Vertebral body MRI related to lumbar fusion results

Abstract

The evaluation of continued pain after a technically successful posterolateral lumbar spine fusion is often challenging. Although the intervertebral disc is often a source of low back pain, abnormal endplates may also be a focus of pain, and possibly a source of continued pain after a posterolateral fusion. MRI allows noninvasive evaluation for disc degeneration, as well as for abnormal endplates and adjacent vertebral body marrow. Previous studies have found inflammatory marrow changes, adjacent to abnormal endplates, associated with disc degeneration in low back pain patients. In this study, preoperative MRI scans in 89 posterolateral lumbar fusion patients were reviewed, by an independent radiologist, to determine whether vertebral body marrow changes adjacent to the endplates were related to contined pain. Independent chart review and follow-up telephone interview of all patients at a 4-year follow-up (mean) formed the basis for the clinical results. Vertebral body MRI signals consistent with inflammatory or fatty changes were found in 38% of patients, and always occurred adjacent to a degenerated disc. Inflammatory MRI vertebral body changes were significantly related to continued low back pain at P = 0.03. We conclude that posterolateral lumbar fusion has a less predictable result for the subset of degenerative disc patients with abnormal endplates and associated marrow inflammation. More research is needed to determine the biological and biomechanical effects of a posterolateral fusion upon the endplate within the fused segments. If indeed further study supports the hypothesis that abnormal endplates associated with inflammation are a source of pain, then treating the endplates directly by anterior fusion may be a preferred treatment for this subset of degenerative patients.

What happens to Modic changes following lumbar discectomy? Analysis of a cohort of 41 patients with a 3- to 5-year follow-up period

“…According to the model of Kirkaldy-Willis and Farfan, 16 segmental instability constitutes an intermediate stage in the natural history of lumbar degenerative disc disease, eventually leading to a final stage of decreased mobility and fixed deformity. Because it is generally accepted that Type 1 changes are strong markers of biomechanical instability while Type 2 changes reflect a more biomechanically stable environment, 6,7,10,23,29,33,37,38 our results therefore suggest that lumbar discectomy may lead to an accelerated transition from the stage of segmental instability to that of fixed deformity in the operated disc. This is further supported by the lower rate of chronic moderate low-back pain in the subgroup of patients exhibiting conversion to Type 2.…”

Pedicle Marrow Signal Hyperintensity on Short Tau Inversion Recovery- and T2-Weighted Images: Prevalence and Relationship to Clinical Symptoms

“…That these changes may reflect altered biomechanical stress is further supported by the observation that type 1 changes can convert to type 2 or a more normal-appearing marrow and that conversion is accelerated and possibly facilitated by fusion and instrumented stabilization. 17,[23][24][25][26] Six of our 16 patients with signal intensity resolution underwent conversion to a type 2 marrow change (Fig 5).…”

The Modic Vertebral Endplate and Marrow Changes: Pathologic Significance and Relation to Low Back Pain and Segmental Instability of the Lumbar Spine

“…They concluded that the persistence of type 1 Modic changes after fusion suggests pseudarthrosis. Buttermann et al 34 similarly observed that nonfusion was associated predominantly with the persistence of type 1 Modic changes. In a study of 56 patients treated with anterior lumbar interbody fusion for LBP, Chataigner et al 35 found that patients with type 1 Modic changes had much better outcomes than those with isolated DDD and those with type 2 changes, in whom the results were generally poor.…”

“…32 The relationship between Modic type 1 changes and segmental instability is mostly supported by indirect evidence coming from outcome studies following lumbar fusion. 26,[33][34][35][36] In a study assessing osseous union following lumbar fusion in 33 patients, Lang et al 33 found that all 19 patients with solid fusion had type 2 Modic changes, whereas 10 of 14 patients with nonunion had type 1 changes. They concluded that the persistence of type 1 Modic changes after fusion suggests pseudarthrosis.…”