RELIABILITY OF MEASUREMENTS OF LUMBAR SPINE SAGITTAL MOBILITY OBTAINED WITH THE FLEXIBLE CURVE

Presently, there is no available scientific information that examines the interchangeability of tangent and trigonometric methods used to ca lculate measurements of sagittal mobility of the lumbar spine obtained with a flexible curve. Repeated measurements of the lumbar curvature were made with a flexible curve by using a standardized protocol on 10 healthy volunteers under three conditions: 1) standing, 2) sitting wi th maximum trunk forward bending, and 3) lying prone with maximum back ward bending. Measurements were made by a team of two physical therapi sts working together; one therapist instructed the subject, and the ot her therapist performed the measurement. Agreement between the tangent and trigonometric methods was assessed graphically by plotting the di fference between methods against the mean value of each pair of readin gs for each of the three conditions. Measurements differed by 4 to 7-d egrees for each of the three positions of the lumbar spine. We believe such error is clinically acceptable and should not affect the clinica l decision made on the basis of the measurement.