Clinical Relevance of Axial Radiographic Damage in Axial Spondyloarthritis - Evaluation of Functional Consequences by an Objective Electronic Device.

OBJECTIVE: Axial spondyloarthritis (axSpA) is associated with decreased function and mobility of patients due to inflammation and radiographic damage. The Epionics SPINE device (ES), an electronic device that objectively measures spinal mobility, including range of motion (RoM) and speed (RoK) of movement, has been clinically validated in axSpA. We investigated the performance of the ES relative to radiographic damage in the axial skeleton of patients with axSpA.

METHODS: A total of 103 patients with axSpA (31 non- [nr-] and 72 radiographic [r]- axSpA) were consecutively examined. Conventional radiographs of the spine (including presence, number and location of syndesmophytes) and the sacroiliac joints (SIJs, rated by mNY criteria) were analyzed with the ES and assessments of function and mobility using analyses of covariance and Spearman correlation.

RESULTS: The number of syndesmophytes correlated positively with BASMI scores ( r =0.38; P =0.016) and negatively with chest expansion ( r =-0.39; P =0.015) and ES measurements (-0.53 ≤ r ≤ -0.34, P <0.03) except for RoM and RoK regarding rotation and RoK for extension of the lumbar and thoracic spine. In the radiographic evaluation of SIJs, the extent of damage correlated negatively with ES scores and metric measurements (-0.49 ≤ r ≤ -0.33; P <0.001). Patients with r-axSpA showed significantly worse ES scores for RoM, RoK and chest expansion than those with nr-axSpA.

CONCLUSION: The ES scores, in accordance with mobility measurements, correlated well with the presence and extent of radiographic damage in the spine and SIJs. As expected, patients with r-axSpA had more severe impairments than those with nr-axSpA.