Objective: To assess differences in motion and areas of motion when performing cervical retraction in two different sitting positions.

Design: Biomechanical analysis. Setting: University Hospital. Patients: Fourteen healthy adult women aged 30-48 years, without pain and without history of treatment for pain in the past year.

Intervention: The subjects performed seven trials of full active protraction and retraction in two sitting positions, one with a specific lumbar support, and one without. In the less restrained position, the subjects were instructed to sit in a self-selected comfortable position with contact only against the thoracic back rest. In the more restrained position, the subjects were instructed to strictly keep contact with the thoracic and lumbar back rests of the chair.

Main Outcome Measures: 14 reflective markers were used to measure total anterior/posterior and vertical displacement during active protraction and retraction, as well as the amount of motion at four different levels: cervical (neck to C7), cervicothoracic (C7 to T4), middle thoracic (C4 to apex of thoracic kyphosis), and lower thoracic (apex of thoracic kyphosis to T12).

Main results: The difference in total head excursion anterior posterior direction between the two sitting positions was statistically significant (p = 0.005). There were no statistically significant differences between the sitting positions for anterior posterior spinal unit displacements. The cervical unit contributed to anterior posterior total head excursion with 62% in the more restrained and 58% in the less restrained position, the cervicothoracic unit with 28% and 29%, the middle thoracic unit with 7% and 8% and the lower thoracic with 3% and 5%, respectively.

Protraction was significantly smaller in absolute values in the more restrained position compared with the less restrained position (p = 0.003). The lower thoracic unit protraction was significantly smaller in relative values in the more restrained position as compared with the less restrained position (p = 0.009). There were no statistically significant differences in retraction amplitude between the different sitting positions. Resting head posture, i.e. retraction, was 45% of total head excursion in the more restrained and 44% in the less restrained position.

Conclusion: In this study, a large proportion of total head excursion in the sagittal plane was shown to arise from the thoracic region, in healthy women aged between 30 and 48 years. A high correlation between total head excursion and cervicothoracic unitdisplacements was demonstrated, as well as spinal alignment in the sitting position determining the range of active sagittal head excursions. Furthermore, thoracic end range positions influenced sagittal head excursion and limited total head excursion.

Comments: This study demonstrates the extensive involvement of nearly the entire spine when performing seated cervical sagittal plane motions, as even the lower thoracic spine contributed up to 5% of the motion. When subjects were restrained in an attempt to prevent thoracic motion this resulted in a significant decrease in the total cervical movement. Thus, the present McKenzie procedure of performing protrusion and retraction which allows the thoracic spine to freely contribute appears to be the best way of achieving end range.

Patients often demonstrate some concern about feeling symptoms distal to the neck when performing retraction, often in the scapular region. This may be referred pain from the cervical spine, or due to motion in that specific area.

This paper also demonstrates the decrease in end range protrusion range of motion with use of lumbar support. This finding supports the common use of a lumbar roll in sitting for patients with posterior derangement or postural syndrome, with a goal of avoiding sustained end range protraction. We must be careful not to extrapolate these results to all of our patients, as the subjects included only middle-aged, asymptomatic women with no significant history of pain. Testing of a symptomatic population might show different results.

Cervical: Anatomical, physiological, and pain studies