The aim of the present study was to investigate if the presence of anterior cruciate ligament (ACL) injury risk factors depicted in the laboratory would reflect at-risk patterns in football-specific field data. Twenty-four female footballers (14.9 ± 0.9 year) performed unanticipated cutting maneuvers in a laboratory setting and on the football pitch during football-specific exercises (F-EX) and games (F-GAME). Knee joint moments were collected in the laboratory and grouped using hierarchical agglomerative clustering. The clusters were used to investigate the kinematics collected on field through wearable sensors. Three clusters emerged: Cluster 1 presented the lowest knee moments; Cluster 2 presented high knee extension but low knee abduction and rotation moments; Cluster 3 presented the highest knee abduction, extension, and external rotation moments. In F-EX, greater knee abduction angles were found in Cluster 2 and 3 compared to Cluster 1 (p = 0.007). Cluster 2 showed the lowest knee and hip flexion angles (p < 0.013). Cluster 3 showed the greatest hip external rotation angles (p = 0.006). In F-GAME, Cluster 3 presented the greatest knee external rotation and lowest knee flexion angles (p = 0.003). Clinically relevant differences towards ACL injury identified in the laboratory reflected at-risk patterns only in part when cutting on the field: in the field, low-risk players exhibited similar kinematic patterns as the high-risk players. Therefore, in-lab injury risk screening may lack ecological validity.
Primary anterior cruciate ligament (ACL) injury prevention programs effectively reduce ACL injury risk in the short term. Despite these programs, ACL injury incidence is still high, making it imperative to continue to improve cur- rent prevention strategies. A potential limitation of current ACL injury prevention training may be a deficit in the transfer of conscious, optimal movement strategies rehearsed during training sessions to automatic movements required for athletic activities and unanticipated events on the field. Instructional strategies with an internal focus of attention have traditionally been utilized, but may not be optimal for the acquisition of the control of complex motor skills required for sports. Conversely, external-focus instructional strategies may enhance skill acquisition more efficiently and increase the transfer of improved motor skills to sports activities. The current article will present in- sights gained from the motor-learning domain that may enhance neuromuscular training programs via improved skill development and increased reten- tion and transfer to sports activities, which may reduce ACL injury incidence in the long term.
Athletes in team sports have to quickly visually perceive actions of opponents and teammates while executing their own movements. These continuous actions are performed under time pressure and may contribute to a non-contact ACL injury. However, ACL injury screening and prevention programmes are primarily based on standardised movements in a predictable environment. The sports environment provides much greater cognitive demand because athletes must attend their attention to numerous external stimuli and inhibit impulsive actions. Any deficit or delay in attentional processing may contribute to an inability to correct potential errors in complex coordination, resulting in knee positions that increase the ACL injury risk. In this viewpoint, we advocate that ACL injury screening should include the sports specific neurocognitive demands.
The anterior cruciate ligament (ACL) is a strong rope-like tissue which connects the femur to the tibia in the knee joint. Its function is to provide structural stability to the knee while preventing unnatural forward movement of the tibia relative to the femur. Acute complete ACL ruptures during movements like knee hyperextension or sudden changes of direction (pivoting) damage two entities: the ligament itself and its nerve connections to the posterior tibial nerve (PTN). PTN innervation in the ACL is essential for: a) proprioception (e.g. perception of position and movement/acceleration experienced by the ligament), and b) stability of the knee joint. Upon ACL rupture, the orthopedic surgeon reconstructs the ACL with a graft from the hamstring, patellar or quadriceps tendon. After the surgery, the goal is to regain neuromuscular control and dynamic stabilization during rehabilitation as soon as possible for a quick return to sports and daily activities. However, surgeons are not able to reconstruct the nerve gap between the PTN and the grafted ligament due to the microscopic size of the innervation in the ACL. Not linking the PTN to the graft creates a disconnection between the knee joint and the spinal cord. To mitigate these disadvantages in ACL surgery, this study focuses on activating the growth of proprioception nerve endings using a ligament loaded with growth factors (neurotrophins). We hypothesize that neurotrophins will activate proprioceptive fibers of neurons close to the ACL. We describe graft fabrication steps and in vitro experiments to expand on the regeneration capacity of a commercially available ACL-like synthetic ligament called LARS. The results will bring the ACL regeneration field closer to having a graft that can aid patients in regaining mobility and stability during locomotion and running, confidence in the strength of the knee joint, and quick return to sports.
In societies where physical activity levels are declining, stimulating sports participation in youth is vital. While sports offer numerous benefits, injuries in youth are at an all-time high with potential long-term consequences. Particularly, women football's popularity surge has led to a rise in knee injuries, notably anterior cruciate ligament (ACL) injuries, with severe long-term effects. Urgent societal attention is warranted, supported by media coverage and calls for action by professional players. This project aims to evaluate the potential of novel artificial intelligence-based technology to enhance player monitoring for injury risk, and to integrate these monitoring pathways into regular training practice. Its success may pave the way for broader applications across different sports and injuries. Implementation of results from lab-based research into practice is hindered by the lack of skills and technology needed to perform the required measurements. There is a critical need for non-invasive systems used during regular training practice and allowing longitudinal monitoring. Markerless motion capture technology has recently been developed and has created new potential for field-based data collection in sport settings. This technology eliminates the need for marker/sensor placement on the participant and can be employed on-site, capturing movement patterns during training. Since a common AI algorithm for data processing is used, minimal technical knowledge by the operator is required. The experienced PLAYSAFE consortium will exploit this technology to monitor 300 young female football players over the course of 1 season. The successful implementation of non-invasive monitoring of football players’ movement patterns during regular practice is the primary objective of this project. In addition, the study will generate key insights into risk factors associated with ACL injury. Through this approach, PLAYSAFE aims to reduce the burden of ACL injuries in female football players.
