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Collapsing arch in adults

Also called: Posterior tibial tendon dysfunction; adult acquired flatfoot

Exercise is the main treatment Strength Stretch Massage

An arch that is newly flattening in adulthood, usually on one side, with pain behind the inner ankle bone. The tibialis posterior tendon is failing - and unlike a lifelong flat foot, this one progresses to a rigid deformity if it is left.

How common: 3-10% of women over 40; frequently missed until the arch has already collapsed

Open the Foot & Heel Relief routine All problems

What it is

The tibialis posterior tendon runs behind the inner ankle bone and is the main dynamic support of the arch. When it degenerates and stretches, the arch collapses progressively, the heel drifts outward and the forefoot turns out.

The crucial difference from a lifelong flat foot is that this one progresses. It moves through stages: tendon pain with a flexible foot, then a flexible flat foot without much tendon pain, then a foot that becomes rigid and cannot be corrected, and eventually arthritis at the ankle. Caught early it responds well; caught late it is a surgical problem.

What it feels like

  • Pain and swelling behind and below the inner ankle bone
  • An arch that has flattened over months, usually on one side
  • Difficulty or inability to rise onto the toes on that leg
  • Too many toes visible when looking at the foot from behind
  • Later, pain moving to the outside of the ankle as the bones impinge

What causes it

Most people have more than one of these at once, and they feed each other. Read the list looking for the two or three that sound like your week rather than for the one true answer — the ones that describe you are the ones worth acting on.

Degeneration of the tibialis posterior tendon
The tendon has a region of relatively poor blood supply behind the inner ankle bone. Degeneration there weakens and lengthens it, and the arch it supports drops.
Progressive tendon lengthening
Once the tendon has stretched, the arch collapses further, which increases the load on the tendon, which stretches further. It is a self-accelerating process, which is why it does not stabilise on its own.
Failure of the spring ligament
As the tendon fails, the ligaments supporting the arch take more load and progressively give way too. This is the transition from a correctable problem to a structural one.
Obesity
One of the strongest risk factors. Higher load through a tendon with marginal blood supply accelerates the whole process.
Age and sex
Most common in women over forty. The combination of age-related tendon change and the loading pattern is the usual setting.
Diabetes and hypertension
Both are associated, probably through effects on the small blood vessels supplying the tendon.
Inflammatory arthritis
Rheumatoid arthritis and seronegative arthritis both affect this tendon directly and can produce rapid collapse.
A pre-existing flat foot
Starting with a flatter foot means the tendon works at a mechanical disadvantage from the outset, which raises the risk of eventual failure.
Steroid injection around the tendon
Injecting steroid into or around this tendon is associated with rupture and is generally avoided, which is worth knowing since it is a natural instinct for a painful tendon.
Delay in recognition
Not a biological cause but the main determinant of outcome. It is frequently dismissed as an ordinary flat foot for a year or more, by which time the reversible stage has passed.

Who tends to get it

  • Women over forty, in whom it is most common
  • Anyone carrying significant extra weight
  • People with diabetes, hypertension or inflammatory arthritis
  • Anyone with a pre-existing flat foot who develops new inner ankle pain
  • People who have had steroid injections around the inner ankle

What makes it worse, and what settles it

Makes it worse

  • Delay - this is the one foot condition where waiting genuinely costs the outcome
  • Continuing high-load standing and walking without support
  • Steroid injection into the tendon
  • Treating it as an ordinary painless flat foot
  • Ignoring the inability to do a single-leg heel raise, which is the key clinical sign

Settles it

  • Getting it diagnosed early, which is the single most important thing on this page
  • Orthotic support and, in early stages, a boot or brace to unload the tendon
  • Eccentric tibialis posterior strengthening, which has good evidence in the early stages
  • Calf stretching, since a tight calf increases the load on the arch
  • Weight management, which reduces the load driving the progression

What actually helps

The short version: Progressive failure of the tibialis posterior tendon, the main dynamic support of the arch; it progresses through rigid deformity if untreated

Strength work: Legs: Calves: Tibialis Posterior - heel raises with inversion, the single most important exercise; Feet, Toes, Ankles; Glutes: Med; Feet, Toes, Ankles: Intrinsic Foot Muscles

Stretching: Legs: Calves; Legs: Calves: Gastrocnemius - a tight calf drives this

Massage: Legs: Calves; Feet, Toes, Ankles

Also worth doing: Orthotic support; a stiff-soled shoe; catching it in stage 1 or 2 avoids surgery

What the evidence says: Eccentric heel raises with orthoses resolve most stage 1 and 2 cases. Delay means a rigid deformity that only surgery corrects - so early recognition is the whole game.

The names above are the Targets qFIT tracks — the Muscle Guide explains what each one does, and Quick Add switches on the Exercises you already have.

The qFIT routine for this

Ready-made routineFoot & Heel Relief

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Get it checked if…

A flattening arch with pain behind the inner ankle that you cannot do a single-leg heel raise on is stage 2 or worse - refer, this progresses

And whatever the body part: chest pain or unusual breathlessness on exertion; a fever alongside the pain; unexplained weight loss; pain that is constant and unrelated to how you move; new numbness, weakness or loss of bladder or bowel control; or one calf that is swollen, warm and painful. Any of those, stop and get assessed.

How it usually goes

Caught in the early stages - a painful tendon with a foot that is still flexible - orthoses plus eccentric strengthening produce good results in a majority over three to six months. Once the deformity is rigid, exercise cannot correct it and surgery is the option. That contrast is the whole reason this page exists: new inner ankle pain with a dropping arch and difficulty rising onto the toes deserves an assessment now rather than in a year.

Prevalence basis: Foot and ankle epidemiology

Others the same routine covers

These share the Foot & Heel Relief routine, so the work is the same. If one of them also sounds like you, that is a reason to expect more from it, not less.

Foot pain Plantar fasciitis Flat feet and overpronation High arches Ball-of-foot pain Bunions Hammer and claw toes Ball-of-foot nerve pain Burning sole of the foot Stiff big toe Turf toe High heel calf shortening

This is general information, not a diagnosis, and it cannot examine you. If it matches you, use it to ask better questions of a clinician rather than to replace one.

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