Peak Knee Abduction Angles Research Articles

Trunk and Lower Extremity Biomechanics in Female Athletes With and Without a Concussion History.

Athletes with a history of concussion are at a greater risk for lower extremity musculoskeletal injury. Female athletes may be at an even greater risk than male athletes. Previous researchers on postconcussion landing biomechanics have focused on the lower extremities, but the trunk plays a crucial role as an injury risk factor. To compare lower extremity and trunk biomechanics during jump-landing and cutting maneuvers between female athletes with and those without a concussion history. Cross-sectional study. Biomechanics laboratory. A total of 26 athletes (mean ± SD age = 19.0 ± 1.3 years, height = 1.68 ± 0.07 m, mass = 64.02 ± 6.76 kg, body mass index = 22.58 ± 1.97 kg/m2; median [interquartile range] time since most recent concussion = 37.5 months [25.0 months, 65.8 months]) with a concussion history and 38 athletes (age = 19.0 ± 1.1 years, height = 1.71 ± 0.08 m, mass = 64.72 ± 9.45 kg, body mass index = 22.14 ± 1.80 kg/m2) without a concussion history. Peak kinetics (vertical ground reaction force, vertical loading rate, external knee-abduction moment, and external knee-flexion moment) and kinematics (trunk-flexion angle, trunk lateral-bending angle, ankle-dorsiflexion angle, knee-flexion angle, knee-abduction angle, and hip-flexion angle) were obtained during the eccentric portion of jump-landing and cutting tasks. Separate 2 (group) × 2 (limb) between- and within-factors analyses of covariance were used to compare outcomes between groups. We covaried for time since the most recent concussion and the limb that had a history of musculoskeletal injury. Athletes with a concussion history displayed a greater peak knee-abduction angle in their nondominant limb than their dominant limb (P = .01, ηp2 = 0.107) and the nondominant limb of athletes without a concussion history (P = .02, ηp2 = 0.083) during jump landing. They also had less trunk lateral bending during cutting compared with athletes without a concussion history (P = .005, ηp2 = 0.126). Our results indicated landing biomechanics are different between female athletes with and those without a concussion history. This finding may be due to impairments in neuromuscular control postconcussion that may ultimately increase the risk of subsequent lower extremity injury, although further research is warranted given the cross-sectional nature of our study.

Unanticipated mid-flight external trunk perturbation increased frontal plane ACL loading variables during sidestep cuttings

ABSTRACT Unanticipated trunk perturbation is commonly observed when anterior cruciate ligament (ACL) injuries occur during direction-changing manoeuvres. This study aimed to quantify the effect of mid-flight medial-lateral external trunk perturbation directions/locations on ACL loading variables during sidestep cuttings. Thirty-two recreational athletes performed sidestep cuttings under combinations of three perturbation directions (no-perturbation, ipsilateral-perturbation, and contralateral-perturbation relative to the cutting leg) and two perturbation locations (upper-trunk versus lower-trunk). The pushing perturbation was created by customised devices releasing a slam ball to contact participants near maximum jump height prior to cutting. Perturbation generally resulted in greater peak vertical ground reaction force and slower cutting velocity. Upper-trunk contralateral perturbation showed the greatest lateral trunk bending away from the travel direction, greatest peak knee flexion and abduction angles, and greatest peak internal knee adduction moments compared to other conditions. Such increased ACL loading variables were likely due to the increased lateral trunk bending and whole-body horizontal velocity away from the cutting direction caused by the contralateral perturbation act at the upper trunk. The findings may help understand the mechanisms of indirect contact ACL injuries and develop effective cutting techniques for ACL injury prevention.

Falling decreased anterior cruciate ligament loading variables during single-leg landings after mid-flight external trunk perturbation

Mid-flight external upper-trunk perturbation is associated with increased anterior cruciate ligament (ACL) injury risk during landing. This study aimed to assess the effect of natural, soft, and falling landing techniques on knee mechanics and vertical ground reaction forces (VGRF) during single-leg landings with/without mid-flight medial–lateral external upper-trunk pushing perturbation. Twenty-eight participants performed single-leg landings using the three landing techniques with/without mid-flight pushing perturbation. The perturbation was created by a customized apparatus releasing a slam ball and pushing the participants near the peak jump height at the upper trunk. Perturbation resulted in significantly greater lateral trunk bending angles, knee flexion angles at initial contact, peak knee abduction angles, and peak knee adduction moments compared to no perturbation. The falling condition significantly demonstrated the greatest lateral trunk bending angles, knee flexion angles, and peak knee external rotation moments and the smallest peak knee abduction angles, peak VGRF, and peak knee extension moments compared to natural/soft landings regardless of perturbation conditions. Mid-flight external perturbation resulted in variables associated with greater ACL loading during single-leg landings. Falling demonstrated variables associated with smaller ACL loading, particularly for perturbation conditions. Incorporating falling techniques into jump-landing training programs may guide players to safely fall on the ground when perturbation occurs. Falling provides an alternative strategy to potentially decrease indirect contact ACL injury risk when the sports environment allows.

