Frontal Plane Knee Angle Research Articles

The relationship of hip strength and dynamic knee valgus during single leg squat in physically active females

BackgroundSingle leg squat (SLS) is an important motion commonly observed in sports. Excessive dynamic knee valgus (DKV) during SLS may increase non-contact knee injury risks particularly in physically active females. As muscular strength plays crucial role in controlling DKV, the present study aims to evaluate the correlation between hip strength and knee frontal plane angle during SLS among females with and without excessive DKV. MethodsThirty-four volunteers were allocated to the valgus (n = 17) and non-valgus (n = 17) groups. Their motions during SLS at 45° and 60° knee flexion were captured and analyzed using three-dimensional motion analysis system. Isokinetic hip strength was examined at 180°/s in flexion, extension, abduction, and adduction for both legs. Pearson's correlation test was computed to evaluate the relationship between hip strength and knee angle during SLS. FindingsNon-dominant hip extensor strength (r = −0.56, p = 0.02) and dominant hip adductor strength (r = −0.51, p = 0.04) were significantly related to the knee frontal plane angle during 45° SLS among those without DKV. Meanwhile, those with DKV showed a significant relationship between the knee frontal plane angle for both legs and non-dominant hip abductor strength during 60° SLS. InterpretationBoth groups demonstrated the relationship of hip strength on knee frontal plane angle during SLS, whereby increased hip strength may minimize excessive DKV. Those with excessive DKV should train to strengthen their hip abductor to reduce knee valgus particularly during deep squats.

The effect of surface on knee landing mechanics and muscle activity during a single-leg landing task in recreationally active females

ObjectiveInvestigate the effect of surface on frontal plane knee angle, knee moment and muscle activity. DesignRandomised cross over. SettingUniversity Laboratory. MethodsTwenty females performed single-leg hop-landings onto sand, grass and firm surfaces. Kinematic, kinetic and muscle activity data were obtained. Compatibility curves were used to visualise parameter estimates alongside P- values, and S-value transforms. ResultsKnee angle for firm-sand (mean difference (d)‾ = −2.2°; 95% compatibility interval (CI): −4.6 to 0.28, p = 0.083, s = 3.6) and firm-grass (d‾ = −1.9; 95% CI: −4.3 to 0.5, p = 0.125, S = 3) yielded <4 bits of reputational information against the null hypothesis (H). 5 bits (p = 0.025) of information against H were observed for knee moment between firm-sand (d‾ = 0.17 N m/kg-1. m-1; 95% CI: 0.02 to 0.31) with similar effects for firm-grass (d‾ = 0.14 N m/kg-1. m-1; 95% CI: −0.02 to 0.29, p = 0.055, S = 4). Muscle activity across surfaces ranged from almost no (S = 1) reputational evidence against H (Quadriceps and Hamstrings) to 10–13 ‘bits’ against H for lateral gastrocnemius (lower on sand). ConclusionsOur study provides valuable information for practitioners of the observed effect sizes for lower-limb landing mechanics across surfaces in asymptomatic females.

Movement Quality Assessment of Army Reserve Officers' Training Corps Cadets: A Report of Validity and Normative Data.

