Physical therapists commonly examine the postural alignment and curvature of the low back region in patients with low back pain, presumably because of an assumed relationship between postural alignment and dysfunction. As an adjunct to visual observation, clinicians may also use a special device to obtain noninvasive measurements of the curvature. Many different devices have been used, but a largely unanswered question is whether the measurements obtained with the various devices can be used interchangeably. Based on the literature, the 2 types of devices that appear to be used most commonly are inclinometers and flexible rulers. This technical note concludes that regardless of the device used – inclinometer or Metrecom, a microcomputer-interfaced, electromechanical, three-dimensional (3D) digitizer, the results for tangent method measurements were similar. Trigonometric method measurements taken with the Metrecom were larger than tangent method measurements obtained with either the inclinometer or Metrecom. The difference between actual and predicted depth of the curve was a large and significant predictor of the difference between tangent and trigonometric measurements. The use of the trigonometric method with a computer-interfaced digitizer, such as the Metrecom, may be preferable compared to the use of an inclinometer if information about the depth of the curve is of particular importance for either research or clinical purposes. Additional testing is required to generate age- and gender-specific referent values, as well as to assess the sensitivity and specificity of the measures for categorization of spinal conditions.
J Ortho Sports Phys Ther. 2002; 32(8):405-414.