What are the results of progressive posterior tibialis tendon dysfunction?

Progressive posterior tibialis tendon dysfunction primarily affects the stability and support provided to the medial longitudinal arch of the foot. As the condition progresses, the posterior tibialis tendon becomes weakened, leading to a loss of function. This results in an inability to maintain the medial arch, ultimately causing its collapse.

Additionally, as the medial longitudinal arch collapses, the subtalar joint may also become increasingly unstable, resulting in hindfoot valgus. In this position, the heel tilts outward relative to the lower leg, contributing to a flatfoot deformity.

The combination of these two results – both the medial longitudinal arch collapse and hindfoot valgus – is characteristic of the degenerative changes observed in progressive posterior tibialis tendon dysfunction. This explains why the correct answer encompasses both of these outcomes.