New methodology to assess in-vivo quality of motion in cervical spine.

Abstract Background Understanding the kinematics of the spine in the interaction with an implanted device is of utmost importance from a clinical point of view. The characterization of the biomechanical movement of the spine occurring at each functional unit is a difficult task as it involves the measurement of complex patterns of motion while identifying more delicate abnormalities that could result in longer-term disease complications. Center of rotation is a biomechanical parameter that represents the ratio between rotation and translation. It has been recognized as a valid and reliable parameter to identify any delicate abnormal movement of the spine as opposed to the range of motion. However, center of rotation is still not widely used in clinical practice. Methods In this study, an algorithm intended to easily identify an imbalanced spine through the center of rotation calculation and a new parameter called distance to the ellipse is presented. In this new approach the distance to the ellipse is a key parameter which represents the distance of the center of rotation lying outside the ellipse that represents the asymptomatic group, from the ellipse itself. Findings The presented algorithm allows the comparison of pre-op and post-op outcomes, and the rapid identification of cases needing more attention. Interpretation When a comprehensive analysis is required, a dashboard is provided with detailed information for each functional spine unit at each follow-up appointment. It is found that the new approach has the potential to become a new methodology in clinical practice. Level of Evidence: Biomechanical Study.