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COJ Nursing & Healthcare

The Risk Factors that Affecting the Anterior Cruciate Ligament (ACL) Injury in Some Contacts Sports

Mehdi Kasbparast Jr*, Alireza Rahimi, Mehdi Kohandel and Fariba Aghaie

Department of sport injury and biomechanics, Islamic Azad University, Iran

*Corresponding author: Mehdi Kasbparast Jr, Department of sport injury and biomechanics, Faculty of Physical Education and Sport Sciences, Islamic Azad University, karaj Branch, Alborz, Iran, Email:

Submission: October 02, 2017; Published: February 22, 2018

DOI: 10.31031/COJNH.2018.01.000518

ISSN: 2577-2007
Volume1 Issue4


The purpose of the present study was to determine of some risk factors influencing of non-contact Anterior Cruciate Ligament (ACL) injury in Soccer, basketball and Taekwondo players. If an athlete injured anterior cruciate ligament the most important thing is to identify factors that affect the injury. However, a growing research implicates hormonal, anatomical, environmental and neuromuscular factors that may predispose athletes to these injuries. For this research selected 510 athlete for assess ACL injury factors by two different methods

    a. Questionnaire and

    b. Interview that information collected among athletes who were play soccer, basketball and taekwondo.

Our results indicate 61.4% of ACL injury occurred in practice time and 38.6% of ACL injury was during competition. Also our finding showed that 69% mechanism of injury was non-contact, 4.7% via accident and 26.3% with unknown reason. Furthermore dynamic alignment at the time of the injury included: Knee-in & Toe- out 44%, Knee-out & Toe-in 22.5 and Hyperextension 11.1%.

The ACL prevents the femur from moving forward during weight bearing. It also helps to prevent rotation of the joint. Injury of the ACL most often occurs when an athlete is pivoting, decelerating suddenly or landing from a jump. The injury can also be caused by another player falling across the knee. ACL injuries are, probably, the most common devastating knee ligament injuries amongst sports persons. Usually these injuries are isolated, mainly in non-contact sports, but many often are a part of more complex ligamentous injuries. They occur more often in contact sports, such as soccer, basketball or taekwondo. In conclusion, our study produced strong evidence in support of a significant some factors influencing of ACL injury in Soccer, basketball and Taekwondo players.

Keywords: Non-contact; Anterior cruciate ligament; Risk factors


The anterior cruciate ligament (ACL) is one of the most commonly disrupted ligaments in the knee. Despite the explosion of information on the ACL over the past 25 years, little attention has been focused on the causes and prevention of injury. The mechanism of non-contact ACL injuries has been elucidated (see "ACL Injury Mechanisms," below). However, numerous theories have been proposed to explain what predisposes patients to noncontact ACL injury. These theories are divided into four categories: hormonal, anatomical, environmental, and neuromuscular (Table 1) also anatomical position of Anterior Cruciate Ligament (ACL) showed in Figure 1.

Table 1: Proposed Causes of ACL Injury.

Figure 1 : Anatomical position of Anterior CruciateLigament (ACL) [48].

It has been well recognized that multiple factors, whether individually or in combination, contribute to non-contact ACL injury. The ongoing mission of the ACL research retreat is to bring clinicians and researchers together to present and discuss the most recent advances in ACL injury epidemiology, risk factor identification, and injury-risk screening and prevention strategies and to identify future research directives [1]. A different approach to the problem of ACL tears involves prevention. Approximately 80% of all ACL tears are non-contact injuries, suggesting that a substantial percentage of tears could be avoided [2,3]. New treatment options, such as regenerative treatments based on tissue engineering methods, are being developed but are not available for clinical use [4-6].

Indeed, a number of ACL injury prevention programs have been developed and have been shown to reduce ACL injury rates significantly [7-9]. These programs usually target high-risk groups, such as young female athletes, and aim to improve dangerous motion patterns. For example, a program may aim to improve landing technique from “flat foot” landing with an extended lower extremity to landing with deep hip and knee flexion. However, the effectiveness of these programs has not been comprehensively analyzed and described. The goal of understanding what causes a non-contact ACL injury is to implement preventive strategies. Though there is a plethora of literature on the ACL, we found only a few reports that address prevention [10-13].

Consequently, identification of factors associated with increased risk of suffering ACL injury during sport and physical activity has become a focus of musculoskeletal research. This information is needed to understand the mechanisms that produce this debilitating injury and may allow identification of those at increased risk so that targeted interventions can be implemented. Researchers have utilized a range of measurement techniques, focused on different at risk groups, evaluated many sports, identified an array of injury mechanisms, and utilized different study designs. Current investigations concerning ACL injury risk focus on a range of potential factors, and the majority of these studies are based on small sample sizes and, as a result, are underpowered. Research in this field has primarily focused on a single potential risk factor in isolation. Over time it became apparent that multiple variables act in combination to influence ACL injury risk [14-16].

