Tibial posterior tendon dysfunction in the athlete.
Tibialis posterior dysfunction (TPD) also sometimes called Adult Aquired Flat Foot (AAF) represents one of the most important foot injuries encountered in sport, and whilst considered uncommon in the younger athlete, it is frequently overlooked in older individuals.
Any athlete reporting a visible unilateral flattening of the arch over a relatively short period of time, either idiopathic or associated with trauma, should be evaluated for the diagnosis of TPD.
Etiology and Pathomechanics
The appearance of a unilateral flat foot in an adult athlete is the principle characteristic of TPD and, according to Mueller (1991), there are four different categories for the etiology of TPD.
Type I – Direct injury: Trauma/laceration
Type II – Pathological rupture: Secondary to some other disease process e.g. rheumatoid arthritis.
Type III – Idiopathic rupture: Unknown cause.
Type IV – Functional rupture: Tendon intact, but functioning poorly, e.g. long term tensile forces or abnormal insertion (os tibiale externum).
This classification seems a sensible summary of the potential causes of TPD, with Type IV highlighting the importance of long term tensile loading as a cause of the lesion. Prolonged abnormal pronation has also been suggested as a cause (Welton and Rose 1993) of TPD, with Ross (1997) explaining that the resultant eversion of the rearfoot, overpowers the gastrocnemius/soleus complex and acts at the level of the midfoot, specifically the talonavicular joint.
As tibialis posterior loses function, peroneus brevis is allowed to act more independently, thereby creating an abduction and eversion force. As these dynamic forces progress, a gradual attenuation of the medial static constraints of the longitudinal arch occurs.
The disorders now builds momentum, with a quite rapid loss of integrity of the secondary soft-tissue supports of the midfoot, notably the spring ligament, deltoid ligament and talonavicular capsule.
This creates a self-fulfilling prophecy, with an increase in valgus loading, increase in intratendon force on the tendon of tibialis posterior, accelerated loss of tibialis posterior function and everted medial subluxation of the talus, gross calcaneal valgus and rotation-tightening deformity at the Achilles tendon.
This creates an equinus deformity in association with chronic malalignment of the talonavicular joint, medial column and rearfoot.
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Director of Bartold Clinical