Which radiographic sign indicates instability with a pars or spondylolisthesis at the L5 level?

Prepare for the Bodalia Exam with engaging quiz questions. Explore multiple choice questions, hints, and explanations to boost your readiness. Aim for success!

Multiple Choice

Which radiographic sign indicates instability with a pars or spondylolisthesis at the L5 level?

Instability from a pars defect or spondylolisthesis at the lumbosacral junction shows up on X‑rays as a change in the shape of the involved vertebral body due to abnormal tilt and forward translation. The best indicator here is the trapezoidal shape of the L5 vertebral body. When L5 slips forward (and often rotates relative to S1), its normally rectangular profile becomes irregular, giving a trapezoid silhouette on the viewing plane. That trapezoidal appearance directly reflects the angular deformity and translational motion associated with instability at this level. Other signs described are not specific to this instability pattern. Rounding of the sacral base can occur but doesn’t specifically signal instability at L5. Narrowed foramina points to foraminal narrowing, not to dynamic instability. Widened pedicles aren’t the typical hallmark of this particular instability. The trapezoidal silhouette of L5 most clearly conveys the abnormal motion characteristic of pars/interarticularis defects with listhesis.

Instability from a pars defect or spondylolisthesis at the lumbosacral junction shows up on X‑rays as a change in the shape of the involved vertebral body due to abnormal tilt and forward translation. The best indicator here is the trapezoidal shape of the L5 vertebral body. When L5 slips forward (and often rotates relative to S1), its normally rectangular profile becomes irregular, giving a trapezoid silhouette on the viewing plane. That trapezoidal appearance directly reflects the angular deformity and translational motion associated with instability at this level.

Other signs described are not specific to this instability pattern. Rounding of the sacral base can occur but doesn’t specifically signal instability at L5. Narrowed foramina points to foraminal narrowing, not to dynamic instability. Widened pedicles aren’t the typical hallmark of this particular instability. The trapezoidal silhouette of L5 most clearly conveys the abnormal motion characteristic of pars/interarticularis defects with listhesis.

More practice questions