Tibialis Posterior Tendon Dysfunction (Adult Acquired Flatfoot Deformity)
Testing tibialis posterior strength
Significant History/Physical symptoms
Posterior tibial tendon dysfunction (disorder or rupture) is a term that covers a constellation of signs and symptoms. It is increasingly referred to as adult acquired flatfoot deformity (AAF) as a diagnostic term because the condition is more complex and involved than simply a dysfunction of the tibialis posterior muscle and tendon. Conservative treatment is advocated early as mild deformity can progress rapidly and lead to increasing pain and loss of function for the patient.
Some evidence suggests the underlying mechanism for chronic TPTD is degenerative tendinosis rather than tendinitis.
Any disruption to the tibialis posterior tendon results in other ligaments becoming plastically deformed and a flatfoot can result. Also the force generated by the gastrocnemius and soleus muscles is reduced. Gait will therefore be adversely disrupted. The loss of strength of the tibialis posterior tendon can be sudden or gradual.
Radiographic evaluation is not required in order to make a diagnosis of dysfunction of the posterior tibial tendon, the diagnosis is based on clinical evaluation.
- 3 times more common
- ≥ 40 years old
- pain location medial ankle/foot
- aggravated by activity
- patient recalls traumatic (often minor) event
- difficulty walking on uneven ground
Stage 1 | Stage 2 | Stage 3 | Stage 4 | |
Posterior tibial tendon | Tenosynovitis, degeneration, or both | Elongation and degeneration | Elongation and degeneration | Elongation and degeneration |
Deformity | Absent | Flexible, reducible pes planovalgus deformity with hindfoot held in equinus | Fixed, irreducible pes planovalgus deformity | Fixed, irreducible pes planovalgus deformity |
Pain | Medial | Medial, lateral, or both | Medial, lateral, or both | Medial, lateral, or both |
Single limb heel-rise | Mild weakness; hindfoot inverts normally | Marked weakness; None or limited inversion of the hindfoot | Unable to perform test; no inversion of hindfoot | Unable to perform test; no inversion of hindfoot |
Too many toes sign | Negative | Positive | Positive | Positive |
Valgus deformity and arthritis of the ankle | No | No | No | Yes |
Table showing the 4 stages of Posterior Tibial Tendon Dysfunction (PTTD), adapted from Johnson KA, Strom DE. Tibialis posterior tendon dysfunction. Clin Orthop 1989;239:197 |
Less Common Differential Diagnoses not included in this pathway:
- Spring ligament strain / rupture
- Tarsal coalition
- Inflammatory arthritis
- Charcot arthropathy
- Neuromuscular disease