Lower extremity coordination strategies to mitigate dynamic knee valgus during landing in males and females

Frontal and sagittal plane landing biomechanics differ between sexes but reported values don’t account for simultaneous segment or joint motion necessary for a coordinated landing. Frontal and sagittal plane coordination patterns, angles, and moments were compared between 28 males and 28 females throughout the landing phase of a drop vertical jump. Females landed with less isolated thigh abduction (p = 0.018), more in-phase motion (p < 0.001), and more isolated shank adduction (p = 0.028) between the thigh and shank in the frontal plane compared with males. Females landed with less in-phase (p = 0.012) and more anti-phase motion (p = 0.019) between the thigh and shank in the sagittal plane compared with males. Females landed with less isolated knee flexion (p = 0.001) and more anti-phase motion (p < 0.001) between the sagittal and frontal plane knee coupling compared with males. Waveform and discrete metric analyses revealed females land with less thigh abduction from 20 % to 100 % and more shank abduction from 0 to 100 % of landing, smaller knee adduction at initial contact (p = 0.002), greater peak knee abduction angles (p = 0.015), smaller knee flexion angles at initial contact (p = 0.035) and peak (p = 0.034), greater peak knee abduction moments (p = 0.024), greater knee abduction angles from 0 to 13 % and 19 to 30 %, greater knee abduction moments from 19 to 25 %, and smaller knee flexion moments from 3 to 5 % of landing compared with males. Females utilize greater frontal plane motion compared with males, which may be due to different inter-segmental joint coordination and smaller sagittal plane angles. Larger knee abduction angles and greater knee adduction motion in females are due to aberrant shank abduction rather than thigh adduction.

The Association of Trunk and Hip Kinematic With Knee Abduction Angle During Single-Leg Landing

Objectives: Children aged 10 to 12 years often show dangerous maneuvers during landing, which include increased knee valgus, placing them at higher risk of anterior cruciate ligament (ACL) injuries. The study aimed to investigate the relation of the trunk and hip kinematics with the peak knee abduction angle during single-leg landing among preadolescent female soccer players. Methods: Thirty-six preadolescent female soccer players aged 10 to 12 years attended the study. Participants did a static trial and after that performed landing trials. A single-leg landing was applied to assess the landing kinematics. A three-dimensional motion capture system was applied to analyze trunk, hip, and knee kinematics. Results: Pearson correlation coefficient demonstrated a significantly positive relationship between peak hip internal rotation angle (r=0.361) (P=0.03) and peak knee abduction angle. Furthermore, no significant relationship was identified between peak hip adduction (r=-0.102) (P=0.55), peak trunk rotation (r=0.239) (P=0.16), peak trunk lateral flexion (r=0.052) (P=0.76), and peak valgus knee. Discussion: Peak hip rotation angle was correlated with the valgus knee with a weak correlation value among preadolescent female soccer players. Future studies should consider kinematic risk factors related to ACL injuries in combination with neuromuscular control trunk and hip during more demanding tasks.

Association of Proximal and Distal Factors With Lower Limb Kinematics During a Classical Ballet Jump

Excessive dynamic lower limb misalignment may predispose ballet dancers to jump-related injuries. However, it is unknown whether proximal and distal factors influence this movement pattern. The aim of this study was to investigate whether hip abduction strength, foot alignment, and ankle dorsiflexion range of motion (ROM) are associated with peak angles of hip adduction and internal rotation and knee abduction during the preparation and landing phases of a classical ballet jump. Cross-sectional study. Forty-one healthy amateur ballet dancers were included. Hip abduction strength was evaluated isometrically using a handheld dynamometer, foot alignment was determined by the shank-forefoot alignment, and weight-bearing ankle dorsiflexion ROM was measured by performing the lunge test. Peak hip and knee angles were analyzed 3-dimensionally during the preparation and landing phases of a single-leg jump. A Pearson correlation matrix was used to investigate the association of hip abduction strength, shank-forefoot alignment, and ankle dorsiflexion ROM with peak angles of hip adduction and internal rotation and knee abduction during the preparation and landing phases of the jump. Greater hip abduction strength was associated with greater peak hip internal rotation angle (r = .43, P < .05), but not with peak hip adduction and knee abduction angles during the preparation phase of the jump. There were no associations of shank-forefoot alignment and ankle dorsiflexion ROM with peak hip and knee angles during the preparation (r = -.23 to .36, P > .05) and landing (r = -.20 to .24, P > .05) phases of the jump. There was no association of hip abduction strength with peak hip and knee angles during the landing phase of the jump (r = -.28 to .16, P > .05). Hip abductors strengthening, correction of foot misalignments, and increasing ankle dorsiflexion ROM may not prevent excessive hip and knee movements during a classical ballet single-leg jump in amateur dancers.