Movement quality screening in early-career military populations, like Army Reserve Officers' Training Corps (AROTC) cadets, could decrease the negative impact of musculoskeletal injury observed within the military. Movement quality screening techniques should be valid before being pursued in the field. Normative data describing movement quality of AROTC cadets are also needed. Therefore, the aims of this study were to determine criterion validity of several movement quality assessments and report normative jump-landing kinematics of AROTC cadets. This cross-sectional research was approved by the Institutional Review Board. As part of a larger study, 20 AROTC cadets (21.3 ± 3.4 years; 1.7 ± 0.1 m; 73.8 ± 14.8 kg) had 3-dimensional (3D) and 2-dimensional (2D) kinematic data collected simultaneously while performing a jump-landing task. Variables of interest were 3D hip and knee sagittal, frontal, and transverse joint angles at maximum knee flexion. An experienced rater calculated sagittal and frontal 2D joint angles at maximum knee flexion. Averages of 2D and 3D angles were calculated to describe normative data and for further data analysis. Bivariate correlations between 3D and 2D variables were used to determine criterion validity. Moderate correlations were found between 2D and 3D hip frontal plane angles (P = .05, r =-0.33), 2D and 3D knee sagittal plane angles (P = .04, r = 0.35), and 2D and 3D knee frontal plane angles (P = .03, r = -0.36). Normative values of knee and hip kinematics demonstrated averages of 17.58° of knee adduction, 16.48° of knee external rotation, 11.57° of hip abduction, 10.76° of hip internal rotation, and 103.47° of knee flexion during landings. However, ranges demonstrated that landing patterns vary within AROTC cadets. The normative values of 3D jump-landing kinematic data indicate that movement quality varies greatly within AROTC cadets, and some cadets display potentially injurious movements. Therefore, screening movement quality could be beneficial to determine musculoskeletal injury risk in AROTC cadets. Based on the correlations discovered in this study, we recommend the 2D techniques used in this study be researched further as they may serve as alternatives to expensive, timely 3D techniques that could be better utilized in military environments.

Either Autonomy Support or Enhanced Expectancies Delivered Via Virtual-Reality Benefits Frontal-Plane Single-Leg Squatting Kinematics.

Our purpose in this study was to determine the effects of a virtual reality intervention delivering specific motivational motor learning manipulations of either autonomy support (AS) or enhanced expectancies (EE) on frontal plane single-leg squatting kinematics. We allocated 45 participants (21 male, 24 female) demonstrating knee, hip, and trunk frontal plane mechanics associated with elevated anterior cruciate ligament injury risk to one of three groups (control, AS, or EE). Participants mimicked an avatar performing five sets of eight repetitions of exemplary single-leg squats. AS participants were given the added option of choosing the color of their avatar. EE participants received real-time biofeedback in the form of green highlights on the avatar that remained on as long as the participant maintained pre-determined 'safe' frontal plane mechanics. We measured peak frontal plane knee, hip, and trunk angles before (baseline) and immediately following (post) the intervention. The control group demonstrated greater increases in knee abduction angle (Δ = +2.3°) than did the AS (Δ = +0.1°) and EE groups (Δ = -0.4°) (p = .003; η2p = .28). All groups demonstrated increased peak hip adduction (p = .01, ηp2 = .18) (control Δ = +1.5°; AS Δ = +3.2°; EE Δ = +0.7°). Hip adduction worsened in all groups. AS and EE motivation strategies appeared to mitigate maladaptive frontal plane knee mechanics.

Video Analysis of 26 Cases of Second ACL Injury Events in Collegiate and Professional Athletes.

Significant effort has gone into the identification and quantification of the underlying mechanisms of primary ACL injury. Secondary ACL injury is observed in approximately 1/4 to 1/3 of athletes who return to sport following ACL reconstruction. However, little has been done to evaluate the mechanisms and playing circumstances surrounding these repeat injuries. The purpose of this study was to characterize the mechanisms of non-contact secondary ACL injuries using video analysis. It was hypothesized that in video recordings of secondary ACL injury, athletes would exhibit greater frontal plane hip and knee angles, but not greater hip and knee flexion, at 66 ms following initial contact (IC) as compared to at IC and 33ms following IC. Cross-Sectional Study. Twenty-six video recordings of competitive athletes experiencing secondary ACL ruptures via noncontact mechanisms were analyzed for lower extremity joint kinematics, playing situation, and player attention. Kinematics were assessed at IC as well as 33 ms (1 broadcast frame) and 66 ms (2 broadcast frames) following IC. Knee flexion and knee frontal plane angles were greater at 66 ms than IC (p ≤ 0.03). Hip, trunk, and ankle frontal plane angles were not greater at 66 ms than IC (p ≥ 0.22). Injuries were distributed between attacking play (n=14) and defending (n=8). Player attention was most commonly focused on the ball (n=12) or an opponent (n=7). A single-leg landing accounted for just over half of the injuries (54%), while a cutting motion accounted for the remainder of the injuries (46%). Secondary ACL injury was most likely to occur during landing or a sidestep cut with player attention external to their own body. Knee valgus collapse combined with limited hip motion was identified in the majority of secondary injuries. Level IIIb.

