Ligaments are key features of the ankle joint which work to provide stability and control range of motion (Hunt & Lawson, 2019). Ankle sprains can result in damage to the medial ligaments, lateral ligaments or the syndesmotic tibiofibular joint (Ângelo de Castro & Torres, 2019). Respectively, these injuries are referred as medial, lateral or high ankle sprains. Sprains are usually graded based on severity and range from mild (grade I), indicating no significant structural damage to severe (grade III), a complete rupture of the ligamentous structures (Kaminski et al., 2013). Lateral ankle sprains are the most common and are often caused by exaggerated supination and inversion of the foot, with external rotation of the tibia (Ângelo de Castro & Torres, 2019). This movement creates tension which stretches the ligaments beyond their tensile strength, resulting in damage. A lateral ankle sprain (LAS) is a highly prevalent musculoskeletal injury among the general population and athletes; it is one of the most common injuries in competitive and recreational sport, accounting for 10% to 30% of all sports injuries (Kobayashi, Tanaka, & Shida, 2016). More than 40% of patients who suffer a LAS will experience a repeated ankle sprain which can result in chronic ankle instability (CAI) or ankle osteoarthritis (Kobayashi et al., 2016). It is important that effective prevention strategies are developed in order to minimise the frequency of ankle sprains. An exercise prescription is a specific plan of fitness-related activities that are designed to meet the health and fitness needs of an individual to allow them to achieve their goals and maintain healthy function (Hoffmann et al., 2016). Exercise programmes can be used by athletes to reduce their risk of developing an ankle sprain.
Brinkman and Evans (2011) state that a key step in preventing ankle sprains, is identifying their risk factors. Risk factors for ankle sprains can be classified into intrinsic (factors related to the individual) and extrinsic factors (environmental components). There are many intrinsic risk factors for the development of LAI, including strength, proprioception, range of motion and balance (Kerkhoffs et al., 2012). Amongst reduced range of motion, limited dorsi flexion appears to be a key element. It is important that when clinicians are addressing these risk factors, that they consider whether they can be modified or not (Vuurberg et al., 2018). Modifiable risk factors can be targeted using prehabilitation programmes in order to reduce injury rates, whereas non-modifiable factors cannot be altered. Despite this, non-modifiable factors are still of clinical use, as they allow professionals to identify groups who are at an increased risk of injury and adapt prevention strategies to minimise this risk.
Previous ankle sprains are identified as the strongest intrinsic risk factor (Noronha, França, Haupenthal, & Nunes, 2012). The literature suggests that individuals who have suffered an ankle sprain are six times more likely to suffer subsequent sprains than those who have not (Hartley, Hoch, & Boling, 2018). Even though ligaments go through a healing process, they may not return to their original functional capacity (Noronha et al., 2012). Consequently, following a sprain, the ligaments that stabilise the ankle joint are no longer optimal, increasing the risk of a subsequent sprain.
Furthermore, high BMI is identified as a risk factor for ankle sprains; Kobayashi et al., (2016)performed a systematic review to identify specific intrinsic factors that can predict LAS, in order to minimise the prevalence. The findings of the study showed a significant correlation between high BMI and LAS, with a significantly greater BMI present in the injury group than in the noninjury group. An increase in BMI increases the magnitude of inversion torque that must be resisted by the ankle-complex when the foot is in an at-risk position (Ângelo de Castro & Torres, 2019).
Inadequate strength of the ankle and hip-joint muscles are believed to be risk factors for sustaining an ankle sprain. Fousekis, Tsepis, and Vagenas (2012), reported that asymmetries in the eccentric isokinetic strength of the ankle-joint dorsiflexors and plantar flexors were risk factors for noncontact ankle sprains among football players. Preseason eccentric strength asymmetries of 15% in the ankle joint correlated to an 8.8 times greater risk of sustaining a noncontact ankle sprain compared to players who had no eccentric strength asymmetry. Furthermore, De Ridder, Witvrouw, Dolphens, Roosen, and Van Ginckel (2017), reported that reduced hip-extension strength was linked to an increased risk of sustaining a LAS.
The peroneal muscles are the main evertors of the foot and ankle complex (Lin, Chen, & Lin, 2011); their muscle spindles contract when the ankle is forced into inversion to restrict this movement and prevent damage to the ankle structures (Heckman, Reddy, Pedowitz, Wapner, & Parekh, 2008). Decreased ankle eversion strength (Arnold, Linens, de la Motte, & Ross, 2009) and delayed peroneal muscle reaction time (Hoch & McKeon, 2014; Strøm et al., 2016) are associated with ankle sprains; these factors mean that the peroneal muscles cannot correct the foot position to stop the ankle inverting in time to prevent injury. It is crucial that the peroneus longus and peroneus brevis contact simultaneously to generate adequate force to prevent inversion.
An additional intrinsic risk factor is poor postural balance. Attenborough AS, Sinclair PJ, and Sharp T (2017), studied balance using the Star Excursion Balance Test and found that impaired dynamic postural balance was a risk factor for ankle sprains. Proprioception plays an essential role in balance control; central processing of ankle proprioceptive information, along with other sensory information, enables optimal balance control (Cullinane, Boocock, & Trevelyan, 2014; Pasma, Boonstra, Campfens, Schouten, & van der Kooij, 2012).In many sports, good balance is necessary to reduce the risk of ankle sprains.Ankle proprioception is believed to be one of the most important components of balance, especially in sports, as during most activities the ankle-foot complex is the only body part in contact with the ground (Han, Anson, Waddington, Adams, & Liu, 2015). Ankle proprioception provides essential information to enable adjustment of ankle positions to prevent injury (Han et al., 2015). Poor ankle proprioception is therefore a key risk factor; proprioceptive training should be incorporated into prehabilitation programmes to reduce this risk.
The rate of incidence varies across genders and ages, with children believed to be at the highest risk of sustaining an ankle sprain (Doherty et al., 2014). This could be explained by children having incomplete development in sensorimotor function (Quatman-Yates, Quatman, Meszaros, Paterno, & Hewett, 2012). It is essential that the rate of injury in children is reduced, as injury at a young age can have a negative impact on their activity levels and may lead to long term complications (Ângelo de Castro & Torres, 2019), thus showing the importance of prehabilitation programmes.
Literature supports the association between fatigue and impairment of joint position sense; neuromuscular feedback can be inhibited by muscle fatigue around the joint (Jahjah et al., 2018). It is believed that fatigue increases the risk of inversion ankle sprains, as most ankle sprains occurred in the last third of the first and second halves of matches.
Extrinsic factors can include the sport, level of competition and the position (Kerkhoffs et al., 2012). Aero ball, wall climbing, indoor volleyball, rock climbing, basketball and field sports had the highest reported incident rates. Furthermore, the level of competition and contact with opponents also plays a role; defenders and attackers are at a higher risk due to contact nature of these positions (Kerkhoffs et al., 2012).
To conclude, there are a number of intrinsic and extrinsic factors. Coordination and balance training have been shown to prevent recurrent ankle sprains (Vuurberg et al., 2018), therefore these methods should be incorporated into all prehabilitation programmes.
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