Abstract
BackgroundLimitations 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.MethodsFifteen 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.ResultsIn 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.ConclusionsAccelerometer 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.
Highlights
Limitations in spinal mobility are a characteristic feature of Axial Spondyloarthritis
Combining the risks associated with repeated exposure to ionizing radiation for obtaining radiographs and the aforementioned lack of criterion-concurrent validity for current clinical measures of spine mobility necessitates a search for clinically viable alternatives for evaluating spine mobility in AxSpA patients
Since the relative angle between two sensors placed at the top and bottom of a spine curve mathematically parallels the measure taken at the vertebral bodies on plain film radiographs, it is logical that these measures may have a higher criterion-concurrent validity than tape measures that curve along the back at the static end range of motion (RoM)
Summary
Limitations in spinal mobility are a characteristic feature of Axial Spondyloarthritis. Lumbar spine angles measured with inclinometers or accelerometers have previously reported excellent accuracy (≤ 1° RMS error) [14] and reliability (ICC = 0.964 and r = 0.91 respectively) [15, 16]. These sensors are routinely used in biomechanics studies to quantify spine angles when tasks are relatively static (e.g. office and automotive seating studies) and line of sight issues preclude the use of optoelectrical motion capture systems [17, 18]. Since the relative angle between two sensors placed at the top and bottom of a spine curve mathematically parallels the measure taken at the vertebral bodies on plain film radiographs, it is logical that these measures may have a higher criterion-concurrent validity than tape measures that curve along the back at the static end RoM
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