Dense connective tissue is mostly comprised of collagen, a protein made by cells called fibroblasts. Dense connective tissue can be arranged into ligaments, tendons, fascia and fibrocartilage.
• Ligaments connect two bones across a joint. Ligaments are the continuous joint stabilizers.
• Tendons attach muscle to bone across a joint.
• Muscles and tendons move joints and can stabilize joints only during muscle contraction. Muscles are dynamic joint stabilizers.
• Fibrocartilage is a protective dense connective tissue within joints, such as a meniscus.
Another type of connective tissue is hyaline cartilage, which protects the surfaces of bones in freely moving joints by decreasing friction and absorbing shock.
Chronic pain from tendons, ligaments, and joints is often due to a degenerative process of these tissues, not an inflammatory process:
The body has a difficult time maintaining the health of dense connective and cartilage tissues in joints, ligaments and tendons. The reason is that these structures do not have a good blood supply, which also explains why musculoskeletal injuries take weeks to months to heal.
Sprains (ligaments) and strains (tendons) are the result of acute or repetitive injury causing a partial or complete tear of the tissue. The majority of healing occurs in the first eight weeks after an injury. During this time new collagen is made to replace the damaged fibers. Next, the tissue thickens and tightens and hopefully the new tissue is as strong as the old.
However, connective tissue strength often only recovers 50 or 60 percent of preinjury strength. If the tissue does not have sufficient tensile strength, or is too loose, a scar forms which does not restore function. When this happens, the nerve receptors in the scarred tissue continue to fire pain signals. In the case of joints, lack of stability by poorly healed ligaments leads to muscle spasm and predisposition for the early-onset of arthritis later in life.
As such, musculoskeletal injuries result in increased susceptibility to reinjury and chronic low grade pain. Damage to ligaments and tendons that are not fully repaired lead to a cycle as reinjury causing further weakening, which results in reinjury. As time goes on strength and stability continue to decrease until chronic pain occurs.