Assessing validity of thoracic spine rotation range of motion measurement methods: comparison of magnetic resonance imaging and clinical measurements.

[Purpose] This work was designed to establish criteria for assessing common clinical measurement methods for thoracic spinal rotation angles by comparing their results with magnetic resonance imaging measurements. [Participants and Methods] Twenty-six healthy participants underwent thoracic rotation angle assessments using an electronic goniometer in three positions: lumbar-locked, seated, and half-kneeling. We compared these results with measurements obtained by magnetic resonance imaging. [Results] A moderate but significant positive correlation was observed between the thoracic rotation angle measured by magnetic resonance imaging and the lumbar-locked rotation test. The respective 95% confidence intervals of these correlation coefficients were 0.09 and 0.72. Bland-Altman analysis revealed a fixed error in the lumbar-locked rotation test, suggesting that the test tended to overestimate thoracic rotation compared with magnetic resonance imaging, but proportional errors could not be definitively identified. [Conclusions] Thoracic spine rotation angles measured using magnetic resonance imaging aligned closely with previously reported results. Notably, although measurements obtained by the lumbar-locked rotation test correlated with magnetic resonance imaging results, they exhibited fixation errors. Functional tests (seated and half-kneeling) showed limited correlations with magnetic resonance imaging results. The influence of adjacent joints on clinical measurements should be considered.