The development of Modic changes after lumbar surgical procedures and their association with patients´ baseline demographic characters and disc degeneration
Modic changes (MCs) are vertebral endplate-related signal abnormalities in the subchondral bone marrow, which are visible on MRI. Depending on the changes in the MRI they are classified in three different types (MC1, MC2, MC3). These changes were found to contribute to chronic low back pain. As lumbar surgery may alter biomechanical properties at a micro-structural level they may cause or aggravate preexisting MCs.Almost all studies that were previously conducted have focused on investigating the effect of a specific type of lumbar surgery on the development of Modic changes (MCs) in the levels operated on, but have ignored that different type of operations may have different effects on the operated and their adjacent levels. It still remains to be determined whether the etiological factor of MCs are degenerative changes or inflammation, and whether the patients baseline demographic characters are associated with the development of MCs. Therefore, this study aimed to compare the effects of four common types of lumbar surgery (fusion, decompression, sequestrectromy and discectomy) on MCs at the operated levels and their adjacent levels on MCs. Additionally, three classifications of intervertebral disc degeneration (IDD) and serum inflammation indexes were used in this study to further explore the relationship between IDD, inflammation, and MCs.In order to address the above scientific questions, 270 patients, who underwent one of the above mentioned lumbar surgical procedures were retrospectively analysed. Patients baseline characteristics were evaluated. The incidence of postoperative MCs and the volume changes of MCs meausured on MRI-images using an image analysis system, were used to systematically evaluate the impact of the different types of lumbar surgeries on the development of MCs. We evaluated lumbar IDD on MRI by using three different classification standards.The data show that 1) all four commonly used types of lumbar surgeries can lead to the occurrence of postoperative MCs. Based on their incidence and the volume changes of MCs in MRI before and after surgery, lumbar fusion seems to have a smaller impact on the development of MCs. 2) Modic changes type 2 are the primary type of MCs that occur after lumbar surgery. In terms of location, MCs can occur at the operative levels as well as at their adjacent levels, or at both locations. However, MCs were mainly observed at the operative levels. The three types of MCs may be found at any time after surgery. The first year after surgery appears to be the most active period for the occurrence of Modic changes Type 1 and Modic changes Type 2, whereas Modic changes Type 3 tend to represent a more stable state of bone marrow lesions. 3) Lumbar instability caused by surgery might be an important risk factor to contribute to the occurrence of MCs following lumbar surgical procedures. 4) The current study did not find any correlation between MCs and age, sex or BMI in the patients requiring surgical treatment. However, higher levels of C-reactive protein in MCs patients may reveal, that MCs might be associated with inflammation. 5) This study reinforces the conclusion that IDD and MCs are positively correlated, but there is still insufficient evidence that acute MCs have more severe imaging presentation of disc degeneration than non-acute MCs.
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