Instrumental assessment of cervical spine mobility in patients with whiplash injury for forensic application

Introduction: Residuals of whiplash injury (W.I.) represent one of most common causes of compensation claims in forensic medicine. Until 2012, clinical assessment was deemed sufficient to ascertain the reduction of neck mobility. A new law (n. 27 year 2012/3-ter;3-quarter) has established that in order to assess adamage it is now necessary to demonstrate it both with clinical and instrumental methods. As a consequence, the mere clinical assessment ofW.I. is not anymore accepted by the insurance companies. Sowe need an instrumental evaluationmethod, that should be non invasive, easy to perform, and guarantees a high reproducibility [2]. In forensic medicine there is also another problem: since the assessment of neck mobility has an effect on the economic compensation, the patients may be inclined to demonstrate a deeper damage. So the test should not rely on voluntary actions and should provide some indication of reliability. In our intention this can be achieved by quantifying the passive range of motion (PROM) and by analyzing its variability. Methods: An opto-electronic stereo-photogrammetric system (POSEIDON system BTS, Italy) was employed for obtaining the relative motion between head and upper trunk. Three retroreflective markers were applied to the temples and nasion respectively, and three on acromions and apex of sternum (six markers in total). Only 3-TV camera was sufficient to obtain a reliable acquisition of kinematics at 60 frames/s. While specific physical maneuvers were performed on the subject, the system computed the markers trajectories, the main rotation angles of the head in relation to the trunk (flexion–extension, lateral bending, axial rotation), speed and acceleration. The automatic output was a clinical report that integrates all data related to the morphology and kinematics of the analyzed body segment. Our preliminary study was carried out on 6 healthy, non symptomatic subjects and 6 subjects with history of W.I., whose evaluation was finalized to the insurance assessment. The test was performed in two steps: (1) pure clinical assessment; (2) instrumental assessment. In this second step the subjects were seated on a armchair, in front of the TV-cameras, while the examiner performed the maneuvers to test their PROM inflexion–extension, lateral bending and rotation of the head/neck. Each movement was repeated at least 6 times. The results were compared to age matched control data. Results: Our preliminary data collected on the healthy, asymptomatic subjectsmatched verywellwith data provided in literature [1,3]. Subjects who had residuals ofW.I., exhibited a lower range of motion and some asymmetries that well correlated to the reported symptoms. More interestingly, the standard deviation (SD) of the measured PROM ranged from 1.6◦ to 2.6◦ in the subjects that had no interest in the insurance compensation, and ranged from 3.5◦ to 4.0◦ in symptomatic subjects that were assessed for insurance purposes. In one of them, whose attempt to overstate his reduced mobility was evident clinically, the SD was 8.1. Another interesting observation was that left/right asymmetry for lateral bending and axial rotationwas in the range 0–3◦ in the healthy subjects and 6–21◦ in the W.I. subjects. Discussion: The analysis system adopted allows us to perform an instrumental non invasive, high reliability, easy to use assessment, does not require a large space around the subject and needs only few minutes to produce the written report. When comparing the results of the pure clinical method with results of the instrumental method, the higher resolution of the instrumental method proved to be a clear advantage and allowed us to better understand the clinical condition. It is our impression that this instrumental method offers a major possibility to recognize the simulation. Our aims isnowtocollect a largedatabaseof control subjects, in relation to age and sex, in order to obtain a reference formotion assessment in subjects with history of W.I.