A validity of ultrasound subdivision of Risser grade 4 in assessment of skeletal maturity

In the treatment of adolescent idiopathic scoliosis, one of the most frequently used technique to determine skeletal maturity is the method described by Risser. The ossification of iliac apophysis progresses from ventral to caudal through the four zones and the fusion of the iliac apophysis to the iliac crest (Risser grade 5) indicated vertebral growth completion, therefore the termination of scoliotic deformity progression. The main disadvantages of Risser method are exposure to radiation and the questionable reliability, so there are efforts to examine iliac apohysis by ultrasound. There is also no resolute recommendation when to discontinue brace treatment of scoliosis. Using ultrasound, in this study, we subdivided Risser grade 4 to grade 4a and 4b, according to the amount of cartilage left unossified, in order to make clear when is safe to end brace treatment. We measured increase in height, during six month period, for 92 healthy children, who were classified by ultrasound in Risser 4a or 4b group. There was significantly larger increase in height for group 4a (p < 0.001). For girls, we also noted time past from menarche as sign of biological maturity. Girls from group Risser 4b got menarche 2.74 years before they were examined while group Risser 4a got menarche only 1.57 years before (p < 0.001). Subdvision of Risser 4 grade by ultrasound is promising method in determining end of brace treatment for scoliosis.