Predictability of the effects of facet joint infiltration in the degenerate lumbar spine when assessing MRI scans

Abstract

Background: Imaging results are frequently considered as hallmarks of disease by spine surgeons to plan their future treatment strategy. Numerous classification systems have been proposed to quantify or grade lumbar magnetic resonance imaging (MRI) scans and thus objectify imaging findings. The clinical impact of the measured parameters remains, however, unclear. To evaluate the pathological significance of imaging findings in patients with multisegmental degenerative findings, clinicians can perform image-guided local infiltrations to target defined areas such as the facet joints. The aim of the present retrospective study was to evaluate the correlation of MRI facet joint degeneration and spinal stenosis measurements with improvement obtained by image-guided intraarticular facet joint infiltration.

Methods: Fifty MRI scans of patients with chronic lumbar back pain were graded radiologically using a wide range of classification and measurement systems. The reported effect of facet joint injections at the site was recorded, and a comparative analysis performed.

Results: When we allocated patients according to their reported pain relief, 27 showed no improvement (0-30%), 16 reported good improvement (31-75%) and 7 reported excellent improvement (> 75%). MRI features assessed in this study did, however, not show any relevant correlation with reported pain after facet joint infiltration: Values for Kendall's tau ranged from τ = - 0.190 for neuroforaminal stenosis grading as suggested by Lee, to τ = 0.133 for posterior disc height as proposed by Hasegawa.

Conclusion: Despite the trend in evidence-based medicine to provide medical algorithms, our findings underline the continuing need for individualised spine care that, along with imaging techniques or targeted infiltrations, includes diagnostic dimensions such as good patient history and clinical examination to formulate a diagnosis.

Trial registration: ClinicalTrials.gov , NCT03308149 , retrospectively registered October 2017.

Keywords: Facet joint degeneration; Facet joint injection; Lumbar degenerative disease; Lumbar spinal stenosis; MRI.

Conflict of interest statement

Authors’ information

Not applicable.

Ethics approval and consent to participate

Full departmental, institutional and local ethical committee approvals were obtained from the University of Tübingen before commencement of the study (project number 503/2016BO2). No consent to participate was required for this study due to the retrospective character.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

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Figures

Fig. 1

Quantitative measurements: a Sagittal T2, b, c, e, f axial T2 and d sagittal T1 images. a Posterior disc height [21]. b Neuroforaminal antero-posterior distance at the level where the root can be seen to traverse it [22] and c at the level of the intervertebral disc. The blue median arrow shows the sagittal diameter of the dural sac at that level. d Cross-sectional area of the neuroforamen [23], e ligamentous interfacet distance [26] as a line connecting the ventral joint space of the facet joints between the inner surface of the flaval ligaments and f cross-sectional area of the dural sac [–29] at the level of the intervertebral disc. The lateral margins of the dura in the neuroforaminal area were extrapolated from the images above and below

Fig. 2

a Histogram displaying patient age with a peak around 55 years. b Heterogeneous improvement after facet joint infiltration ranging from 0 to 100%, with a median improvement of 30%

Fig. 3

Improvement obtained by infiltration and radiomorphometric measurements described as scatterplots: posterior disc height [21] (a), neuroforaminal width [22] (b), cross-sectional area of the neuroforamen [23] (c), ligamentous interfacet distance [26] (d), cross-sectional area of the spinal canal (e) and sagittal spinal canal diameter [, –57] (f). No relevant correlation could be observed. CSA cross-sectional area, lig. ligamentous, sag. sagittal

Fig. 4

Correlation of observed improvement by infiltrations with qualitative facet joint degeneration and spinal stenosis classifications in the form of heat maps (left column) and boxplots (right column). a Facet joint degeneration (Weishaupt [20]), b neuroforaminal stenosis (Lee [25]) and c spinal stenosis (Schizas [30]). Pain relief obtained by the infiltrations is grouped into three categories: 1, no improvement (below 30%); 2, good (30–74%); and 3, excellent (75–100%) improvement. Colour intensity in the heat maps is shown according to absolute frequencies