Introduction

Ankle sprains are among the most frequently occurring injuries [1] and are the most common injuries observed in basketball players [2–4]. Additionally, they have a high recurrence rate of 56–74% [5]. Repeated injuries can result in ligament reinjury and residual instability of the ankle joint, ultimately leading to chronic ankle instability (CAI) [6]. CAI is a precursor to ankle osteoarthritis, with some cases requiring surgical intervention [3]. Furthermore, ankle sprains have been identified as a risk factor for anterior cruciate ligament (ACL) injuries, which are the most severe knee injuries occurring in basketball [2]. Given these concerns, establishing effective methods to prevent ankle sprains is crucial for reducing ACL injury risk.

A history of ankle sprains is considered the most significant risk factor for future sprains. Basketball players with a history of ankle injuries had a fivefold higher likelihood of developing another ankle injury compared with those without past injuries [3]. Many other studies have also identified a history of ankle sprains as a major risk factor for recurrence [2,5,6]. One of the most effective ways to prevent recurrent sprains and chronic instability is to implement appropriate rehabilitation following the initial injury [7]. However, as mentioned earlier, both the recurrence rate of ankle sprains as well as the prevalence of CAI remains high among basketball players.

Despite the high incidence of ankle sprains in basketball, they may not be given sufficient attention in sports settings. Regarding the classification of ankle sprain severity, Grade 1 sprains are defined as slight stretching and minor damage to the ligament fibers. More severe injuries are likely to be reported to medical staff or receive medical attention, making them more apparent in injury statistics. However, Grade 1 sprains often allow for an immediate return to play, and in many cases, athletes do not seek medical consultation, potentially leading to underreporting in epidemiological data. Thus, athletes’ injury histories, which are a key risk factor for recurrent ankle sprains, may not be accurately documented, and inadequate rehabilitation before returning to play creates a cycle of repeated injury.

For decades, a four-stage process for sports injury prevention has been proposed [8]. However, the first stage—epidemiological investigation—may not be accurately conducted. Supporting this concern, an epidemiological study has indicated that over 55% of athletes do not seek medical evaluation after sustaining an ankle sprain [3], highlighting the challenge of accurately assessing the true extent of the issue. Previous research has also reported that 90% of individuals who sustained an ankle sprain did not receive rehabilitation from a medical professional within 30 days of developing the injury [7].

In the present study, we specifically focused on under-12 (U-12) and under-15 (U-15) basketball players, because early prevention of ankle sprains and ACL injuries in younger athletes is crucial for reducing the risk of these injuries as they continue to develop their motor skills and sport-specific movements [9]. The physical growth and musculoskeletal changes that occur during these years may influence injury susceptibility, particularly in sports such as basketball, which involve dynamic, high-impact movements [10]. Furthermore, patterns of healthcare utilization and rehabilitation practices during these formative years could markedly impact future injury risk and long-term joint health [8]. Therefore, the present study aimed to investigate the actual incidence of ankle sprains and post-injury management among U-12 and U-15 basketball players through a large-scale questionnaire survey. Additionally, the study examined the prevalence of CAI and ACL injuries to assess the epidemiological impact of ankle sprains on young athletes. By examining these age groups, this study aimed to provide insights into potential preventive strategies and the need for appropriate medical intervention during early athletic development [8].

Participants and methods

Results

Valid responses were obtained from 2,747 participants, including 1,400 U-12 players (735 male players, mean age: 9.84 ± 1.40 years; 665 female players, mean age: 9.81 ± 1.38 years) and 1,347 U-15 players (711 male players, mean age: 13.40 ± 0.94 years; 636 female players; mean age: 13.30 ± 0.92 years) (Table 1). The corresponding response rates were 28.2% (128 teams) and 27.2% (112 teams), and the overall response rate was 27.7%. The competition levels of the teams ranged widely, from national tournament-level teams to recreational-level teams. A history of ankle sprains was reported by 546 (39.0%) and 824 (61.2%) players in the U-12 and U-15 groups, respectively, with the prevalence being significantly higher in the latter (OR 2.46, 95% CI 2.11–2.87, χ² = 135.0, df = 1, P < 0.001; Table 2A).

