Background context: Although explored in humans and animal models, the pathomechanisms of discogenic low back pain (LBP) remain unknown.
Purpose: The aim of this study was to review the literature about the pathomechanisms of discogenic LBP.
Methods: Animal models of discogenic pain and specimens from degenerated human intervertebral discs (IVDs) have provided clues about the pathomechanisms of discogenic LBP. Painful discs are characterized by a confluence of innervation, inflammation, and mechanical hypermobility. These three possible mechanisms are discussed in this review.
Results: Animal models and specimens from humans have revealed sensory innervation of lumbar IVDs and sensory nerve ingrowth into the inner layer of IVDs. Cytokines such as tumor necrosis factor-α and interleukins induce this ingrowth. Nerve growth factor has also been recently identified as an inducer of ingrowth. Finally, disc degeneration induces several collagenases; their action results in hypermobility and pain.
Conclusions: To treat discogenic LBP, it is important to prevent sensitization of sensory nerve fibers innervating the IVD, to suppress pathogenic increases of cytokines, and to decrease disc hypermobility.
Keywords: Hypermobility; Inflammation; Intervertebral disc; Pain; Psychosocial factors; Sensory nerve.
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