Introduction

Although participation in sport offers distinct physical, mental and social benefits, it is also associated with a significant risk of sustaining injuries which may have long-lasting effects. Accordingly, sport injuries and fear thereof may either preclude one from participation in sports or affect one’s life in another manner. The incidence, prevalence and type of sports injuries vary depending on the sports discipline, age, sex, flexibility, and proprioception of its players, local climate, type of surface on which the sport is played and its equipment (Sallis et al., 2001; Bahr & Holme, 2003; Ristolainen et al., 2009). The most common definition of a sport injury determines it as any injury or trauma which prevents, limits or modifies one’s participation in sport for at least one day (Ferrara & Peterson, 2000). Sports injuries can be classified into acute and chronic (overuse) injuries. Acute injuries most commonly result from a single traumatic incident involving contact or non-contact forces (Yang et al., 2012), whereas chronic injuries result from repetitive and cumulative micro-traumas (Fuller et al., 2006, 2007).

Sports injuries in able-bodied athletes most often interrupt or cut short an athlete’s career (Laux et al., 2015), but can also be a burden for the society, with funds needed for medical treatment, physical therapy, and offsetting reduced work capacity (Textbook of Sports Medicine, 2002). For athletes with disabilities, sports injuries have more serious consequences, since this group often experience difficulties in accessing emergency and ongoing healthcare services or obtaining appropriate treatment (Vanlandewijck and Thompson, 2011). Additionally, consequences of serious sport related injuries in athletes with disabilities tend to go well beyond expected changes in sports participation, work capacity and leisure patterns, directly affecting the athletes’ activities of daily living (Bauerfeind et al., 2015; Fagher and Lexell, 2014; Ferrara and Peterson, 2000; Urbański et al., 2021). Previous studies have demonstrated the existence of at least two models of the injury occurrence in athletes with disabilities, classified according to either the type of disability or the sports discipline (Willick and Webborn, 2011). Even though some researchers have claimed that the incidence of sports injuries is similar in ablebodied athletes and athletes with disabilities, athletes participating in Paralympic sports usually incur only minor injuries and are often cleared to resume their training in less than seven days (Ferrara and Peterson, 2000; Nyland et al., 2000).

The number of athletes with disabilities participating in sports and the popularity of sporting events for such athletes are steadily increasing. Some athletes with disabilities have professionalized their participation, increasing their performance and training times (Fagher and Lexell, 2014). In consequence, sports science researchers and the International Paralympic Committee have jointly recommended to increase efforts to collect epidemiological data to better inform injury prevention programs for athletes with disabilities (Kasińska and Tasiemski, 2017; Wieczorek et al., 2017; Gunaydin 2020, 2021). Indeed, the data indicate that the growing professionalization of that group directly results in an ever-increasing number of sports injuries. During the 2002 Winter Paralympics, every tenth athlete suffered an injury (Webborn et al., 2016); in Beijing during the 2008 Summer Paralympics, over 2,000 medical interventions were recorded (Willick and Webborn, 2011), while during the 2016 Paralympic Games in Rio, a total of 510 injuries were reported over two weeks (Derman et al., 2018).

Relevantly to this study, football is classified as a sport with one of the highest injury incidence rates (IRs) among athletes with disabilities. During the London 2012 Paralympic Games, participation in a 5-a-side of football was considered most risky (Willick et al., 2013), whereas during the Rio 2016 Paralympic Games the sports with highest IRs were 5-a-side football, judo, and 7-a-side football (Demers et al., 1999). Amputee football is a relatively new sport for people with unilateral amputations/defects of upper and lower limbs. According to player selection criteria in amputee football, a participant with an amputated or damaged lower limb can play as a field player and a participant with an amputated or damaged upper limb can play as a goalkeeper. In many respects amputee football resembles traditional association football, with some key differences: the outfield players use crutches, the pitch is smaller (40 x 60 m) and the game itself is played by 7 players, with one match consisting of two halves of 25 min each. Rapidly rising in popularity, amputee football players intend to have their discipline registered in the Paralympic Games program; accordingly, it is of vital importance to assess how injury-prone its players are going to be.

