Adult acquired flatfoot

Last evidence check April 2011

windswept heels

Windswept heels. The normal left side goes into varus on tiptoe, but the abnormal left side does not.


It is important to establish the range of ankle, subtalar and midtarsal movement. In assessing the range of ankle dorsiflexion, it is essential to test with the heel in neutral, otherwise a large range of apparent ankle dorsiflexion may be produced by subtalar eversion. Most patients have a very tight Achilles tendon which may not be detected unless ankle dorsiflexion is carefully assessed.

In a flexible flatfoot the heel normally corrects into varus and the arch reconstitutes on tiptoe standing. Two abnormal signs have been described in tibialis posterior insufficiency:

Normal single foot tiptoe test. Make sure the patient lifts the opposite foot before doing the test so they cannot use it push up. Patient should be able to do repeated tiptoes without undue pain

Abnormal single foot tiptoe test The patient cannot get the heel off the ground properly, because of weakness or pain or both

Remember heel varus is controlled by the plantar fascia as well as tibialis posterior - these signs are not pathognomonic of tibialis posterior rupture.

Obviously, if the hindfoot is stiff these tests will be meaningless. Tansey also demonstrated that heel varus on tiptoe is mainly controlled by the plantar fascia windlass mechanism. Therefore, an abnormal single foot tiptoe test does not automatically mean the tibialis posterior tendon is ruptured.

No study has been reported correlating these findings with radiological, gait analysis or surgical findings. Hence the accuracy of these tests is unknown and they may be much less useful than commonly thought.

Even if the subtalar joint can be completely reduced, there may be fixed forefoot varus/supination which can be appreciated from behind with the patient prone, or from the front. This is of considerable importance on planning treatment (see below). Some patients have a gross peritalar subluxation and the reducibility of this can be assessed.

Strength testing tibialis posterior:plantarflexion/inversion.

The strength of the tibialis posterior is best tested in plantarflexion-inversion to exclude the help of tibialis anterior. Resisted eversion tests muscle strength and irritability.


At the end of the clinical examination, the examiner should be able to answer the following questions, which will guide treatment: