Narrative review of the mechanisms, intrinsic risk and predictive factors, and incidence of lateral ankle sprains amongst male and female athletes participating in sex-similar sports

Abstract

Background

Lateral ankle sprains (LAS) are the most common sports-related injuries. Despite increased female participation in sport, there is little information explaining how sex-specific musculoskeletal anatomy lends itself to the mechanisms that cause LAS.

Objective

Perform a narrative review of the literature from 2000 to the present (2025) that investigates if and how sex affects the mechanism, risk and predictive factors, and incidence of LAS amongst male and female athletes participating in sex-similar sports and activities.

Methods

Three electronic systematic literature searches of PubMed were performed. One on July 6^th, 2022, one on March 2^nd, 2023, and the last on August 28^th, 2025. Included articles contained information regarding the lateral ligament complex (LLC) or LAS in individuals participating in sex-similar sports, activities, or movements. Articles focused on the diagnosis, recovery, prevention, and long-lasting effects of LAS were excluded. For parallel LAS incidence studies conducted on males and females, two-sample t-tests, assuming unequal variances, were performed using a 5% significance level.

Results

One hundred sixteen articles met the study inclusion criteria. Lower body kinematics and kinetics, history of previous sprain, and multiple hop and balance tests were risk factors for LAS in males and females. History of previous sprain, anatomical alignment, weight, ankle joint laxity, general balance, BMI, and hip strength may be more prevalent risk factors in males, while postural sway and instability may be a more prevalent risk factor in females. Epidemiology studies investigating LAS incidence relative to all injuries did not find females to sustain significantly more LAS than males. Epidemiology studies investigating LAS incidence relative to all ankle injuries found females to sustain significantly more LAS than males.

Conclusions

Although sex was found to influence the morphology and morphometry of the LLC, there was a lack of research that used these anatomical differences to justify differences in LAS risk factors, thresholds for injury, or mechanisms of injury that exist between males and females. Future work should look to distinguish whether musculoskeletal anatomical differences between male and female ankles influence sex-specific biomechanics and mechanisms of injury, as these factors contribute to LAS incidence and risk factors.

Supplementary Information

The online version contains supplementary material available at https://doi.org/10.1186/s13102-026-01857-9.

Introduction

Ankle injuries, particularly sprains, are some of the most common sports-related injuries in the United States across all ages and levels of play [1–6]. These injuries are especially prevalent in sports that combine jumping and rapid changes in direction [7–13]. Most ankle injuries in physically active populations are lateral ankle sprains (LAS) [6, 8, 14–18], which correspond to time away from sport [2, 19] and billions of dollars in medical costs each year [9, 18, 20].

There is reason to believe female athletes are at higher risk of ankle sprain injuries than their male counterparts [2, 19, 21, 22]. A two-year investigation of injury data of NCAA athletes [2] found that 44% of the missed time injuries involved the ankle, and when compared to their male counterparts, female athletes sustained significantly higher foot and ankle injury incidence rates. Studies amongst high school [23] and collegiate [24] athletes have concluded that while overall ankle sprain rates may not differ between male and female athletes, in sex-comparable sports, ankle sprain rates were higher for girls, with a majority of sprains being to at least one ligament of the lateral ligament complex (LLC) [23].

Despite continuously increasing rates of female participation in sport [25, 26] and evidence that foot and ankle injuries might be more prominent in female athletes, female athletes remain significantly underrepresented within ankle injury research [19, 22, 25–30]. An overwhelming amount of scientific investigation into ankle injuries has and continues to focus on male athletes, and be generalized to female athletes [19, 25, 28, 30–32].

While there has been some comparison between male and female ankle injury rates, there is little information explaining if and how sex-specific musculoskeletal anatomy lends itself to the mechanisms that cause LAS [19, 33–35]. It is possible that in addition to differences in exposure, there exist physiological and anatomical differences that impact injury rates [19, 24, 36]. Research evaluating the factors influencing differences in LAS between males and females must be performed to identify how to best prevent injury in both male and female athletes [19, 28, 30, 33–35, 37]. The purpose of the present study is to perform a narrative review of the literature from 2000 to the present (2025) that investigates if and how sex affects the mechanism, risk and predictive factors, and incidence of LAS amongst male and female athletes participating in sex-similar sports and activities.

Methods

Design and search strategy

This narrative review incorporates evidence identified through a systematic literature search. Three electronic systematic literature searches of PubMed were performed. One on July 6th, 2022, one on March 2nd, 2023, and the last on August 28th, 2025. The keyword string of the search performed on July 6th, 2022 was ‘(injury OR injuries OR sprain) AND (sport OR sports OR athletes OR athletic) AND ankle’, which appeared in the title or abstract. The keyword string of the searches performed on March 2nd, 2023 and August 28th, 2025 was ‘(injury OR injuries OR sprain) AND ankle’, which appeared in the title or abstract, and ‘(sport OR sports OR athletes OR athletic) AND sprain AND lateral’, which could appear anywhere in the article. For each search, the literature was restricted to articles published from 2000 to the present.

Study selection

Articles included in the search were limited to publication in the English language. The inclusion and exclusion criteria used to trim the dataset are provided in Table 1. While a goal of this review was to evaluate anatomical, physiological, and biomechanical differences in relation to sex, these factors were only to be evaluated in relation to the LLC and LAS. One investigator reviewed all the titles and abstracts produced by the search to exclude non-related studies based on the inclusion and exclusion criteria.

Table 1.

Inclusion and exclusion criteria

Inclusion Criteria

Exclusion Criteria

The study must • contain information regarding LAS or the LLC anatomy and physiology. • evaluate the ankle joint complex prior to or during the occurrence of LAS or evaluate the incidence of LAS. • be performed on individuals participating in sex-similar sports/activities/movements.

The study must not • solely be about injury management, treatment, recovery, rehabilitation, or intervention. • solely be about extrinsic risk factors. • focus on diagnosing a sprain or methods of ankle assessment. • be about surgical interventions. • be about protective equipment or orthoses (i.e. ankle braces, taping) • focus on the long-lasting effects of LAS. • focus on individuals with either functional ankle instability (FAI) or chronic ankle instability (CAI) • focus on post-injury analysis. • focus on comparisons between injured and healthy individuals. • focus on a sport outside of the 24 NCAA sports. • Be a case study with sample size ≤ 5 • Focus on hormonal or molecular biological factors

Data extraction

The first, second, and third searches produced 1,131, 768, and 1,010 articles, respectively. After accounting for duplicates, 1,722 articles were produced from the combined searches. Following the initial screening of titles and abstracts, 158 articles were selected for screening. Further breakdown of study section is shown in Fig. 1. The title, authors, year of publication, and journal or conference of publication of each study were extracted. If applicable, the sample size, sample sex, and sport under evaluation were also extracted. Each study’s aims, outcome measures, and key findings relevant to the purpose of this review were extracted.

Fig. 1.

Flow diagram of study selection

The information contained within this review is based off more than just the 158 articles selected for screening from the three electronic literature searches. Information included from outside of the electronic literature searches was discovered from references within the articles produced by the literature searches and from background research efforts.

