Reliability and measurement error of sagittal spinal motion parameters in 220 patients with chronic low back pain using a three-dimensional measurement device.
BACKGROUND
A basic premise for any instrument measuring spinal motion is that reliable outcomes can be obtained on a relevant sample under standardized conditions.


OBJECTIVE
The purpose of this study was to assess the overall reliability and measurement error of regional spinal sagittal plane motion in patients with chronic low back pain (LBP), and then to evaluate the influence of body mass index, examiner, gender, stability of pain, and pain distribution on reliability and measurement error.


METHODS
This study comprises a test-retest design separated by 7 to 14 days.


METHODS
The patient cohort consisted of 220 individuals with chronic LBP.


METHODS
Kinematics of the lumbar spine were sampled during standardized spinal extension-flexion testing using a 6-df instrumented spatial linkage system.


METHODS
Test-retest reliability and measurement error were evaluated using interclass correlation coefficients (ICC(1,1)) and Bland-Altman limits of agreement (LOAs).


RESULTS
The overall test-retest reliability (ICC(1,1)) for various motion parameters ranged from 0.51 to 0.70, and relatively wide LOAs were observed for all parameters. Reliability measures in patient subgroups (ICC(1,1)) ranged between 0.34 and 0.77. In general, greater (ICC(1,1)) coefficients and smaller LOAs were found in subgroups with patients examined by the same examiner, patients with a stable pain level, patients with a body mass index less than below 30 kg/m(2), patients who were men, and patients in the Quebec Task Force classifications Group 1.


CONCLUSIONS
This study shows that sagittal plane kinematic data from patients with chronic LBP may be sufficiently reliable in measurements of groups of patients. However, because of the large LOAs, this test procedure appears unusable at the individual patient level. Furthermore, reliability and measurement error varies substantially among subgroups of patients.
Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Campusvej 55, DK-5230, Odense M, Denmark. Electronic address: rmieritz@health.sdu.dk.
Rune M
RM
Mieritz
Wolfe Harris Center for Clinical Studies, Northwestern Health Sciences University, 2501 W. 84th St, Bloomington, MN 55431, USA; Nordic Institute of Chiropractic and Clinical Biomechanics, University of Southern Denmark, Campusvej 55, DK-5230, Odense M, Denmark.
Gert
G
Bronfort
Research Centre for the Working Environment, Lersø Parkalle 105, DK-2100, Copenhagen, Denmark.
Markus D
MD
Jakobsen
Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Campusvej 55, DK-5230, Odense M, Denmark.
Per
P
Aagaard
Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Campusvej 55, DK-5230, Odense M, Denmark; Nordic Institute of Chiropractic and Clinical Biomechanics, University of Southern Denmark, Campusvej 55, DK-5230, Odense M, Denmark.
Jan
J
Hartvigsen
D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009068:Movement; D009460:Neurologic Examination / Q000295:instrumentation / Q000592:standards; D011199:Potentiometry / Q000295:instrumentation* / Q000592:standards; D016059:Range of Motion, Articular; D012016:Reference Values; D015203:Reproducibility of Results; D013131:Spine / Q000503:physiopathology*
Biomechanics; Device; Functional evaluation; Instrument; Low back pain; Measurement; Motion analysis; Reliability; Reproducibility; Spine