Coronal Spine Imbalance May Separate Degenerative from Isthmic Spondylolisthesis

A retrospective study of 150 patients with single-level lumbar spondylolisthesis suggests that the shape of the spine in the frontal plane may help tell two common forms of the condition apart. Their analysis, published in Frontiers in Medicine, found that degenerative cases showed measurably greater coronal imbalance and segmental wedging than isthmic cases.

The cohort consisted of patients whose symptoms persisted after at least three months of conservative treatment. Using anteroposterior radiographs, the team measured a battery of coronal parameters: clavicle angle, T1 tilt, pelvic coronal tilt, segmental wedge angle, spondylolisthesis vertebral tilt angle, lateral vertebral translation, lumbar Cobb angle, lumbar coronal balance, and the deviation of the C7 plumb line from the central sacral vertical line. They then compared demographic, clinical, and radiographic variables between the two diagnostic groups.

The groups differed in body habitus as well as radiographically.

Three radiographic measures were significantly greater in the degenerative group. The segmental wedge angle averaged 2.7 plus or minus 1.9 degrees versus 1.8 plus or minus 1.7 degrees in the isthmic group (P = 0.005). The spondylolisthesis vertebral tilt angle averaged 4.7 plus or minus 3.6 degrees versus 3.5 plus or minus 2.4 degrees (P = 0.016). Lumbar coronal balance, a measure of sideways deviation, averaged 10 plus or minus 7 millimeters versus 5 plus or minus 3 millimeters (P < 0.001).

In a multivariable logistic regression, two of these parameters independently distinguished degenerative from isthmic spondylolisthesis: the segmental wedge angle and lumbar coronal balance. This suggests that when a slipped vertebra also wedges the disc space and pulls the lumbar spine off its frontal-plane axis, degenerative disease is the more likely diagnosis, although the retrospective design means the parameters may aid differentiation rather than establish cause.

Symptom profiles also differed. The degenerative group reported higher leg-pain scores on the visual analog scale, averaging 6.0 plus or minus 1.1 versus 4.6 plus or minus 1.6 in the isthmic group (P < 0.001). Back-pain VAS scores and Oswestry Disability Index scores, however, did not differ significantly between the groups, indicating that the coronal differences were reflected mainly in leg symptoms rather than overall disability in this cohort.

The study went a step further by asking whether the geometry of the wedged segment could predict where patients felt their leg pain. Using a decision tree analysis in patients with degenerative spondylolisthesis, the researchers found that when the segmental wedge angle fell between 1.3 degrees and less than 5.0 degrees, lower limb pain was associated with wedge orientation and occurred mainly on the concave side of the wedge. Outside that range, the relationship broke down: when the angle was smaller than 1.3 degrees or 5.0 degrees or greater, pain distribution was not predictable from wedge orientation.

The authors conclude that degenerative spondylolisthesis is associated with greater lumbar coronal imbalance and segmental wedging than isthmic spondylolisthesis, and that segmental wedge angle and lumbar coronal balance may help clinicians distinguish the two conditions on plain radiographs. In degenerative cases with a wedge angle in the intermediate range, wedge orientation may additionally hint at which leg is likely to hurt.

Several limitations frame these findings. The study was retrospective, included only single-level spondylolisthesis in symptomatic patients who had failed conservative care, and relied on frontal-plane radiographs alone. The decision tree finding is an association observed within this cohort rather than a validated clinical rule, and the pain-side relationship applies only within the 1.3 to less than 5.0 degree window. Even so, the work adds a relatively simple set of measurements, obtainable from standard standing films, to the toolkit for evaluating which type of spondylolisthesis a patient has and where the pain may localize.

Subject of Research: Coronal radiographic balance in degenerative versus isthmic lumbar spondylolisthesis

Article Title: Comparative analysis of coronal balance with clinical correlation between degenerative and isthmic lumbar spondylolisthesis: a retrospective study

Article References: Li, H., Liu, C., Liu, X., Yang, H., Liu, X., Jia, F., & Cui, X. (2026). Comparative analysis of coronal balance with clinical correlation between degenerative and isthmic lumbar spondylolisthesis: a retrospective study. Frontiers in Medicine, 13, Article 1902310. https://doi.org/10.3389/fmed.2026.1902310

Image Credits: AI Generated

DOI: 10.3389/fmed.2026.1902310

Keywords: lumbar spondylolisthesis, degenerative spondylolisthesis, isthmic spondylolisthesis, coronal balance, segmental wedge angle, spine radiography, leg pain, retrospective study, decision tree, VAS score, Comparative, analysis