Cognitive Load Influences Drop Jump Landing Mechanics During Cognitive-Motor-Simulated Shooting.

Military duties require immense cognitive-motor multitasks that may predispose soldiers to musculoskeletal injury. Most cognitive challenges performed in the research laboratory are not tactical athlete specific, limiting generalizability and transferability to in-field scenarios. The purpose of this study was to determine the impact of a cognitive-motor multitask (forward drop jump landing while simultaneously performing simulated shooting) on knee kinetics and kinematics. Twenty-four healthy collegiate Reserve Officer's Training Corps members (18 males and 6 females, 20.42 ± 1.28 years, 174.54 ± 10.69 cm, 78.11 ± 14.96 kg) volunteered, and knee kinetics and kinematics were assessed between baseline and cognitive-loaded conditions. Repeated measures ANOVAs were conducted for each dependent variable with the within-subject factor of condition (baseline vs. cognitive load). Univariate ANOVAs indicated that knee flexion angle at initial contact (IC) (decreased 6.07°; d = 3.14), knee flexion displacement (increased 6.78°; d = 1.30), knee abduction angle at IC (increased 2.3°; d = 1.46), peak knee abduction angle (increased 3.04°; d = 0.77), and peak vertical ground reaction force (increased 0.81 N/kg; d = 2.13) were significant between conditions (P < .001). Therefore, cognitive load resulted in decreased knee flexion and increased knee abduction angle at IC and greater peak vertical ground reaction force, all factors commonly associated with knee injury risk. Peak knee flexion angle and knee abduction displacement were not significant between conditions (P > .05). Cognitive challenge induced knee landing biomechanics commonly associated with injury risk. Injury risk screening or return-to-training or duty assessments in military personnel might consider both baseline and cognitive conditions.

Indirect contact matters: Mid-flight external trunk perturbation increased unilateral anterior cruciate ligament loading variables during jump-landings

PurposeTo determine the effect of unanticipated mid-flight medial-lateral external perturbation of the upper or lower trunk on anterior cruciate ligament (ACL) loading variables during jump-landings. MethodsThirty-two participants performed double-leg vertical jump-landings while bilateral kinematics and kinetics were collected under 6 conditions (upper or lower trunk perturbation locations; no, left, or right perturbation directions). Two customized catapult apparatuses were created to apply pushing perturbation to participants near the maximal jump height. ResultsThe ball contacted participants near the center of mass for the lower-trunk conditions and approximately 23 cm above the center of mass for the upper-trunk conditions. Under upper-trunk perturbation, the contralateral leg demonstrated significantly smaller knee flexion angles at initial contact and greater peak knee abduction angles, peak vertical ground reaction forces, peak knee extension moments, and peak knee adduction moments compared to other legs among all conditions. Under lower-trunk perturbation, the contralateral leg showed significantly smaller knee flexion angles at initial contact and increased peak vertical ground reaction forces and peak knee extension moments compared to legs in the no-perturbation conditions. ConclusionMid-flight external trunk pushing perturbation increased ACL loading variables for the leg contralateral to the perturbation. The upper-trunk perturbation resulted in greater changes in ACL loading variables compared to the lower-trunk perturbation, likely due to trunk and ipsilateral leg rotation and more laterally located center of mass relative to the contralateral leg. These findings may help us understand the mechanisms of indirect-contact ACL injuries and develop jump-landing training strategies under mid-flight trunk perturbation to better prevent ACL injury.

Do Cutting Kinematics Change as Boys Mature? A Longitudinal Cohort Study of High-School Athletes.