Statistical analysis

For parallel LAS incidence studies conducted on independent samples of NCAA male and female athletes in sex-similar sports, statistical analysis could be performed. For these parallel studies, a two-sample t-test, assuming unequal variances between the male and female data for each sport was performed. A 5% significance level was used for each t-test. The same statistical methods were also performed on parallel studies of male and female physical education students.

Results

Full text screening of the remaining articles produced 116 articles for inclusion (Fig. 1). Of the 116 articles, 30 had samples of males only, 12 had samples of females only, 56 had mixed samples of males and females, and 18 had unclear sample demographics. Of the 56 articles with mixed samples, only 26 performed sex-specific analyses to show if differences existed between males and females.

Ankle anatomy

The ankle joint complex forms the linkage between the long bones of the lower extremity and the bones of the foot [38]. It is comprised of three joints: the talocrural joint, the subtalar joint, and the distal tibiofibular syndesmosis [9, 38–41]. The motions of the three joints are dependent on one another and combine to create fluid motion of the rearfoot [9, 39]. For the purposes of this review, we will only focus on the anatomy of the talocrural and subtalar joints since these articulations are most relevant to LAS. A lateral ankle sprain constitutes injury to one or more of the ligaments in the lateral ligament complex (LLC), which is comprised of the anterior talofibular ligament (ATFL), posterior talofibular ligament (PTFL), and calcaneofibular ligament (CFL) (Fig. 2) [7, 35, 40, 42–50].

Fig. 2.

The LLC is comprised of the ATFL, CFL, and PTFL

Talocrural joint

The talocrural joint is formed by the distal tibia and fibula of the lower leg and the dome of the talus [9, 38, 39]. The malleoli of the distal tibia and fibula constrain the talus, creating an oblique axis of rotation through the malleoli, which allows the joint to function primarily as a hinge, permitting motions in plantarflexion and dorsiflexion [9, 38, 39, 41, 51]. Plantar and dorsiflexion are critical for gait cycle mechanics during running and takeoff and landing mechanics during jumping. The talocrural joint contains all three ligaments of the LLC, which stabilize the lateral side of the joint [9, 39, 47, 51].

Subtalar joint

The subtalar joint is formed by the talus and calcaneus [9, 39]. The talus rests on the anterior portion of the calcaneus, creating an oblique axis of rotation which originates from the posterior distal lateral calcaneus and angulates medially through the talus [38, 39, 41, 51]. The axis of rotation allows for pronation and supination of the ankle joint complex [39, 41, 51]. Pronation involves a combination of eversion, dorsiflexion, and abduction [7, 38, 39, 51]. Supination involves a combination of inversion, plantarflexion and adduction [7, 38, 39, 41, 51]. Inversion and eversion are the primary motions of the subtalar joint [9, 38] and because the fibula typically extends further than the tibia, there is more of a barrier on the lateral side obstructing eversion [35, 41]. Pronation and supination are critical for cutting movements, rapid changes of direction, and landing stabilization during jumping. The CFL is the only ligament of the LLC that is included in the subtalar joint [39, 47].

LLC

ATFL

The ATFL originates on the lateral malleolus of the fibula and attaches anteriorly and medially to the neck of the talus [7, 39, 41, 42, 46, 49]. The ATFL is the weakest ligament in the LLC, the most commonly injured, and usually the first ligament to rupture during LAS [9, 35, 39–43, 47–50, 52–58]. Ruptures to the ATFL are generally evenly distributed between the proximal, middle, and distal portions of the ligament [56]. The ATFL is the primary restraint against excessive ankle inversion and plantarflexion and internal rotation of the foot by preventing anterior translation of the talus with respect to the tibia, and is most likely to be injured in plantarflexion [7, 9, 35, 39, 41, 42, 46, 49, 50, 59]. LAS consist of an isolated ATFL rupture 65% to 73% of the time and a combined rupture of the ATFL and CFL 20% to 30% of the time [40, 41, 53].

A cut-down cadaveric study further distinguished the ATFL as having a superior and inferior fascicle, with the superior fascicle serving as the more important structure for ankle stability by best sustaining ligament strains in plantarflexion while restraining internal rotation and anterior translation of the talus [43]. Although the superior fascicle has proven more critical for ankle stability, sequential cuts to the superior and inferior fascicles have substantial impacts on internal talar rotation [43].

CFL

The CFL originates roughly on the lateral malleolus of the fibula and attaches postero-laterally to the calcaneus [7, 39, 42, 46, 49]. The CFL is the second most injured ligament of the LLC and rarely tears in isolation [9, 39, 40, 48, 55, 56]. Ruptures of the CFL have been found to occur mostly at the calcaneal insertion, with CFL rupture location showing no dependence on ATFL rupture location, should both ATFL and CFL rupture be present. The CFL restrains against excessive inversion and supination of the talocrural and subtalar joints [7, 39, 46]. Most studies performed to characterize the functional role of the CFL have been conducted on cadaveric specimens and found the CFL to be relaxed in plantarflexion while taut and more likely to be injured or stressed in dorsiflexion [7, 39, 41, 42]. In contrast, musculoskeletal modeling studies, based off human volunteer kinematics, and cadaveric studies that keep the ankle surrounding tissue and muscle structures in tact have observed the CFL to be elongated in plantarflexion, especially when inversion is present [48, 53].

PTFL

The PTFL originates on the lateral malleolus of the fibula and attaches postero-laterally to the talus [39, 42, 46]. The PTFL provides restraint to inversion and internal rotation of the joint and injury to the PTFL during LAS is rare [39, 40].

Sex differences

Although several of the papers included in this review that discussed the ankle anatomy and disclosed their sample demographics had mixed samples of males and females, evaluation of whether anatomical differences existed between male and female ankles was limited. Rochelle et al. [47] used 3 male, and 3 female cadaveric specimens and showed the ATFL ultimate failure load was lowest in female specimens, but there was no similarly observable trends in the ultimate failure loads of the CFL and PTFL. Adult ankle specimens from Asian cadavers (8:2 male to female ratio) showed variability in ATFL length, width, and thickness, but the variability of the ATFL was not analyzed by sex [49]. Hlengwa et al. [44] evaluated the morphometry of the ATFL, CFL, and PTFL in 31 cadaveric ankles from 16 human cadavers (9 male; 7 female) and observed sex differences across ligament lengths and widths. Although not significantly different, ATFL and CFL ligaments were longer and thicker in males but wider in females [44]. The PTFL was significantly longer and wider in female cadaveric ankle specimens when compared to males [44].

Bone morphology studies have identified morphological variations in the ligaments that make up the LLC in relation to sex, with males containing more single band LLC ligaments and females containing more double- and triple-band LLC ligaments [44]. The number of bands within a ligament impacts its strength and flexibility, thus dictating the functional variability of these ligaments, which has greater implications for understanding the biomechanics of the entire ankle joint in relation to sex [44].

