Chiropractic biophysics digitized radiographic mensuration analysis of theanteroposterior lumbopelvic view: A reliability study

Objective: To investigate the reliability of a radiographic measurement pro cedure that uses a computer and sonic digitizer to determine projected spin al displacements from an ideal normal position. Design: A blind, repeated-measure design was used. Anteroposterior lumbopel vic radiographs were presented to each of 3 examiners in random order. Each film was digitized, and the films were randomized for a second run. Setting: Private, primary-care chiropractic clinic. Main Outcome Measures: The angle of the sacral base in comparison to a true horizontal line (horizontal base angle), lumbodorsal angle, lumbosacral an gle, and the thoracic translational displacement from true vertical determi ned as the perpendicular distance from the center of T12 to a vertical axis line drawn from the center of the SI spinous process cephalad and parallel to the lateral edge of the x-ray film. Results: Intraexaminer reliability for the (a) horizontal base angle was .7 2 to .94, with confidence intervals included in the range of .52 to .97; (b ) lumbodorsal angle was .90 to .96, with confidence intervals in the range of .82 to .98; (c) lumbosacral angle was .84 to .96, with confidence interv als in the range of .72 to .98, and (d) thoracic translational displacement from Vertical was .95 to .97, with confidence intervals included in the ra nge of .91 to .99. Interexaminer reliability for the three examiners ranged from .71 to .97. Conclusions: Measures similar to those described in this study are commonly used to measure and categorize spinal displacements from true vertical ali gnment (ie, scoliosis measurements). Most patient assessment methods used i n chiropractic have poor or unknown reliability. The one possible exception to this rule is spinal displacement analysis performed on radiographs. In chiropractic, intraclass correlation coefficients values greater than .70 a re considered accurate enough for use in clinical and research applications . The measures tested here would fit within these sidelines of reliability. Establishing reliability is an important first step in evaluating these me asures so that future studies of validity may be undertaken.