Smartphone Versus Back Range of Motion: Validity and Reliability in Lumbar Range of Motion Assessment

During lumbar flexion and extension measurements using the Back Range of Motion (BROM) device, patients stand upright with extended knees and feet approximately 17 centimeters apart. For flexion, they bend forward to touch the floor, while for extension, they bend backward with crossed arms. An inclinometer is secured over the sacrum, and its position is centered to record readings in degrees. An L-shaped slide arm measures the distance between the T12 and S1 spinous processes. The device isolates lumbar motion from pelvic motion, and the stationary flexion/extension unit minimizes errors, enhancing measurement accuracy.

For measuring lumbar lateral flexion, the subject's sides are parallel to a wall to prevent compensatory forward trunk flexion. An inclinometer is secured over the sacral region at S1, using a belt for stability. A gravity goniometer is placed on the upper thoracic region to capture trunk angular displacement during side bending. The inclinometer is levelled and zeroed before movement, allowing for precise measurement of lateral lumbar movement while reducing thoracic and pelvic compensations. Accurate placement of the device is essential for reliable results. The subject slides their hand down the thigh, keeping weight on the opposite leg to ensure the measurement reflects true lateral flexion.measures]

To measure lumbar flexion range of motion (ROM) using the iPhone Level app, participants are positioned standing upright with feet shoulder-width apart. T12-L1 and S1-S2 spinal levels are identified through palpation and marked on the skin. The iPhone is placed at these levels to record angles during maximum lumbar flexion. Total lumbar flexion ROM is calculated by subtracting the angle at S1-S2 from T12-L1. Subjects perform maximum lumbar flexion and extension with straight knees, and measurements are taken across three trials.

During the measurement of lumbar side bending using the iPhone Level application, the subject will stand in a neutral upright position with feet shoulder-width apart and hands placed on the hips to prevent arm movement from influencing the measurement. The spinous processes of T12 and S2 are identified and marked on the skin. The iPhone is first placed and zeroed at the T12 level, and the subject is instructed to bend sideways (toward one side) as far as possible without lifting the heels or rotating the trunk. The device remains aligned at T12 to capture the angular displacement. The same procedure is repeated with the device positioned at S2, and the final lumbar side bending range of motion is calculated by subtracting the angle at S2 (pelvic movement) from that at T12 (trunk movement). This method isolates lumbar lateral flexion and has shown good reliability and validity in clinical settings