Are Modic changes 'Primary infective endplatitis'?-insights from multimodal imaging of non-specific low back pain patients and development of a radiological 'Endplate infection probability score'.

Abstract

To probe the pathophysiological basis of Modic change (MC) by multimodal imaging rather than by MRI alone. Nineteen radiological signs found in mild infections and traumatic endplate fractures were identified by MRI and CT, and by elimination, three signs unique to infection and trauma were distilled. By ranking the Z score, radiological 'Endplate Infection Probability Score' (EIPS) was developed. The score's ability to differentiate infection and traumatic endplate changes (EPC) was validated in a fresh set of 15 patients each, with documented infection and trauma. The EIPS, ESR, CRP, and Numeric Pain Rating Scale (NRS) were then compared between 115 patients with and 80 patients without MC. The EIPS had a confidence of 66.4%, 83% and, 100% for scores of 4, 5 and, 6, respectively, for end plate changes suggesting infection. The mean EIPS was 4.85 ± 1.94 in patients with Modic changes compared to - 0.66 ± 0.49 in patients without Modic changes (p < 0.001). Seventy-eight (67.64%) patients with MC had a score of 6, indicating high infection possibility. There was a difference in the NRS (p < 0.01), ESR (p = 0.05), CRP (p < 0.01), and type of pain (p < 0.01) between patients with and without MC. Multimodal imaging showed many radiological signs not easily seen in MRI alone and thus missed in Modic classification. There were distinct radiological differences between EPCs of trauma and infection which allowed the development of an EIPS. The scores showed that 67.64% of our study patients with Modic changes had EPCs resembling infection rather than trauma suggesting the possibility of an infective aetiology and allowing us to propose an alternate theory of 'Primary Endplatitis'.