Cervical spine collars are applied in trauma situations to immobilise patients' cervical spines. Whilst movement of the cervical spine following the application of a collar has been well documented, the movement in the cervical spine during the application of a collar has not been. There is universal agreement that C-spine collars should be applied to patients involved in high speed trauma, but there is no consensus as to the best method of application.

The clinical authors have been shown two different techniques on how to apply the C-spine collars in their Advanced Life Support Training (ATLS). One technique is the same as that recommended by the Laerdal Company (Laerdal Medical Ltd, Kent) that manufactures the cervical spine collar that we looked at. The other technique was refined by a Neurosurgeon with an interest in pre-hospital care. In both techniques the subjects' head is immobilised by an assistant whilst the collar is applied.

We aimed to quantify which of these techniques caused the least movement to the cervical spine. There is no evidence in the literature quantifying how much movement in any plane in the unstable cervical spine is safe. Therefore, we worked on the principle: the less movement the better.

The Qualisys Motion Capture System (Qualisys AB, Gothenburg, Sweden) was used to create an environment that would measure movement on the neck during collar application. This system consisted of cameras that were pre-positioned in a set order determined by trial and error initially. These cameras captured reflected infra-red light from markers placed on anatomically defined points on the subject's body. As the position of the cameras was fixed then as the patients moved the markers through space, a software package could deduce the relative movement of the markers to each camera with 6 degrees of freedom (6DOF).

Six healthy volunteers (3 M, 3 F; age 21-29) with no prior neck injuries acted as subjects. The collar was always applied by the same person. Each technique was used 3 times on each subject. To replicate the clinical situation another volunteer would hold the head for each test.

The movements we measured were along the x, y, and z axes, thus acting as an approximation to flexion, extension and rotation occurring at the C-spine during collar application. The average movement in each axis (x, y and z) was 8 degrees, 8 degrees and 5 degrees respectively for both techniques. No further data analysis was attempted on this small data set.

However this pilot study shows that our method enables researchers to reproducibly collect data about cervical spine movement whilst applying a cervical collar.