Validity of an artificial intelligence, human pose estimation model for measuring single-leg squat kinematics

Few studies have investigated the validity of 2D pose estimation models to evaluate kinematics throughout a motion and none have included adolescents. Adolescent athletes completed single-leg squats while 3D kinematic data and 2D sagittal and frontal plane videos were recorded. Sagittal and frontal plane joint motion throughout the single-leg squats and angles at peak knee flexion were compared among 2D pose estimation, 3D motion analysis, and traditional 2D motion analysis techniques. Statistical parametric mapping compared waveforms while Pearson’s correlation compared the relationships of joint angles at peak knee flexion among techniques, respectively. We observed significant waveform differences between 2D pose estimation and 3D motion analysis at the beginning and end of the squat for sagittal plane hip and knee motion, for most of the squat for frontal plane hip motion, and throughout the entire squat for sagittal plane ankle motion and frontal plane pelvic motion. We observed moderate-to-strong relationships (r = 0.68-0.94) for sagittal plane joint angles between 2D pose estimation and 3D techniques. We observed fair correlations (r = 0.53-0.54) for frontal plane pelvic and hip joint angles between 2D pose estimation and 3D motion analysis. We observed poor relationships for the frontal plane knee angle between 3D motion analysis with 2D pose estimation (r = 0.20) and traditional 2D motion analysis (r = 0.05), respectively, but observed a strong relationship (r = 0.95) between the 2D techniques. 2D pose estimation is a valid alternative to 3D motion analysis and traditional 2D motion analysis for evaluating most sagittal and frontal plane angles during a single-leg squatting task.

ACL Research Retreat IX March 17–19, 2022 High Point, NC

ACL Research Retreat IX March 17–19, 2022 High Point, NC

Biomechanical Risk Factors of Injury-Related Single-Leg Movements in Male Elite Youth Soccer Players

Altered movement patterns during single-leg movements in soccer increase the risk of lower-extremity non-contact injuries. The identification of biomechanical parameters associated with lower-extremity injuries can enrich knowledge of injury risks and facilitate injury prevention. Fifty-six elite youth soccer players performed a single-leg drop landing task and an unanticipated side-step cutting task. Three-dimensional ankle, knee and hip kinematic and kinetic data were obtained, and non-contact lower-extremity injuries were documented throughout the season. Risk profiling was assessed using a multivariate approach utilising a decision tree model (classification and regression tree method). The decision tree model indicated peak knee frontal plane angle, peak vertical ground reaction force, ankle frontal plane moment and knee transverse plane angle at initial contact (in this hierarchical order) for the single-leg landing task as important biomechanical parameters to discriminate between injured and non-injured players. Hip sagittal plane angle at initial contact, peak ankle transverse plane angle and hip sagittal plane moment (in this hierarchical order) were indicated as risk factors for the unanticipated cutting task. Ankle, knee and hip kinematics, as well as ankle and hip kinetics, during single-leg high-risk movements can provide a good indication of injury risk in elite youth soccer players.