Examine longitudinal changes in trunk, hip, and knee kinematics in maturing boys during an unanticipated cutting task. Prospective cohort study. Biomechanical laboratory. Forty-two high-school male basketball, volleyball, and soccer athletes. Trunk, hip, and knee range-of-motion (RoM), peak angles, and angles at initial contact during an unanticipated 45 degrees sidestep cutting task were estimated using laboratory-based three-dimensional optoelectronic motion capture. Maturation was classified using a modified Pubertal Maturational Observational Scale (PMOS) into prepubertal, midpubertal, or postpubertal stages. Trunk total RoM in frontal, sagittal, and transverse planes; peak trunk flexion, right lateral flexion and right rotation angles; hip total RoM in frontal, sagittal, and transverse planes; hip flexion angle at initial contact; peak hip flexion and adduction angles; knee total RoM in frontal, sagittal, and transverse planes; knee flexion angle at initial contact; peak knee flexion and abduction angles. As boys matured, there was a decrease in hip sagittal-plane RoM (49.02 degrees to 43.45 degrees, Benjamini-Hochberg adjusted P = 0.027), hip flexion at initial contact (29.33 degrees to 23.08 degrees, P = 0.018), and peak hip flexion (38.66 degrees to 32.71 degrees, P = 0.046), and an increase in trunk contralateral rotation (17.47 degrees to 25.05 degrees, P = 0.027). Maturing male athletes adopted a more erect cutting strategy that is associated with greater knee joint loading. Knee kinematic changes that increase knee joint loading were not observed in this cohort.

Kinesiophobia Is Associated with Peak Knee Abduction Angle during Jump Landing after ACL Reconstruction.

This study aimed to investigate the associations between kinesiophobia, knee abduction angle (KAA) during the first 100 ms of landing, and knee flexion excursion (KFE) in individuals 5-12 months after anterior cruciate ligament reconstruction (ACLR). We hypothesized that greater kinesiophobia would be associated with greater peak KAA and lesser KFE during landing on the ACLR limb, but not on the contralateral limb. Thirty-six participants between 14 and 35 yr old (females = 19, age = 19.9 ± 5.1 yr, height = 172.5 ± 9.4 cm, weight = 76.7 ± 20.0 kg, time since surgery =7.2 ± 1.7 months) were recruited from a sports medicine clinic at 5-12 months after primary unilateral ACLR. Participants completed the Tampa Scale of Kinesiophobia-11 (TSK-11) to measure kinesiophobia and three successful trials of a standard drop vertical jump task. A 10-camera three-dimensional motion capture system synchronized with two embedded force plate platforms was used to capture jump-landing kinematics. Separate stepwise linear regression models were used to examine the associations between kinesiophobia, peak KAA, and KFE on the ACLR and contralateral limbs after accounting for time since surgery and biological sex. When accounting for time since surgery and biological sex, every 1-point increase on the TSK-11 (i.e., increase in kinesiophobia) associated with a 0.37° increase (i.e., a 7.1% increase) in ACLR limb KAA ( P = 0.02). Kinesiophobia was not associated with contralateral limb KAA, ACLR limb KFE, or contralateral limb KFE. Higher kinesiophobia was related to greater amounts of peak KAA during landing in individuals 5-12 months post-ACLR. Modifying kinesiophobia may help to decrease KAA and lead to reduced secondary ACL injury risk. Future research should investigate feasible psychological interventions to reduce kinesiophobia and improve KAA in patients post-ACLR.

Association Between the Functional Movement Screen and Landing Kinematics in Individuals With and Without Anterior Cruciate Ligament Reconstruction

The purpose of this study was to compare functional movement screen (FMS) scores and drop vertical jump (DVJ) kinematics between those with and without anterior cruciate ligament reconstruction (ACLR), and to evaluate the association between FMS composite score and DVJ kinematics. Cross-sectional. Sixty individuals with and without a history of ACLR. Composite FMS score and the dorsiflexion, knee-flexion, hip-flexion, knee abduction, hip adduction, and trunk-flexion angles during a DVJ. The FMS scores did not differ between groups (P > .05). There were smaller peak and initial contact hip-flexion angles in the ACLR and contralateral limbs compared with controls, and smaller peak dorsiflexion angles in the ACLR compared with contralateral limbs (P < .05). Lower FMS score was associated with a smaller peak dorsiflexion angle, smaller peak knee-flexion angle, and larger peak knee abduction angle in the ACLR limb (ΔR2 = .14-.23); a smaller peak dorsiflexion angle and smaller peak knee-flexion angle in the contralateral limb (ΔR2 = .17-.19); and a smaller peak dorsiflexion angle, smaller peak knee-flexion angle, and larger peak knee abduction angle in the control limb (ΔR2 = .16-.22). The FMS scores did not differ between groups, but were associated with DVJ kinematics and should be a complementary rather than substitute assessment.

