Flat feet linked to enzymes

Adult-acquired flat feet may be caused by an increase in activity of proteolytic enzymes in tendons of the lower leg, a new study suggests.

The findings could eventually lead to new drug treatments for the painful condition, as well as others which affect the tendons, scientists from the University of East Anglia said.

Adult-acquired flat foot is most common in women over 40, and is a result of the gradual "stretching out" of a tendon near the ankle bone over time, known as the tibialis posterior tendon. This then causes the arch of the foot to slowly fall, causing pain.

The exact causes of tendon stretching are not fully understood, the scientists said.

Known risk factors for the condition include obesity, high blood pressure and diabetes, and some think that wearing high heels and standing or walking for long periods may play also play a role. 

However, the scientists found evidence of increased activity of some proteolytic enzymes in tendon samples. These enzymes may break down the constituents of the tibialis posterior tendon and weaken it, causing the foot arch to fall. 

Further research is now needed into which specific proteolytic enzymes should be targeted and whether people could be genetically predisposed to tendon injuries of this type, the scientists said.

Dr Graham Riley, who led the study, said: "Our study may have important therapeutic implications since the altered enzyme activity could be a target for new drug therapies in the future.

“We have shown that similar changes also take place in other painful tendon conditions such as Achilles tendonitis, so this advance may ultimately result in an effective alternative to surgery for many patients."

Prof Alan Silman, medical director of Arthritis Research UK, added: "Foot problems are an important and not sufficiently recognised cause of pain and disability in the elderly.

"Ageing changes to the supporting tendons contribute to these problems and this research represents a first step to successfully unravelling some of the complex biochemistry that regulates tendon disorders – knowledge that could have a major impact on developing simple but effective therapeutic choices in the not so distant future."

The study is published online in the journal Annals of the Rheumatic Diseases.

This article was published on Thu 12 January 2012