Straight-leg-raising test. Comparison of three instruments.

The purpose of this study was to compare three instruments in the assessment of the passive straight-leg-raising test: a standard plastic goniometer, a flexometer, and a tape measure. Hip flexion angles at the initial point of pelvic tilt were measured in 10 healthy subjects. All three methods showed excellent intrasession reliability with alpha coefficients greater than .94. The intersession reliabilities were identical for the goniometer and the flexometer (.88) and were higher than the reliability of the tape measure (.74). The tape measure had improved intersession reliability (.93) when a distance was used for calculation of the angle. Significantly lower hip flexion angles were obtained with the trigonometric method through use of tape measures than from use of either of the other two instruments. The flexometer is recommended for use in assessment of passive straight leg raise because it permits measurement by a single therapist without assistance.