Running Biomechanics Of Youth With Autism Spectrum Disorder

PURPOSE: Research examining gait biomechanics of persons with autism spectrum disorder (ASD) has grown significantly in recent years and has demonstrated that persons with ASD walk at slower self-selected speeds and with shorter strides, wider step widths, and reduced lower extremity biomechanics compared to neurotypical controls. In contrast to walking, running has yet to be examined in persons with ASD. The purpose of this study was to examine lower extremity running biomechanics in adolescents (13-18 year-olds) with ASD and matched (age, sex, and body mass index) neurotypical controls. METHODS: Three-dimensional kinematics and ground reaction forces (GRF) were recorded while participants ran at two matched speeds: self-selected speed of adolescents with ASD and at a standardized 3.0 m/s. Sagittal and frontal plane ankle, knee, and hip biomechanics along with vertical ground reaction force (GRF) waveforms were normalized to the stance phase of running. Waveforms were compared using two-way ANOVAs group x speed) via statistical parametric mapping (alpha at 0.04). RESULTS: Adolescents with ASD ran with reduced GRFs (by 14.5%), plantarflexion moments (18.5%), hip abduction moments (44.4%), and knee abduction moments (69.4%), each surrounding their respective peaks (all p < 0.001). Running at 3.0 m/s increased sagittal plane hip and knee moments surrounding initial contact (both 10.4%; p < 0.004) and frontal plane knee angles during mid (2.9 deg; p = 0.003) and late stance (2.8 deg; p = 0.003) compared to self-selected speeds. CONCLUSIONS: This study illustrates that adolescents with ASD run with reduced contributions from the plantarflexors and hip abductor musculature, which contribute to vertical GRFs. Educators and therapists should consider examining running mechanics, in addition to walking, of adolescents with ASD to determine if muscular or neural deficiencies contribute to reduced hip and ankle involvement.

Running Biomechanics of Adolescents With Autism Spectrum Disorder.

Research examining gait biomechanics of persons with autism spectrum disorder (ASD) has grown significantly in recent years and has demonstrated that persons with ASD walk at slower self-selected speeds and with shorter strides, wider step widths, and reduced lower extremity range of motion and moments compared to neurotypical controls. In contrast to walking, running has yet to be examined in persons with ASD. The purpose of this study was to examine lower extremity running biomechanics in adolescents (13-18-year-olds) with ASD and matched (age, sex, and body mass index (BMI)) neurotypical controls. Three-dimensional kinematics and ground reaction forces (GRFs) were recorded while participants ran at two matched speeds: self-selected speed of adolescents with ASD and at 3.0 m/s. Sagittal and frontal plane lower extremity biomechanics and vertical GRF waveforms were compared using two-way analyses of variances (ANOVAs) via statistical parametric mapping (SPM). Adolescents with ASD ran with reduced stride length at self-selected speed (0.29 m) and reduced vertical displacement (2.1 cm), loading-propulsion GRFs (by 14.5%), propulsion plantarflexion moments (18.5%), loading-propulsion hip abduction moments (44.4%), and loading knee abduction moments (69.4%) at both speeds. Running at 3.0 m/s increased sagittal plane hip and knee moments surrounding initial contact (both 10.4%) and frontal plane knee angles during midstance (2.9 deg) and propulsion (2.8 deg) compared to self-selected speeds. Reduced contributions from primarily the ankle plantarflexion but also knee abduction and hip abduction moments likely reduced the vertical GRF and displacement. As differences favored reduced loading, youth with ASD can safely be encouraged to engage in running as a physical activity.

A clinical test examination procedure to identify knee compartment overloading: A reliability and validity study using SPECT-CT as reference

BackgroundMechanical forces and joint misalignment are considered risk factors for the development of knee osteoarthritis (KOA). Early detection of KOA and distinction between lateral and medial compartment overloading (CO), might be important to inform appropriate preventative interventions. This study evaluated reliability and validity of a test battery consisting of ten clinical tests to predict knee CO. MethodsIndependent observers examined 30 participants with symptoms of KOA. Inter-rater reliability of the ten tests, as well as the anticipated CO based on the whole test battery, was determined. All participants received a SPECT-CT, which served as reference standard for CO. The agreement for CO between SPECT-CT and clinical examination was assessed to determine criterion validity. ResultsThe Kappa coefficients (k) for the ten individual clinical tests ranged from 0.19 to 0.80. The k for determining CO was 0.52 (95% CI = 0.28–0.76). The agreement for CO between SPECT-CT and clinical examination (i.e. criterion validity) yielded a k of 0.26 (95% CI = −0.06 - 0.58). Logistic regression indicated that valgus alignment was strongly related with lateral CO. No other relationships were found between individual tests and CO. ConclusionAccurate measurement of frontal plane knee angle is important to determine CO. This particular test yielded good reliability, but low validity. Reliability of the nine remaining clinical tests was fair to moderate. Criterion validity of the clinical examination to predict CO was low. Therefore, this test battery in its current form cannot be used in practice to determine CO.

