I spy with my little eye … a knee about to go \u27pop\u27? Can coaches and sports medicine professionals predict who is at greater risk of ACL rupture?

BACKGROUND: The vertical drop jump (VDJ) test is widely used for clinical assessment of ACL injury risk, but it is not clear whether such assessments are valid. AIM: To examine if sports medicine professionals and coaches are able to identify players at risk of sustaining an ACL injury by visually assessing player performance during a VDJ test. METHODS: 102 video clips of elite female handball and football players performing a baseline VDJ test were randomly extracted from a 738-person prospective cohort study that tracked ACL injuries. Of the sample, 20 of 102 went on to suffer an ACL injury. These 102 videos were uploaded to an online survey. Sports medicine professionals and coaches were invited to assess athlete performance and rate each clip with a number between 1 and 10 (1 representing low risk of sustaining an ACL injury and 10 representing high risk). Receiver operating characteristic analyses were used to assess classification accuracy and between-group differences were analysed using one-way analysis of variance. RESULTS: 237 assessors completed the survey. Area under the curve values ranged from 0.36 to 0.60, with a mean score of 0.47, which is similar to random guessing. There were no significant differences in classification accuracy between groups (physicians, coaches, certified athletic trainers, researchers or physical therapists). CONCLUSION: Assessors have poor predictive ability (no better than chance), indicating that visual assessment of a VDJ test is a poor test for assessing ACL injury risk in elite female handball and football players

Calculation of ankle and knee joint moments during ACL-injury situations in soccer

AbstractThe basis of ACL-injury prevention is the understanding of the injury mechanism. Therefore a new approach was developed and validated that enables the calculation of knee and ankle joint moments during the injury. Detailed analysis of ACL-injury situations was performed to detect the kinematics as input data for a simplified 3D-human body model. An inverse-dynamics approach was used to realize the movement. The model was driven by Net-Muscle-Torque-Motors that calculate 3-D ankle and knee joint moments. Although there are some limitations that have to be considered this approach has the potential to generate a better understanding of injury mechanisms

EFFECT OF LOAD AND VARIOUS EQUIPMENT MODALITIES ON BACK SQUAT BIOMECHANICS IN ELITE POWERLIFTERS

This study compared back squat biomechanics in elite powerlifters under various equipment and intensity manipulations. Eleven elite powerlifters performed back squats in the following conditions: belt only (Raw), belt and elastic band attached to the bar (Band), and competition attire consisting of a belt, knee wraps, and squat suit (Equipped). In Raw lifts, back angle and hip moment at minimum upward velocity increased as intensity increased. Maximum hip moment at minimum upward velocity was greater in the Raw compared to the Band lift. Back angle, total hip moment at the bottom position, and total knee moment at the minimum upward velocity was greater in the Equipped compared to the Raw lifts. Overall, the Band condition was biomechanically similar to the Raw lifts. However, the Equipped condition displayed substantial biomechanical differences compared to the Raw condition

Athletes with high knee abduction moments show increased vertical center of mass excursions and knee valgus angles across sport-specific fake-and-cut tasks of different complexities

