Skeletal maturity determination is an important procedure for assessing bone age. Skeletal maturity means that both length and thickness growth of the bones has ended and the skeleton has reached its final shape. Changes to which the adult skeleton is subjected throughout its life are not negligible, but are not important here. The determination of skeletal maturity serves the following purposes:
- Assessment of the stage of development of the skeleton.
- Prediction of the expected height of the body
- Prognosis of the growth period still to be expected
Indications (areas of application)
- Developmental and growth disorders – the causes may be genetic, caused by external circumstances such as malnutrition, or the result of a variety of medical conditions
- Endocrinological diseases with growth disorders – e.g. pituitary short stature due to lack of STH (growth hormones).
- Forensic determination of biological age
- Determination of growth duration and expected body size.
The procedure
Under physiological (normal, healthy) conditions, the skeleton reaches different stages of maturity that can be chronologically assigned to a specific age. Important clues are the ossification of certain skeletal elements (some bone elements are initially composed of cartilage and ossify during growth) and the epiphyseal fossa (growth plate). The epiphyseal fossa usually closes around age 18 – earlier in females and tending to close later in males. The growth in length of the long bones (e.g. femur – thigh bone) takes place on both sides at the epiphyses by enchondral ossification. Here is an explanation: a long bone consists of the diaphysis (bone shaft) and two epiphyses (bone end pieces). The epiphyseal fossa, which lies between the diaphysis and epiphysis, is the growth zone of the bone and consists of cartilage that ossifies during growth. The epiphyseal groove can be used to determine radiographically the growth that can still be expected. In general, two different methods are often used to determine skeletal maturity:
- Assessment of bone age according to Greulich and Pyle: using a radiograph of the left hand, the characteristic ossification pattern (pattern of ossification) of the individual bones of the hand can be used to determine the bone age, since ossification occurs according to a lawful sequence.
- Risser’s assessment of iliac apophyses: an x-ray of the pelvis is used to assess the progression of ossification of the iliac apophysis (an apophysis is a bone nucleus that develops into bony prominences and usually serves as an attachment for muscles and ligaments). Risser divides this process into six distinct stages:
- Risser 0 – The apophysis is not visible [residual spinal growth: > 5 cm].
- Risser 1 – Apophysis begins to develop laterally and is up to 25% of the iliac crest [residual spine growth: 4 cm]
- Risser 2 – The apophysis extends up to 50% of the iliac crest [residual spine growth: 3 cm].
- Risser 3 – Apophysis spans up to 75% of the iliac crest [residual spine growth: 2 cm]
- Risser 4 – The apophysis is completely visible over the iliac crest [residual spine growth: 1 cm].
- Risser 5 – The iliac crest apophysis is fused to the ilium [residual spine growth: 0 cm].
Note: A handheld mobile ultrasound scanner for age estimation that measures ossification of the epiphyseal fossa is in the clinical evaluation phase. Note: Endocrinological diseases in particular can have a significant impact on bone growth, greatly delaying or accelerating it. When assessing bone age, gender must also be taken into account, as the ossification status at a certain age is more advanced in girls than in boys. In addition, it must be taken into account that skeletal maturation varies from individual to individual and is subject to a certain spread. Skeletal maturity determination is used both for growth prognosis and for supplementary diagnostics in the case of disease-related developmental and growth disorders.
