Background context: The Torg ratio is used as a universal indicator of cervical canal stenosis despite reports of differences between gender and race. Normal values of this ratio have been established for subjects of different ethnicity, but the differences between genders and race have not been critically compared.
Purpose: To establish normal cervical spinal dimensions and analyze the differences observed between men and women, and between reports using subjects of different ethnicity.
Study design/setting: Observational.
Patient sample: Forty men and 40 women of Chinese descent with no history or symptoms of neck pathology selected from patients presenting to the Emergency Department for foreign body ingestion.
Outcome measures: Measurements of the sagittal developmental diameter (SDD) and vertebral body diameter (VB) on the lateral cervical radiograph with calculation of SDD/VB (Torg ratio).
Methods: Lateral radiographs of the cervical spine were taken in a standardized manner with a 180-cm film-to-tube distance. Comparison was made between genders in the study population and with previous reports on subjects of different ethnicity.
Results: The SDD was narrowest at the C4 level in both men and women. Women had smaller SDDs at all levels of the cervical spine. Female VBs were of sizes similar to their corresponding SDDs, whereas men had larger VBs. This resulted in small Torg ratios in men averaging 0.87. Comparison with previous reports demonstrated consistent variation in the SDD, which increased serially from Japanese, through Chinese and Indian, to white subjects. The relationship of VB to the corresponding SDD displayed wide variation between reports. This resulted in Torg ratios differing not only between subjects of different ethnicity but also between genders within the same population.
Conclusions: The Torg ratio is not a consistent indicator of the SDD and may not be used to reliably identify the presence of cervical canal stenosis.