Noninvasive, accurate and reliable measurement of the cervical spine motion with a 3D real-time ultrasound motion analyser.

Aims: The kinematic analysis of cervical spine motion is important to assess objectively the effects of therapeutic interventions. In this study, precision and reliability of a 3D ultrasound motion analyser was determined. Using this tool the physiologic range of movement of healthy volunteers was assessed. The aim was to test the clinical practicability of this system. Methods: The active and passive cervical spine range of motion of 20 healthy volunteers with a mean age of 23 years (range 19-28 years) was determined using a CMS 3D ultrasound realtime motion analyser (Zebris Medizintechnik, Tubingen, Germany). Precision was assessed by comparison with a precision goniometer. Two observers determined the inter-rater and retest reliability and the Pearson correlation coefficients were calculated. Results: The maximum measurement difference between CMS and precision goniometer was 0.6 degrees. Inter-rater- and retest reliability correlated significantly (0.84 < r < 0.96, p < 0.001). The range of motion found by the CMS corresponded well with motion values determined using other devices. Conclusions: The range of motion of the cervical spine can be assessed accurately and reliably using a 3D ultrasound motion analyser. The CMS motion analyser is suitable for clinical practice.