Biomechanical features of drop vertical jump are different among various sporting activities

BackgroundRisk for non-contact anterior cruciate ligament (ACL) injury can be assessed based on drop vertical jump (DVJ). However, biomechanics of DVJ may differ with various sporting activities. The purpose of the present study was to clarify whether biomechanical features of DVJ are different among various sporting activities in female athletes.MethodsA total of 42 female athletes, including 25 basketball, 8 soccer and 9 volleyball players, participated in the current investigation. DVJ was done for each female athlete using a three-dimensional motion analysis system which consisted of six cameras, two force plates and 46 retro-reflective markers. Kinematic and kinetic data were recorded for both limbs in each athlete. Simultaneously, frontal and sagittal plane views of the DVJ were recorded using two different high-resolution video cameras to evaluate Landing Error Scoring System (LESS) score. Three-dimensional biomechanical parameters at the knee joint and LESS were compared among three different sporting activities using ANOVA or Kruskal–Wallis test after confirming normality assumption. Thereafter post hoc Tukey or Steel–Dwass was utilized for multiple comparison.ResultsSoccer players had better LESS score, and peak knee flexion angle was significantly larger in soccer players compared to the other sports. In addition, knee abduction angle at initial contact (IC), peak knee abduction angle, knee internal rotation angle, and knee abduction moment within 40 ms from IC were significantly smaller in soccer players, compared to basketball players. In terms of volleyball players, knee abduction angle at IC and knee internal rotation angle at IC were significantly larger than soccer players, whereas no significant biomechanical differences were found between basketball and volleyball players.ConclusionsFrom the present study, female basketball and volleyball players have worse LESS score, smaller peak knee flexion angle, greater knee abduction angle at IC and greater knee internal rotation angle at IC, compared to female soccer players. Thus, female basketball and volleyball players may have an increased risk of non-contact ACL injury during the jump-landing task, compared to soccer players. Biomechanics of DVJ depends on characteristics of the athlete's primary sport.

Changes in landing mechanics using augmented feedback: 4-Week training and retention study

ContextNon-contact ACL injuries are common in female athletes during landing tasks. Post-trial performance-based feedback may be an effective method to reduce landing forces and knee valgus during landing. Information regarding the retention of these changes based on such training is generally lacking for weekly and monthly retention. ObjectiveTo determine the effectiveness of post-trial feedback training to promote and retain changes in vertical ground reaction force (vGRF) and knee to ankle (K:A) ratio during a dual task drop landing in female collegiate athletes. DesignRepeated measures; SettingUniversity campus. Participants22 female collegiate athletes. Materials and methodsDual task drop landings were performed over 4 successive weeks with immediate post trial feedback on peak vGRF, symmetry, and K:A ratio. K:A ratio was a surrogate measure for knee valgus in drop landing. ResultsSignificant decreases in vGRF and increases in K:A ratio were found within training sessions (p = .000). Both variables were retained each week over the 4 weeks. ConclusionUsing a custom portable clinical feedback system may be an effective tool in reducing peak vGRFs and knee abduction angles during a drop landing over a 4-week period in female collegiate athletes.

When puberty strikes: Longitudinal changes in cutting kinematics in 172 high-school female athletes

ObjectivesYoung female athletes involved in high-speed cutting and change-of-direction sports are particularly susceptible to anterior cruciate ligament (ACL) injuries. Little is known if maturational changes in cutting technique contribute to the increased injury risk. Our objective was to examine longitudinal changes in cutting kinematics in female athletes as they matured through puberty. DesignLongitudinal cohort study MethodsHigh school female athletes (n=172) performed an unanticipated 45° cutting task in the biomechanics laboratory across two or more pubertal stages. Pubertal stages were classified using a modified Pubertal Maturational Observational Scale (pre-, mid-, or post-pubertal stages). Generalized linear mixed models were used to compare kinematics across pubertal stages. ResultsAs girls matured through puberty, they displayed a decrease in sagittal-plane hip (1.8-2.6°, p<0.03) and knee range-of-motion (ROM) (2.7-2.9°, p≤0.01), and decreased peak hip (2.9-3.2°, p≤0.02) and knee flexion angles (2.7-2.9°, p≤0.01), which is indicative of greater quadriceps dominance. Peak knee abduction angles also increased as girls progressed through puberty (0.9-1.4°, p≤0.02), suggesting greater ligament dominance. In terms of trunk dominance, there were mixed findings with a decrease in trunk frontal- (2.5-5.7°, p≤0.03) and sagittal-plane ROM (2.0°, p≤0.01), but an increase in trunk transverse-plane ROM (2.8-3.6°, p≤0.02) observed as girls mature. Other significant changes in cutting technique were decreased peak trunk flexion (3.8-7.8°, p≤0.01), and decreased hip flexion (2.9-3.3°, p≤0.02) and knee flexion angles (2.0-3.0°, p≤0.03) at initial contact, suggesting a more upright and stiffer cutting posture. ConclusionsAs girls mature through puberty, there is a change in cutting strategy characterized by greater quadriceps and ligament dominance.

