Measuring Lumbar Motion Angle With a Small Accelerometer: A Reliability Study

Objective

The purpose of this study was to investigate the reliability of measuring the lumbar motion angle using a small accelerometer for movement tests in the sagittal plane, and to determine the number of measurements required to obtain reliable data.

Methods

In total, 102 healthy adults (56% women, 44% men; 20.1 ± 1.1 years of age) participated in this study. The intra- and interexaminer reliability of lumbar motion angle measurements during forward and backward trunk bending and prone hip extension were investigated. Lumbar motion angles were measured with small accelerometers placed at the thoracolumbar transition, lumbosacral transition, and thigh, during motion and at the final position. Intraclass correlation coefficients and Bland-Altman analysis were used for statistical analysis.

Results

The intraclass correlation coefficients ranged from 0.6 to 0.8 in intraexaminer analyses and from 0.5 to 0.7 in interexaminer analyses. Intraexaminer systematic biases were found only in the maximum angle of trunk forward bending. Interexaminer biases were found in all angles of trunk forward bending.

Conclusion

In the measurement of lumbar motion angle in the sagittal plane using a small accelerometer, it was necessary to repeat measurements 2 to 4 times, because a single measurement was not sufficiently reliable either within or between examiners.