INTRODUCTION: The relationship of Modic change to pain and inflammation remains unclear. Recently, some authors have reported that Modic type 1 signals are closely related to infection. However, if the patients do not have severe back pain, fever, or an abnormal blood profile, it is difficult to distinguish between common Modic change and infection. The purpose of this study was to examine the prevalence of pyogenic spondylitis in patients who showed Modic type 1 change without other signs of infection.
METHODS: Seventy‐one patients with Modic type 1 change were evaluated (average age 55; 32 male and 39 female). X‐ray and magnetic resonance imaging were performed to investigate low‐back and leg pain. Body temperature was measured and blood analysis (including white blood cell count and level of C‐reactive protein) was conducted for all patents. All 71 patients with Modic type 1 change but without other signs of infection were followed for 2 years. Low‐back pain, X‐ray, and blood analyses were performed every 3 months; and magnetic resonance imaging every year.
RESULTS: Severe low‐back pain or abnormal signs developed in five patients during the follow‐up. Pyogenic spondylitis was diagnosed in three patients by symptoms, blood results, and imaging, and confirmed by biopsy. Two of the three patients were diabetic.
DISCUSSION: A total of 4.2% of patients with Modic type 1 change, but without other signs of infection were diagnosed as having pyogenic spondylitis during the 2‐year follow‐up, so it is important to consider this before treating Modic type 1 change.