Speaker
Description
"Introduction
The last decade, efforts have been made in developing more effective diagnostics for low back pain. The focus was addressed towards Modic Changes (MCs), pathological signal intensity changes in the vertebral bone marrow and endplates of the intervertebral disc (IVD), which can be detected on Magnetic Resonance Imaging (MRI)1. In contrast to the human situation, little is known about the prevalence and characteristics of MCs in dogs, that are often used as a model to study intervertebral disc disease and new regenerative therapies2. For this reason, the aim of this study was to examine the prevalence and imaging/histologic characteristics of MCs in dogs.
Methodology
High field 1.5 Tesla MRI images of canine patients with low back pain and/or neurological deficits were retrospectively analysed. Inclusion criteria were the availability of sagittal T1- and T2-weighted turbo spin-echo sequences for the whole lumbar spine and exclusion criteria were (para)spinal neoplasia, resulting in 340 dogs and 2496 spinal segments. Dogs that underwent necropsy on the same day of the MRI were used for histo(patho)logical analysis (modified Boos score3, including endplate morphology, new bone formation, and subchondral bone sclerosis; n=16 dogs, 39 segments). The adjacent vertebral bone was assessed for infiltration of inflammatory cells, neovascularization, fatty infiltration, and the presence of chondroid cells, fibrous tissue, or Schmorl’s nodes. Multivariable logistic regression models were built to test the association between the presence of MCs and explanatory variables.
Results
MCs were most often detected at the lumbosacral junction (L7-S1 in the dog), the majority was MC type 3 (subchondral bone sclerosis). Previous spinal surgery at the investigated level predisposed dogs for the development of MC type 1 (proliferation of fibrovascular (granulation) tissue, oedema in vertebral bone marrow) and 2 (fatty infiltration). As in humans, MCs in dogs were interconvertible over time. The prevalence of MCs appeared positively associated with age and disc protrusion/extrusion. Lasty, histological analysis indicated that IVDs in which MCs were detected showed more histopathological changes in the endplate and vertebral bone than IVDs without MCs. However, the histological changes described in human literature were not detected in the segments with the specific MC types. Instead, mostly chondroid infiltration was encountered in MC types 1 and 3.
Conclusions
As humans, also dogs show MCs, mostly at the lumbosacral junction. However, MCs in dogs exhibit other subchondral bone pathologies than humans, as chondroid proliferation was mostly encountered and little proliferation of fatty, fibrous, or granulation tissue.
References
1. Dudli, S., et al. Eur. Spine J. 25, 3723–3734 (2016).
2. Bach, F. C. et al. BMC Vet. Res. 10, 3 (2014).
3. Bergknut, N. et al. Vet. J. 195, 156–163 (2013).
The European Union’s Horizon 2020 program (iPSpine; #825925) supported this work."
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