Sport injuries in amputee football have been the subject of two publications so far (Kasińska and Tasiemski, 2017; Wieczorek et al., 2017), with both studies classifying it as a low-risk discipline. However, those authors did not provide any IR in their texts, impeding attempts to accurately compare IRs in this and other types of football. The lack of data on sports injuries among athletes with disabilities contrasts sharply with a wealth of information on injuries of able-bodied players; the disparity arises due to better testing practices, since able-bodied players are routinely tested during every major sports event and at the end of the playing season (Junge and Dvořák, 2015; UEFA Injury Study Report, 2016).

Due to many similarities among amputee football, 5-a-side football, 7-a-side football, and football of able-bodied players, we assumed that players with amputations would suffer from injuries of a similar frequency and type (Webborn et al., 2016; Willick et al., 2013; UEFA Elite Club Injury Study, 2017), but with more severe consequences for their daily activities. Permanent or prolonged damage to a remaining healthy lower limb can lead to forced locomotion by means of a wheelchair. Therefore, the main goal of this study was to determine the characteristics, IRs, incidence proportion (IP), and time of recovery from sports injuries in the Polish national amputee football team during an annual training cycle.

Methods

Results

Discussion

During the 9-month duration of the study, players of the Polish national amputee football team incurred 22 injuries. The IR was 5.73 per 1000 athlete-days (95% Cl, 3.33-8.12). Thus, it has been shown that the IR in the amputee football is lower than in 5-a-side football (IR 22.4 per 1000 athlete-days, 95% CI, 14.1-33.8), and 7-a-side football (IR = 10.4 per 1000 athlete-days, 95% Cl, 5.4-15.5), played at the London Paralympics (Webborn et al., 2016; Willick et al., 2013). In turn, the IP level in amputee football was higher (IP 48.0 per 100 athletes, 95% Cl, 28.4-67.6) than in 5-a-side football (IP 31.4 per 100 athletes, 95% Cl, 20.9-43.6), and 7-a-side football (IP 14.6 per 100 athletes, 95% Cl, 7.5-21.6) (Webborn et al., 2016). These data indicate that participation in amputee football induces a higher risk of injury than participation in 5- and 7-a-side football. It is difficult to compare injury rates reported in studies on three types of football for players with disabilities with those reported by able-bodied players of traditional football. For example, the report of the Union of European Football Associations after the 2016 European Championship provided the IR of 22.6 (UEFA Injury Study Report, 2016); nevertheless, that IR was calculated on the basis of the number of injuries suffered per 1000 hours of training/matches, while for persons with disabilities, the IR is calculated on the basis of training/match days (Blauwet et al., 2016; Fagher and Lexell, 2014). The difference in reporting stems from the fact that regular football as a professional sport usually requires players to train twice a day, while amputee football and many other sports for persons with disabilities are played by amateurs, dividing their time between irregular training (several hours a week), work and other responsibilities.

The results of this study confirmed what previous studies indicated for persons with disabilities playing three kinds of football, i.e., that their lower limbs were most vulnerable to injury. In our study, lower limb injuries amounted to 68.2%, a proportion broadly in line with previous research. In 5-a-side football, 54.5% of injuries concerned the lower limb and in 7-a-side football, this value was of 78.6% (Webborn et al., 2016). Comparable results were also obtained when juxtaposing locations of injury in amputee football and football for able-bodied athletes. In our study, 32.8% of the injuries were to the thigh, 13.6% to the ankle, and 9.1% to the knee. Similarly, during the 2014 Football World Cup in Brazil, 25% of injuries were to the thigh, 12% to the knee and 10% to the ankle (Junge and Dvořák, 2015). During the 2016/2017 football season, 28.9% of injuries were to the thigh, 17.2% to the knee and 15.4% to the ankle (UEFA Elite Club Injury Study, 2017). Thus, this research confirms that athletes with disabilities and able-bodied athletes playing the same sport are exposed to similar injuries resulting from its specificity (Ferrara and Peterson, 2000; Laskowski and Murtaugh, 1992).

