Illustration comparing damaged tendon fibers (tendinosis) to healthy, aligned tendon fibers, representing the concept of tendon repair and healing.

Tendinitis vs. Tendinosis: Decoding Your Aches and Pains

Rhea Morgan in Health & Wellness August 2025 • 3 min read.

"Are you struggling with persistent aches and pains? Understanding the difference between tendinitis and tendinosis is key to effective treatment and recovery."

If you're experiencing persistent pain, burning sensations, decreased strength, and limited flexibility, especially when performing everyday activities, you might think you have tendinitis. However, research indicates that tendinosis is a more frequent culprit behind these symptoms.

Tendinitis involves inflammation of the tendon, often resulting from micro-tears due to sudden or excessive force. Tendinosis, on the other hand, is a degenerative condition of the tendon's collagen in response to chronic overuse and inadequate healing time.

Distinguishing between these conditions is vital for healthcare practitioners to administer the most appropriate and effective treatment strategies.

Tendinitis vs. Tendinosis: What's the Real Difference?

Illustration comparing damaged tendon fibers (tendinosis) to healthy, aligned tendon fibers, representing the concept of tendon repair and healing.

The common understanding of "tendinitis" often masks the reality of what's truly occurring within the body. While tendinitis involves inflammation, tendinosis is characterized by the degeneration of the tendon's collagen due to chronic overuse. Repetitive strain injuries can lead to tendinosis, even from minor movements when performed repeatedly.

The confusion between tendinitis and tendinosis is widespread. For example, tennis elbow is frequently misdiagnosed as tendinitis of the extensor carpi radialis brevis. However, clinical findings often reveal that tennis elbow is, in fact, tendinosis.

Here's a quick microscopic comparison:

Tendinosis: Immature type III collagen fibers, loss of collagen continuity, increased ground substance, and haphazard vascularization.
Healthy Tendon Tissue: Dominated by mature type I collagen fibers.

In tendinosis, the tendon's appearance shifts from a reflective, "white, glistening, and firm" surface to a "dull-appearing, slightly brown, and soft" surface, indicative of mucoid degeneration.

These changes lead to a loss of strength and increased bulk in the tendon, contributing to a cycle of injury. In the forearm and wrist, tendinosis can potentially lead to secondary carpal tunnel syndrome due to the thickening of tendons and surrounding tissue.

Key Takeaways for Long-Term Tendon Health

Understanding the nuances between tendinitis and tendinosis is essential for effective treatment and long-term tendon health. Addressing the underlying issues, restoring tendon strength, and preventing re-injury are vital for returning to pain-free, normal daily activities.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

Everything You Need To Know

What exactly is tendinitis?

Tendinitis is a condition characterized by the inflammation of a tendon, often resulting from micro-tears due to sudden or excessive force. This inflammation is the body's immediate response to injury. Understanding tendinitis is important because it requires a treatment approach focused on reducing inflammation and promoting healing of the acute injury. However, it's worth noting that while tendinitis is commonly diagnosed, research suggests that tendinosis is a more frequent cause of tendon pain. This distinction is crucial because anti-inflammatory treatments that might work for tendinitis may not be as effective for tendinosis.

What is tendinosis, and how does it differ from tendinitis?

Tendinosis is a degenerative condition affecting the tendon's collagen, usually as a result of chronic overuse and inadequate healing time. Unlike tendinitis, which involves inflammation, tendinosis is characterized by the breakdown of the tendon's structure. This degeneration leads to a loss of strength and increased bulk in the tendon, contributing to a cycle of injury. Recognizing tendinosis is vital because it necessitates a different treatment strategy, focusing on stimulating collagen repair and restoring tendon strength rather than simply reducing inflammation. Ignoring tendinosis can lead to chronic pain and reduced function.

What's the real difference between tendinitis and tendinosis?

The key difference lies in the underlying pathology. Tendinitis involves inflammation of the tendon, often due to acute injury. In contrast, tendinosis is a degenerative condition characterized by the breakdown of collagen within the tendon due to chronic overuse. Microscopically, tendinitis might show inflammatory cells, while tendinosis displays immature type III collagen fibers, loss of collagen continuity, increased ground substance, and haphazard vascularization. This distinction is crucial because treatments targeting inflammation (for tendinitis) will differ from those aimed at collagen repair and strengthening (for tendinosis).

How do repetitive strain injuries relate to tendon problems?

Repetitive strain injuries can lead to tendinosis. These injuries occur from minor movements when performed repeatedly over time. For example, tennis elbow is frequently misdiagnosed as tendinitis of the extensor carpi radialis brevis, but clinical findings often reveal that tennis elbow is, in fact, tendinosis. The repeated strain causes microscopic damage to the tendon, which, without adequate healing time, leads to the degeneration characteristic of tendinosis. This highlights the importance of proper ergonomics, adequate rest, and progressive loading exercises in preventing and managing tendinosis.

Why is it important to understand the difference between tendinitis and tendinosis?

Understanding the difference between tendinitis and tendinosis is crucial for effective treatment and long-term tendon health. Addressing the underlying issues, whether it's inflammation in tendinitis or collagen degeneration in tendinosis, is vital. Restoring tendon strength through appropriate exercises and preventing re-injury are essential components of recovery. If tendinosis is left unaddressed in the forearm and wrist, it can potentially lead to secondary carpal tunnel syndrome due to the thickening of tendons and surrounding tissue. Therefore, accurate diagnosis and targeted treatment are key to returning to pain-free, normal daily activities.