Factors affecting the thickness of the cervical prevertebral soft tissues.

Lateral cervical spine films of 227 patients examined over 2 years were analyzed to determine the thickness of the soft tissues anterior to C2 through C4. These measurements were correlated with patient age, sex, weight, shoulder width, neck width, and calculated radiographic magnification. We found that only patient weight and age had any statistically significant effect on the soft tissue thickness. A stepwise regression model produced a simple equation for predicting the mean value of the soft tissue thickness (specifically at C3) using the patient's age and weight: C3 width = 3.7 mm-0.02 x age (years) + 0.01 x weight (pounds). Using this formula we determined that weight and age account for 28% of the observed variability in the soft tissue measurements at C3. These relationships were similar at C2 and C4. Interestingly, patient sex and radiographic magnification had no detectable effect on the measured widths.