Mechanistic study of modic changes in nonspecific low back pain

S.
S.
Surgery, Department of Spine Surgery, Ganga Hospital, India Rajasekaran et al.
found 19 radiological features in patients with mild infection or traumatic endplate fracture by MRI and CT imaging, and screened out 3 signs unique to infection and trauma
.

The researchers established an imaging "endplate infection probability score" to distinguish infection from traumatic endplate changes
.

Its ability to discriminate was validated
in 15 new patients in the infection group or 15 new patients in the trauma group.

On this basis, the results
of EIPS, ESR, CRP and digital pain grading scale were compared between 115 MC patients and 80 non-MC patients.

Article published in November 2022 in the European Spine Journal
.

- Excerpted from the article chapter

【Ref: Rajasekaran S, et al.
Eur Spine J.
2022 Nov; 31(11):2884-2896.
doi: 10.
1007/s00586-022-07335-3.
Epub 2022 Aug 5.
】

Research background

80% of patients with low back pain have non-specific low back pain (NSLBP); Poor response, patient disappointment, physician dissatisfaction, and severe socioeconomic losses make it urgent to determine the etiological grouping to make treatment specific and targeted
.

Thirty years ago, the American scholar Modic TM based on MRI-T1W and T2W sequences to image the signal changes of cartilage endplate (EP) and vertebral bone during lumbar disc degeneration, defined as Modic change (MC).


This category of patients is a special group of low back pain, severe pain, frequent attacks, long duration, often accompanied by sleep disturbance, poor response to treatment, and high
incidence of postoperative complications.

The etiology and pathological mechanisms are unclear
.

Previously thought to be trauma-induced, MC is now proposed to be the result of low-virulence anaerobic infection, and it is explored from clinical prognosis, microbiology, immunology, proteomics and culture methods
.

However, multimodal radiology imaging has not been studied in depth
.

Modic changes are usually "endplate changes" (EPC), and pathological changes are actually more pronounced
in subchondral bone than in cartilage endplate.

Bone changes associated with acute traumatic injury, as well as trabecular destruction, bone erosion, cavitation formation, calcification, and bone sclerosis thickening during active or healing periods of inflammation and infection, and the presence of dead bone are more prominent on CT scan, and may be missed by MRI imaging alone (Figure 1).


Therefore, the pathophysiology of MC should be determined
by multimodal imaging rather than solely on MRI studies.

Figure 1.
MRI and CT imaging show features of
modic changes.

MRI imaging in three patients with recurrent nonspecific low back pain showed typical modic changes
.

The first two columns show MRI-T1W and MRI-T2W imaging of the lumbar spine, and the third column shows the corresponding CT scan images
.

CT-enhanced images show extensive endplate changes, erosion, and hardening, but are not evident
on MRI imaging.

Case 1: At least 2 severe episodes of low back pain per year in the past 4 years; a, b, and c illustrate, MRI imaging typical type 1 modic changes, CT scan showing severe erosion and sclerosis
of the lumbar vertebral limb.

Case 2: Patient type 2 modic changes; d, e, f figures, MRI imaging did not show obvious spherical bone lesions above the end plate above the intervertebral disc, and CT scan was clearly visible
.

Case 3: Patients with type 3 modic changes; Illustration of g, h, and i, CT scan shows chronic pathological changes, usually with infection of bones elsewhere in the body, but not obvious on MRI imaging
.

Study results

The results showed that EIPS confidence levels were 66.
4%, 83%, and 100%,
respectively, on scores of 4, 5, and 6 in the endplate change of infection.

The mean EIPS was 4.
85±1.
94 for patients with modic changes and -0.
66±0.
49 (p<0.
001)<b12> for patients without modic changes.

Seventy-eight (67.
64%) MC patients scored a score of 6, indicating a high
likelihood of infection.

There were differences in NRS (p<0.
01), ESR (p=0.
05), CRP (p<0.
01), and pain type (p<0.
01) in patients with or without MC (see Figure 2-4 for typical imaging findings<b16>).

Figure 2.
Specific signs of infection
.

MRI and CT imaging showed three highly specific signs of infection, which were divided into types
I.
, II.
, and III.

a, b diagram, type I: 94% of cases involve the upper and lower endplates
of the intervertebral disc.

Even if only one terminal plate is involved, closer inspection often reveals that the other terminal is
involved at the same time.

Illustration c, d Figure, Type II.
: 94% of patients have typical large-scale infectious bone erosion
.

However, the MRI image is blurry and very obvious on CT scan, and the lesion is cauliflower-like, dense sclerosis
extending along the full length of the endplate on both sides.

e, f Figure, type III.
: 83% of patients with modic changes have extensive hardening of the upper and lower endplates of the intervertebral disc, far beyond the eroded edge
.

CT scans are more pronounced, and more than 50% of the vertebral body may also develop extensive sclerosis
.

Figure 4.
Patients with NSLBP with modic changes have relatively intact discs
.

Conclusion of the study

Finally, the researchers pointed out that multimodal imaging showed radiological signs of modic changes that were not easily seen on a single MRI imaging, resulting in missed diagnosis of modic changes
.

Through the "endplate infection probability score", 67.
64% of patients with modic changes had endplate changes that were infectious rather than traumatic, indicating the possibility of infectious etiology; Researchers have proposed the concept of "primary endplateitis", that is, infection of hematogenous subchondral bone
.

This study deepens the understanding of MC and refines the treatment strategy
for NSLBP patients.