Table 2.
Comparison of degeneration in the intervertebral disc and articular joint
| Intervertebral disc | Articular joint (eg, the knee) | |||||
|---|---|---|---|---|---|---|
| Extracellular matrix26, 76, 77, 120, 121, 122, 123 | Degradation of the proteoglycans: Less fluid attracted to nucleus pulposus | Degradation of the proteoglycans: Less fluid attracted to the articular cartilage | ||||
| Decrease in intradiscal pressure | Decrease in intra‐articular pressure | |||||
| Shift to collagen type I: Nucleus pulposus becomes more fibrous | Shift to collagen type I: Articular cartilage becomes more fibrous | |||||
| Biomechanics48, 121, 124 | Reduced disc height | Reduced joint space | ||||
| Increase in shear stresses | Increase in shear stresses | |||||
| Less resistive to compressive loads | Less resistive to compressive loads | |||||
| Cells95, 96, 97, 98, 99, 100 | Inflammatory mediators: Production of catabolic factors | Inflammatory mediators: Production of catabolic factors | ||||
| Catabolism by the chondrocyte‐like cells: Degradation of ECM | Catabolism by the chondrocytes: Degradation of ECM | |||||
| Caused by 58, 74, 75, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94 | Local inflammation | Systemic inflammation by | Diabetes | Local inflammation | Systemic inflammation by | Diabetes |
| Obesity | Obesity | |||||
| Smoking | Smoking | |||||
| Mechanical overloading | Mechanical overloading | |||||
| Inflammatory factors93, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 125, 126, 127 | TNF‐α and IL‐1β | TNF‐α and IL‐1β | ||||
| MMP 1–3, MMP 7–10, and MMP 12–14 | MMP 1‐3 and 7–14 | |||||
| ADAMTSs 4 and 5 | ADAMTSs 4 and 5 | |||||
| TIMP 1–3 | TIMP 1–3 | |||||
| Clinical symptoms12, 13, 14, 128 | Pain | Pain | ||||
| Dysfunction | Dysfunction | |||||
| Morning stiffness | Morning stiffness | |||||
| Radiological findings4, 15, 129, 130 | Formation of cysts and osteophytes | Formation of cysts and osteophytes | ||||
| Loss of joint space | Loss of joint space | |||||
| Subchondral sclerosis | Subchondral sclerosis | |||||
| Adjacent structures involved25, 74, 81, 131 | Vertebrae | Bone of tibia and femur | ||||
| Facet joints | Meniscal tears | |||||
| Modic changes | Synovitis | |||||
| Nerve roots, ligaments and muscles | Nerve roots, ligaments and muscles | |||||