Computerized Motion Diagnostic Imaging (CMDI) Systems (Motion Diagnostics Laboratories, Hauppauge, NY) employ a dual-inclinometer and/or a long-arm goniometer and computer software to track range of motion and can allegedly estimate the percentage of impairment of the spine. However, there is a lack of evidence in the published peer-reviewed medical literature to support the usefulness of these devices in improving clinical outcomes.
Piche and colleagues (2007) developed a measurement method that could be implemented in chiropractic for the evaluation of angular and translational intervertebral motion of the cervical spine. Flexion-extension radiographs were digitized with a scanner at a ratio of 1:1 and imported into a software, allowing segmental motion measurements. The measurements were obtained by selecting the most antero-inferior point and the most postero-inferior point of a vertebral body (anterior and posterior arch, respectively, for C1), with the origin of the reference frame set at the most postero-inferior point of the vertebral body below. The same procedure was performed for both the flexion and extension radiographs, and the coordinates of the 2 points were used to calculate the angular movement and the translation between the 2 vertebrae. These researchers reported that this method provided a measure of intervertebral angular and translational movement. It uses a different reference frame for each joint instead of the same reference frame for all joints and thus provides a measure of motion in the plane of each articulation. The calculated values obtained are comparable to other studies on intervertebral motion and support further development to validate the method. The authors concluded that the present study proposes a computerized procedure to evaluate intervertebral motion of the cervical spine. This procedure needs to be validated with a reliability study but could provide a valuable tool for doctors of chiropractic and further spinal research.
Harrison et al (2008) examined the accuracy in measuring the pelvic orientations of a phantom model (a mannequin was fixed on a rotating platform) using the PosturePrint method. For a set of 3 photographs (left lateral, anterior to posterior, right lateral) of each position, the mannequin pelvis was placed in 68 different postures on a stand, 61 cm from a wall, in front of a digital camera. The camera was at 83.8 cm in height and at 3.35 m from a calibrated wall grid. Mannequin postures were in 5 degrees of freedom: lateral translation (Tx), lateral flexion (Rz), axial rotation (Ry), flexion-extension (Rx), and anterior-posterior translation (Tz). Average errors were the differences of the positioned postures to the PosturePrint computed values. Mean and SD of computational errors for rotation displacements were Rx = 0.5 degrees +/- 0.8 degrees , Ry = 1.3 degrees +/- 0.8 degrees , and Rz = 0.5 degrees +/- 0.3 degrees , and for translation, Tz = 1.2 +/- 0.6 mm and Tx = 0.9 +/- 0.5 mm. The authors concluded that the PosturePrint system allowed for accurate postural measurement of rotations and translations of a mannequin pelvis. The next step in evaluation of this product would be a reliability study on human subjects.
MacDonald and colleagues (2010) stated that previous research has quantified cervical spine motion with conventional measurement techniques (e.g., cadaveric studies, motion capture systems, and fluoroscopy), but these techniques were not designed to accurately measure three-dimensional (3-D) dynamic cervical spine motion under in- vivo conditions. The purposes of this study were to characterize the accuracy of model-based tracking for measuring 3-D dynamic cervical spine kinematics and to demonstrate its in-vivo application. The accuracy of model-based tracking for measuring cervical spine motion was determined in an in-vitro experiment. Tantalum beads were implanted into the vertebrae of an ovine specimen, and biplane X-ray images were acquired as the specimen's neck was manually moved through neck extension and axial neck rotation. The 3-D position and orientation of each cervical vertebra were determined from the biplane X-ray images using model-based tracking. For comparison, the position and orientation of each vertebra were also determined by tracking the position of the implanted beads with dynamic radio-stereometric analysis. To demonstrate in-vivo application of this technique, biplane X-ray images were acquired as a human subject performed 2 motion tasks: neck extension and axial neck rotation. The positions and orientations of each cervical vertebra were determined with model-based tracking. Cervical spine motion was reported with standard kinematic descriptions of translation and rotation. The in-vitro validation demonstrated that model-based tracking is accurate to within +/- 0.6 mm and +/- 0.6 degrees for measuring cervical spine motion. For the in-vivo application, there were significant rotations about all 3 anatomical axes for both the neck extension and axial neck rotation motion tasks. The authors concluded that model-based tracking is an accurate technique for measuring in-vivo, 3-D, dynamic cervical spine motion. They noted that these preliminary data acquired using this technique are in agreement with previous studies. It is anticipated that this experimental approach will enhance the understanding of cervical spine motion under normal and pathologic conditions.
Mieritz et al (2012) reviewed the literature on reproducibility (reliability and/or measurement error) of 3-D regional lumbar motion measurement systems. Electronic searches were performed in PubMed, Cumulative Index of the Nursing and Allied Health Literature, Embase, and Mantis databases. To be included, original studies had to report on the reproducibility of a 3-D computerized regional lumbar spinal motion analysis system in human subjects. A detailed checklist was developed based on guidelines for reporting reliability and agreement studies, the standards for reporting of diagnostic accuracy, and quality assessment of diagnostic accuracy studies and used for data extraction and quality assessmentt. The checklist consisted of descriptive items divided into 4 domains: (i) study population, (ii) testing circumstances, (iii) equipment, and (iv) data analysis and presentation. The descriptive items were used as foundation for the quality assessment reflecting the reporting level of the included articles. A total of 15 articles were included in this study. These researchers found incomplete reporting in 1 or more domains in all articles. A varying amount of measurement error was reported in 8 of the 15 articles. Because of incomplete reporting, these reliability and measurement error estimates are difficult to interpret. The authors concluded that the current literature on the reliability and measurement error of measures created by regional 3-D spinal instruments contained uncertainties especially in relevant clinical populations. There is uncertainty with respect to the degree that repeated measurements by 3-D regional spinal motion instruments are reproducible. However, limited to the studies where reliability estimates were provided, most instruments used under standardized conditions may be considered reliable enough to be used for research purposes on the group level, but it is uncertain if they can be used on the individual patient level.