Utility of Flexion-Extension Radiographs in Lumbar Spondylolisthesis: A Prospective Study

Prospective cohort study in consecutive patients.

To investigate and compare the use of 2 diagnostic modalities in the evaluation of stability in lumbar spondylolisthesis.

Evaluating potential instability in lumbar spondylolisthesis is significant to its management. Lateral lumbar flexion-extension (FE) radiograph is frequently obtained on the basis of a thought that this forward-backward movement can actually describe hypermobility at the listhetic segment. However, simply comparing standard upright lumbar lateral radiograph (U) with a supine sagittal magnetic resonance image (S) (combined, US), something typically conducted for patients with lumbar spondylolisthesis, may also be used.

This prospective study included a cohort of 68 consecutive patients with lumbar spondylolisthesis seen in the outpatient clinic of a single hospital. The mobility observed in US was compared with that observed in FE. The ability to identify "instability" using US was compared with that using FE. In addition, the relationships between mobility determined using FE or US and sex, age, height, weight, body mass index, primary symptom (with or without back pain), nature of spondylolisthesis (degenerative or isthmic), listhetic segment, slippage grade, and focal disc height were examined.

Overall, the mobility in US was significantly higher than that in FE (7.68 ± 5.34% vs. 4.90 ± 3.82%, t =-3.545, P = 0.001). The ability to identify "instability" on the basis of US was improved compared with that obtained using FE. Female patients demonstrated higher mobility in FE than male patients to a significant degree. Back pain, isthmic spondylolisthesis, and slippage grade also showed some relevance with mobility but without statistical significance.

US may offer an easily available, alternative diagnostic modality in lumbar spondylolisthesis, with the potential of reducing both radiation exposure and costs. Further studies should focus on its influence in clinical decision making.

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