On average, players reporting injuries during the study were significantly more likely to have played amputee football for longer time than those players who did not. One possible explanation for this correlation takes into account the fact that experienced players might have accumulated microtraumas which hampered natural recovery mechanisms and made injuries more likely; future studies will likely demonstrate whether this hypothesis is true or not. The average recovery time between injury and return to unimpeded sport activity among our study participants was 9.8 days. Six injuries necessitated only a short recovery time (Fuller et al., 2006). The longest recovery time, i.e., 35 days, was brought about by a tear of the femoral biceps. One player in the study suffered two reinjuries of same body parts. In the first case, the player stretched his ischio-shin muscles (in general) and subsequently tore the femoral biceps; in the second case, the same player pulled his back musculature, an injury which healed and then reoccurred after two months of training.

The data obtained in this study did not match conclusions drawn by authors of previous reports, who claimed that athletes with disabilities mostly incurred only minor injuries. In our study, medically consulted injuries 63.6% (n = 14) almost doubled the non-consulted ones 36.4% (n = 8). Perhaps the divergence in data sets came from methodological differences as authors of previous reports collected data on abrasions (possibly inflating the number of minor injuries), whereas our study did not include abrasions as a category of injuries (Ferrara and Peterson, 2000; Kasińska and Tasiemski, 2017; Molik and Marszałek, 2013).

Some authors link the location of injury to the type of disability and the discipline practiced (Fuller et al., 2006). Nyland et al. (2000) indicated that visually impaired players and other players with disabilities who practiced in a standing position incurred more lower limb injuries (e.g. in 5-a-side football). Similar results were obtained in our study, with 68% of injuries incurred to the lower limb. In contrast, a study by Klenck and Gebke (2007), having compared players with various types of disabilities, surmised that amputees were more exposed to injuries to the stump than other players (Klenck and Gebke, 2007). However, Klenck and Gebke (2007) did not specify stumps of which limb were most injury-prone; on the other hand, our data recorded only a single injury of the lower limb stump. The low incidence of stump injuries among players of the Polish national team was perhaps due to the team’s consistent use of elastic bandages and specialized stump compression bands under the gaiters to minimize the risk of injury, a practice not mentioned in the article by Klenck and Gebke (2007).

After an injury, a decision whether to return to intensive training or to fully recover is often influenced by multiple factors. Based on previous findings, it is known that many players want to resume their training as soon as possible, either encouraged by coaches or driven by attention they receive due to their sport participation (Podlog and Eklund, 2005), but premature resumption of an intensive training program may result in another injury or negative psychological consequences (Janse van Rensburg and Nolte, 2011; Podlog and Eklund, 2005). To protect athletes’ health and reduce incidents of injury and illness are key responsibilities of every coach, who should insist on athletes’ receiving medical clearance before their return to active participation, optimally in consultation with a physiotherapist. Ideally, an athlete would receive clearance only in the event of complete recovery, i.e., full range of movement in the affected body part, unimpaired strength, complete neuromuscular control, cardiorespiratory tens, and demonstration of other sport-specific functional skills (Janse van Rensburg and Nolte, 2011).

Some limitations were encountered during this study. First of all, we did not collect information of injury history of players which could be related with injuries during the studied period. Another limitation was the small sample size, however, it consisted of all members of the Polish National Amputee Football team (n = 25). Previous research studies, either on 5-a-side (n = 70), 7-a-side (n = 96) or able-bodied (n = 529) football, benefitted from much larger sample sizes; studies on 5-a-side and 7-a-side players included members of all national teams during the London Paralympics, whereas the study on able-bodied players took place during Euro 2016 in France. Future research should ideally include the entire population of amputee football players in Poland (Polish Amputee Football League members), with a necessary step of appraising their sport performance levels beforehand.

Conclusions

The obtained results indicate that amputee football players rather frequently incur play-related injuries, but a single athlete incurs relatively few of them, with the lower limb being most commonly injured. The injury risk in amputee football is comparable with risks in football for abled-bodied, with 5-a-side and 7-aside football considered high-risk disciplines.