Additionally, preliminary bone morphology studies, using both male and female cadaveric feet have revealed a bony ridge between the fibular obscure tubercle and proximal region of the fibula that distinctly separates the fibular attachments of the ATFL and CFL [54]. The presence of this bony ridge has only been validated in vivo via ultrasonographic imaging on women [54]. Although likely this fibular bony ridge is present in living males, since male cadaveric feet were used to help first identify this boundary between the ATFL and CFL at the fibula, further ultrasonographic imaging is necessary to confirm this anatomic similarity exists between males and females.

Mechanism of injury

Kinematics

No single motion is responsible for the onset of LAS. Many different combinations of movements have been found to lead to LLC injury. Amongst all these combinations, some component of ankle inversion is almost always present [35, 57, 60–63]. The most common mechanism of injury in LAS involves ankle inversion and an internal rotation of the foot [39, 41, 57, 59, 60, 62, 64–66]. Occasionally, internal rotation of the foot leads to coupled external rotation of the lower leg [9, 39–41, 59].

There is disagreement on whether the presence of plantarflexion is necessary for LAS to occur. While some of the literature considers plantarflexion at the ankle an integral part of the mechanism that induces LAS [5, 9, 11, 41, 42, 55, 62, 67, 68], others have found that while plantarflexion may be present at the instance of injury, it is not necessary for injury to occur [60, 64, 65]. It seems likely that plantarflexion greatly increases the chances of suffering LAS since plantarflexion of the foot/ankle complex primarily stresses, the ATFL, which is typically the first ligament of the LLC to be injured [35, 39, 41, 45, 46, 56, 57].

Of the reviewed studies that had mixed male and female samples, none performed separate analyses to address why and how, if at all, the thresholds of ankle inversion, internal rotation of the foot, and plantarflexion differed between males and females.

Contact/noncontact

Most studies investigating LAS categorize them as contact or noncontact injuries. Contact injuries can either be direct (player-to-player), and involve an external force to the lower leg or foot, or indirect, and involve external force to other parts of the body besides the lower leg or foot that, as a result, alter forces applied to the foot [9, 69]. Noncontact injuries, which typically occur during rapid movements and changes of direction, involve landing or planting the foot awkwardly with no external forces from physical objects [9].

In high school, collegiate, and elite male soccer players, contact injuries, whether due to direct or indirect contact, were the most frequent LAS injury mechanism [52, 69, 70]. Mineta et al. [69] also found direct and indirect contact injuries to be the most frequent LAS injury mechanism for female high school and collegiate soccer players, although their classification of indirect contact mechanisms shares some overlap with noncontact mechanism classifications from other studies. In the Mineta et al. [69] study, LAS injury due to landing of the plant foot awkwardly as a result of a previous contact was considered an indirect contact injury mechanism; whereas, in most other studies this was considered a noncontact injury mechanism. In contrast, an epidemiology study by Gulbrandsen et al. [35] was performed on both male and female collegiate soccer players and found the most common mechanism of ankle injuries to be noncontact mechanisms. In the Gulbrandsen et al. [35] study, although not significant, females sustained more LLC tears than males, which may have been responsible for skewing the noncontact injuries as the more common mechanism of injury in this study of males and females. Female basketball players, when compared to their male counterparts, have also been found to be more likely to be injured through noncontact mechanisms [37]. Video analysis of LAS injuries in indoor court sports, where more than two-thirds of retrieved injury episodes were sustained by male athletes, mainly characterized LAS injury for basketball, handball and volleyball by direct contact mechanisms and LAS injuries for tennis and badminton by noncontact mechanisms [60]. Within the NCAA Injury Surveillance Program, lateral ankle sprains were more prevalently attributed to player contact in men’s than women’s sports [71].

Intrinsic risk factors

Anatomical

Knee, hip, and ankle alignment and angles

The relationship between ankle joint configuration, anatomical abnormalities in ankle and knee alignment, and an increased risk of sustaining an acute lateral ankle sprain has yet to be strongly defined [14]. Prospective studies of male athletes have found that knee surface alignment and the magnitude of knee angles [72], tibiofemoral angle [73], Q angle [11, 74], tibia vara [11], and tibia torsion [11] did not affect the probability of sustaining LAS. Of the studies with only male athletes, the only risk factor found to have an association with an increased chance of sustaining LAS was increased knee recurvatum [11]. Although no sex-specific analysis was conducted, Zamani Moghadam et al. [75] found Q angle to be a significant risk factor for LAS when performing an epidemiology study on male and female basketball players. Although Q angle was not a significant risk factor for LAS in solely male research studies [11, 74], there is no guarantee that the inclusion of females [75] was what impacted the significance of Q angle as a risk factor.

Anatomical alignment

While Hubbard and Wikstrom [55] reported anatomical alignment as a risk factor for sustaining LAS, other studies have found the relationship between anatomical alignment and LAS to be unclear [4, 31]. Willems et al. [76, 77] found some alignment characteristics to be significant risk factors that predisposed males to LAS while no significant relationship between anthropometrical or alignment characteristics and LAS could be found in females [76, 77].

Anatomical foot type

Anatomical foot type (pronation, supination, neutral) was not found to be a risk factor based off studies with male and female samples [31, 41]. Only one of the reviewed studies [11], which was comprised of a completely male sample, found that people with foot pronation and supination could have an increased risk of sustaining LAS.

Foot characteristics

There is conflicting evidence in the literature on whether foot characteristics, such as foot size, foot length, foot width, foot posture index, and other foot-related measurements can be used as predictive values for LAS. Studies on male soccer and basketball players have found that foot posture could not be attributed as a risk factor for ankle injuries [20, 78]. Foot length and foot width were also not found to be risk factors for LAS in males [20]. Increased navicular drop and decreased medial longitudinal arch were associated with an increased occurrence of LAS in males [11]. The only study that evaluated foot characteristics and focused on a solely female sample found navicular tubercle height, which was being used as a flat foot index, to have no association with increased risk of new-onset LAS [79]. Studies that incorporated male and female samples found foot length, width and posture index were risk factors for sprain [14, 41, 67, 80]. Other measurements such as navicular-medial malleolus distance, high longitudinal arch, and cavovarus deformity have been found to be risk factors for LAS [67, 80, 81].

Height/weight

Of the studies reviewed in this search, four [14, 55, 82, 83] found height to be associated with an increased risk of sustaining LAS, four [75, 79, 84, 85] did not, and one [31] found the relationship between height and LAS to be unclear. It cannot be concluded whether lack of sex-specific analyses is responsible for the inconclusiveness of height as a risk factor for LAS. Mason et al. [85], which performed a systematic review and meta-analysis of ankle sprains in males and females, did not find height to be a significant risk factor in neither males or females. McCann et al. [83] and Taketomi et al. [79], who evaluated two different samples of female soccer players reached opposite conclusions on the association between height and increased risk of sustaining LAS. By default, the studies performed on samples of female soccer players [79, 83], were the only studies to perform sex-specific analyses on height as a risk factor for lateral ankle sprain.

