Radiographic evaluation of ventral instability in lumbar spondylolisthesis: do we need extension radiographs in routine exams?

Abstract

Purpose To determine the usefulness of acquiring extension radiographs for the evaluation of the degree of spondylolisthesis. Methods Routine radiographs of the lumbar spine were retrospectively evaluated in 87 patients (mean-age 63, range 32-86) by two independent radiologists. All patients received radiographs in standing neutral, flexion and extension position. Vertebral body depth, sagittal translational displacement and lordosis angle were measured and slip percentage (SP) was calculated on standing neutral, flexion and extension radiographs. Statistical analysis was performed with a two-sided t test. Inter-and intraobserver reliability was assessed using the kappa-coefficient. Results There was no statistically significant SP-difference between neutral standing and extension images. Ventral instability was diagnosed in 25-34 % (cut-off [8 % SP-difference) for neutral versus flexion comparison. The detection rate of flexion-extension radiographs representing the extremes of motion was lower with 15-22 %. Inter-and intraobserver reliability was good to excellent. Conclusion Slip percentage in routine standing extension radiography ultimately does not differ from that obtained in a static neutral standing view. Extension radiography may therefore be omitted in a routine work-up of ventral instability in lumbar spondylolisthesis.

Dynamic MR in patients affected by neurogenical claudication: technique and results from a single-center experience

“…Radiographs are acquired in dynamic modality with upright anterior-posterior and true lateral neutral-flexion-extension projections [14], but these fail to visualize soft tissues.…”

Image Correlation Between Facet Effusion and Lumbar Instability

“…Low back pain is a common complaint, affecting approximately 84% of the population at some point in their lives. 8 In spite of the technological advances in diagnostic methods, the identification of the specific cause of low back pain can be costly. 1 It is believed that segmental instability is one of the main causes of pain.…”

“…5,21 Although several studies question its reproducibility and validation, traditionally, the most accepted method for evaluating anteroposterior lumbar instability is the dynamic X-ray (flexion and maximum extension). 1,3,4,[8][9][10][11]14,22 The amount of translation and rotation in the sagittal plane is calculated and compared with normality variations. 1 White and Panjabi defined radiographic instability as translation in the sagittal plane greater than 4.5 mm or greater than 15% of the vertebral body, as well as rotation in the sagittal plane greater than 15º in segments L1-L2, L2-L3, and L3-L4, greater than 20º in segment L4-L5, and greater than 25º in segment L5-S1.…”

“…1,4,6 The biomechanical concept of segmental stability is widely known, but the radiological definition of instability is under discussion. 2,7,8 Several methods have been developed over the last few decades to assess the presence of instability radiographically. 8 In this context, magnetic resonance imaging (MRI) of the lumbar spine, currently more available, has become a routine study in the evaluation of patients with low back pain.…”

“…2,7,8 Several methods have been developed over the last few decades to assess the presence of instability radiographically. 8 In this context, magnetic resonance imaging (MRI) of the lumbar spine, currently more available, has become a routine study in the evaluation of patients with low back pain. 5,9,10 This modality provides, among other information, important data about disc degeneration and compression of the neural elements.…”