A marathon runner with rigid cavus feet experiences knee pain after using custom orthotics. What could be the issue?

In the case of a marathon runner with rigid cavus feet experiencing knee pain after using custom orthotics, the issue could indeed be that the orthotics are too hard. Rigid cavus feet typically have a high arch and reduced flexibility, which can lead to an increased amount of stress placed on the foot and lower extremities during activities like running. If the orthotics are too rigid or hard, they may provide inadequate cushioning and shock absorption for the runner's needs.

In such scenarios, the lack of adequate cushioning from overly hard orthotics could lead to increased impact forces traveling up the kinetic chain, potentially resulting in knee pain. It’s important for orthotics to be specifically tailored not only to the shape of the foot but also to how the foot functions during high-impact activities. A more appropriately designed orthotic, which balances support with sufficient cushioning, may help alleviate these symptoms.

Considering the other options, while they address various aspects of orthotic fit and function, they do not directly align with how overly rigid custom orthotics could exacerbate the condition at hand, leading to knee pain for this athlete. Too soft would not provide the necessary support needed for cavus foot, too short could affect overall foot placement, and insufficient subtalar joint control would