Of the four studies which evaluated weight as a risk factor for LAS in males and females but did not perform sex-specific analyses, two studies [55, 75] found weight to be associated with an increased risk of sustaining LAS and two [16, 84] did not. Of the two studies which evaluated weight as a risk factor and did perform sex-specific analyses, Beynnon et al. [31] found the relationship between weight and LAS to be unclear, while Mason et al. [85] found weight to be a significant risk factor for ankle sprains in males but not females. Finally, a prospective study following a sample of female soccer players [79] did not find weight to be associated with an increased risk of new-onset LAS.

Body Mass Index (BMI) and physical fitness

Physical fitness components were not associated with ankle sprains in female team ball players [32]. Of the studies that investigated BMI as a risk factor, most found that higher BMI was associated with a greater risk of sustaining LAS [14, 16, 64, 73–75, 82, 86, 87]. The studies that found BMI to be a risk factor for ankle sprain had samples of either males or males and females, for which no sex-specific analyses were performed. Mason at al. [85], which performed a sex-specific analysis and investigated BMI as a risk factor, found BMI to be a significant risk factor for ankle sprain injuries in males but not females. Four studies [32, 79, 83, 88], three of which were conducted solely on female athletes, did not find BMI to be predictive of an individual’s chance of sustaining an ankle sprain.

Generalized and ankle joint laxity

Generalized joint laxity

The studies that investigated generalized joint laxity had samples that included solely females and samples of males and females. No study found generalized joint laxity to be a risk factor for LAS [31, 41, 79, 89]. No difference in generalized joint laxity between males and females was identified [89].

Ankle joint laxity

Although women have more ligamentous laxity of the lateral ankle than males [90, 91], which is at least partially due to differences between male and female hormones, how ankle joint laxity contributes to risk for LAS is not clear [31]. Beynnon et al. [89] found that males with increased talar tilt were more susceptible of sustaining LAS, although they did not record a difference in the range of talar tilt measured for males and females. Two studies [20, 55] reported that ankle joint laxity could increase an individual’s risk of lateral ankle sprain, and two [85, 92] did not find ankle joint laxity to be a significant risk factor for LAS in neither males nor females.

Range of Motion (ROM)

General ankle ROM was not found to be a risk factor for LAS [11, 79, 82, 85, 87, 88]. Compared to general ankle ROM, there was not much consensus on the risk of dorsiflexion ROM on LAS. Two studies, one with a sample of male soccer and basketball players [20], and one with a mixed sample of males and females [31], found that dorsiflexion ROM was not related to risk of LAS. Two studies [81, 93], both of which had mixed male and female samples but neither of which performed a sex-specific analysis, found dorsiflexion ROM to be a strong predictor of risk of ankle sprain. When risk factors were separately analyzed in samples of males and females, Fong et al. [41] found decreased dorsiflexion ROM was only a significant risk factor for males; whereas, Mason et al. [85] did not find either dorsiflexion or plantarflexion ROM to be a significant risk factor for males nor females.

Muscle strength and reaction time

Muscle strength and imbalances

There is conflicting evidence on whether muscle strength and imbalances are risk factors for LAS [4]. Four studies [16, 32, 89, 93] found no association between muscle strength or muscle strength imbalances and LAS. Two papers [55, 86] found general muscle strength and imbalances corresponded with individuals more at risk of sustaining an injury. For female soccer players, Taketomi et al. [79] found that smaller hamstring to quadricep muscle strength ratios were associated with an increased risk of new-onset LAS, while knee flexion/extension strength was not. In male and female samples, some studies have found plantarflexion, dorsiflexion, inversion, and eversion concentric and eccentric strength to increase the injury risk of ankle sprain [41, 85], while others have not [85]; although, both studies that evaluated these parameters concluded risk factors differed between male and female athletes. Significant strength differences between males and females have been documented when comparing inversion moments [94] and other muscle properties (tone, elasticity, passive/active stiffness, etc.) [90], but these differences have not been related back to risk of LAS. Willems et al. [76, 77] found dorsiflexion muscle strength to have an opposite effect in males and females. Decreased dorsiflexion muscle strength and increased dorsiflexion muscle strength were found to be risk factors that predisposed male and female athletes, respectively.

Hip strength has been postulated to expose the ankle to injury since it influences ankle position in the frontal and sagittal planes, affecting postural control and stability [10, 95, 96]. Two studies [10, 97] on male soccer players found significant relationships between decreased hip strength and LAS; whereas, a study [79] on female soccer players did not find an association between hip abduction strength and LAS. A review paper on studies including male and female athletes across multiple sports [82], which did not perform sex-specific analyses, did not find hip strength to be associated with pediatric lateral ankle injuries. A systematic review and meta-analysis on male and female athlete ankle sprain risk factors, which did perform sex-specific analyses, found poor isometric hip abduction strength to be a significant risk factor for males but not females.

Muscle reaction time and fatigue

While Hubbard and Wikstrom [55] reported muscle reaction time to increase an individual’s risk of LAS, neither Vuurberg et al. [16] nor Beynnon et al. [89] observed an association between muscle reaction and risk of sustaining LAS. Although males and females were found to have differences in their short-loop reaction time of the gastrocnemius and peroneal brevis muscles, Beynnon et al. [89] did not find these differences to impact the association between muscle reaction time and risk of LAS. Other studies, which included female only [98] and mixed samples [87, 94, 99], found increased ankle and peroneal muscle reaction times, caused by fatigue, made players more vulnerable to ankle injury since these muscles serve as a defense mechanism against rapid and forceful ankle inversion [13, 94, 99–102]. During different landing strategies, fatigue decreases force sustained by the peroneus longus muscle, increasing plantarflexion and inversion angles and peak inversion moments at the ankle [103]. As a result, both fatigue and longer muscle reaction times have been related to increased injury risk in the literature [87, 94, 95, 98, 99, 103, 104]. The association between reaction time and LAS risk may have some dependence on sex, as a review paper on studies including male and female athletes across multiple sports [41] found faster reaction of the tibialis anterior and gastrocnemius muscles were significant risk factors for males only.

Balance

General balance

Poor balance has been found to increase the risk of sustaining ankle sprains when considering male and female athletes in mixed [82] and independent samples [32, 105]. An independent analysis on male and female physical education students found less general balance and less movement coordination to be risk factors that predisposed only male athletes to LAS [76, 77]. Similarly, sex-specific analysis of male and female athletes found dynamic balance performance to be a risk factor only for male athletes [85]. Vuurberg et al. [16] was the only study included in this literature review to have concluded that balance, coordination, and stability were not risk factors for any athletes.

Postural sway/stability

Although Beynnon et al. [89] found postural stability to be unrelated to risk of sustaining LAS, sex-specific analysis of the sample identified that anterior-posterior center of gravity sway angle was significantly larger for women, highlighting the fact that postural stability differed between males and females. Hartman et al. [90] also found postural sway to be significantly greater in women, as a consequence of hormone changes during ovulation, although they did not relate greater postural sway to LAS incidence. Of the nine studies [14, 16, 31, 55, 64, 87, 89, 93, 106] performed on samples with a combination of males and females, six [14, 16, 55, 64, 93, 106] found that poor postural control was associated with increased risk of injury. Vuurberg et al. [16] was another study that compared the postural control deficits between males and females. While postural control, postural stability index, and postural sway were deemed risk factors for LAS across the entire sample, postural control deficits were found to be larger in female athletes, increasing the risk of female athletes to LAS [16]. Identical studies on male [76] and female [77] samples found less coordination of postural control to be a risk factor that predisposed only female athletes to LAS.