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Table 1. Participant demographics.

https://doi.org/10.1371/journal.pone.0344196.t001

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Table 2. Survey results.

https://doi.org/10.1371/journal.pone.0344196.t002

Although injury severity was subjectively assessed by the players or their coaches, contact with an orthopedic or other medical institution was reported by 1,134 (80.1%) and 762 (56.6%) players in the U-12 and U-15 groups, respectively, with the rate being significantly higher in the U-12 group (OR 0.31, 95% CI 0.26–0.36, χ² = 191.6, df = 1, P < 0.001; Table 2B). Professional involvement was defined as consultation or treatment by licensed healthcare professionals, including orthopedic surgeons, physicians, physical therapists, or nationally licensed Judo therapists in Japan. Players who reported not seeking medical attention numbered 120 (8.6%) in the U-12 group and 354 (26.3%) in the U-15 group, with the rate being significantly lower in the former (P < 0.05). Additionally, players who sought care from a judo therapist (judo seifukushi), a nationally licensed practitioner in Japan certified by the Ministry of Health, Labor and Welfare who provides non-surgical management of acute musculoskeletal injuries such as sprains, contusions, and muscle strains; and who treats fractures and dislocations only with physician consent except for emergency first aid, included 158 (11.3%) and 230 (17.1%) in the U-12 and U-15 groups, respectively (Table 1). Regarding return to play, 766 players (54.7%) in the U-12 group and 721 players (53.5%) in the U-15 group resumed competition despite persistent pain in the injured ankle with no significant difference between age groups (OR 0.95, 95% CI 0.82–1.11, χ² = 0.39, df = 1, P = 0.53; Table 2C). Based on the inclusion criteria of the International Ankle Consortium, 173 (12.4%) and 167 (12.4%) players in the U-12 and U-15 groups, respectively, were identified as having CAI, with similar prevalence between age groups (OR 1.00, 95% CI 0.80–1.26, χ² = 0.00, df = 1, P = 0.97; Table 2D). Furthermore, no players in the U-12 group had undergone ACL reconstruction surgery, whereas 12 (0.9%) in the U-15 group did. Using a continuity correction because of the zero cell in the U-12 group, the odds of having a history of ACL reconstruction were substantially higher in U-15 than in U-12 players (OR 26.22, 95% CI 1.55–443.26, χ² = 11.6, df = 1, P < 0.001), although the absolute number of ACL-reconstructed players was small. Among U-15 players who had undergone ACL reconstruction, six (50%) developed CAI in the same ankle (Table 2D).

Discussion

This study aimed to determine the actual incidence of ankle sprains and post-injury management among U-12 and U-15 basketball players through a large-scale questionnaire survey. The study also examines the prevalence of CAI and ACL injuries to assess the epidemiological impact of ankle sprains on young athletes. The results of this study reveal that the incidence of ankle sprain during basketball competition was significantly higher in the U-15 age group. Previous studies have also reported that the risk of ankle sprain increases with growth owing to increased competition intensity and game frequency [8,11]. However, given that a considerable number of ankle sprains also occur in the U-12 age group, early education on injury prevention strategies and promotion of higher medical consultation rates among younger athletes are important. Studies have shown that early intervention and appropriate management of ankle sprains can reduce the risk of recurrent injuries and long-term complications [3]. When comparing the incidence of ankle sprains across different sports, basketball, with its frequent directional changes and high-impact landings, presents a higher risk than that associated with many other sports, particularly sports with less physical contact and less frequent sharp movements, sports in which ankle sprains are generally less common. [12,13].

