Relationship of peak height velocity to other maturity indicators in idiopathic scoliosis in girls

Background Our aim was to compare height velocity data, obtained from clini cal height measurements, for girls who had idiopathic scoliosis with the da ta for adolescents who did not have scoliosis. We also compared the growth data with chronological age, menarchal age, and Risser sign in terms of the ir accuracy in the prediction of growth and progression of the scoliosis. Methods: One hundred and twenty of 371 patients in a database of girls mana ged with a brace for the treatment of idiopathic scoliosis had sufficient h eight data for us to quantify their growth peak. Height velocity data was g enerated from standing-height measurements obtained, in a scoliosis clinic, with a minimum six-month interval between measurements, and the timing of peak height velocity was calculated. The age at menarche was recorded from the patients' records. The Kisser sign and Cobb angle were determined by a single observer. Progression of the scoliosis was defined as an increase in the Cobb angle of at least 10 degrees, compared with the curve magnitude a t the time of the initial evaluation, after a minimum of six months. Progre ssion to a magnitude requiring surgery was defined as progression of at lea st 10 degrees to a magnitude of 45 degrees or more. Results: The height velocity plot grouped by peak height velocity showed a high peak and a sharp decline with values similar to those in normal popula tions. Extrapolating from percentile charts, 90 percent of our patients cea sed growing by 3.6 years after peak height velocity. The growth peak was bl unted (averaged over too long a period such that the data for the period of most rapid growth was averaged in with that for a period of slower growth) when chronological age, menarchal age, and Kisser sign were used to predic t growth; this indicated that these maturity scales grouped the patients po orly in terms of growth. The primary curve was progressive in eighty-eight of the 120 patients. Sixt y of these patients had a curve of more than 30 degrees at peak height velo city, and in fifty (83 percent) of the sixty the curve progressed to 45 deg rees or more. The remaining twenty-eight patients had a curve of 30 degrees or less at peak height velocity, with only one curve (4 percent) progressi ng to 45 degrees or more. Peak height velocity also grouped patients for maximal progression of the c urve more accurately than did the other maturity scales, as most of the cur ves progressed maximally at peak height velocity. There was a wider spread of timing of maximal progression when chronological age, menarchal age, and Risser sign were used to predict progression. Conclusions Height velocities generated from clinical height measurements f or patients with idiopathic scoliosis document the growth peak and predict cessation of growth reliably. Knowing the timing of the growth peak provide s valuable information on the likelihood of progression to a magnitude requ iring spinal arthrodesis.