Mechanical Conditions That Accelerate Intervertebral Disc Degeneration: Overload Versus Immobilization

Abstract

Study Design. A review of the literature on macromechanical factors that accelerate disc degeneration with particular focus on distinguishing the roles of immobilization and overloading.Objective. This review examines evidence from the literature in the areas of biomechanics, epidemiology, animal models, and intervertebral disc physiology. The purpose is to examine: 1) what are the degenerationrelated alterations in structural, material, and failure properties in the disc; and 2) evidence in the literature for causal relationships between mechanical loading and alterations in those structural and material properties that constitute disc degeneration.Summary of Background Data. It is widely assumed that the mechanical environment of the intervertebral disc at least in part determines its rate of degeneration. However, there are two plausible and contrasting theories as to the mechanical conditions that promote degeneration: 1) mechanical overload; and 2) reduced motion and loading.Results. There are a greater number of studies addressing the "wear and tear" theory than the immobilization theory. Evidence is accumulating to support the notion that there is a "safe window" of tissue mechanical conditions in which the discs remain healthy.Conclusions. It is concluded that probably any abnormal loading conditions (including overload and immobilization) can produce tissue trauma and/or adaptive changes that may result in disc degeneration. Adverse mechanical conditions can be due to external forces, or may result from impaired neuromuscular control of the paraspinal and abdominal muscles. Future studies will need to evaluate additional unquantified interactions between biomechanics and factors such as genetics and behavioral responses to pain and disability.

Both endoplasmic reticulum and mitochondria are involved in disc cell apoptosis and intervertebral disc degeneration in rats

“…As shown by epidemiological surveys (Battie et al 1995;Stokes and Iatridis 2004), both overloading and immobilization of the spine contribute to IVDD. Various animal models also demonstrated that IVDD can be induced by different unphysiologic spinal loadings such as static axial compression (Lotz and Chin 2000;Lotz et al 1998), static bending compression (Court et al 2001), and dynamic axial compression (Walsh and Lotz 2004), associated with increased disc cell apoptosis.…”

Disc space narrowing as a new risk factor for vertebral fracture: The OFELY study

“…DSN is more frequently seen in the lowest part of the lumbar spine, where the gravity loading of the spine is greater. Moreover, the lower spine is more exposed to large forces generated by falls, heavy lifting, or activities that accentuate bending and twisting, increasing the risk of disc degeneration (52,53).…”

Regulation of gene expression in intervertebral disc cells by low and high hydrostatic pressure

“…Disc degeneration is influenced by multiple factors like age [4], nutrition [2,17], mechanical factors [16] and genetics [19,18]. In the present study we focus on the influence of mechanical loading on intervertebral disc (IVD) cells as both overload as well as immobilisation are supposed to accelerate the disc degeneration.…”

“…In the present study we focus on the influence of mechanical loading on intervertebral disc (IVD) cells as both overload as well as immobilisation are supposed to accelerate the disc degeneration. A recently published review of the literature clearly pointed out that in animal models at least disc degeneration can be provoked by inappropriate mechanical signals [16,19]. Multiple mechanical factors affect the IVD in vivo [1,14], as this structure has to provide flexibility, stabilization and shock absorbance in its function as the joint of the spine.…”