The effect of angle on change of direction biomechanics: Comparison and inter-task relationships

ABSTRACT The aim of this was study to examine the inter-task relationships and compare change of direction (COD) biomechanics between different angles (45°, 90°, and 180°). Twenty-seven men performed three COD tasks, whereby lower-limb and trunk kinematics and kinetics were assessed via 3D motion and ground reaction force (GRF) analysis. Key mechanical differences (p ≤ 0.025, η 2 = 0.024–0.940) in velocity profiles, GRF, sagittal joint angles and moments, multiplanar knee joint moments, and technical parameters existed between CODs. The primary findings were that as COD angle increased, velocity profiles decreased (p < 0.001, d = 1.56–8.96), ground contact times increased (p < 0.001, d = 3.00–5.04), vertical GRF decreased (p < 0.001, d = 0.87–3.48), and sagittal peak knee joint moments decreased (p ≤ 0.040, d = 0.62–2.73). Notably, the greatest peak knee internal rotation (KIRMs) and abduction moments (KAMs) and angles were observed during the 90° COD (p < 0.001, d = 0.88–1.81), indicating that this may be the riskiest COD angle. Small to very large (r = 0.260–0.702) associations in KAMs and KIRMs were observed between tasks, indicating that evaluations at different angles are needed to develop an athlete’s biomechanical injury risk profile. The results support the concept that COD biomechanics and potential surrogates of non-contact anterior cruciate ligament injury risk are “angle-dependent”; which have important implications for COD coaching, screening, and physical preparation.

Bilateral Squatting Mechanics Are Associated With Landing Mechanics in Anterior Cruciate Ligament Reconstruction Patients

Background: Proper lower extremity biomechanics during bilateral landing is important for reducing injury risk in athletes returning to sports after anterior cruciate ligament reconstruction (ACLR). Although landing is a quick ballistic movement that is difficult to modify, squatting is a slower cyclic movement that is ideal for motor learning. Hypothesis: There is a relationship between lower extremity biomechanics during bilateral landing and bilateral squatting in patients with an ACLR. Study Design: Descriptive laboratory study. Methods: A total of 41 patients after a unilateral ACLR (24 men, 17 women; 5.9 ± 1.4 months after ACLR) completed 15 unweighted bilateral squats and 10 bilateral stop-jumps. Three-dimensional lower extremity kinematics and kinetics were collected, and peak knee abduction angle, knee abduction/adduction range of motion, peak vertical ground-reaction force limb symmetry index (LSI), vertical ground-reaction force impulse LSI, and peak knee extension moment LSI were computed during the descending phase of the squatting and landing tasks. Wilcoxon signed-rank tests were used to compare each outcome between limbs, and Spearman correlations were used to compare outcomes between the squatting and landing tasks. Results: The peak vertical ground reaction force, the vertical ground reaction force impulse, and the peak knee extension moment were reduced in the surgical (Sx) limb relative to the nonsurgical (NSx) limb during both the squatting and landing tasks (P < .001). The relationship between squatting and landing tasks was strong for the peak knee abduction angle (R = 0.697-0.737; P < .001); moderate for the frontal plane knee range of motion (NSx: R = 0.366, P = .019; Sx: R = 0.418, P = 0.007), the peak knee extension moment LSI (R = 0.573; P < .001), the vertical ground reaction force impulse LSI (R = 0.382; P < .014); and weak for the peak vertical ground reaction force LSI (R = 0.323; P = .039). Conclusion: Patients who have undergone an ACLR continue to offload their surgical limb during both squatting and landing. Additionally, there is a relationship between movement deficits during squatting and movement deficits during landing in patients with an ACLR preparing to return to sports. Clinical Relevance: As movement deficits during squatting and landing were related before return to sports, this study suggests that interventional approaches to improve squatting biomechanics may translate to improved landing biomechanics in patients with an ACLR.

