Enzymes that break down tendons may cause adult-acquired flat feet, a condition that particularly affects middle-aged women, a new study found.

Researchers said that the findings could eventually lead to a new drug therapy for common tendon conditions like Achilles tendonitis.

Adult-acquired flat feet is a painful condition common in women over 40 and often goes undiagnosed, according to researchers. The study found that this condition is caused by the gradual “stretching out” of the tibialis posterior tendon which is the main stabilizer of the foot arch and is found near the ankle bone.

Some researchers believe that wearing high heels and standing or walking could play a role in this “stretching out” of the tendon, however they are still unsure.

Scientists have shown that the structure and composition of tendon specimens had changed when there was increased activity of some proteolytic enzymes, which can break down and weaken the constituents of the tibialis posterior tendon that causes the foot arch to fall.

"Our study may have important therapeutic implications since the altered enzyme activity could be a target for new drug therapies in the future," said lead author Graham Riley, of University of East Anglia’s School of Biological Sciences.

New treatments could be 10-15 years away, and more research is needed to assess which specific proteolytic enzymes are responsible for the foot condition, and if people were genetically predisposed to tendon injuries of this type.

The research is published in the Journal Annals of the Rheumatic Diseases.