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Ankle sprains are extremely common, especially for athletes and active individuals. In fact, if you’re athletically involved to any extent, there’s a strong chance that you will sprain your ankle at some point down the road. Ankle sprains account for up to 45% of all sports–related injuries, and approximately 25,000 people sprain their ankle every day. Playing certain sports will also affect your odds, as football, basketball, and soccer have the highest rates of ankle sprains because they involve fast speeds and frequent changes in direction.

The good news is that most ankle sprains are relatively mild, and patients can typically expect to recover and return to their respective activity or sport in a reasonable amount of time; however, recovering from an ankle sprain is not always the end of the story. About 40% of individuals who sprain their ankle will go on to develop chronic ankle instability (CAI), which is a condition that involves persistent instability and an increased risk of experiencing additional ankle sprains due to a combination of impairments. On account of these impairments, patients with CAI may also be at an increased risk for subsequent injuries of the joints proximal to the ankle—the knees, hips, and lower back—because each of these joints influences the movement of the others.

Many experts believe that CAI increases the risk for injury to these proximal joints, but this has not yet been confirmed with research. Therefore, a study was conducted to investigate how many patients who initially suffered an ankle sprain went on to experience any knee, hip, or back issues within the following year, and whether therapeutic exercise had any effect on this relationship.

Researchers extracted data from the medical records of military personnel in the US Military Health Repository and searched for individuals who experienced an ankle sprain over a two–year period. Medical records of these individuals were then examined to determine if any additional injuries occurred to the knee, hip, or lower back region within the following 12 months. Researchers also looked for data on how many patients underwent therapeutic exercise—such as physical therapy—and whether it affected their risk for experiencing subsequent injuries.

From this search, 33,361 patients who suffered an ankle sprain were identified and included in the study. Of these, 6,848 individuals (20.5%) went on to sustain a secondary injury within the following 12 months, with 40% of these patients having a lower back injury, 39% having a knee injury, and 8% having a hip injury. The remaining patients had a combination of injuries in at least two regions. Further analysis revealed that only 28% of patients were prescribed therapeutic exercise after their initial ankle sprain; however, therapeutic exercise had a protective effect, as these individuals had a lower risk for experiencing a hip injury (32% reduction), lower back injury (18% reduction), or knee (13% reduction) injury.

Although these findings do not prove that ankle sprains directly cause secondary injuries in other joints of the body, they do suggest that there is a relationship between these events, and that ankle sprains appear to be associated with an elevated risk. Furthermore, this study provides evidence that patients who undergo therapeutic exercise after an ankle sprain are less likely to sustain further injury to the hips, knees, or lower back.

We therefore encourage athletes and active individuals to recognize the importance of safely recovering from an ankle sprain and avoiding further exacerbations during this time. Since therapeutic exercise was found to have a protective effect on injury risk, we also recommend seeing a physical therapist if you experience an ankle sprain for a comprehensive rehabilitation program that will help to reduce your risk for future injuries of the ankle and other joints in the region.