Posterior distraction forces of the posterior longitudinal ligament stratified according to vertebral level

R. Shane Tubbs, Marios Loukas, April Phantana-Angkool, Mohammadali Mohajel Shoja, Mohammad R. Ardalan, Ghaffar Shokouhi, W. Jerry Oakes

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Introduction: Although considered significant in resisting midline intervertebral disc herniation, the posterior longitudinal ligament (PLL) has had relatively few studies performed regarding its morphology and function. We performed the present experiment to discern the amount of posterior tensile force necessary to disrupt the PLL at each vertebral level. Materials and methods: Twenty-five adult cadavers underwent laminectomies of vertebrae C1 to S1. After removal of the spinal cord, nerve roots, and dura mater, the PLL was identified for each vertebral level and a steel wire placed around its waist in the midline and a tensile gauge attached and posterior tension applied perpendicular to the spine. Forces necessary to failure of the PLL were noted for each vertebral level. Results: The PLL was found to be stronger in the thoracic spine compared to the cervical and lumbar vertebrae (P < 0.05). Dividing the vertebral levels in this manner, we found an average posterior distraction force to failure of 48.3 N in the cervical region, 61.3 N in the thoracic region, and 48.8 N in the lumbar region. Conclusions: These findings support clinical observations that thoracic disc herniation is rare. We hypothesize that this clinical observation is partially due to a stronger PLL in the thoracic spine.

Original languageEnglish (US)
Pages (from-to)667-670
Number of pages4
JournalSurgical and Radiologic Anatomy
Issue number8
StatePublished - Dec 1 2007
Externally publishedYes


  • Anatomy
  • Intervertebral disc herniation
  • Pathology
  • Posterior longitudinal ligament
  • Spine

ASJC Scopus subject areas

  • Anatomy
  • Radiology Nuclear Medicine and imaging
  • Radiological and Ultrasound Technology


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