Adult acquired flatfoot is a progressive collapse of the arch, usually from failure of the posterior tibial tendon. Caught early, custom orthotics and a loading programme can halt progression. Left to advance, the deformity becomes fixed and needs reconstructive surgery, so early assessment matters.
Symptoms
- Pain and swelling along the inner ankle and arch (often mistaken for a sprain)
- A slowly flattening arch on one side
- As it advances, the heel tilts outward
- A "too many toes" sign when viewed from behind
- Pain may shift to the outer ankle in later stages
Causes & risk factors
- Posterior tibial tendon dysfunction (the usual cause)
- Inflammatory arthritis
- Charcot change in diabetes
- Ligament laxity
Conservative treatment comes first
- Custom medial-arch orthotics
- Physiotherapy to strengthen tibialis posterior and stretch the calf
- A walking boot for an acute flare
- Motion-control footwear
- These cannot reverse an existing deformity but can stop it progressing
When surgery is considered
A flexible deformity is treated with a heel-bone osteotomy and tendon transfer, sometimes with medial column stabilisation. A fixed deformity needs a fusion (subtalar or triple). There is a non-weight-bearing period and full recovery takes 9–12 months.
Questions & answers
No, but used early they can prevent it progressing to a stage that needs major surgery.
Usually not. Childhood flat feet are typically both sides and painless; adult acquired flatfoot is usually one side and progressive.
Not early on. An arch that is changing shape on one side is worth assessing even without much pain.
Sources & further reading
- OrthoInfo (AAOS) — PTTD
- BOFAS — flat feet in adults
