Denis classification is used to asses -

Ans. is 'a' i.e., Stability of spine Denis Classification for Spinal stability:* In assessing spinal stability, three structural elementsmust be considered:i) The posterior osseoligamentouscomplex (or posterior column) consisting of thepedicles, facet joints, posterior bony arch, interspinousand supraspinous ligaments;ii) The middle column comprising the posterior half of the vertebralbody, the posterior part of the intervertebral disc andthe posterior longitudinal ligament; andiii) The anteriorcolumn composed of the anterior half of the vertebralbody, the anterior part of the intervertebral disc andthe anterior longitudinal ligament.* Allfractures involving the middle column and at least oneother column should be regarded as unstable.* Fortunately,only 10 per cent of spinal fractures are unstableand less than 5 per cent are associated with corddamage.