Presence of preoperative Modic changes and severity of endplate damage score are independent risk factors for developing postoperative surgical site infection: a retrospective case-control study of 1124 patients

PURPOSE

There is increasing evidence of an association between Modic changes (MC) and subclinical infection. However, the association of MC with postoperative surgical site infection (SSI) has not been adequately probed. This study primarily aimed to investigate a probable association between preoperative MC, total endplate damage score (TEPS), and SSI.

METHODS

A retrospective analysis of 1124 patients who underwent surgery in a single institution (2016-2018) was performed, using both univariate and multiple logistic regression analyses to identify independent risk factors for SSI.

RESULTS

The prevalence of SSI was 4% (44/1124 patients), with no association with age or sex. The prevalence of MC in the SSI group was significantly higher-79.54% (35/44) compared to 58.79% (635/1080) (p value = 0.006) in the control group with no specific relation to type or location of MC. A higher TEPS was associated with SSI (p value = 0.009). A receiver operating characteristic (ROC) curve for TEPS values to assess predictiveness of SSI showed TEPS ≥ 5.5 to have a better sensitivity of 84% than 72% for a TEPS ≥ 6.5. Univariate analysis showed TEPS > 6 (odds ratio 3.887) to have a stronger association with SSI than the presence of MC (odds ratio 2.725). Among various types of surgeries, discectomy had a higher association with SSI (p value = 0.03) when compared to fusion (p value = 0.071). However, multiple logistic regression analysis revealed only TEPS > 6, presence of MC and hypothyroidism as independent risk factors for SSI.

CONCLUSION

Our data suggest that preoperative MC and TEPS > 6 are independent risk factors for developing surgical site infections. MC could be foci of chronic subclinical infection and not mere markers of degeneration, as initially described.

Measuring and reporting of vertebral endplate bone marrow lesions as seen on MRI (Modic changes): recommendations from the ISSLS Degenerative Spinal Phenotypes Group

PURPOSE

The positive association between low back pain and MRI evidence of vertebral endplate bone marrow lesions, often called Modic changes (MC), offers the exciting prospect of diagnosing a specific phenotype of chronic low back pain (LBP). However, imprecision in the reporting of MC has introduced substantial challenges, as variations in both imaging equipment and scanning parameters can impact conspicuity of MC. This review discusses key methodological factors that impact MC classification and recommends guidelines for more consistent MC reporting that will allow for better integration of research into this LBP phenotype.

METHODS

Non-systematic literature review.

RESULTS

The high diagnostic specificity of MC classification for a painful level contributes to the significant association observed between MC and LBP, whereas low and variable sensitivity underlies the between- and within-study variability in observed associations. Poor sensitivity may be owing to the presence of other pain generators, to the limited MRI resolution, and to the imperfect reliability of MC classification, which lowers diagnostic sensitivity and thus influences the association between MC and LBP. Importantly, magnetic field strength and pulse sequence parameters also impact detection of MC. Advances in pulse sequences may improve reliability and prove valuable for quantifying lesion severity.

CONCLUSIONS

Comparison of MC data between studies can be problematic. Various methodological factors impact detection and classification of MC, and the lack of reporting guidelines hinders interpretation and comparison of findings. Thus, it is critical to adopt imaging and reporting standards that codify acceptable methodological criteria. These slides can be retrieved under Electronic Supplementary Material.

Pathobiology of Modic changes

PURPOSE

Low back pain (LBP) is the most disabling condition worldwide. Although LBP relates to different spinal pathologies, vertebral bone marrow lesions visualized as Modic changes on MRI have a high specificity for discogenic LBP. This review summarizes the pathobiology of Modic changes and suggests a disease model.

METHODS

Non-systematic literature review.

RESULTS

Chemical and mechanical stimulation of nociceptors adjacent to damaged endplates are likely a source of pain. Modic changes are adjacent to a degenerated intervertebral disc and have three generally interconvertible types suggesting that the different Modic change types represent different stages of the same pathological process, which is characterized by inflammation, high bone turnover, and fibrosis. A disease model is suggested where disc/endplate damage and the persistence of an inflammatory stimulus (i.e., occult discitis or autoimmune response against disc material) create predisposing conditions. The risk to develop Modic changes likely depends on the inflammatory potential of the disc and the capacity of the bone marrow to respond to it. Bone marrow lesions in osteoarthritic knee joints share many characteristics with Modic changes adjacent to degenerated discs and suggest that damage-associated molecular patterns and marrow fat metabolism are important pathogenetic factors. There is no consensus on the ideal therapy. Non-surgical treatment approaches including intradiscal steroid injections, anti-TNF-α antibody, antibiotics, and bisphosphonates have some demonstrated efficacy in mostly non-replicated clinical studies in reducing Modic changes in the short term, but with unknown long-term benefits. New diagnostic tools and animal models are required to improve painful Modic change identification and classification, and to clarify the pathogenesis.

CONCLUSION

Modic changes are likely to be more than just a coincidental imaging finding in LBP patients and rather represent an underlying pathology that should be a target for therapy.