Spinal mobility in radiographic axial spondyloarthritis: criterion concurrent validity of classic and novel measurements

Abstract

Background Limitations in spinal mobility are a characteristic feature of Axial Spondyloarthritis. Current clinical measurements of spinal mobility have shown low criterion-concurrent validity. This study sought to evaluate criterion-concurrent validity for a clinically feasible measurement method of measuring spine mobility using tri-axial accelerometers. Methods Fifteen radiographic-Spondyloarthritis patients were recruited for this study. Two postural reference radiographs, followed by three trials in forward, left and right lateral bending were taken. For all trials, three measurements were collected: tape (Original Schober’s, Modified Schober’s, Modified-Modified Schober’s, Lateral Spinal Flexion Test and Domjan Test), followed immediately by synchronized radiograph and accelerometer measurements at end range of forward and bilateral lateral flexion. The criterion-concurrent validity of all measurement methods was compared to the radiographic measures using Pearson’s correlation coefficients. A Bland-Altman analysis was conducted to assess agreement. Results In forward bending, the accelerometer method (r = 0.590, p = 0.010) had a stronger correlation to the radiographic measures than all tape measures. In lateral bending, the Lateral Spinal Flexion tape measure (r = 0.743, p = 0.001) correlated stronger than the accelerometer method (r = 0.556, p = 0.016). The Domjan test of bilateral bending (r = 0.708, p = 0.002) had a stronger correlation to the radiographic measure than the accelerometer method. Conclusions Accelerometer measures demonstrated superior criterion-concurrent validity compared to current tape measures of spinal mobility in forward bending. While a moderate correlation exists between accelerometer and radiographs in lateral bending, the Lateral Spinal Flexion Test and Domjan Test were found to have the best criterion-concurrent validity of all tests examined in this study.

Future Challenges and Critical Approach to Metrology in Patients with Axial Spondyloarthritis

“…Swinnen et al proposed to automate and objectify the functional BASFI test, introducing the use of an accelerometer (a small electronic sensor that measures the acceleration forces acting on an object, in order to determine object movement, speed, and orientation) and specific algorithms [ 9 ]. Snow et al [ 10 ], compared concurrent criteria validity of a tri-axial accelerometer compared with a conventional lumbar mobility test: original and modified Schöber and lateral flexion and radiographic assessments, with the accelerometer providing better results in forward bending. Kiefer et al [ 11 ] tested a specific electromagnetic device, the Epionics SPINE (Epionics Medical GmbH, Potsdam, Germany) for measuring lumbar and thoracic mobility in axSpA, with good validity results, although this device is only designed for the back and not for neck mobility, which is also affected in axSpA.…”

Schober test is not a valid assessment tool for lumbar mobility

“…Due to concerns that the conventional Schober test may fail to evaluate movement of the whole lumbar spine 11 , the test was changed leading to two modified versions: the modified Schober test 18 and the modified-modified Schober test 19 . Over the years, contradicting evidence regarding the validity and reliability of each of these tests has been published when comparing it to inclinometer measurements 20 – 22 or radiological analysis 23 , 24 .…”