A radiographic analysis of the influence of initial neck posture on cervical segmental movement at end-range extension in asymptomatic subjects.

In the management of neck pain disorders, McKenzie recommends performing neck extension exercises from a fully neck retracted position in order to achieve a maximum range of lower cervical extension. However, no study has investigated the impact of pre-positioning the neck prior to the extension exercise. This study compared end-range sagittal cervical segmental rotation and translation from three starting positions: the neck in neutral (Ex), retraction (Ret-Ex) and protraction (Pro-Ex). Twenty asymptomatic healthy volunteers were recruited. Lateral radiographs were taken in neutral and at each of the three end-range extension positions and differences in sagittal rotation angles and translation from the neck neutral posture were calculated at each segment. The results indicated that there was a significant difference in the pattern of the sagittal segmental rotation (P < 0.001) but no difference in summed rotations (total extension) between the three conditions (P > 0.05). Pro-Ex generated significantly (P < 0.05) greater extension range at C1-2 and Ret-Ex produced significantly (P < 0.05) greater extension range at C6-7 than alternate conditions. In contrast, there was no significant difference in segmental translation values between the three conditions (P > 0.05). These results indicate initial neck positions can influence cervical segmental extension range at C1-2 and C6-7.