Can the shape of my foot make me more prone to ankle sprains and fractures of the foot?

smaller ankle issues

dr duggal foot and ankle specialist

Commentary by Naven Duggal, MD

Sprained ankles are the most frequently seen sports injury, with ankle sprains and fractures of the fifth metatarsal common in athletes following inversion of the ankle with a flexed foot. Lateral ankle sprains affect an estimated two million people in the US each year with associated health care costs estimated at $4.2 billion. One of the most common long-term consequences of lateral ankle sprains is chronic ankle instability, affecting 30-70% of those who experience a first-time sprain. Fifth metatarsal fractures are unique because the blood supply can be disrupted and thereby compromise the bone’s ability to heal compared to fractures in other bones of the foot.

Given these details, it has been asked if some people are more prone to fractures than others? In fact, foot deformities are often associated with gait abnormalities that may contribute to the development of fractures and sprains in the ankle. One such deformity, the high arched, or cavus foot, has been associated with lateral ankle sprains and instability as well as fractures of the fifth metatarsal. The cavus foot is characterized by a high longitudinal arch, a flexed great toe, claw toes, and callous over the fifth metatarsal base. The patient with a cavus foot will often overload the fourth and fifth metatarsals, thereby increasing the likelihood of developing a stress fracture. The position of the calcaneus in a cavus foot will also increase the chance of turning the ankle when an athlete lands from a jump with the foot malpositioned.

How best to treat these injuries? Nonoperative management with an early functional rehabilitation program remains the most important intervention with most ankle sprains. The majority of fifth metatarsal fractures can also be treated in a nonoperative fashion with casting or the use of a walking boot. Patients with a cavus foot with an ankle sprain or fifth metatarsal can follow the same initial nonoperative protocol, however, they may need to be monitored closely to confirm that their fractures and ligaments are healing appropriately. In addition, cavus patients will often benefit from the use of an orthotic with an outer foot support that can be helpful in decreasing episodes of instability and provide additional fracture stability.

Recognizing the cavus foot is important in ensuring a successful outcome in the nonoperative and operative treatment of patients with ankle sprains and fifth metatarsal fractures. My colleagues and I at the Harvard Biomechanics Laboratory are currently forming additional biomechanical research studies which are designed to further understand the relationship between a patient’s anatomy and their risk of developing an ankle sprain or fracturing the foot. We look forward to sharing the learnings and outcomes.