Landing error scoring system (LESS) and three- dimensional (3D) movement analysis of the lower extremity in female football players

Purpose: It is known that athletes' lower extremity alignments and dynamics are important in ligament injuries. The relationship between dynamic examination and non-contact (without collision or contact) ligament injury was investigated in volleyball players. However, although ligament injuries are common in other sports, especially in female football players, there is no study that quantitatively examines jumping dynamics and investigates its relationship with ligament injuries. The aim of this study is to obtain more detailed information about the prevention of non-contact anterior cruciate ligament injuries and landing mechanics in female football players through the integration of the post-jump landing error scoring system (LESS) and three-dimensional (3D) motion analysis. Method: 28 professional female football players (age 18-30 years) were included in the study. The LESS scores of the athletes were calculated by jumping down from the 30 cm high block twice and then making the second jump at the falling point. According to LESS scores, football players were divided into two as good jumpers (those who scored 5 or lower) and poor jumpers (those who scored 6 or higher). The movements of the football players during jumps were evaluated with a 3D motion analysis system, and the degrees of movement in the lower extremity joints were measured. The load on each joint was calculated by measuring the forces on the ground during the jumps. The joint movements and the loads on the joints of the good jumping and bad jumping groups were compared using statistical methods. Results: There was no significant difference between the groups in terms of age, football playing time, dominant foot, and body mass index. The LESS score was significantly lower in the good jumping group (4.4±0.8 vs 8.1±1.2, p<0.<001). Inter- rater reliability in calculating the LESS score was found to be high (Kappa = 0.848). In the good jumping group, maximum vertical ground reaction force and ankle and knee strength at first contact were significantly lower (17.3±3.8N and 20.9±2.6N, respectively, p=0.006, 2.8± 0.8N and 4.5±1.2N, p<0.001, 7.5±0.8N and 8.8±1.0N p=0.001). There was no difference in hip strength at first contact between groups. Considering the angle measurements, knee and hip flexion angle degrees at first contact were significantly higher in the good jumping group (58.0±11.3 and 16.5±10.6 p<0.001 and 53.4±10.3 and 31.5±10.5 p<0.001, respectively). In the good jumping group, the mean value of the coronal plane alignment of the knee at first contact was 2.9 degrees varus. In the poor jumping group, the coronal alignment was significantly different and 5.2 degrees valgus (2.9±8.6 and -5.2±7.4 p=0.013). Hip abduction angle and ankle at first contact in both groups. The angle of inversion was similar. Conclusion: When female football players are divided into two as good jumpers and bad jumpers according to their IHPS scores, the most important differences between the groups are that hip and knee flexions, especially at the first contact with the ground at the time of landing, are increased in good jumpers compared to poor jumpers, and maximum vertical reaction, ankle and knee strength are higher. was that it was less. Between the groups, the forces exerted directly on the knee were significantly lower in good jumpers, and it was thought that the higher knee flexion angle and hip flexion angle enabled better absorption of the force. Angle measurements showed that the knee was at varus angles in the coronal plane alignment in the good jumpers and at a valgus angle in the poor jumpers group. However, there is no difference in the hip abduction position. In this study, it was shown by 3D motion analysis that high loads were placed on the knee in extension and valgus, which are known risk factors for ACL injury in athletes with high IHPS scores and poor jumping mechanics. In order to reduce the risk of ACL injury for athletes with high IHPS scores, improving landing mechanics by increasing hip and knee flexion degrees with 3D motion analysis and optimizing the alignment of the knee in the coronal plane should be investigated in jumping training. Keywords: anterior cruciate ligament, woman, football player, jumping, analysis