Cervical spine stenosis measures in normal subjects

Ryan T. Tierney, Catherine Maldjian, Carl G. Mattacola, Stephen J. Straub, Michael R. Sitler

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


Objective: To compare 2 methods of determining cervical spinal stenosis (Torg ratio, space available for the cord [SAC]); determine which of the components of the Torg ratio and the SAC account for more of the variability in the measures; and present standardized SAC values for normal subjects using magnetic resonance imaging (MRI). Design and Setting: The research design consisted of a posttest-only, comparison-group design. The independent variable was method of measurement (Torg ratio and SAC). The dependent variables were Torg ratio and SAC scores. Subjects: Fourteen men (age = 24.4 ± 2.5 years, height = 181.0 ± 5.8 cm, weight = 90 ± 13.5 kg) participated in this study. The C3 to C7 vertebrae were examined in each subject (n = 70). Measurements: The Torg ratio was determined by dividing the sagittal spinal-canal diameter by the corresponding sagittal vertebral-body diameter. The SAC was determined by subtracting the sagittal spinal-cord diameter from the corresponding sagittal spinal-canal diameter. The Torg ratio and SAC were measured in millimeters. Results: The SAC ranged from 2.5 to 10.4 mm and was greatest at C7 in 71% (10 of 14) of the subjects. The SAC was least at C3 or C5 in 71% (10 of 14) of the subjects. A Pearson product moment correlation revealed a significant relationship between the Torg ratio and SAC (r = .53, P < .01). Regression analyses revealed the vertebral body (r2 = .58) accounted for more variability in the Torg ratio than the spinal canal (r2 = .48). Also, the spinal canal (r2 = .66) accounted for more variability in the SAC than the spinal cord (r2 = .23). Conclusions: The SAC measure relies more on the spinal canal compared with the Torg ratio and, therefore, may be a more effective indicator of spinal stenosis. This is relevant clinically because neurologic injury related to stenosis is a function of the spinal canal and the spinal cord (not the vertebral body). Further research must be done, however, to validate the SAC measure.

Original languageEnglish (US)
Pages (from-to)190-193
Number of pages4
JournalJournal of Athletic Training
Issue number2
StatePublished - 2002
Externally publishedYes


  • MRI
  • Spinal cord
  • Spinal stenosis

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation


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