Adult acquired flatfoot

and tibialis posterior tendonopathy

Examination

Feel

Palpation of the tibialis posterior tendon	Lateral impingement pain in severe hindfoot valgus

Palpation of the tendon may demonstrate tenderness, thickening, synovitis or a thinned or apparently absent tendon. The deltoid and spring ligaments should be carefully palpated. Tenderness may be found in the sinus tarsi, especially with hindfoot abduction.

Move

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:

• failure of the heel to move into varus on double tiptoe standing; if the opposite heel goes into varus "windswept heels" may be noted
• inability, or extreme difficulty, in doing a single foot tiptoe test; in a few patients the heel comes off the ground but a midfoot breach develops and the forefoot does not rise.

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

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.

Conclusions

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

• what is the main problem – tendon pain, ankle pain, deformity, lateral impingement, arthritic pain
• is there an apparent underlying cause such as inflammatory arthritis?
• is the foot deformed?
• is the deformity mainly peritalar or cuneometatarsal?
• is the hindfoot deformity correctable?
• is there fixed hindfoot/forefoot malalignment?
• is the Achilles tendon tight?
• are there any associated problems – hallux valgus, secondary arthritis, tarsal tunnel syndrome?

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