Disc inflammation and Modic changes show an interaction effect on recovery after surgery for lumbar disc herniation

Abstract

Purpose To study the interaction between Modic changes (MC) and inflammation by macrophages in the disc, in relation to clinical symptoms before and after discectomy for lumbar disc herniation. Methods Disc tissue was embedded in paraffin and stained with haematoxylin and CD68. Subsequently, tissue samples were categorized for degree of inflammation. Type of MC was scored on MRI at baseline. Roland Disability Questionnaire (RDQ) score and visual analogue scale for back pain and leg pain separately were considered at baseline and 1-year followup post-surgery. Main and interaction effects of MC and inflammation were tested against clinical outcome questionnaires. In addition, this analysis was repeated in bulging and extruded discs separately. Results Disc material and MRI's of 119 patients were retrieved and analysed. Forty-eight patients demonstrated mild inflammation, 45 showed moderate inflammation, and 26 showed considerable inflammation. In total, 49 out of 119 patients demonstrated MC. Grade of disc inflammation did not associate with the presence of MC. At baseline, no main or interaction effects of MC and inflammation were found on the clinical scores. However, during follow-up after discectomy, significant interaction effects were found for RDQ score: Only in patients with MC at baseline, patients remained significantly more disabled (3.2 points p = 0.006) if they showed considerable disc inflammation compared to patients with mild inflammation. The additional analysis showed similar results in extruded discs, but no significant effects in bulging discs. Conclusions An interaction effect of MC and disc inflammation by macrophages is present. Only in patients with MC, those with considerable inflammation recover less satisfactory during follow-up after surgery.

Modic changes - An evidence-based, narrative review on its patho-physiology, clinical significance and role in chronic low back pain

“…7 The disc is avascular with sparse nerve distribution and lacks a strong physiological basis as a primary pain generator. 8 Over years, the attention has therefore shifted to other anatomical structures like endplates to explain the etiological basis of LBP. 9 Vertebral endplate is a thin interface between bone marrow (BM) and disc; and any loss of its integrity can potentially trigger a cascade of degenerative events.…”

“…Increased number of PGP-9.5 nerve fibers and TNF-a positive cells inside MC type I and II endplates may contribute to endplate-origin pain. 86e88 Djuric et al 8 demonstrated the importance of signs of disc inflammation in MC. They showed that patients with preoperative disc inflammation had less satisfactory outcome after discectomy.…”

Study protocol: effect of infection, Modic and inflammation on clinical outcomes in surgery for radiculopathy (EIMICOR)

“…This makes the disc prone to neovascularisation and macrophage infiltration, which is often seen in cervical and lumbar discs [ 2 , 3 ]. Macrophage infiltration of the extruded material could promote a foreign body response and thereby worsen the symptoms [ 4 ]. However, they can also help to resorb the herniated material and thus alleviate the symptoms.…”

“…In our previous work, we found that the impact of the presence of macrophages on clinical outcomes was dependent on the presence of Modic changes (MC), which are considered inflammatory vertebral endplate signal changes that occur frequently on cervical and lumbar endplates [ 10 , 11 ]. We found that in patients with MC, a higher degree of macrophage infiltration, was accompanied by more radicular pain symptoms and less favourable clinical outcomes [ 4 ]. In addition, we also showed that in patients without MC, a higher degree of macrophage infiltration was associated with less radicular pain and a better clinical outcome [ 4 ].…”

“…We found that in patients with MC, a higher degree of macrophage infiltration, was accompanied by more radicular pain symptoms and less favourable clinical outcomes [ 4 ]. In addition, we also showed that in patients without MC, a higher degree of macrophage infiltration was associated with less radicular pain and a better clinical outcome [ 4 ]. Based on these findings, it is to be expected that patients with MC have a higher degree of M1 macrophages, which would be in line with their slower recovery, while in patients without MC, larger numbers of M2 are to be expected, thereby explaining their faster recovery.…”