Researchers at the University of East Anglia (UEA; Norwich, United Kingdom), the University of Bristol (United Kingdom), and other institutions obtained normal PTTs from patients with no history of tendon problems. Samples of dysfunctional PTT and replacement flexor digitorum longus tendon (FDLT) tissue were then obtained from patients undergoing surgical reconstruction. The samples were then analyzed and compared for total collagen and glycosaminoglycan (GAG), pentosidine, collagen cross-links, and the expression of matrix and metalloproteinase mRNA.

The results showed that dysfunctional PTT contained higher levels of GAG and lower levels of pentosidine than normal PTT or FDLT. In contrast, collagen in FDLT contained fewer ketoimine and more aldimine cross-links than either normal or dysfunctional PTT. mRNA encoding types I and III collagens, aggrecan, biglycan, MMP-2, -13 and -23, and a disintegrin and metalloproteinase (ADAM)-12L each showed increased levels in dysfunctional PTT compared with either normal PTT or FDLT. In principal, the findings suggest that over time the structure and composition of the tendons changes due to increased activity of proteolytic enzymes. These enzymes then break down the constituents of the PTT and weaken it, causing the foot arch to fall. The study was published on January 12, 2012, in Annals of the Rheumatic Diseases.

“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, PhD, of the UEA School of Biological Sciences. “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.”

Adult-acquired flat foot is most common in women over 40, and often goes undiagnosed. The condition results from the gradual “stretching out” over time of the PTT, the main stabilizer of the foot arch. The causes of this stretching are not fully understood, though some believe wearing high heels and standing or walking for long periods may play a role. Known risk factors for the condition include obesity, hypertension, and diabetes. Treatment usually involves surgical transfer of the FDLT.

Related Links:
University of East Anglia
University of Bristol