NEURAL ACTIVITY PROFILES ASSOCIATED WITH ACL INJURY-RISK MECHANICS IN ECOLOGICAL SPORT SPECIFIC VIRTUAL REALITY

Background:Anterior cruciate ligament (ACL) injury is secondary to a multifactorial etiology encompassing anatomical, biological, mechanical, and neurological factors. The nature of the injury being primarily due to non-contact mechanics further implicates neural control as a key injury-risk factor, though it has received considerably less study.Purpose:To determine the contribution of neural activity to injury-risk mechanics in ecological sport-specific VR landing scenarios.Methods:Ten female high-school soccer players (15.5±0.85 years; 165.0±6.09 cm; 59.1±11.84 kg) completed a neuroimaging session to capture neural activity during a bilateral leg press and a 3D biomechanics session performing a header within a VR soccer scenario. The bilateral leg press involved four 30 s blocks of repeated bilateral leg presses paced to a metronome beat of 1.2 Hz with 30 s rest between blocks. The VR soccer scenario simulated a corner-kick, requiring the participant to jump and head a virtual soccer ball into a virtual goal (Figure 1A-E). Initial contact and peak knee flexion and abduction angles were extracted during the landing from the header as injury-risk variables of interest and were correlated with neural activity.Results:Evidenced in Table 1 and Figure 1 (bottom row), increased initial contact abduction, increased peak abduction, and decreased peak flexion were associated with increased sensory, visual-spatial, and cerebellar activity (r2= 0.42-0.57, p corrected < .05, z max > 3.1, table & figure 1). Decreased initial contact flexion was associated with increased frontal cortex activity (r2= 0.68, p corrected < .05, z max > 3.1).Conclusion:Reduced neural efficiency (increased activation) of key regions that integrate proprioceptive, visual-spatial, and neurocognitive activity for motor control may influence injury-risk mechanics in sport. The regions found to increase in activity in relation to higher injury-risk mechanics are typically activated to assist with spatial navigation, environmental interaction, and precise motor control. The requirement for athletes to increase their activity for more basic knee motor control may result in fewer neural resources available to maintain knee joint alignment, allocate environmental attention, and handle increased motor coordination demands. These data indicate that strategies to enhance efficiency of visual-spatial and cognitive-motor control during high demand sporting activities is warranted to improve ACL injury-risk reduction.Figure 1The virtual reality soccer landing scenario (A, C, E: first person perspective in virtual reality; B, D: articipant wearing the virtual reality headset from an external perspective) and neural activity associated with abduction mechanics (bottom‐left) and flexion mechanics (bottom‐right)

Ankle Dorsiflexion Affects Hip and Knee Biomechanics During Landing.

Restricted ankle dorsiflexion range of motion (DFROM) has been linked to lower extremity biomechanics that place an athlete at higher risk for injury. Whether reduced DFROM during dynamic movements is due to restrictions in joint motion or underutilization of available ankle DFROM motion is unclear. We hypothesized that both lesser total ankle DFROM and underutilization of available motion would lead to high-risk biomechanics (ie, greater knee abduction, reduced knee flexion). Cross-sectional study. Level 3. Nineteen active female athletes (age, 20.0 ± 1.3 years; height, 1.61 ± 0.06 m; mass, 67.0 ± 10.7 kg) participated. Maximal ankle DFROM (clinical measure of ankle DFROM [DF-CLIN]) was measured in a weightbearing position with the knee flexed. Lower extremity biomechanics were measured during a drop vertical jump with 3-dimensional motion and force plate analysis. The percent of available DFROM used during landing (DF-%USED) was calculated as the peak DFROM observed during landing divided by DF-CLIN. Univariate linear regressions were performed to identify whether DF-CLIN or DF-%USED predicted knee and hip biomechanics commonly associated with injury risk. For every 1.0° less of DF-CLIN, there was a 1.0° decrease in hip flexion excursion (r2 = 0.21, P = 0.05), 1.2° decrease in peak knee flexion angles (r2 = 0.37, P = 0.01), 0.9° decrease in knee flexion excursion (r2 = 0.40, P = 0.004), 0.002 N·m·N-1·cm-1 decrease in hip extensor work (r2 = 0.28, P = 0.02), and 0.001 N·m·N-1·cm-1 decrease in knee extensor work (r2 = 0.21, P = 0.05). For every 10% less of DF-%USED, there was a 3.2° increase in peak knee abduction angles (r2 = 0.26, P = 0.03) and 0.01 N·m·N-1·cm-1 lesser knee extensor work (r2 = 0.25, P = 0.03). Lower levels of both ankle DFROM and DF-%USED are associated with biomechanics that are considered to be associated with a higher risk of sustaining injury. While total ankle DFROM can predict some aberrant movement patterns, underutilization of available ankle DFROM can also lead to higher risk movement strategies. In addition to joint specific mobility training, clinicians should incorporate biomechanical interventions and technique feedback to promote the utilization of available motion.

