While those with advanced training may readily recognize the landmarks, other research staff may have a difficult time accurately and reproducibly identifying the correct levels. The flexicurve ruler, gently pressed onto the back, adopts the thoracic and lumbar contours of the participant. The researcher then traces the ruler’s retained shape onto paper and calculates the kyphosis index (Fig. 1) [21]. One can also

calculate an inscribed angle of kyphosis from the tracing, using geometric formulae (Fig. 1) [14]. Fig. 1 Three PF299 chemical structure Methods of quantifying thoracic kyphosis angles are illustrated. The modified T4–T12 Cobb angle (dotted lines) measures the angle created by lines Crenigacestat ic50 drawn parallel to the limit vertebrae visualized on a lateral standing thoracolumbar radiograph. In this case, the limit vertebrae are pre-specified at T4 and T12. The Flexicurve kyphosis index and angle are computed using measurements taken from the flexicurve Bucladesine tracing of the thoracic curve, represented here by the solid dark curve posterior to the

thoracic vertebral bodies. To calculate the Flexicurve kyphosis index, the apex kyphosis height (E) is divided by the length of the entire thoracic curve (L). The Flexicurve kyphosis angle, Theta (θ), is calculated using lines drawn perpendicular to the short sides of the triangle inscribed by the thoracic curve. This triangle is demarcated by points a (Apex), b (at the cranial end of the curve), and c (at the caudal end). Theta equals arc tan (E/L1) + arc tan (E/L2) Although the non-radiological kyphosis measures minimize cost and obviate radiation, they have enjoyed limited adoption. One explanation may be that they are not calibrated to the Cobb angle, which limits their clinical interpretation. A metric that translates a non-radiological kyphosis result into an approximate Cobb angle would allow estimation of clinical severity from non-Cobb measures. Demonstrations of the reliability and validity of the non-radiological measures, especially in older persons, have been minimal,

a possible second reason for limited use [13, 20, 22–24]. Therefore, we designed this study to describe: (1) the intra-rater and inter-rater reliability of three non-radiological kyphosis Acetophenone measures, the Debrunner kyphosis angle, the flexicurve kyphosis index, and the flexicurve kyphosis angle; (2) the validity of each non-radiological measure using the modified Cobb angle as the criterion standard; and (3) a translational formula that provides an approximate Cobb angle based on results of the non-radiological measures. We used baseline data from the Yoga for Kyphosis trial, during which we performed standing lateral radiographs to assess modified Cobb angle as well as multiple, same-day, intra-rater and inter-rater measures of the non-radiological assessments. Methods Participants The analysis sample came from the Yoga for Kyphosis Trial, a single masked, randomized, controlled trial (RCT) of Yoga intended to improve thoracic hyperkyphosis [14].