Accurate noninvasive measurements of spinal curvature are crucial in planning treatment and assessing curve progression in adolescent idiopathic scoliosis. An inter-rater agreement trial and an intrarater agreement trial were undertaken to estimate the reliability of axial rotation measurement using the Scoliometer (Orthopedic Systems, Inc., Haywood, California). In the inter-rater trial, two orthopedic surgeons and two orthopedic surgery residents independently measured the thoracic and lumbar axial rotations of 22 patients with idiopathic scoliosis using the Scoliometer. In the intrarater, trial a single orthopedic surgeon measured the thoracic and lumbar axial rotations of 25 patients on four separate occasions with the Scoliometer. Inter-rater agreement using the Scoliometer to estimate the magnitude of the hump (in centimeters) in the thoracic and lumbar regions was poor (intraclass correlation coefficient, Rho = 0.57 and Rho = 0.76 for the thoracic and lumbar regions, respectively). Inter-rater agreement using the Scoliometer to estimate the degree of axial trunk rotation was better (Rho = 0.81 and Rho = 0.82 for the thoracic and lumbar regions, respectively). Intrarater agreement using this device to estimate the magnitude of the hump (in centimeters) in the thoracic and lumbar regions was good (Rho = 0,90 and Rho = 0.84 for the thoracic and lumbar regions, respectively). Intrarater agreement using the Scoliometer to estimate the degrees of curvature was outstanding (Rho = 0.995 and Rho = 0.998 for the thoracic and lumbar regions, respectively). These results indicate that the Scoliometer can be a reliable noninvasive method for repetitively assessing spinal axial rotation when used by a single trained observer.