Star Excursion Balance Test (SEBT)

Three studies [82, 84, 88] found that SEBT scores in at least one direction (posteromedial, posterolateral, and anterior) or poor composite scores were predictive of increased risk for LAS, while one [20] found no relationship between SEBT scores and LAS.

Single leg hop and balance and multiple hop tests

Three studies performed on samples which included a combination of males and females found that single leg hop and balance and multiple hop tests were predictive of risk of LAS [82, 84, 107], while one found no relationship [99]. Decreased stability during the single and double leg balance tests were also predictive of LAS in solely female [79, 108] and solely male [20] samples.

Lower body kinematics and kinetics

Mediolateral force and mean resultant horizontal ground reaction force following a single-legged drop-jump landing were predictive of LAS in male soccer players [109]. Toe-in landings, which corresponded with high inversion angular velocities and high inversion moments, were also predictive of LAS [110]. It’s been proposed that only the motion causing increased ankle inversion angle could be related to LAS injury [92]. Only one study found ankle and lower limb kinematics not to be risk factors for sustaining LAS [16]. The only studies to have evaluated the association between lower body kinematics and kinetics and LAS made these analyses based on the kinematics and kinetics of participants performing single legged landings. While this movement is representative of an athletic movement, it does not encompass all the movements that take place in sport. It is possible that during different tasks, different lower body kinematics and kinetics may predict LAS.

History of previous sprain

Of the eleven studies [11, 15, 55, 64, 73–75, 79, 82, 85, 88] that investigated history of previous sprain as a risk factor, all but one [16] found that a history of previous ankle sprain was predictive of subsequent ankle sprains. Two studies [85, 111] have found previous ankle sprain injury to be a significant risk factor for males but not females.

Incidence

Multiple groups have demonstrated that some risk factors differ between males and females. Review of the epidemiology of LAS should identify whether the differences in risk factors contributes to a difference in incidence of LAS among males and females. For this section, first, we investigated the incidence of LAS in NCAA (National Collegiate Athletics Association) athletes, which represents a much more controlled environment with a narrow age range window and similar rate of participation across male and female athletes. Then, we investigated the incidence of LAS in a much broader sample of individuals to see if the loss of a more controlled space changes the incidence rates reported.

NCAA epidemiology

Basketball

Partial or complete LLC tears are the most common injuries sustained by both male and female NCAA basketball players [37, 112, 113]. Adjacent studies were done on NCAA basketball players from the 2014–2015 through 2018–2019 seasons [112, 113]. LLC tears consisted of 14.3% and 16.2% of injuries for females and males, respectively (Fig. 3A) [112, 113]. When comparing the incidence rates between the two groups, there was a significant difference (alpha = 0.05) in the incidence rates between males and females, with male NCAA basketball players sustaining significantly more LAS than female NCAA basketball players. On the other hand, a 10-year epidemiology study from the 2004–2005 through 2014–2015 seasons on male and female NCCA basketball players [37] found that 79.97% and 83.47% of ankle injuries were LLC tears in males and females, respectively (Fig. 4A). The 10-year epidemiology study [37] showed that relative to all ankle injuries, female NCAA basketball players sustained a significantly (alpha = 0.05) greater proportion of LAS than male NCAA basketball players.

Fig. 3.

A Lateral ankle sprain injury incidence for NCAA basketball players from the 2014-2015 through 2018 -2019 seasons [112, 113]; (B) Lateral ankle sprain injury incidence for NCAA cross-country athletes from the 2014-2015 through 2018 -2019 seasons [114, 115]; (C) Lateral ankle sprain injury incidence for NCAA lacrosse players from the 2014-2015 through 2018 -2019 seasons [116, 117]; (D) Lateral ankle sprain injury incidence for NCAA soccer players from the 2014-2015 through 2018 -2019 seasons [118, 119]

Fig. 4.

A Lateral ankle sprain injury incidence for NCAA basketball players from the 2004-2005 through 2014 -2015 seasons [37]; (B) Lateral ankle sprain injury incidence for NCAA athletes from the 2018-2019 through 2020 -2021 seasons [120]

Cross-country and track and field

LLC tears were reported as the most common injuries sustained by male NCAA cross-country athletes (8.2% of injuries) and the second most common injuries sustained by female NCAA cross-country athletes (4.2% of injuries) from the 2014–2015 through 2018–2019 seasons (Fig. 3B) [114, 115]. There was a significant difference (alpha = 0.05) in the incidence rates between males and females, with male NCAA cross-country athletes sustaining significantly more LAS than their female counterparts.

Lacrosse

LLC tears were reported as the most common injuries sustained by female NCAA lacrosse players and the second most common injuries sustained by male NCAA lacrosse players from the 2014–2015 through 2018–2019 seasons [116, 117]. Although LAS were not the most common injury in male lacrosse players, there was not a significant difference in the incidence of LAS when comparing the male (7.7% of 1872 male lacrosse injuries) and female (9.1% of 1435 female lacrosse injuries) incidence data (Fig. 3C) [116, 117].

Soccer

Partial or complete LLC tears are the most common injuries sustained by both male and female NCAA soccer players [35, 70, 83, 89, 118, 119]. For NCAA soccer players, there did not appear to be a significant difference in the incidence of LAS sustained by females when compared to males (Fig. 3D) [35, 118, 119].

Volleyball

Only one study [121] was performed on NCAA volleyball players. Although LLC tears, which composed of 11.1% of injuries, were the most common injury sustained by female volleyball players [121], no comparisons could be made because an adjacent study for males was not performed.

Misc

Some studies were performed on NCAA athletes from multiple sports. Similar to the studies that investigated the epidemiology of LAS by sport, studies that spanned across multiple sports found LAS to be one of the most common injuries, if not the most common injury, sustained by NCAA student-athletes [120, 122]. From the 2018–2019 academic year through the 2020–2021 academic year, 1,242 LAS from 732 team seasons and 17.431 player seasons were recorded [120], which meant that LAS represented 5.5% of all sport-related injuries and 72% of all ankle sprains. LAS represented 68.5% (725/1058) and 77.0% (517/671) of all types of ankle sprains in males and females, respectively (Fig. 4B) [120]. This led to a significant difference (alpha = 0.05) between males and females in the percentage of ankle sprains that were classified as LAS, with a larger percentage of female ankle sprains being classified as LAS.

From the 2009–2010 academic year through the 2014–2015 academic year, the NCAA Injury Surveillance Program (NCAA-ISP) reported that LAS comprised 7.3% of all injuries and 73.9% of all ankle sprains [122]. In all sex-comparable sports combined, except basketball, the incidence of LAS did not differ overall or in practices. Although there were no significant differences in LAS incidence, the NCAA-ISP did find 3 of the 4 sports with the largest incidence of LAS were women’s sports (men’s basketball, women’s basketball, women’s volleyball, and women’s lacrosse) [122].

