A “fallen arch” in adulthood is known medically as adult acquired flatfoot deformity (AAFD) or posterior tibial tendon dysfunction (PTTD). This is a progressive condition that develops over time due to the gradual weakening of the structures supporting the foot’s inner curve. Unlike a flexible flatfoot, which may not cause symptoms, a fallen arch involves a structural collapse that leads to pain and altered walking mechanics.
Visual and Pain Indicators of Arch Collapse
The most noticeable sign of arch collapse is the loss of the natural inward curve on the foot’s inner side. When standing, the entire sole of the foot may touch the ground, and the foot can appear longer or wider than it used to. This flattening is often accompanied by the heel bone tilting outward, which causes the front of the foot to point outward as well.
A distinct visual cue is the “Too Many Toes” sign, observed when looking at the feet from behind. In a foot with a collapsed arch, a person can see more toes on the affected side than on the normal foot. This occurs because the midfoot collapses and the forefoot moves outward.
Pain is a common symptom, usually beginning along the inside of the ankle and the arch. This tenderness is located where the posterior tibial tendon runs, often accompanied by swelling, warmth, and redness in that area. As the condition progresses, pain may shift to the outside of the ankle and lower leg due to bone impingement.
The altered alignment of the foot often leads to secondary pain in other joints. Because the foot rolls inward excessively (overpronation), it changes the mechanics of the entire leg. This can result in discomfort in the knee, hip, or lower back, especially after periods of standing or walking.
Simple Self-Tests to Confirm a Fallen Arch
The Wet Test, or footprint test, is a simple way to visually assess the degree of arch collapse at home. To perform this, wet the bottom of your foot and step onto a piece of cardboard, a paper bag, or a concrete surface. A normal arch will show a footprint with a distinct inward curve, where only the heel, the ball of the foot, and the toes make contact. If your arch has fallen, the resulting imprint will be wide, with the entire midfoot area filled in, showing little to no curve. Performing the test on both feet simultaneously can help identify a difference if only one arch has collapsed.
The Single Heel Raise Test is an important functional assessment that checks the strength of the posterior tibial tendon. Stand near a wall for balance, lift the unaffected foot off the ground, and attempt to raise yourself up onto the toes of the foot being tested. A healthy tendon will allow you to raise the heel fully and cause the heel bone to tuck inward (invert). If the arch has significantly collapsed, you may be unable to perform the single heel raise or experience pain when attempting it. An inability to invert the heel bone on the affected foot while rising is a strong indicator of tendon weakness or dysfunction.
Underlying Causes and Risk Factors
The collapse of the arch is most commonly linked to damage or inflammation of the posterior tibial tendon (PTT). This tendon is a major supporting structure that runs from a calf muscle, behind the inner ankle bone, and attaches to bones in the midfoot, helping to hold up the arch. When this tendon becomes overused or weakened, it can no longer provide adequate support, allowing the arch to flatten.
Age is a factor, with the condition most often seen in adults between 40 and 60 years old, as tendons naturally degenerate over time. Excess body weight significantly increases the load placed on the PTT, making obesity a substantial risk factor for arch collapse.
Certain medical conditions also predispose individuals to arch collapse. Inflammatory conditions like rheumatoid arthritis can damage the joints and ligaments in the foot, weakening the support structures. Other systemic issues such as diabetes, hypertension, and previous foot or ankle trauma can also contribute to the development of this acquired deformity.
Initial Home Management and Criteria for Seeing a Doctor
For initial management of a newly painful or fallen arch, the R.I.C.E. protocol is a traditional approach to reduce inflammation and discomfort.
R.I.C.E. Protocol
Rest involves avoiding activities that aggravate the foot, giving the stressed tendons and ligaments time to recover. Applying ice to the inner ankle where the tendon is swollen can help reduce pain and local swelling. Compression using an elastic bandage and elevating the foot above heart level can further help manage swelling in the foot and ankle.
Temporary use of supportive, over-the-counter arch supports or shoe inserts may offer immediate relief by mechanically supporting the arch and reducing strain on the posterior tibial tendon. These should be viewed as temporary measures, as they do not address the underlying tendon weakness.
It is important to seek professional medical attention if pain persists for more than a few weeks despite home care. A visit to a podiatrist or orthopedic specialist is warranted if the foot flattening progresses rapidly or if you experience significant difficulty walking. Early diagnosis is important because untreated arch collapse can lead to more serious complications, including arthritis in the foot and ankle joints.