Frontal plane knee alignment mediates the effect of frontal plane rearfoot motion on knee joint load distribution during walking in people with medial knee osteoarthritis

To examine the nature of differences in the relationship between frontal plane rearfoot kinematics and knee adduction moment (KAM) magnitudes. Cross-sectional study resulting from a combination of overground walking biomechanics data obtained from participants with medial tibiofemoral osteoarthritis at two separate sites. Statistical models were created to examine the relationship between minimum frontal plane rearfoot angle (negative values=eversion) and different measures of the KAM, including examination of confounding, mediation, and effect modification from knee pain, radiographic disease severity, static rearfoot alignment, and frontal plane knee angle. Bivariable relationships between minimum frontal plane rearfoot angle and the KAM showed consistent negative correlations (r=-0.411 to-0.447), indicating higher KAM magnitudes associated with the rearfoot in a more everted position during stance. However, the nature of this relationship appears to be mainly influenced by frontal plane knee kinematics. Specifically, frontal plane knee angle during gait was found to completely mediate the relationship between minimum frontal plane rearfoot angle and the KAM, and was also an effect modifier in this relationship. No other variable significantly altered the relationship. While there does appear to be a moderate relationship between frontal plane rearfoot angle and the KAM, any differences in the magnitude of this relationship can likely be explained through an examination of frontal plane knee angle during walking. This finding suggests that interventions derived distal to the knee should account for the effect of frontal plane knee angle to have the desired effect on the KAM.

Potential Predictors of Vertical Jump Performance: Lower Extremity Dimensions and Alignment, Relative Body Fat, and Kinetic Variables.

Daugherty, HJ, Weiss, LW, Paquette, MR, Powell, DW, and Allison, LE. Potential predictors of vertical jump performance: Lower extremity dimensions and alignment, relative body fat, and kinetic variables. J Strength Cond Res 35(3): 616-625, 2021-The association of structural and kinetic variables with restricted vertical jump (RVJ) displacement without and with added mass was examined in 60 men and women. Added mass (weighted vest) simulated a 5% increase in body fat (BF%). Independent variables included BF%, thigh length, and static Q-angle (Q-angles), and while performing RVJ, different expressions of frontal-plane knee angle (FPKA), dynamic Q-angle (Q-angled), vertical ground reaction force (vGRF), concentric vertical impulse (Iz), concentric rate of force development (CRFD), and vertical power (Pz). Variables having significant (p ≤ 0.05) negative correlations with RVJ displacement included BF% (r = -0.76) and Q-angles (r = -0.55). Those having significant (p ≤ 0.05) positive correlations with RVJ displacement included peak and average concentric Pz (r range = 0.74-0.81), peak and average concentric vGRF (r range = 0.46-0.67), Iz (r range = 0.32-0.54), thigh length (r = 0.31), minimum Q-angled (r = 0.31), and maximum FPKA (r = 0.28). Variables not associated (p > 0.05) with RVJ displacement included minimum and excursion FPKA (r = 0.11 and 0.23), maximum, excursion, and average Q-angled (r = 0.24, 0.11, and 0.22), and CRFD (r range = 0.19-0.24). A simple regression model predicted RVJ displacement (p = 1.00) for the simulated 5% increase in body fat. To maximize jumping performance, (a) high levels of body fat should be avoided, (b) peak and average Pz, vGRF, and Iz should be maximized through training, and (c) having a lower Q-angles is associated with better jumping ability.