Young female handball players represent a high-risk population for anterior cruciate ligament (ACL) injuries. While the external knee abduction moment (KAM) is known to be a risk factor, it is unclear how cutting technique affects KAMs in sport-specific cutting maneuvers. Further, the effect of added game specificity (e.g., catching a ball or faking defenders) on KAMs and cutting technique remains unknown. Therefore, this study aimed: (i) to test if athletes grouped into different clusters of peak KAMs produced during three sport-specific fake-and-cut tasks of different complexities differ in cutting technique, and (ii) to test whether technique variables change with task complexity. Fifty-one female handball players (67.0 ± 7.7 kg, 1.70 ± 0.06 m, 19.2 ± 3.4 years) were recruited. Athletes performed at least five successful handball-specific sidestep cuts of three different complexities ranging from simple pre-planned fake-and-cut maneuvers to catching a ball and performing an unanticipated fake-and-cut maneuver with dynamic defenders. A k-means cluster algorithm with squared Euclidean distance metric was applied to the KAMs of all three tasks. The optimal cluster number of koptimal = 2 was calculated using the average silhouette width. Statistical differences in technique variables between the two clusters and the tasks were analyzed using repeated-measures ANOVAs (task complexity) with nested groupings (clusters). KAMs differed by 64.5%, on average, between clusters. When pooling all tasks, athletes with high KAMs showed 3.4° more knee valgus, 16.9% higher downward and 8.4% higher resultant velocity at initial ground contact, and 20.5% higher vertical ground reaction forces at peak KAM. Unlike most other variables, knee valgus angle was not affected by task complexity, likely due to it being part of inherent movement strategies and partly determined by anatomy. Since the high KAM cluster showed higher vertical center of mass excursions and knee valgus angles in all tasks, it is likely that this is part of an automated motor program developed over the players' careers. Based on these results, reducing knee valgus and downward velocity bears the potential to mitigate knee joint loading and therefore ACL injury risk

Kiss goodbye to the ‘kissing knees’: no association between frontal plane inward knee motion and risk of future non-contact ACL injury in elite female athletes

The aim of this study was to investigate if frontal plane knee and hip control in single-leg squats or vertical drop jumps with an overhead target were associated with future non-contact anterior cruciate ligament (ACL) injury in elite female athletes. Of the 429 handball and 451 football athletes (age 21.5 ± 4.0 years, height 169.6 ± 6.4 cm, body weight 67.1 ± 8.0 kg), 722 non-injured and 56 non-contact ACL injured participants were eligible for analysis. We calculated lateral pelvic tilt, frontal plane knee projection angle, medial knee position, and side-to-side asymmetry in these from 2D videos recorded at baseline, and recorded any new ACL injuries prospectively. None of the aforementioned variables in either screening task were different or could discriminate between injured and non-injured athletes (all p values \u3e .05 and Cohen’s d values \u3c .27). Two-dimensional video assessment of frontal plane knee and hip control during both a single-leg squat and vertical drop jump was unable to identify individuals at increased risk of non-contact ACL injury, thus should not be used for screening

ANKLE LIGAMENT STRAIN DURING SUPINATION SPRAIN INJURY – A COMPUTATIONAL BIOMECHANICS STUDY

This study presents ankle ligament strain data during a grade I mild anterior talofibular ligamentous sprain. Kinematics data obtained during the injury and a 3BW were imported to a validated dynamic foot model. Four simulations were done: (1) inversion, (2) inversion plus plantarflexion, (3) inversion plus internal rotation, and (4) inversion, plantarflexion and internal rotation. Results showed that in situation (1), the calcaneofibular ligament was strained the most (12%), followed by the anterior talofibular ligament (10%). In situations (2) and (3), both ligaments were strained to about 14-16%. In situation (4), the anterior talofibular ligament was strained to 20%. This study suggested that plantarflexion and internal rotation, together with inversion, may have greatly strained and torn the anterior talofibular ligament during the reported injury event

Change of Direction Biomechanics in a 180-Degree Pivot Turn and the Risk for Noncontact Knee Injuries in Youth Basketball and Floorball Players

