Flatfoot in Adults
Flatfoot is a foot deformity characterized by the loss of the inner longitudinal arch of the foot, causing the heel to shift outward abnormally.
When people hear “flatfoot,” they often associate it with children. However, flatfoot is not only congenital. Adults who have had normal arches throughout their lives may begin to develop flatfoot in their 30s or 40s.
This condition may be caused by rheumatologic diseases, but it can also develop without any underlying illness—due to excess body weight, inappropriate footwear, or poor distribution of body weight across the feet.
What Causes Flatfoot?
The primary cause of adult-acquired flatfoot is the degeneration of the posterior tibial tendon, which attaches to the highest point of the foot’s inner arch. This tendon may weaken due to aging, overuse, obesity, or rheumatologic conditions, eventually losing its ability to function.
This tendon acts like the central pole of a tent, supporting the foot arch. When it fails to function properly—much like a collapsing tent pole—the arch gradually collapses.
The collapse doesn’t occur suddenly; rather, it progresses silently over time. The patient may first notice pain on the inner side of the foot. If diagnosed correctly at this stage, the progression of the deformity can be prevented with appropriate interventions. Unfortunately, this early stage often goes undiagnosed, allowing the condition to worsen.
As the pain in the inner foot persists, patients may start to notice a bulge or bump in the area. This isn’t a true bone spur, but a visual deformity caused by the rotation and misalignment of the foot.
Over time, the arch continues to collapse, and the heel shifts outward. As this happens, patients may begin to feel pain on the outer side of the foot as well. Eventually, this heel pain can become more intense than the inner foot pain. Some patients may also experience tightness or tension in the calf muscles.
How Is Flatfoot Treated?
If the patient receives an accurate diagnosis during this phase, it is often possible to restore the normal shape and function of the foot through a series of surgeries, performed in a single session, without the need to fuse the foot joints.