The focus on ACL injury is warranted considering that the cost of reconstructing and rehabilitating the ACL in these athletes at a conservative cost of $17,000 per patient [14]. However, nowadays, most athletes return to competition following reconstructive surgery, but the time loss from sport and the financial cost of suffering an ACL injury are high [17]. ACL tear in soccer is quite frequent and they seriously affect players' career with short-term and long-term consequences. It has also been seen that ACL injuries are very invalidating events that require surgical treatments and keeps majority of soccer players out of competition at least four months every season. In professional soccer it has significant economic consequences.

Soccer is particularly known as a sport with a reasonably high risk for ACL injuries [18-21]. Injury rates as high as 2.8 and 3.2 injuries per 10,000 athlete exposures have been reported in women's collegiate basketball and soccer [22]. As in many other combat sports, there is high potential for injury associated with elite athletic performance in taekwondo [23-29]. Defining injury as any circumstance for which the athlete sought the assistance of onsite medical personnel, the latest reviews on competition injuries in taekwondo concluded that total injury rates are 20.6-139.5 per 1000 athlete-exposure (A-E) for elite men and 25.3-105.5 per 1000 A-E for elite women. When only time-loss injuries are considered, rates are 6.9-33.6 per 1000 A-E for men and 2.4-23.0 per 1000 A-E for women [30].

Materials and Methods

Information on some factors influencing of non-contact ACL injury was collected in 2 different ways, from the questionnaire (n=372) and through interviews with injured players (n=138). Information was collected prospectively through the 2010-2013. The sport activities that were considered for the study included: soccer, basketball and Taekwondo male athlete (Table 2).

Table 2: Sports activities participation (n=510).

In an epidemiological study we assessed the evolution in the incidence and possible risk factors of knee injuries, especially anterior cruciate ligament injuries in soccer, basketball and taekwondo among male athlete. This study aimed to investigate the incidence of knee injuries among collegiate soccer, basketball and taekwondo player and to identify influencing risk factor for ACL injuries. As a result, all acute injuries that occurred during training activities or during competition are reported and collected in the injury registry. Of course an understanding of the non- contact injuries mechanism has lagged behind diagnosis and treatment. However, a growing research implicates hormonal, anatomical, environmental and neuromuscular factors that may predispose athletes to these injuries [31]. Also there are some factors which include genetic, cognitive function, previous injury, and extrinsic risk factors. Case-control studies are an efficient method for studying relatively rare events such as ACL injuries (in comparison with more common musculoskeletal injuries associated with sports, such as ankle sprains) because they allow researchers to accumulate a large sample size in a relatively short period, depending on the level of competition and the sport under investigation. All injured players were interviewed during the 2010-2013 to compare player recall with the questionnaire. The interview data were also used to check whether the questionnaire we obtained was a representative sample.

The entire athletes were diagnosed as having an ACL injury confirmed by magnetic resonance imaging (MRI) and/or an arthroscopic procedure. Approximately seventy five percent of the subjects visited the clinic within one month, and 25 percent of the subjects visited the clinic within one week after an ACL injury incident.

We classified the activity of the subject at the time of the ACL injury in two categories

    A. Competitions

    B. Practice

Also we classified the injury factors in three categories

    A. Non-contact: No contact with another person or things at the time of the injury

    B. Accident: Particular situations during sports activities such as basketball and

    C. Unknown: The injury factors data missing in medical records, and dynamic alignment at the time of the injury.

We classified the dynamic alignment at the time of the injury into six categories [32].

    A. Knee-in & Toe-out: Knee valgus and foot abduction position

    B. Knee-out & Toe-in: Knee varus and foot adduction position

    C. Hyperextension: Hyper-extended knee position

    D. Unclear: Injury factors that were not expressed clearly by the patients

    E. Unknown: The injury factors data missing in medical records

    F. Other


The ACL is a ligament whose main purpose is to prevent anterior translation of the knee along with prevention of hyperextension, resistance of internal rotation of the tibia, and assists with stabilization of varus and valgus stresses [33]. The length of the ACL varies from 25 to 35mm long, 7 to 12mm wide, and 4 to 7 mm thick. The ACL has two bundles of fibers that start at the posterolateral femoral condyle and cross the notch of the center of the knee to end at the anterior medial tibia .The main mechanism of injury to the ACL being torn is usually non-contact involvement. When it happens though, it is most often in contact sports. These sports are soccer, basketball and Taekwondo. The reason for this difference in the type of sport and how it happens involves the activities done in each sport. With these sports, there is usually a rapid change of direction or landing form a jump involved.

