If less dorsiflexion is observed with the knee extended, but increased with the knee flexed, what type of equinus is indicated?

If less dorsiflexion is observed with the knee extended, but increased with the knee flexed, what type of equinus is indicated?

• A. Achilles equinus
• B. Tibialis equinus
• C. Gastroc equinus
• D. Soleus equinus

Answer: (C)

The observed phenomenon of less dorsiflexion with the knee extended but increased dorsiflexion with the knee flexed indicates a specific type of equinus known as gastrocnemius equinus. This condition primarily involves the gastrocnemius muscle, which is responsible for plantarflexion and crosses both the knee and ankle joints. When the knee is straightened (extended), the gastrocnemius muscle is placed on tension, which limits the available dorsiflexion at the ankle joint. Conversely, when the knee is flexed, the gastrocnemius is relaxed, allowing for greater dorsiflexion at the ankle. This differential behavior in dorsiflexion based on the knee's position is a distinguishing characteristic of gastrocnemius equinus. Other forms of equinus may involve different muscles or conditions but do not exhibit this pattern tied directly to knee extension and flexion as seen with gastrocnemius equinus. For instance, isolated soleus involvement would not produce this specific response, as the soleus muscle does not cross the knee joint and thus does not rely on knee positioning to affect ankle dorsiflexion.

The observed phenomenon of less dorsiflexion with the knee extended but increased dorsiflexion with the knee flexed indicates a specific type of equinus known as gastrocnemius equinus. This condition primarily involves the gastrocnemius muscle, which is responsible for plantarflexion and crosses both the knee and ankle joints. When the knee is straightened (extended), the gastrocnemius muscle is placed on tension, which limits the available dorsiflexion at the ankle joint. Conversely, when the knee is flexed, the gastrocnemius is relaxed, allowing for greater dorsiflexion at the ankle.

This differential behavior in dorsiflexion based on the knee's position is a distinguishing characteristic of gastrocnemius equinus. Other forms of equinus may involve different muscles or conditions but do not exhibit this pattern tied directly to knee extension and flexion as seen with gastrocnemius equinus. For instance, isolated soleus involvement would not produce this specific response, as the soleus muscle does not cross the knee joint and thus does not rely on knee positioning to affect ankle dorsiflexion.