Antibiotic treatment for chronic low back pain?

Modic type 1 changes/bone edema in the vertebrae are present in 35–40 % of the low back pain population as opposed to the 6 % of the general population. It is strongly associated with low back pain. Antibiotic treatment in patients with chronic low back pain (>6 months) and Modic type 1 changes (bone edema) seems to be an efficacious therapy.

Lumbar spine MRI (Sagittal STIR sequence)

Modic changes are only visible on magnetic resonance images (MRI) and three types have been identified. Histological studies of material harvested during surgery, show that Type 1 involve disruption and fissuring of the endplate with regions of degeneration, regeneration, reactive bone formation, endplate edema and vascular granulation tissue.

Infection is one of the hypothetical causes of the bone edema underlying Modic type 1 changes. Nuclear tissue removed under strict sterile conditions during surgery for lumbar herniated discs proved to be infected with low virulent anaerobic organisms (Proprionibacterium acnes and Corynebacterium propinquum) in 3o-70 % of the patients. It is thought that these anaerobic mouth and skin commensal organisms gain access to the disc during normal bacteremias as a result of the neovascularisation associated with disc degeneration or herniation. Local inflammation in the adjacent bone may be a secondary effect due to cytokine and propionic acid production, i.e., the infection is in the disc and the Modic change is a “side effect” manifest in the bone. P. acnes cannot live in the highly vascularised/aerobic bone and is not present there. The possible role of bacteria in developing Modic changes after a disc herniation was confirmed hence, 80 % with anaerobic cultures developed new Modic changes in the vertebrae adjacent to the previous disc herniation, compared to the 44 % with no identified infection or aerobic bacterial infection.

In a recently published uncontrolled pilot study, 32 patients with chronic low back pain, following a lumbar disc herniation and of up to 2 years duration associated with Modic type 1 changes/bone edema, were treated with Amoxicillin–clavulanate (500 mg/125 mg) 3 × day for 90-100 day. The aim of this study was to test the efficacy of Modic antibiotic spine therapy (MAST) in patients with chronic low back pain, new Modic type 1 changes (MR) in the vertebrae adjacent to a previously herniated disc.

A double-blind randomized controlled trial was then carried out in 2013, in the same famous Danish Spine Center with 144 patients whose only known illness was chronic LBP of greater than 6 months duration occurring after a previous disc herniation and who also had bone edema demonstrated as Modic type 1 changes in the vertebrae adjacent to the previous herniation. Patients on antibiotic treatment had statistically significant improvements compared to the placebo group in all measured parameters, including MRI at 1 yr.

Antibiotics could be considered as a treatment option for this special subgroup of patients with CLBP and Modic type 1 changes after a lumbar disc herniation when all other treatment options have failed.