General epidemiology

Basketball

All but two basketball epidemiology studies [123, 124] had samples of professional athletes. For recreational basketball players, the most frequently injured body part was the ankle, with the majority of ankle injuries affecting the LLC [123]. Studies performed on samples of recreational basketball players [123, 124] either did not separate incidence by sex or did not have a sample size large enough to evaluate sex-specific differences. Other epidemiology studies on professional basketball players followed WNBA players from the 2015–2016 through 2018–2019 seasons [27], and NBA players from the 1988–1989 through 2004–2005 [125], 2013–2014 through 2016–2017 [126], and 1988–1989 through 1997–1998 seasons [127]. LAS were the most frequent injury reported in both the WNBA and NBA and were the type of ankle sprain most experienced by players [27, 125–128]. In the 2013–2014 through 2016–2017 seasons, LAS accounted for 638 of the 796 ankle sprains (80.2%) experienced by NBA players, with a majority classified as contact injuries [126]. In the WNBA, from the 2015–2016 through 2018–2019 seasons, 39 out of the 43 ankle injuries were classified as LAS (90.7%) [27].

Cross-country and track and field

Enoki et al. [129] evaluated the incidence of injuries in track and field jumping athletes and found the lateral ankle to be one of the most common injury locations in these athletes, accounting for 17% of injuries. No sex-specific analyses were performed to investigate if the incidence rate of LAS deviated between male and female athletes.

Soccer

Regardless of age, sex, or level of competition, LAS are the most common ankle and general injuries in soccer players [15, 130–134]. Studies performed on youth, recreational, and amateur players have found the incidence rate of LAS relative to all injuries to be as high as 18% [97] and the proportion of LAS relative to other ankle injuries to be anywhere from 69.7% to 91% [15]. In elite and professional players, the incidence rate of both contact and noncontact LAS relative to all injuries have been reported as 11% [134], 13.9% [130], and 21.4% [10]. Relative to all ankle injuries in elite and professional players, LAS have been found to account for anywhere between 53.75% [131]-77% [134] of injuries. Of the prospective epidemiology studies in this literature review that concentrated on soccer players, eight [10, 15, 97, 131–135] evaluated males, one [130] evaluated females, and three [69, 124, 136] evaluated both male and female players. Comparisons could not be made between the one female study and six male studies because of differences in sample levels of exposure. Of the three studies that evaluated samples of male and female players, two [124, 136] did not separate incidence by sex and therefore did not allow for comparisons to be made between LAS incidence in male and female soccer players. Mineta et al. [69] compared LAS incidence by injury mechanisms and found a significant difference of the indirect LAS incidence between male and female players, with males sustaining significantly more LAS due to indirect injuries. Indirect injuries were classified as LAS injuries sustained as a result of external forces initially applied to parts of the body other than the lower leg or foot [69].

Volleyball

While several studies included in this review incorporated volleyball players in their samples, only one analysis was performed solely on volleyball specific injury data [137]. Acute LAS were found to be the most common injury diagnosis for both high school and collegiate female players [137]. No adjacent studies on male volleyball players were performed, so comparisons across the two groups could not be made.

Multiple

Studies on male and female athletes across multiple sports [33, 36, 138] have found that the incidence of ankle sprain does have a dependence on sport with those sports involving running, cutting, and jumping as the most likely to induce an injury. Interestingly, when performing independent analyses on males and females, Beynnon et al. [36] found the incidence of ankle sprain to have a dependence on sport in female athletes, but not male athletes. There was no significant difference in injuries between males and females when including all sports; however, when separated by sport, female basketball players were at a significantly greater risk of injury than their male counterparts [36]. Doherty et al. [33] and Herzog et al. [138] have found that the overall incidence of sprains was higher in females than males and the incidence rate varied substantially by sport. Luciano and Lara [139], which did not have enough females in their sample to make conclusions on how sex impacted LAS incidence, found an association with sport and injury.

Two identical studies were performed on male [76] and female [77] physical education students. Both males and females were more prone to injury depending on the sport they played [76, 77], demonstrating that there is a relationship between the movements of particular activities and the induction of LAS. During the two studies, 44 of the 241 male subjects (18%) and 32 of the 159 female subjects (20%) suffered LAS [76, 77]. A two-sample t-test assuming unequal variances and using a 5% significance level did not find the overall incidence of injuries to be significantly different from one another.

Evaluation of ankle sprain injuries reported in United States Emergency Departments found that female patients sustained more LAS than male patients; however, this study did not control for exposure to activities that would induce injury [140]. Studies performed on US miliary personnel have found that women had an overall increased risk for sustaining ankle sprain injuries, the majority of which involved the LLC [12, 34]. While there is some evidence from studies on military personnel that the difference between male and female incidence rates does not hold true once exposures are controlled for [12], others have concluded that even once occupation was controlled for, female officers had a higher risk than their male counterparts in all but two of the military occupational groups assessed [34].

Discussion

This review investigated how sex-specific factors are currently understood to influence ankle anatomy and the incidence, intrinsic risk factors and mechanisms of LAS injury. While ankle inversion coupled with internal rotation are the most common LAS kinematics, there exist differences in the prominence of contact types (contact vs. noncontact) and risk factors that facilitate these kinematics in males and females. More studies that allow for sex-specific analyses are required to link sex-specific anatomical and biomechanical justifications to LAS injury thresholds, incidence, and risk factors.

Our search identified a limited number of epidemiology studies evaluating LAS across multiple sports, activities, and populations that controlled for sex while holding all other factors, particularly test environments and exposure, constant. This gap in the literature makes it difficult to perform sex-specific analyses and discern consistent differences in overall LAS incidence rates between males and females.

The studies conducted by Willems et al. [76, 77], which independently evaluated LAS on male and female physical education students, were the only general epidemiology studies that controlled for environment, exposure, and sex differences to allow for sex-specific comparisons. While, the analysis of the LAS incidence reported by Willems et al. [76, 77] did not find the overall incidence of LAS to significantly differ between males and females, this study alone is not enough to conclude there exists no difference in LAS incidence between males and females participating in similar physical activities.

Epidemiology studies limited to one sport but performed on samples of varying levels of experience also rarely offered parallel test environments and exposures for males and females. Excluding the epidemiology studies performed on NCAA athletes, of the nineteen epidemiology studies limited to one sport, nine [10, 15, 97, 125–127, 132–134] evaluated males only, three [27, 130, 137] evaluated females only, and five [69, 123, 128, 129, 136] evaluated mixed samples, with only one study [69] separating incidence rates of LAS by sex. Of these single sport epidemiology studies performed on single sex samples, only those on professional male and female basketball players were conducted in enough of a parallel environment where male and female incidence could be compared. Although there were big differences in samples sizes and injurious events, LAS accounted for a larger percentage of WNBA ankle injuries than NBA ankle injuries [27, 138]. Although differences in LAS incidence were observed among professional male and female basketball players, this sample cannot be extrapolated to make generalizations about differences that might exist in LAS incidence across males and females participating in sex-similar sports or activities. This is evidenced by the fact that LAS incidence discrepancies observed between male and female professional basketball players was not observed by Willems et al. [76, 77] in male and female physical education students. Additional epidemiology studies with larger sample sizes and sex-specific analyses across a range of sports/activities is required to determine if sex predisposes individuals to LAS. Alternatively, disagreements in male and female incidence of LAS across professional basketball players and physical education students might be a consequence of the different maneuvers required of the different sport/activities the individuals are participating in and not be dependent on sex.