The most frequent way that the ACL is torn is the athlete has a planted foot with the knee in an almost extended position (sometimes hyper-extended) .An example is the foot is planted for a pivot and then the athlete cuts quickly resulting in an increased rotation at the knee. The tibia is generally rotated toward the inside or mid-line of the body while the knee is flexed greater than 90° [8]. Hormonal differences between men and women could to some extent explain the discrepancy in injury rates. The risk of an ACL injury seems to be higher in the preovulatory than the postovulatory phase of the menstrual cycle [5,34,35].

Results from measurement of estrogen, progesterone and luteinizing hormone metabolites levels at the time of the anterior cruciate ligament tear have indicated that women had a significantly greater than expected percentage of anterior cruciate ligament injuries during midcycle (ovulatory phase) and a less than expected percentage during the luteal phase ofthe menstrual cycle [14,15,16]. Also recent research in the area of ACL injury risk factors has centered on neuromuscular performance. Neuromuscular control of the knee involves a complex interplay between the neurologic system and the muscles that cross the knee joint. Perhaps in noncontact ACL injury, expected motor recruitment patterns that control the knee are altered, which lead to injury. Activity, Injury factors and Dynamic alignment at the time of the injury showed in Table 3-5 respectively.

Table 3: Activity at the time of the injury.

Table 4: Injury factors at the time of the injury.

Table 5: Dynamic alignment at the time of the injury.


Understanding the injury pattern of a particular sport and its inherent risk factors is a key area of current sports medicine [36]. ACL tears can also occur during rough play, mover vehicle collisions, falls, and work-related injuries. About 80% of sports-related ACL tears are "non-contact” injuries. This means that the injury occurs without the contact of another athlete, such as a tackle in soccer. Most often ACL tears occur when pivoting or landing from a jump. The knee gives-out from under the athlete when the ACL is torn. Our result showed an ACL injury occurred more often during a practice than during competition. The situations during a competition and a practice are different in many respects. Athletes usually spend a much longer time in practice than in competition.

Non-contact ACL injuries typically occur during deceleration and change of direction with the foot fixed Knee torsion that results from making a sudden directional change on a planted foot has been implicated as a cause of ACL tears. Data such as contact versus non-contact, position of the knee and lower leg, direction of knee collapse, direction of body twisting, and other events were recorded. The number of variables an athlete must respond to in team sports may explain the higher incidence of injuries in sports such as soccer, basketball and taekwondo. It may not be possible to measure neuromuscular control and muscle activation variables during dynamic activities after an ACL disruption. The investigation on the dynamic alignment at the time of the injury revealed that the knee-in & toe-out alignments were most often reported. In retrospective interviewing studies, the subjects often encounter difficulty in recalling the dynamic alignment at the time of the injury, which may be related to the passage of time between the injury and the interview. The interview was usually held long after the injury occurred; for example, Boden [22] reported that the interview was held 3.4 years after the injury on average.

In addition, whether the information obtained is accurate or not may depend on how the subject described the dynamic alignment at the time of the injury. Therefore, there might be questions about the accuracy of the information obtained in the retrospective interviewing study [37,38]. We confirmed that the data from both sources (questionnaire and interview) exactly matched each other. The number of variables an athlete must respond to in team sports may explain the higher incidence of injuries in sports such as soccer, basketball and taekwondo. Though the exact moment of injury was impossible to determine from interview, the position of the leg before collapse in most of non-contact injuries was near foot strike with the knee in slight flexion. None were associated with a sharp, pivoting motion of the body around a planted leg or varus collapse of the knee. Valgus collapse of the knee in varying degrees was noted in most injuries.

These findings have several important implications. Our findings concluded that most important risk factor for ACL injuries in sports involving jumping, cutting and pivoting maneuvers among soccer and basketball. In accordance to other studies, we also found that competitive activities were more likely to induce ACL injuries than training activities. Several explanations might be found for the higher incidence of ACL injuries in older players such as fatigue due to longer training and competition times, higher speed and a more aggressive play style [39,40]. Of interest is that a higher level of performance was not associated with an increased risk for ACL injuries, despite the fact that the aforementioned parameters are even more pronounced in elite soccer players. Better training modalities and prevention measures may explain this finding [10,41-45].

The highest injury prevalence occurs at different ages according to sex: 23-24 years in male athletes. Many related studies have found a significant correlation between age and injury incidence [46]. The data from this study confirm these results, indicating age as a potential risk factor for injury incidence in elite taekwondo athletes. Sex difference according to weight category is a clear indicator that men suffer more injuries in all weight categories with the exception of the intermediate weight category.

This exception can be explained by the fact that there are fewer male taekwondo athletes represented in this category. Moreover, the weight category emerges as a possible injury risk factor. The injuries occurred predominantly during landing, pivoting and sudden direction change. Although the majority of the injuries did not involve contact at the assumed point of injury, the movement patterns were likely perturbed by an opponent, for example, by pushing before the injury. Further research is needed to achieve a better understanding of elite taekwondo, in relation to sex and different training systems [47].


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