Additionally, the proportion of players who sought medical attention after an ankle sprain was significantly lower in the U-15 group than in the U-12 group. Prior research has indicated that as competition levels rise, athletes tend to rely more on self-assessment or coaches’ judgment, leading to inadequate medical intervention [14,15]. Moreover, players with a history of CAI may have a higher rate of re-injury than those without, suggesting that CAI increases the likelihood of future sprains, further complicating recovery and rehabilitation [16,17]. Furthermore, CAI remained consistent at approximately 12.4% in both age groups. Some athletes with CAI also experienced ACL injuries, suggesting that CAI may increase the risk of other lower limb injuries [17,18]. Although the CAI classification criteria used in this study were based on established definitions commonly applied in previous research, these criteria were originally developed for adult populations. Therefore, caution is warranted when interpreting CAI prevalence in younger athletes, particularly in the U-12 age group, because developmental differences in neuromuscular control, injury perception, and symptom reporting may influence questionnaire responses and classification outcomes. The coexistence of CAI and ACL reconstruction observed in some players suggests a possible association; however, causal relationships cannot be inferred due to the cross-sectional design and the small number of ACL cases. This highlights the importance of maintaining ankle stability in sports such as basketball, which involve rapid directional changes and landing movements. Previous studies have also indicated that CAI can lead to biomechanical abnormalities in the knee and hip joints, increasing the likelihood of more severe injuries [2,19].

Several epidemiological studies have reported varying prevalence rates of CAI and ACL injuries across different sports and age groups. For instance, previous research has indicated that the prevalence of CAI among young athletes ranges from 9% to 23%, depending on the sport and competition level [20]. In basketball, the frequent occurrence of ankle sprains and the high risk of re-injury contribute to a relatively high CAI prevalence compared with that in other sports such as soccer and volleyball [21]. Similarly, ACL injuries have been extensively studied in young athletes, with reports showing a higher incidence among female basketball players because of biomechanical and hormonal factors [22]. While this study finds a consistent CAI prevalence of approximately 12.4% in both age groups, other studies have reported slightly higher rates in older age groups, possibly owing to accumulated exposure to high-impact movements and inadequate rehabilitation following previous injuries [23]. These variations in CAI and ACL injury prevalence highlight the need for sport-specific and age-specific injury prevention strategies. Furthermore, a meta-analysis examining return-to-play outcomes following ACL reconstruction has shown that delayed or inadequate rehabilitation is a major factor contributing to poor functional outcomes and increased re-injury risk [24]. These findings emphasize the importance of structured rehabilitation programs and medical supervision to mitigate the long-term consequences of ankle and knee injuries.

The findings of this study suggest that a history of ankle sprains not only increases the risk of recurrence during sports activities but also may serve as a risk factor for more severe injuries, such as ACL tears [25]. Notably, the lower rate of medical consultation after injury in the U-15 group may lead to inadequate rehabilitation and treatment, potentially contributing to a higher incidence of CAI [26]. Research has shown that insufficient rehabilitation after an initial ankle sprain increases the likelihood of developing CAI [27].

Moreover, this study finds that approximately half of the players returned to competition while still experiencing residual pain in the injured ankle. Continuing to play despite persistent pain can lead to impaired ankle function and an increased risk of re-injury. Existing research has also indicated that returning to competition with pain can cause a decline in athletic performance and biomechanical abnormalities, ultimately increasing the risk of re-injury [28,29]. A significant issue highlighted in this study is that the severity of ankle sprains is often determined by self-assessment or coaches’ judgment. In sports settings, minor sprains are frequently overlooked, leading to inadequate rehabilitation and ultimately increasing the risk of developing CAI or sustaining more severe injuries [17,30].

These findings underscore the importance of proper management and rehabilitation of ankle sprains to prevent CAI and ACL injuries. For U-15 athletes, education and guidance are essential to ensure proper evaluation and treatment after injury. Additionally, strengthening the involvement of medical staff in sports settings and ensuring appropriate care even for minor sprains are necessary to reduce the risk of re-injury [31]. Previous research has also shown that rehabilitation programs supervised by healthcare professionals lower the risk of developing CAI, which aligns with the results of this study [32].

Supporting information