Chronic tendinopathies are often difficult to resolve because of several key biological, mechanical, and behavioral factors that hinder the natural healing process. These conditions are characterised by long-term degeneration rather than inflammation, and the body's ability to repair and regenerate the damaged tendon tissue is compromised over time. Here are some of the main reasons why chronic tendinopathies tend to persist:
1. Degenerative Changes (Tendinosis)
In chronic tendinopathies, the tendon undergoes degenerative changes rather than acute inflammation. This condition, known as tendinosis, is marked by:
Collagen disorganisation: The normal, tightly aligned collagen fibers in tendons become disorganised, which weakens the tendon structure and reduces its ability to handle mechanical stress.
Cell death: Over time, cells within the tendon may die (apoptosis), further limiting the tendon’s ability to repair itself.
Inadequate blood supply: Tendons generally have a poor blood supply, especially in certain areas (e.g., the Achilles or rotator cuff tendons). This limits the delivery of nutrients and healing factors to the site of injury, delaying or preventing repair.
2. Failed Healing Response
Tendons normally undergo a healing process in three phases: inflammation, repair, and remodeling. In chronic tendinopathies, the body fails to progress properly through these stages:
Prolonged remodeling phase: The tendon may remain in a prolonged state of incomplete healing, where tissue repair is slow or absent.
Scar tissue formation: Instead of healthy tendon fibers regenerating, fibrotic (scar) tissue may form. This tissue is less elastic and more prone to re-injury.
3. Continuous Overload and Mechanical Stress
Chronic tendinopathies often result from repetitive overuse or strain on the tendon without sufficient rest for recovery. Key reasons include:
Microtrauma accumulation: Continuous mechanical stress causes microtears in the tendon, which accumulate over time. Without proper rest or treatment, these microtears do not heal, leading to a cycle of degeneration.
Poor biomechanics: Incorrect movement patterns or imbalances in muscle strength can place excessive stress on certain tendons, perpetuating injury.
Lack of adaptation: The tendon may not have enough time to adapt to the stresses placed on it, especially in athletes or individuals with physically demanding jobs.
4. Persistent Inflammation and Pain Mechanisms
Chronic tendinopathies involve a shift from an acute inflammatory response to more complex pain mechanisms, which can perpetuate the problem:
Chronic low-grade inflammation: Although tendinosis is not primarily an inflammatory condition, there can be persistent low-grade inflammation that inhibits proper healing.
Central sensitisation: In chronic cases, the nervous system may become sensitised, amplifying pain signals from the affected tendon, even if the tissue damage itself is not progressing. This can lead to a cycle of pain and dysfunction.
5. Aging and Reduced Tendon Healing Capacity
As people age, tendons naturally lose elasticity and become more prone to degeneration:
Reduced collagen production: Aging decreases the body’s ability to produce and repair collagen, the primary structural protein in tendons.
Slower healing response: Older individuals generally have a slower overall healing response, making chronic tendinopathies more difficult to resolve.
6. Inadequate or Ineffective Treatment
Many chronic tendinopathies become prolonged because initial treatments may be ineffective or insufficient, such as:
Rest without addressing the root cause: Resting alone may reduce symptoms temporarily, but without correcting biomechanical issues or addressing tissue quality, the problem can recur.
Inadequate rehabilitation: In some cases, rehabilitation programmes may not fully restore tendon strength, flexibility, and function, leading to incomplete healing and future injury.
7. Lack of Tendon Adaptation to Load
Tendons require gradual loading to maintain their strength and adaptability. When an individual experiences chronic tendinopathy, they may avoid using the affected tendon due to pain. This lack of activity leads to deconditioning of the tendon, which further reduces its ability to tolerate mechanical stress and heal properly.
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