Epidemiology studies conducted on NCAA student athletes in sex-similar sports offered the most controlled and comparable environments for LAS incidence analysis between males and females. When evaluating LAS incidence relative to other injuries, lacrosse [116, 117] and soccer [35, 118, 119] found no significant differences in incidence between NCAA male and female athletes; whereas, basketball [37, 112, 113] and cross-country [114, 115] suggested male athletes had a significantly higher incidence rate of LAS than their female counterparts. Soccer and lacrosse may show similar patterns in male and female LAS incidence due to commonalities in the external factors of the two sports, such as grass playing surfaces and cleated footwear. Although these external risk factors influence LAS injury occurrence [31, 141, 142], their investigation was outside of the scope of this review. Cross country races occur on natural terrain surfaces, which largely include grass, but also dirt and gravel surfaces. Basketball is played on indoor courts. It is possible that there are significant interactions between the playing surface of these sports and sex that exist and influence LAS incidence, however the investigation of these types of relationships was outside the scope of this review.

The absence of a trend in the overall LAS incidence across individuals of various experience and exposure levels (recreational-level participants, amateur athletes, collegiate athletes, and professional athletes) participating in sex-similar general activities and sports furthers the argument that there is a LAS dependence on sport. This finding is in agreement with previous work, which has confirmed dependencies between LAS occurrence and mechanism of injury on sport and positions within a sport [60, 131]. It is difficult to conclude whether the lack of agreement in the overall LAS incidence across individuals of various experience and exposure levels (recreational-level participants, amateur athletes, collegiate athletes, and professional athletes) participating in sex-similar general activities and sports is a consequence of the small sample size of studies that allow for true sex-specific LAS incidence comparisons or the activity itself. It is possible that any relationships that exist between LAS incidence and sex are being overshadowed by the dependence of LAS on sport.

Overall LAS rates, relative to all incurred injuries, appear similar between sexes, but among ankle injuries, LAS is more prevalent in females. When evaluating LAS incidence relative to other ankle injuries, NCAA female athletes had a significantly higher incidence rate of LAS than their male counterparts both in basketball and across all athletes when sport was not controlled for [37, 120]. Additionally, LAS accounted for a larger percentage of WNBA ankle injuries than NBA ankle injuries [27, 138]. This finding suggests that female athletes are exposed to a wider variety of general injuries and smaller variety of ankle injuries compared to male athletes.

Several kinematics can result in LAS. The mechanism of ankle inversion, usually accompanied by internal rotation, is the most agreed upon mechanism for LAS. While plantarflexion is often common during LAS, there is disagreement in the field whether plantarflexion is necessary for LAS to occur. Although the kinematics that influence LAS have been investigated across males and females, the authors could not find any mention in the literature of kinematics or ROM threshold differences that exist across male and female subjects that would affect the mechanism of LAS injury. Although there are no reported differences on the mechanism of LAS injury between males and females, the current literature suggests females may be more susceptible to noncontact injuries [35, 37]. The susceptibility of women to noncontact injuries could be due to different styles of play between male and female versions of the same sport or could be due to inherent biomechanical and anatomical differences between males and females that exist beyond sport and style of play but have yet to be discovered.

Although no risk factors were unanimously confirmed through the analysis in this review, there is strong evidence that lower body kinematics and kinetics, the SEBT, and single leg hop and multiple hop balance tests are predictive risk factors for LAS. While outside of the scope of this review, sex has been shown to have a significant effect on lower body kinematic and kinetic compensatory strategies in individuals with long-term ankle instability [143], with females employing hip-dominant compensatory strategies and exhibiting greater ankle inversion than males during high-risk maneuvers. These strategies could leave females at higher risk for LAS, should there exist no differences in kinematic or ROM thresholds between males and females. Supplemental work should be performed to investigate if healthy, uninjured females demonstrate the same patterns of increased hip flexion and ankle inversion during high-risk maneuvers, as this would suggest that sexual dimorphism at the hip enables differences in lower body kinematics and kinetics. This review has already demonstrated that hip strength and alignment may have differing significance as risk factors in males and females, further suggesting that anatomical differences at the hip might offer further insight into differences in LAS risk and occurrence.

History of previous sprain may be a stronger predictor for males than females. One might expect a history of previous sprain to be associate with greater generalized joint laxity and ankle ROM; however, generalized joint laxity and general ankle ROM were not found to be risk factors for LAS in males nor females. There is not enough research in the field to know if anatomical foot type is a risk factor for males or females. For both males and females, there was disagreement in the field if foot characteristics, height, or dorsiflexion ROM were risk factors for LAS. There was also disagreement in the field if anatomical alignment, weight, ankle joint laxity, and general balance were risk factors for LAS, although the current literature indicates these may be more prevalent risk factors in males. Although beyond the scope of this review, it must not be ignored that disagreements across risk factors might be dependent on the sports, activities, or manuevers being performed. Current evidence is insufficient to determine whether ankle joint laxity is a risk factor for LAS in females An association between muscle strength, imbalance, and reaction time and LAS injury risk could not be determined based on the current literature. Disagreement on the impacts of muscle strength, imbalance, and reaction time on LAS injury existed across studies performed independently on males and females as well as across studies that did not make clear distinction between sexes. Since muscle strength, imbalance, and reaction times were evaluated over a wide range of activities and sports (general literature reviews for which activities could not be distinguished, team ball sports, soccer, lacrosse, field hockey, soccer, basketball, etc.), it could be these are only risk factors for LAS when considering certain maneuvers, which might be more prevalent in certain sports compared to others.

There were several scenarios for which risk factors were sex-dependent or appeared to exhibit some dependence on sex but require further investigation. Observed differences between male and female risk factors for LAS demonstrate the existence of inherent anatomical and musculoskeletal differences between males and females. Dorsiflexion muscle strength had the opposite effect in males and females. Decreased dorsiflexion muscle strength predisposed male athletes to LAS, whereas increased dorsiflexion muscle strength predisposed female athletes to LAS [76, 77]. While postural sway and instability were often found to be risk factors for LAS injury, these factors were found to be more prevalent and greater risk factors in females. BMI and hip strength were found to be risk factors for LAS in male athletes. Hip strength was not a risk factor for LAS in females [79]. BMI doesn’t seem to be a risk factor for female athletes, but more evidence is needed. Knee, hip, and ankle alignment were not risk factors for male athletes but show potential as risk factors that make females more prone to injury than males [11, 73–75]. This finding is reasonable as we know that knee, hip, and ankle alignment predispose females to greater risk of knee (i.e. ACL) injuries than males, so it would not be surprising if this alignment influences the prevalence of other lower extremity injuries in females. More research needs to be done, especially on the relationship between Q angle and risk for LAS in female athletes before any definite conclusions can be drawn. Lower extremity alignment, especially when measured during dynamic tasks, introduce strength and moment disparities at the knee between males and females, predisposing females to greater risks of knee injuries [144–146]. As these factors have been shown to influence knee kinematics and kinetics, further investigation of their relationship to LAS occurrence in females is warranted.

