# The baseline bubble inclinometer measurement of sagittal thoracic spinal range of motion is reliable: Validated by optoelectronic motion capture system

## TL;DR

This study shows that baseline bubble inclinometers are reliable for measuring thoracic spine movement when compared to a high-tech motion capture system.

## Contribution

The study validates baseline bubble inclinometers for measuring thoracic spinal range of motion and proposes standardized guidelines for their use.

## Key findings

- Baseline bubble inclinometers showed moderate to high correlation with optoelectronic motion capture for thoracic spinal ROM.
- Flexion ROM measurements had the highest correlation (r = 0.84–0.89) with the control system.
- Females showed higher correlation with Vicon results, suggesting they are more suitable for inclinometer-based measurements.

## Abstract

The thoracic spinal range of motion (ROM) is a commonly used in pathological and functional assessment. Baseline bubble inclinometers are one of the most frequently employed thoracic ROM measurement methods. However, there is currently no consensus on the accuracy and standardized procedure of their utilization.

The purpose of this study is to validate the accuracy of baseline bubble inclinometers in measuring the sagittal thoracic spinal ROM and to propose the standard guideline for their utilization.

28 participants were recruited for this study. The maximum thoracic spinal ROM during flexion and extension was measured using inclinometers, with the optoelectronic motion capture system (Vicon) serving as the control group.

Result: The thoracic spinal ROM during flexion was 14.5 ± 10.5°; during extension was 19.0 ± 9.2°, and the total ROM was 33.5 ± 14.0°. The inclinometers showed moderate to high correlations with the Vicon results, particularly in measuring flexion ROM, which exhibited the highest effectiveness (r = 0.84∼0.89). The accuracy of the inclinometers was enhanced by ensuring a cervical nodding and fixation position. Additionally, it was observed that females were more suitable candidates for thoracic spinal ROM measurement using inclinometers, as they exhibited higher correlations with the Vicon results.

This study successfully validated the accuracy of the inclinometer as a convenient thoracic spinal ROM measurement method, that can save significant time for physiotherapists in clinical settings. The measurements obtained in this study may serve as a preliminary reference for the thoracic spinal ROM in healthy individuals and standardized protocols for using the baseline bubble inclinometer.