Background: Studies investigating biomechanical risk factors for knee injuries in sport-specific tasks are needed. Purpose: To investigate the association between change of direction (COD) biomechanics in a 180-degree pivot turn and knee injury risk among youth team sport players. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 258 female and male basketball and floorball players (age range, 12-21 years) participated in the baseline COD test and follow-up. Complete data were obtained from 489 player-legs. Injuries, practice, and game exposure were registered for 12 months. The COD test consisted of a quick ball pass before and after a high-speed 180-degree pivot turn on the force plates. The following variables were analyzed: peak vertical ground-reaction force (N/kg); peak trunk lateral flexion angle (degree); peak knee flexion angle (degree); peak knee valgus angle (degree); peak knee flexion moment (N.m/kg); peak knee abduction moment (N.m/kg); and peak knee internal and external rotation moments (N.m/kg). Legs were analyzed separately and the mean of 3 trials was used in the analysis. Main outcome measure was a new acute noncontact knee injury. Results: A total of 18 new noncontact knee injuries were registered (0.3 injuries/1000 hours of exposure). Female players sustained 14 knee injuries and male players 4. A higher rate of knee injuries was observed in female players compared with male players (incidence rate ratio, 6.2; 95% CI, 2.1-21.7). Of all knee injuries, 8 were anterior cruciate ligament (ACL) injuries, all in female players. Female players displayed significantly larger peak knee valgus angles compared with male players (mean for female and male players, respectively: 13.9 degrees +/- 9.4 degrees and 2.0 degrees +/- 8.5 degrees). No significant associations between biomechanical variables and knee injury risk were found. Conclusion: Female players were at increased risk of knee and ACL injury compared with male players. Female players performed the 180-degree pivot turn with significantly larger knee valgus compared with male players. However, none of the investigated variables was associated with knee injury risk in youth basketball and floorball players.Peer reviewe

THE KINEMATICS OF HEAD IMPACTS IN CONTACT SPORT: AN INITIAL ASSESSMENT OF THE POTENTIAL OF MODEL BASED IMAGE MATCHING

Model Based Image Matching (MBIM) has potential to assess three-dimensional linear and rotational motion patterns from multiple camera views of head impact events in contact sports. The goal of this study is to assess the accuracy of the MBlM method for estimating 6DOF head kinematics in a vehicle-cadaver impact scenario for which Vicon motion analysis data are available as an independent measure. A three camera view MBlM reconstruction yielded RMS errors between 0.14-0.26 mls for change in head linear velocities ranging from 0.56-5.70 m/s, and 0.27-1.38 rad/s for change in head angular velocities ranging from 6.1041 -90 rad/s. The results from this study indicate that the MBlM method is a useful approach for measuring the kinematics of head impacts in sport

Analysis of ball carrier head motion during a rugby union tackle without direct head contact: A case study

Rugby union players can be involved in many tackles per game. However, little is known of the regular head loading environment associated with tackling in rugby union. In particular, the magnitude and influencing factors for head kinematics during the tackle are poorly understood. Accordingly, the goal of this study was to measure head motion of a visually unaware ball carrier during a real game tackle to the upper trunk with no direct head contact, and compare the kinematics with previously reported concussive events. Model-Based Image-Matching was utilised to measure ball carrier head linear and angular velocities. Ball carrier componential maximum change in head angular velocities of 38.1, 20.6 and 13.5 rad/s were measured for the head local X (coronal plane), Y (sagittal plane) and Z (transverse plane) axes respectively. The combination of a high legal tackle height configuration and visually unaware ball carrier can lead to kinematics similar to average values previously reported for concussive direct head impacts

Functional and Anthropometrical Screening Test among High Performance Female Football Players: A Descriptive Study with Injury Incidence Analysis, the Basque Female Football Cohort (BFFC) Study

The main objectives of the present study were to describe the injury incidence and to analyze the anthropometric and physical characteristics of players from three high-level women’s football teams. The present study involved 54 female football players (21.9 ± 4.9 years old) from three different teams competing in the Spanish Reto Iberdrola-Segunda División PRO league. A battery of tests was carried out to determine the anthropometric and physical performance characteristics of the players along with an injury incidence record during a full competitive season. The obtained results showed that there was a high incidence of injury, as 38% of the players suffered some type of injury during the season (range 1–5; 1.75 ± 1.02 injuries per player). Injuries occurred in both matches and during training at a similar percentage (48.6 vs. 51.4%), and the majority of the registered episodes were graded as moderate or severe injury types (60%). Players suffering from an injury accumulated a total of 1587 chronological days off work due to injury during the season, with a recurrence rate of 55%. Considering the high incidence of injury, and the injury burden and the reinjure rate observed in this research, it seems necessary to apply the most efficient prevention and recovery measures possible in these female football teams. These descriptive data could serve athletic trainers and medical staff of female football teams to better understand their own screening procedure-derived data