The Basis for Skeletal Age Assessment
Skeletal age assessment is based on the fact that the cartilage structures of the wrist undergo a process of ossification (that is, hardening into bone) during growth. As in other long bones, the development process begins with the appearance of a center of ossification in the diaphysis, followed by ossification centers in the epiphyses and the formation of epiphyseal growth plates. The fusion of the epiphyseal growth plates marks the end of the child's growth. These changes in the cartilage and bone structure of the wrist have been documented in the widely used Greulich and Pyle Atlas, which records the appearance of the bone structure at the left hand and wrist of male and female children and adolescents at 3-12-month intervals, depending on the child's age.
One way of measuring skeletal age, or bone age, is to take an X-ray picture of the left hand and wrist of a child or adolescent patient and compare it to the pictures in the Greulich and Pyle Atlas to find a match between the appearance of the wrist in the X-ray and one of the photos in the Atlas. The age indicated under the matching photo will be the patient's bone age score.
Using BonAge for Skeletal Age Assessment
BonAge, a novel skeletal maturity assessment device, instead assesses skeletal age with a unique technology that measures the velocity of an ultrasound wave transmitted through the wrist, and uses a proprietary gender- and ethnicity-based algorithm to produce a numeric result in years and months. The device includes a main unit and a measurement unit with an ultrasound probe.
The measure-ment unit is made up of a base that supports an ultrasound probe with two ultrasound transducers, and an an armrest between the transducers for the patientís hand and wrist.
The path of the ultrasound wave through the wrist with the BonAge bone age assessment method.
BonAge operates as seen above: Ultrasonic waves are passed through the patientís measurement area on the left wrist via attached transducers. The ultrasound-based method used by the device is simple to operate and radiation-free, with no side effects for the patient or operator.
BonAge Measurement Results
The device calculates the Speed-of-Sound (SOS) and provides a on-the-spot numeric bone age result (in years and months). Clinical studies have shown that results are highly correlated with conventional bone age readings using the Greulich and Pyle method.