What condition is characterized by the inability of the posterior tibialis tendon to function properly, leading to medial ankle pain?

• A. Achilles tendon rupture
• B. Posterior tibial tendon dysfunction
• C. Medial plantar nerve entrapment
• D. Flexor digitorum longus strain

Answer: (B)

The condition characterized by the inability of the posterior tibialis tendon to function properly, resulting in medial ankle pain, is posterior tibial tendon dysfunction. This condition occurs when the posterior tibialis tendon, which plays a crucial role in supporting the arch of the foot and stabilizing the ankle, becomes overstretched, torn, or degenerates over time. As this tendon fails to function effectively, it can lead to symptoms such as pain along the medial aspect of the ankle, swelling, and potential flatfoot deformity due to the loss of support for the arch.

In contrast, other options, such as Achilles tendon rupture, primarily involve the heel and the back of the ankle rather than the medial aspect, making them less relevant to the described symptoms. Medial plantar nerve entrapment may cause pain in the medial anatomy but would not directly relate to the dysfunction of the posterior tibialis tendon. Similarly, a flexor digitorum longus strain would generally cause pain in the toes and foot rather than the medial ankle specifically, further clarifying the relevance of posterior tibial tendon dysfunction to the given symptoms.