75% iliac apophysis ossification.
o Risser 4: 100% ossification, with no fusion to iliac crest . Indicates slowing of growth
o Risser 5: Iliac apophysis fuses to iliac crest Indicates cessation of growth.

Risser 1 is seen at age 13.8 in girls and 15.2 in girls. Risser 5 is first seen at age 16 in girls and 18 in boys.


3. Hand and Wrist Bone X Rays

A common and accurate way of skeletal age measurement is to compare x rays taken of the left hand and writ to standardized X ray pictures in the Greulich and Pyle atlas. The Greulich and Pyle atlas has the advantage of being universally available and has good instructions accompanying the figures.
One problem with this atlas is that there is some user variability, which makes a precise estimation difficult. It was compiled using Caucasian children in America and the data may not always extrapolate to races with different builds.

Age determination in other areas

Other age determination systems are of value to the criminologist and immigration officials. It is sometimes crucial to determine if the individual is over 18 or 21, or at whatever age defines adulthood, and its attendant less lenient judicial treatment.
The third molar roots appear on x rays at age 18 years. The ossification of the sternal clavicular cartilage also occurs at age 18 years.


1. Greulich WW, Pyle SI: Radiographic Atlas of Skeletal Development of the Hand and Wrist, 2nd edition. Stanford,CA: Stanford University Press, 1959.
2: Sanders JO, Browne RH, McConnell SJ, Margraf SA, Cooney TE, Finegold DN. Maturity Assessment and Curve Progression in Girls with Idiopathic Scoliosis. J Bone Joint Surg Am 2007;89:64-73.









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