Biomechanical Determinants of Performance and Injury Risk During Cutting: A Performance-Injury Conflict?

BackgroundMost cutting biomechanical studies investigate performance and knee joint load determinants independently. This is surprising because cutting is an important action linked to performance and non-contact anterior cruciate ligament (ACL) injuries. The aim of this study was to investigate the relationship between cutting biomechanics and cutting performance (completion time, ground contact time [GCT], exit velocity) and surrogates of non-contact ACL injury risk (knee abduction [KAM] and internal rotation [KIRM] moments) during 90° cutting.DesignMixed, cross-sectional study following an associative design. 61 males from multidirectional sports performed six 90° pre-planned cutting trials, whereby lower-limb and trunk kinetics and kinematics were evaluated using three-dimensional (3D) motion and ground reaction force analysis over the penultimate (PFC) and final foot contact (FFC). Pearson’s and Spearman’s correlations were used to explore the relationships between biomechanical variables and cutting performance and injury risk variables. Stepwise regression analysis was also performed.ResultsFaster cutting performance was associated (p ≤ 0.05) with greater centre of mass (COM) velocities at key instances of the cut (r or ρ = 0.533–0.752), greater peak and mean propulsive forces (r or ρ = 0.449–0.651), shorter FFC GCTs (r or ρ = 0.569–0.581), greater FFC and PFC braking forces (r = 0.430–0.551), smaller hip and knee flexion range of motion (r or ρ = 0.406–0.670), greater knee flexion moments (KFMs) (r = 0.482), and greater internal foot progression angles (r = − 0.411). Stepwise multiple regression analysis revealed that exit velocity, peak resultant propulsive force, PFC mean horizontal braking force, and initial foot progression angle together could explain 64% (r = 0.801, adjusted 61.6%, p = 0.048) of the variation in completion time. Greater peak KAMs were associated with greater COM velocities at key instances of the cut (r or ρ = − 0.491 to − 0.551), greater peak knee abduction angles (KAA) (r = − 0.468), and greater FFC braking forces (r = 0.434–0.497). Incidentally, faster completion times were associated with greater peak KAMs (r = − 0.412) and KIRMs (r = 0.539). Stepwise multiple regression analysis revealed that FFC mean vertical braking force and peak KAA together could explain 43% (r = 0.652, adjusted 40.6%, p < 0.001) of the variation peak KAM.ConclusionTechniques and mechanics associated with faster cutting (i.e. faster COM velocities, greater FFC braking forces in short GCTs, greater KFMs, smaller hip and knee flexion, and greater internal foot progression angles) are in direct conflict with safer cutting mechanics (i.e. reduced knee joint loading, thus ACL injury risk), and support the “performance-injury conflict” concept during cutting. Practitioners should be conscious of this conflict when instructing cutting techniques to optimise performance while minimising knee joint loading, and should, therefore, ensure that their athletes have the physical capacity (i.e. neuromuscular control, co-contraction, and rapid force production) to tolerate and support the knee joint loading during cutting.

Larger hip external rotation motion is associated with larger knee abduction and internal rotation motions during a drop vertical jump

ABSTRACT Associations among hip motions, knee abduction and internal rotation motion during a drop vertical jump (DVJ), which increases the risk of anterior cruciate ligament injury, remain unclear. The purpose of this study was to examine associations among knee abduction, internal rotation and hip joint motions during a DVJ. Fifty-seven young female participants performed a DVJ from a 30-cm height. Hip and knee kinematics and kinetics were analysed using a three-dimensional motion analysis system and force plates. Multiple regression analysis showed that peak knee abduction angle was negatively associated with knee internal rotation and hip internal rotation excursions from initial contact (IC) to peak knee flexion, and positively associated with peak knee abduction moment (R2 = 0.465, P< 0.001). Peak knee internal rotation angle was negatively associated with the hip flexion excursion from IC to peak knee flexion and peak hip adduction moment (R2 = 0.194, P= 0.001). In addition, hip internal rotation excursion was negatively associated with knee abduction and internal rotation excursion from IC to 50 ms after IC. To avoid a large knee abduction and internal rotation motion during jump-landing training, it might be beneficial to provide landing instructions to avoid a large hip external rotation motion.