Tendons are strong, fibrous connective tissues that play a fundamental role in movement by linking muscles to bones. They transmit the force generated by muscle contractions. While tendons are built to withstand significant stress, they are also prone to injury and pain. Understanding the precise nature of tendon-related discomfort is important, as the underlying causes are not always straightforward.
What is Tendonitis?
Tendonitis refers to an acute inflammatory response within a tendon, often resulting from a sudden increase in activity or direct injury. Common symptoms include localized pain, tenderness to the touch, and often noticeable swelling, warmth, and redness over the affected area.
This inflammatory reaction usually arises from sudden, excessive loading, repetitive microtrauma, or a direct impact to the tendon. For instance, a sudden intense workout or a fall can trigger tendonitis. Symptoms often appear relatively quickly after an inciting event.
What is Tendinosis?
Tendinosis, in contrast, is a chronic condition characterized by the degeneration of the tendon’s collagen fibers without significant inflammation. It occurs over time due to repeated microtrauma that exceeds the body’s natural repair capabilities. The tissue within the tendon becomes disorganized and weakened, rather than inflamed.
Individuals with tendinosis often experience persistent pain, along with stiffness and a palpable thickening of the affected tendon. Reduced function and a limited range of motion are also common. This condition frequently stems from chronic overuse, age-related changes in tendon structure, or poor biomechanics.
How They Differ and Why It Matters
The primary distinction between tendonitis and tendinosis lies in their underlying pathology: tendonitis involves inflammation, whereas tendinosis is characterized by chronic degeneration. Tendonitis typically presents with an acute onset and symptoms like swelling and redness. Conversely, tendinosis develops gradually and is marked by chronic pain, stiffness, and structural changes such as tendon thickening.
Microscopic examination reveals inflammatory cells in cases of tendonitis. In tendinosis, however, studies show disorganized collagen fibers, an increase in ground substance, and new, often abnormal, blood vessel formation (neovascularization). Recognizing these differences is important because an accurate diagnosis dictates the appropriate course of treatment. Misdiagnosing chronic tendinosis as acute tendonitis, for example, can lead to ineffective interventions that fail to address the degenerative changes.
Distinct Treatment Strategies
Treatment approaches for tendonitis and tendinosis differ significantly due to their distinct pathologies. For tendonitis, the focus is on reducing inflammation and alleviating acute pain. This typically involves rest, applying ice to the affected area, and sometimes using non-steroidal anti-inflammatory drugs (NSAIDs). Gentle stretching and addressing the acute overload that caused the condition are also part of the recovery process.
Conversely, treating tendinosis centers on stimulating collagen repair and remodeling within the degenerated tendon. This often includes specific physical therapy exercises, such as eccentric loading, which involves lengthening the muscle while it is contracting. Other interventions may include dry needling or, in some cases, platelet-rich plasma (PRP) therapy, which aims to encourage tissue regeneration. Addressing underlying biomechanical issues and managing the load placed on the tendon are also important for long-term recovery in tendinosis.