Reduced 2-D Frontal Plane Motion During Single-Limb Landing Is Associated With Risk of Future Anterior Cruciate Ligament Graft Rupture After Anterior Cruciate Ligament Reconstruction and Return to Sport: A Pilot Study.

To evaluate the association between 2-D frontal plane movement and second anterior cruciate ligament (ACL) injury risk in young athletes at return to sport (RTS) after ACL reconstruction. Prospective cohort. Forty-nine participants who had ACL reconstruction (mean ± SD age, 16.5 ± 3.0 years) performed a single-leg drop landing from a 31-cm box at the time of their RTS. Frontal plane trunk, pelvis, and knee angles were measured using 2-D video analysis at the point of maximum depth during landing. Summated frontal plane angles were calculated by adding trunk, pelvis, and knee angles. Participants were grouped based on whether or not they sustained an ACL graft rupture over the 24 months after RTS. Seven participants (14%) sustained an ipsilateral graft rupture within 24 months after RTS. Participants who suffered a second ACL injury had a significant reduction in the summated frontal plane angle of the trunk, pelvis, and knee (P = .018) and of the trunk and knee (P = .02) compared to those who did not suffer a second injury. For every 5° increase in the summated trunk, pelvis, and knee angle (odds ratio [OR] = 0.54; 95% confidence interval [CI]: 0.31, 0.94) and the summated trunk and knee angle (OR = 0.48; 95% CI: 0.25, 0.94), the athletes were 46% to 52% less likely to sustain a graft rupture. Athletes who suffered an ACL graft rupture within 24 months of RTS had a more rigid posture when landing compared to their uninjured peers. The results of this pilot study should be replicated in a larger sample to determine whether this method has merit as a screening tool to identify athletes at high risk for second ACL injury. J Orthop Sports Phys Ther 2021;51(2):82-87. Epub 25 Dec 2020. doi:10.2519/jospt.2021.9302.

VALIDITY OF AN MRI-COMPATIBLE MOTION CAPTURE SYSTEM FOR USE WITH LOWER EXTREMITY NEUROIMAGING PARADIGMS.

Emergent linkages between musculoskeletal injury and the nervous system have increased interest to evaluate brain activity during functional movements associated with injury risk. Functional magnetic resonance imaging (fMRI) is a sophisticated modality that can be used to study brain activity during functional sensorimotor control tasks. However, technical limitations have precluded the precise quantification of lower-extremity joint kinematics during active brain scanning. The purpose of this study was to determine the validity of a new, MRI-compatible motion tracking system relative to a traditional multi-camera 3D motion capture system for measuring lower extremity joint kinematics. Fifteen subjects (9 females, 6 males) performed knee flexion-extension and leg press movements against guided resistance while laying supine. Motion tracking data were collected simultaneously using the MRI-compatible and traditional multi-camera 3D motion systems. Participants' sagittal and frontal plane knee angles were calculated from data acquired by both multi-camera systems. Resultant range of angular movement in both measurement planes were compared between both systems. Instrument agreement was assessed using Bland-Altman plots and intraclass correlation coefficients (ICC). The system demonstrated excellent validity in the sagittal plane (ICCs>0.99) and good to excellent validity in the frontal plane (0.84 < ICCs < 0.92). Mean differences between corresponding range of angular movement measurements ranged from 0.186 ° to 0.295 °. The present data indicate that this new, MRI-compatible system is valid for measuring lower extremity movements when compared to the gold standard 3D motion analysis system. As there is growing interest regarding the neural substrates of lower extremity movement, particularly in relation to injury and pathology, this system can now be integrated into neuroimaging paradigms to investigate movement biomechanics and its relation to brain activity. 3.