Muscle characterization, general and ligamentous laxity, and postural sway differences existed across individuals and across sexes [16, 22, 89–91, 94]. Further research is necessary to quantify how these differences are related to injury occurrence and incidence. Muscle size and hormonal factors are highly dependent on sex and largely responsible for the differences observed in male and female muscle characterization, ankle and ligamentous laxity, and postural sway. However, there is limited research that relates these physiological factors and the anatomical differences they induce to differences in LAS risk factors and incidence. There is also limited research relating these physiological factors to the ankle and LLC in general, making evaluation of sex-driven differences in hormonal and muscle properties largely outside of the scope of this review. To isolate the independent effects of hormonal fluctuations on lower limb biomechanics and LAS injury thresholds, future work must strictly control for or record the phases of the menstrual cycle.

The current state of the field is conflicted on several risk factors for LAS. This is partially attributed to the fact that several studies do not analyze risk factors separately for males and females. Although, risk factors have been seen to differ between males and females [41, 76, 77], there is a lack of research done solely on females to understand how far these differences extend. The finding that the current literature lacks female specific LAS research is not unique to the current review [19, 25–30, 60]. Current research is limited in its investigation in how sexual dimorphism relates to LAS injury, and as a result, hinders the evidence-based approaches used for the diagnosis and clinical care of LAS in females [22, 28, 30]. While there is evidence that LLC morphological, morphometric, strength, and flexibility variations exist between males and females, anatomical and biomechanical justification for the differences in risk factors or differences of thresholds for injury are not well described by the current literature.

This review evaluated many studies about the LLC with a wide variation of samples, methods, and levels of competition and exposure. Dependencies on the levels of competition and exposure and how they affect the incidence, mechanism, and risk factors of LAS were not explored in depth in this review. The only separation performed based on level of competition was done at the collegiate level for all NCAA prospective studies. Even when controlling for the level of competition at the NCAA level, rules of sports and styles of play can vary between males and females, further complicating the ability to isolate how sex affects the mechanism, risk and predictive factors, and incidence of LAS amongst male and female athletes participating in sex-similar sports. A limitation of this study is that the dependence of LAS on sport and rules of the sport, occupation, activity, level of competition, the event that caused them, and the method that was used to evaluate them may be stronger than the relationship between sex and LAS. In a perfect environment, differences between males and females could only be identified when all other factors are controlled for.

The review presented is a narrative review which borrowed systematic search components. While this search strategy allowed the authors to synthesize information from over 116 scholarly works, there were several limitations associated with this approach. Although three separate searches were conducted to include the most up-to-date information regarding LAS, all three searches were performed in a single database, PubMed. Use of a single database increased the risk of selection bias. Risk of selection bias was further increased by the fact that only one reviewer was used to screen articles based on the inclusion/exclusion criteria. Presence of a single reviewer increased intra-reviewer reliability and ensured that the inclusion/exclusion criteria outlined in Table 1 were applied consistently throughout the study selection process. However, absence of inter-reviewer reliability may have increased the risk of relevant studies being inadvertently excluded or ineligible studies being included. Given the breadth of the inclusion/exclusion criteria (Table 1), the lack of multiple reviewers could have implications on the final articles selected, which would in turn have an impact on the possible interpretations that could be derived from the presented narrative review. We acknowledge that this bias may have limited our access to other relevant literature and reduces the reproducibility of this work.

Conclusion

This review summarizes the current understanding in the literature of how sex affects the ankle anatomy, and the mechanism, intrinsic risk and predictive factors, and incidence of LAS amongst male and female athletes in sex-similar sports or activities. The most agreed upon mechanism of injury for LAS involves ankle inversion coupled with internal rotation of the foot. In sex-similar sports, females may sustain more noncontact injuries than their male counterparts, which may be due to differences in style of play or inherent anatomical differences. General trends of differences between male and female LAS incidence were dependent on the injurious event space that LAS were evaluated in. Studies performed on individuals participating in multiple sex-similar sports have found that relative to all injuries sustained by male and female athletes within a sport or group of sports, females did not sustain significantly more LAS than their male counterparts. However, relative to all ankle injuries sustained by male and female athletes within a sport or group of sports, females sustained significantly more LAS than their male counterparts.

Lower body kinematics and kinetics, history of previous sprain, the SEBT, and single leg hop, multiple hop and balance tests were found to be risk factors for LAS in males and females. Generalized joint laxity and general ankle ROM were not found to be risk factors for LAS in neither males nor females.

The literature was divided on the significance of several risk factors for LAS injury, which occurred both across generalized male and female analyses and within male and female sex-specific analyses. While more research is required, the findings from this review suggest history of previous sprain, anatomical alignment, weight, ankle joint laxity, general balance, BMI, and hip strength are more prevalent risk factors in males, while postural sway and instability is a more prevalent risk factor in females. There is reason to suspect knee, hip, and ankle alignment as risk factors for female LAS but there is limited research on the significance of these risk factors in females. It seems likely that the prevalence of more LAS risk factors in males is a consequence of both sex-specific inherent anatomical and musculoskeletal differences between males and females and a disparity in female LAS and LLC research.

A handful of anatomical studies on cadaveric specimens have found sex to influence the morphology and morphometry of the LLC ligaments. Future work should focus on bridging the gap between sex-driven LLC anatomical variations and the differences observed in LAS risk factors, thresholds for injury, mechanisms of injury, and incidence between males and females. Doing so will provide strong sex-specific anatomical and biomechanical justifications for LAS injury, which is necessary for optimal prevention of LAS injury in all individuals, but not well described by the current literature.

Abbreviations

LAS

Lateral ankle sprains

LLC

Lateral ligament complex

CAI

Chronic ankle instability

ATFL

Anterior talofibular ligament

PTFL

Posterior talofibular ligament

CFL

Calcaneofibular ligament

BMI

Body mass index

ROM

Range of motion

SEBT

Star Excursion Balance Test

NCAA

National Collegiate Athletics Association

ISP

Injury Surveillance Program

WIST

Women In Sports Technology

Authors’ contributions

Rachel Newman conceptualized the review and criteria, performed the literature search, completed the screening and data extraction, and completed the first draft of the manuscript. Richard Kent provided input and feedback on the manuscript. All authors reviewed, refined, and approved the final manuscript.

Funding

Funding for this study was provided by Women In Sports Technology (WIST). The Open Access fee was paid for by the University of Virginia.

Data availability

All data generated or analyzed during this study are included in this published article and its supplementary information files.

Code availability

Not applicable.

Declarations

Ethics approval and consent to participate

Not applicable. No norm or standard was followed.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.