INTRASUBJECT RELIABILITY OF SPINAL RANGE OF MOTION AND VELOCITY DETERMINED BY VIDEO MOTION ANALYSIS

Background and Purpose. The purpose of this study was to investigate t he repeatability of spinal range of motion (ROM) and movement velocity measurements of patients with chronic low back pain, using a two-dime nsional motion analysis system. This apparatus uses reflective markers placed on anatomical landmarks and video digitization to derive ROM m easurements from three segments of the spine and associated velocities through the respective ROMs. Subjects. Forty-two patients with chroni c LBP underwent ROM and movement velocity testing. Methods. Each subje ct was tested twice without removal of the markers to minimize error c ontribution from differences in marker placement. Results. Results ind icated that both the ROM measures and the velocity measures were highl y repeatable intra-class correlations for the ROM measures ranged from .77 to .96. Velocity measures were also reliable, with intraclass cor relation coefficients ranging from .75 to .97 Conclusion and Discussio n. Overall, the results seem to indicate that the video motion analysi s system used in this system yields repeatable ROM and velocity measur es on a clinical population. In practice, however, the measures may re flect greater errors due to the need of examiners to relocate markers at different testing sessions. These system also offer distinct advant ages over other means of obtaining ROM and velocity measures. The resu lts of this study indicate that these measures may be obtained without undue concern for measurement artifact due to the instrumentation rel iability.