Male and female soccer players exhibit different knee joint mechanics during pre-planned change of direction

ABSTRACT Change of direction manoeuvres is important in soccer and associated with non-contact anterior cruciate ligament injury, yet it is not known how the mechanics differentiate between males and females during 180° turns. Twenty-eight soccer players (14 males and 14 females) performed 180° turns with ground reaction forces collected over penultimate and final contacts. A two-way (contact × limb) multivariate analysis of variance (MANOVA) were run to examine differences between contact (penultimate and final) or limb (dominant and non-dominant) for sagittal plane hip, knee and ankle peak angles and moments, and frontal plane knee abduction moments and angles between sexes. Average horizontal GRF was increased on the dominant limb, compared to non-dominant and for the final contact compared to the penultimate contact. Knee abduction angles were increased in females compared to males, while the opposite was true for knee abduction moments. Statistically significant differences were evident, with increases in peak vertical GRF, peak hip flexion angle, peak knee flexion angle, peak knee extensor moment, and peak ankle dorsiflexion angle observed in the penultimate contact compared to final contact. The results indicate the penultimate contact during turns helps reduce loading on the final contact, yet male and female soccer players exhibit different knee joint mechanics during pre-planned change of direction.

Effects of pelvic and core strength training on biomechanical risk factors for anterior cruciate ligament injuries.

Little is known about the changes in biomechanical risk factors for an anterior cruciate ligament (ACL) injury after participation in a pelvic and core strength training (PCST) program in female team players. This is a randomized controlled trial for which a total of 29 female soccer players were recruited from a soccer club and split into two groups, namely, experimental group (EG, N.=18; mean [SD] age, 17.8 [2.0 years], weight 64.0 [6.6] kg and height 1.7 [0.0] m) and control group (control, N.=11; mean [SD] age, 16.2 [1.2] years, weight 61.6 [7.3] kg and height 1.7 [0.0] m). The EG participated in an in-season 8-week PCST program (twice/week). Participants in the CG performed their normal training without additional pelvic and core strengthening. Pre- and postintervention knee frontal plane projection angle (FPPA), hip, knee and ankle peak flexion angles and jump height were collected during bilateral and unilateral drop jumps. PCST significantly reduced FPPA at dynamic landing, in both dominant (-7.1º) and non-dominant lower extremities (-8º). Further, this training significantly increased the peak hip (24.4º) and knee flexion angles (14.94º), but not the peak ankle dorsiflexion angle (P>0.05) which, significantly decreased in the CG (-3.5º). Following the intervention, EG significantly increased measures obtained for both bilateral (2.84 cm) and unilateral jumps (1.33 cm for the dominant leg and 1.22 cm for the non-dominant leg) (P<0.05), not so for CG (P<0.05). PCST resulted in improvements on ACL injury risk factors and vertical drop jump performance, suggesting that strengthening this body part warrants not only injury prevention, but increases jumping performance.

Influence of age and sex on drop jump landing strategies in élite youth soccer players

The vertical drop jump (VDJ) test evaluates frontal-plane knee control in a controlled environment. Age- and sex-related changes in landing and bouncing mechanisms in youth soccer players are still under investigated. This study characterizes knee biomechanics in a large cohort of élite academy players, stratified by sex and age group. A sample of 189 young soccer players (132 male U10-U12 and U14-U17, 57 females U10-U14) from the Academy of a professional “Serie A” Italian club were tested. Motion capture technology was used to obtain sagittal and frontal plane knee angles, as well as VDJ landing asymmetry and peak vertical ground reaction forces at push-off. Landing kinetics and kinematics changed as a function of age and sex in youth élite soccer players: (i) males and females showed different landing load asymmetry between dominant and non-dominant leg, peak push-off force and knee flexion even before puberty, (ii) landing asymmetry tended to reduce in older players and (iii) knee varus increased in males after adolescence. In conclusion, besides its role in injury prevention, the VDJ can help in monitoring players’ growth and development, and this process should start at an early age. This data collection could be used as a tool for further screening test to highlight anomalous landing behaviour.

