Lateral ankle sprains are a frequently occurring injury amongst the general population and sportspeople. 40% of all traumatic ankle injuries occur during sports (1). Lateral ankle sprains have the highest reinjury rate of all lower limb musculoskeletal injuries (2). Those who experience an acute lateral ankle sprain have a twofold increased re-injury risk in the year following their initial injury (2). 34% of people encounter a residual problem within 3 years following first ankle-sprain incident (3). Studies suggest high reinjury rate may be due to inadequate rehabilitation of the injury and/or premature return to playing sport (12,13).
Experts in ankle injuries recently published a consensus statement in 2018 addressing ankle sprains which included the risk factors for these injuries (1). The risk factors shown below are considered ‘modifiable’; that is they are changeable and therefore can be improved upon. These modifiable risk factors are considered ‘Level 1 Evidence’ meaning that they have been clearly proven as risk factors for ankle sprains when researched in studies.
WHAT ARE THE RISK FACTORS TO DEVELOPING AN ANKLE SPRAIN?
Reduced ankle dorsiflexion range of motion
Following a lateral ankle sprain the ankle can “stiffen up” resulting in a loss of range of motion (4, 5). Extended periods in a boot or brace (sometimes necessary to aid ligament healing) can also contribute to a reduction in range of motion. Particularly the ankle dorsiflexion movement (see video below) is affected. This can result in negative consequences to the individual if not restored. Previous studies have analysed this;
- Those found to have an ankle dorsiflexion range of motion of 34 degrees (i.e. 11 degrees less than the average of 45 degrees) were nearly 5 times more likely to go on to sprain their ankle (6).
- Between 30 to 74% of people diagnosed with ‘chronic ankle instability’ were shown to have 5 degrees less of ankle dorsiflexion range of motion when compared to the other ankle (4)
- Those shown to have less ankle dorsiflexion range of motion demonstrated a less efficient ability to reduce force when performing a single-leg drop landing (4).
- Individuals with chronic ankle instability with reduced ankle dorsiflexion range of motion demonstrate poorer movement quality during a Lateral Step Down task (7).
Video: Ankle dorsiflexion
Reduced proprioception and postural control/balance deficiencies
Proprioception is the ability of the brain to integrate various signals from cells called mechanoreceptors to help determine body position and movements in space. For example, if an individual were to step on a stone when walking causing the ankle to suddenly move slightly inwards; the mechanoreceptor cells at the ankle would send messages immediately to the brain and then in response the brain would send messages to the cells at the ankle to reposition the ankle to help protect it from injury. In those considered to have reduced proprioception; this messaging system does not work optimally therefore potentially affecting a person’s ability to reposition the foot and ankle in a timely and adequate manner to avoid injury. Foot and ankle proprioception can be determined by assessing one’s balance.
Important findings from various studies:
- High school and collegiate athletes that failed to remain balanced on the Single Leg Balance test were at increased risk of going on to sprain their ankle (8).
- High school basketballers that tested poorly for Single Leg Balance when performed on a force plate measuring the pressures of the foot in a medio-lateral direction were significantly more likely to go on to encounter an ankle injury that next season (9).
- Those scoring less than 80% (of their limb length) on the posterolateral direction of the Star Excursion Balance Test (see Video #2) were at 48% increased risk of experiencing a lateral ankle sprain. Those who scored 90% or higher on this component of the test were at significantly reduced risk of ankle injury (10).
- A 4-week pre-season balance training program as well as an in-season maintenance balance program significantly reduced risk of ankle sprains in high school soccer and basketball athletes by 38% (11).
Image: Modified Star Excursion Balance Test; Posterolateral direction.
In summary, there are high rates of re-injury for ankle sprains. Those showing reduced ankle dorsiflexion range of motion and poorer single leg balance, with or without history of injury, are at increased risk of going on to experiencing a subsequent ankle injury. Research shows that by addressing the deficiencies the risk of a future ankle injury can be greatly decreased. At Continuum Physiotherapy we can assess to determine if you’re at risk of ankle injury and provide strategies to help aid in minimising your risk of this occurring.