Ignacio Bermejo Bosch*; Javier Andrade Celdrán; María Francisca Peydro de Moya; Salvador Pitarch Corresa; José Montero Vilela; Helios de Rosario Martínez
Instituto de Biomecánica (IBV). Universitat Politècnica de València. Edificio 9C. Camino de Vera s/n (46022) Valencia. Spain
* IBV’s Healhcare Technology Group, CIBER in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN)
The cervical whiplash syndrome caused by traffic accidents has a high incidence in Spain and, since there are no effective diagnostic tools, it is a controversial condition. This situation results in high personal and economic costs in nowadays society. Against this background, Instituto de Biomecánica (IBV) has developed WAAS/IBV. More than 40 years of experience in biomechanical assessment have allowed the IBV to develop this objective, quick, simple and cost-effective biomechanical assessment system for the evaluation of the cervical whiplash syndrome caused by traffic accidents, based on scientifically validated methodologies.
The cervical whiplash syndrome involves high social and economic costs because of its high incidence and the difficulty in objectively assessing its impact on patients. Most accidents happen at low intensity and, therefore, cervical whiplash syndrome occurs in most of them, . The controversy associated with the assessment of whiplash syndrome is due to the fact that its progression is often torpid and prone to chronicity, and it depends on psychosocial factors. These circumstances, together with the suspicion of malingering, lead to situations of distrust among the actors involved,,,.
The biomechanical assessment of human functions (BA) can objectify the functional impact in people who have suffered a musculoskeletal pathology. Various studies show that the use of BA makes it possible to adapt the treatments and resources to the needs of each patient, and consequently, to treat patients more fairly and to reduce the average costs of the process, .
However, before WAAS/IBV, the BA systems did not meet the requirements of the traffic accident sector. There were large assessment laboratories that involved very high costs, or economic systems without the technical, clinical and scientific guarantees necessary to use them for the cervical whiplash syndrome. For this reason, the IBV took on the challenge of developing a method that meets all the quality standards through a measurement procedure appropriate for traffic accidents.
OBJECTIVES OF WAAS/IBV
The objective of WAAS/IBV is to offer an objective method for assessing the function of the cervical spine in traffic accident victims in order to make fair decisions on the treatment and the compensation for the patients.
WAAS/IBV is based on the IBV experience of more than 40 years in biomechanical assessment and on all the knowledge generated throughout the development of the NedCervical/IBV system. Thus, we have succeeded in developing a functional assessment system for the cervical spine that meets the needs of the treatment and assessment of traffic accidents: objectivity, simplicity, portability, reliability and validity.
DESCRIPTION OF WAAS/IBV
WAAS/IBV is a biomechanical assessment system for the cervical spine that generates objective information that cannot be manipulated, and which makes it possible to determine:
♦ Patient’s function. WAAS/IBV offers a quantitative and objective assessment of the individual’s function. To do this, it generates assessment indices that allow the user to evaluate the degree of functional limitation caused by the cervical whiplash syndrome.
♦ Patient’s cooperation. WAAS/IBV classifies patients into cooperative and non-cooperative using algorithms and specific databases of traffic accident victims.
The most relevant aspects of the WAAS/IBV system are described below:
Sensors and instrumentation
The instrumentation is based on two IMUs (Inertial Monitoring Unit) that analyze the movement of the cervical spine (Figure 1). Each IMU calculates its orientation with an accuracy of 0.7ѻ based on the fusion of the data obtained by the three sensors included (magnetometer, gyroscope and accelerometer).
Figure 1. Example of instrumentation with an inertial sensor.
To ensure the reproducibility of the measurements and to minimize the variability generated by both the evaluator and the patient, special care was taken when defining a controlled measurement protocol. The aspects considered include the patient instrumentation, the recording of the reference position, and the instructions to perform the tests.
The measurement protocol is that developed for the NedCervical/IBV system. This protocol already proved its reproducibility and validity in the article by Baydal et al. (2011) in the Clinical of Biomechanics journal. This protocol is based on a test to analyze the maximum motion limits and a functional test that involves a dual task (Figure 2):
Figure 2. Measurement protocol of WAAS/IBV according to the proposal by Baydal et al. (2011).
Biomechanical assessment systems require a database (DB) to generate reference values in order to assess whether the subjects’ function is altered or whether they have cooperated during the test.
WAAS/IBV is the only system on the market that has its own and validated DBs of healthy subjects, pathological subjects and malingerers. The DB is segmented by homogeneous age groups from 18 to 70 years with equal number of men and women. The group of pathological subjects consists of people who were diagnosed with post-traumatic neck pain caused by a traffic accident. The group of malingerers is made up of individuals who had this pathology and are asked to reproduce the functional limitation.
The data processing performed by WAAS/IBV makes it possible to reduce the usual problems of commercial inertial sensors, such as "drift" and electromagnetic disturbances. The high reproducibility obtained in the validation studies shows that the algorithms to calculate the variables and the filters developed are highly effective.
WAAS/IBV obtains the kinematics of the cervical spine in flexion-extension, lateral flexion and rotation. After various statistical analyses, the parameters that allowed us to significantly distinguish the behaviors of the subjects were selected. These parameters chosen include motion ranges, velocities, accelerations, repeatability, coherence and movement harmony, among other parameters.
We generated classification algorithms that facilitate the interpretation of the WAAS/IBV results based on the DB of healthy subjects, pathological subjects and non-cooperative subjects. Thus, WAAS/IBV automatically generates the following three global results:
♦ Mobility Index. The mobility of the subject is normal or altered.
♦ Velocity Index. The speed of the subject’s movement is normal or altered.
♦ Collaboration pattern. The subject has cooperated during the test and made an effort consistent with their ability, or the subject has not cooperated during the test.
Software application and reports
The WAAS/IBV computer application was developed to facilitate the work of the professionals and to guarantee that both the application of the methodology and the results interpretation are correct.
To achieve our objective, the software guides the user throughout the process and automatically provides the results of the assessment in real time (Figure 3). In addition, once the assessment is completed, WAAS/IBV can generate automatic reports in word and pdf format to speed up the work of the healthcare professional.
Figure 3. Screen of the WAAS/IBV software.
The IBV has developed specific training to use the WAAS/IBV software and to clinically interpret the information that it provides. This training is mandatory and guarantees that the users will perform the protocol properly and that no mistakes will alter the results.
ADVANTAGES OF WAAS/IBV
♦ In less than 12 minutes, a WAAS/IBV test can be performed and an automatic report is obtained. The reports are specially designed to allow the professional to devote time to what really matters: the patients.
♦ The professional training, the software and the assessment indices facilitate the use of WAAS/IBV and the interpretation of the information.
♦ Scientific validity. WAAS/IBV has proven its reliability and validity in the assessment of body damage in the cervical whiplash syndrome and avoids data manipulation. In fact, WAAS/IBV is based on highly verified methods like NedCervical/IBV, validation studies were conducted to calculate the sensitivity and specificity of its classification algorithms, it has the medical device CE marking, and it was developed by the main biomechanical research center in Europe with more than 40 years of experience
♦ Cost-effectiveness. WAAS/IBV supports inertial sensors. This technological change considerably reduces the price compared with laboratories based on photogrammetry cameras, keeps the accuracy required, and provides portability to the system.
WAAS/IBV is the only system on the market – objective, agile, simple and cost-effective – that guarantees a correct assessment of the cervical whiplash syndrome through a scientifically validated methodology specifically designed for traffic accidents.
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