Biomechanical Determinants Of Return To Sport Following Anterior Cruciate Ligament Reconstruction

The ability to return to sport (RTS) after an anterior cruciate ligament reconstruction (ACLR) return to sport is due to many factors. To date, few studies have considered the role of poor biomechanics to predict RTS status. Potentially, higher ground reaction forces (GRF) and better frontal plane knee alignment at a 6 month follow up, may indicate an athlete who is able to return to sport at their pre-injury level. However, this has never been formally tested. Purpose: To determine the biomechanical factors at six months that predict return to sport at pre-injury level following ACLR. Methods: 21 subjects, (13 F, 20.1 ± 5.9 years, 22.3 ± 2.1 BMI, Pre-injury Tegner 8.1 ± 2.1 ) six months (190.6 ± 15.3 days) following ACLR, ran on an instrumented treadmill during three-dimensional assessment. Visual 3D was used to analyze peak GRF, impact peak, and frontal plane knee angle. Subjects were contacted at 4.5 ± 2.1 years post-surgery to answer a questionnaire regarding RTS. Logistic regression model selection was performed using the Feasible Solutions Algorithm with AIC as a criterion. p-values presented here are based on the main effect significance tests from the selected model. Results: Of the 21 subjects, 62% returned to sport at their pre-injury level. Subjects who returned to sport had significantly higher peak GRF (RTS 2.1 ± 0.24 BW, No RTS 1.98 ± 0.18 BW, p=0.03), impact peak (RTS 1.6 ± 0.3 BW, No RTS 1.4 ± 0.16 BW, p=0.04), and maximum frontal plane knee angle (RTS 5.2 ± 3.0o, No RTS 3.3 ± 3.3o, p=0.04). Conclusion: This data indicates that athletes who run with greater axial loading and whose knee is in a more adducted position are more likely to RTS at pre-injury level. We speculate that athletes who land with greater impact forces are more confident in their knee function and, thus, are more likely to return to sport. In addition, positioning the knee in more adduction may help the athlete feel more secure in their knee and, consequently, return to playing sport. Rehabilitation efforts should focus greater impact loading and improved frontal plane alignment of the knee during running to increase the likelihood of RTS at pre-injury level.

Reliability Of Quantitative Kinematics From A Portable Hand-held Device

The current gold standard for assessing kinematics is three-dimensional (3D) motion analysis. However, the equipment required to accomplish this is not generally available in sport or clinical settings. Portable handheld devices (PD) are available that synchronize multiple two-dimensional video views to qualitatively evaluate complex sport skills. However, the use of quantitative kinematic analysis on PD compared to standard computer software (CS) has not been investigated. PURPOSE: To investigate the intra- and inter-rater reliability of PD compared to an open source CS. METHODS: Twenty-seven collegiate male soccer players (height:179.8±5.6cm, mass: 75.9±6.9kg) were analyzed (120 Hz) during a drop vertical jump from a 30-cm box. PD and CS were separately used to 1) select a single frame from the frontal plane view when both knees were visually the most medial during landing and 2) digitize and record the frontal plane knee angle from hip, knee and ankle joint centers to estimate lower extremity valgus. Reliability between systems and reliability between testers were established with intraclass correlations (ICC2,k, ICC3,k, respectively). Precision was calculated with standard error of measurement (SEM). RESULTS: Intra-rater reliability was 0.993 [95% CI 0.985, 0.997] with SEM of 1.09 on the right, and 0.971 [95% CI 0.938, 0.987] SEM of 2.69 on the left limb. Inter-rater reliability on the right side was 0.979 [95% CI 0.954, 0.990] with SEM of 1.97 for the right limb and 0.978 [95% CI 0.943, 0.990] with SEM of 2.37 on the left, respectively. CONCLUSION: In collegiate male soccer players, PD exhibited excellent intra- and inter-rater reliability. The data indicates that it might be a useful tool to integrate into a screening protocol to quickly estimate lower extremity valgus. However, future analyses should compare traditional 3D motion analysis to determine validity.