What is the mechanism of injury for an anterior process fracture of the calcaneus?

• A. Inversion with the foot in dorsiflexion
• B. Inversion with the foot in plantarflexion
• C. Eversion with the foot in dorsiflexion
• D. Eversion with the foot in plantarflexion

Answer: (B)

An anterior process fracture of the calcaneus typically occurs due to a specific mechanism involving inversion and plantarflexion of the foot. This position results in an increased stress on the anterior process of the calcaneus during activities that involve twisting or landing on the foot at an angle. When the foot is in a plantarflexed position combined with inversion, the forces can create a lever effect that exacerbates stress on the anterior process, leading to a fracture.

Inversion, which is the inward rolling of the foot, along with plantarflexion, where the toes point downwards, places the calcaneal region in a vulnerable position. The strain on the anterior part of the calcaneus during these motions is significant, especially in athletic scenarios or when a person loses balance and attempts to stabilize themselves by twisting the foot inwards. This is a common mechanism in contact sports or activities with rapid directional changes.

Other combinations of motions, such as eversion or different foot positions like dorsiflexion, would not typically produce the same kind of stress on the anterior process of the calcaneus in the same manner. Thus, the described mechanism accurately reflects how an anterior process fracture occurs, making the selected answer correct.