Scientists have discovered a molecular trigger that may explain common tendon injuries such as Achilles pain, tennis elbow and jumper’s knee. Researchers identified the protein HIF1 as a central cause of tendon disease, offering new insight into how these painful conditions develop.

The research was led by scientists at ETH Zurich and Balgrist University Hospital, who investigated why tendons become damaged after repeated strain.

🦵 Why tendon injuries are so common

Tendon injuries affect both athletes and older adults. These conditions occur when tendons experience repeated stress and overuse.

Tendons must handle powerful forces generated by muscles. However, their thin structure makes them vulnerable to damage. Doctors refer to these conditions as tendinopathies, which remain among the most common problems treated by orthopaedic specialists.

Despite their prevalence, treatments often provide limited relief. Therefore, researchers have searched for deeper biological explanations behind tendon disease.

🔬 HIF1 identified as the key molecular trigger

The research team discovered that a protein called HIF1 plays a direct role in tendon disease. This protein acts as a transcription factor, meaning it controls gene activity inside cells.

Earlier studies had found HIF1 in damaged tendons. However, scientists did not know whether it caused the disease or simply appeared during injury.

The new research solved this question. Experiments showed that HIF1 actively triggers tendon damage, rather than merely appearing alongside it.

Researchers showed HIF1 is not just present but directly causes disease.

🧪 Experiments reveal direct cause of tendon damage

Scientists conducted experiments using mice and human tendon tissue. They switched HIF1 on permanently in some mice and turned it off in others.

Mice with constantly active HIF1 developed tendon disease even without heavy strain. In contrast, mice without HIF1 in tendon tissue stayed healthy, even when researchers overloaded their tendons.

The team also examined human tendon cells collected during surgeries. In both mice and humans, high HIF1 levels caused harmful structural changes in tendon tissue.

These changes made tendons more brittle and less mechanically effective.

🧬 Why the protein causes pain and damage

Researchers found that HIF1 increases crosslinks in collagen fibres, which give tendons their strength. However, too many crosslinks make tendons brittle.

Scientists also observed increased growth of blood vessels and nerves inside tendon tissue. This growth may explain the pain often linked to tendon disease.

⏱️ Importance of early treatment

The study showed that damage caused by HIF1 can build up over time. Eventually, the injury may become permanent and require surgery.

Researchers therefore emphasised the importance of early treatment, especially for young athletes who often develop tendon problems early.

💊 Future treatments and challenges

The discovery raises the possibility of developing drugs that block HIF1. However, the protein plays a vital role in normal bodily functions, especially in responding to low oxygen levels.

Because of this, researchers aim to find ways to target HIF1 specifically within tendon tissue. Scientists are now studying related biological pathways to identify safer treatment options.

🔭 New hope for tendon disease treatment

The research provides a clearer understanding of tendon disease development. Scientists believe the discovery could lead to new therapies that prevent or reverse tendon injuries.

This breakthrough may improve treatment for millions of people affected by tendon pain worldwide.