The reliability and criterion validity of 2D video assessment of single leg squat and hop landing

A comprehensive two-dimensional scoring system to assess the single-leg squat task in football players

BACKGROUND

The single-leg squat (SLS) is a safe and widespread functional test commonly performed in the mid-stages of rehabilitation after severe knee injuries. The use of reliable objective measures has been advocated to improve the quality of SLS assessment. The aim of this study was to describe a qualitative whole-body scoring system based on two-dimensional (2D) video analysis during SLS test and validate it against three-dimensional (3D) kinetics and kinematics.

METHODS

Thirty-four competitive football (soccer) players performed a series of SLS tasks. 3D kinematics and kinetics were collected through infrared cameras, and 2D video analysis was performed through a scoring system with sub-scores ranging from 0/2 (non-adequate movement) to 2/2 (adequate movement) based on frontal and lateral planes objective measurements. 3D kinematics and kinetics were grouped according to the results of the 2D evaluation and compared through the analysis of variance (P < 0.05).

RESULTS

Higher hip adduction, hip internalrotation, and knee valgus collapse were found in trials rated 0/2 or 1/2 compared with theone rated 2/2 in the limb stability score. Hip flexion and hip/knee moment ratio were lower in those scoring 0/2 comparedwith those scoring 2/2 in the movement strategy criterion. A low total score was associated with higherknee valgus collapse and lower hip/knee extensor moment ratio. Compensatory strategieswere found in frontal plane scores.

CONCLUSIONS

The 2D scoring system described was strongly associated with kinematics and kinetics from gold-standard 3D motion capture and might represent a valid tool to describe the movement quality of an SLS task.

A 2D video-based assessment is associated with 3D biomechanical contributors to dynamic knee valgus in the coronal plane

Introduction

Adolescent athletes involved in sports that involve cutting and landing maneuvers have an increased risk of anterior cruciate ligament (ACL) tears, highlighting the importance of identifying risky movement patterns such as dynamic knee valgus (DKV). Qualitative movement screenings have explored two-dimensional (2D) scoring criteria for DKV, however, there remains limited data on the validity of these screening tools. Determining a 2D scoring criterion for DKV that closely aligns with three-dimensional (3D) biomechanical measures will allow for the identification of poor knee position in adolescent athletes on a broad scale. The purpose of this study was to establish a 2D scoring criterion that corresponds to 3D biomechanical measures of DKV.

Methods

A total of 41 adolescent female club volleyball athletes performed a three-task movement screen consisting of a single-leg squat (SLS), single-leg drop landing (SLDL), and double-leg vertical jump (DLVJ). A single rater scored 2D videos of each task using four criteria for poor knee position. A motion capture system was used to calculate 3D joint angles, including pelvic obliquity, hip adduction, knee abduction, ankle eversion, and foot progression angle. Receiver operating characteristic curves were created for each 2D scoring criterion to determine cut points for the presence of movement faults, and areas under the curve (AUC) were computed to describe the accuracy of each 2D criterion compared to 3D biomechanical data.

Results

3D measures indicated knee abduction angles between 2.4°-4.6° (SD 4.1°-4.3°) at the time point when the center of the knee joint was most medial during the three tasks. AUCs were between 0.62 and 0.93 across scoring items. The MEDIAL scoring item, defined as the knee joint positioned inside the medial border of the shoe, demonstrated the greatest association to components of DKV, with AUCs ranging from 0.67 to 0.93.

Conclusion

The MEDIAL scoring criterion demonstrated the best performance in distinguishing components of DKV, specifically pelvic obliquity, hip adduction, ankle eversion, and foot progression. Along with the previously published scoring definitions for trunk-specific risk factors, the authors suggest that the MEDIAL criterion may be the most indicative of DKV, given an association with 3D biomechanical risk factors.

The effectiveness of the STOP-X training program on the knee valgus angle and balance in female basketball players with dynamic knee valgus: a randomized controlled trial

BACKGROUND

Dynamic knee valgus (DKV) accompanied by poor balance is the cause of anterior cruciate ligament (ACL) injury in athletes, and the identification and correction of these factors are always of interest to researchers. Therefore, the purpose of this research was to investigate the effect of the STOP-X program on the knee valgus angle and static and dynamic balance in female basketball players with DKV defects.

METHODS

The present study was a quasi-experimental study. Thirty female basketball players with DKV defects were purposefully identified by the single-leg landing (SLL) test and were randomly assigned to two control (n = 15) and experimental (n = 15) groups. Static balance status was evaluated with the BASS STICK test, and dynamic balance status was evaluated with the Y-balance test (YBT). The experimental group performed the STOP-X program for 25-40 min for eight weeks (three times per week), and the control group performed their traditional warm-up program. Data were analyzed by means of 2 × 2 repeated measures ANOVA followed by post hoc comparison (Bonferroni) at the significance level of (P < 0.05) with SPSS version 26.

RESULTS

The results showed that with the use of the STOP-X program, there was a significant difference between the experimental and control groups in variables of the static balance (F = 56.45; P = 0.001; ES = 0.66, PC=↑59.64%), total dynamic balance score (F = 107.57; P = 0.001; ES=↑0.79, PC=↑19.84%), and knee valgus angle (F = 119.46; P = 0.001; ES = 0.81, PC=↓34.36%).

CONCLUSION

In addition to reducing the knee valgus angle, applying the STOP-X injury prevention program can improve static and dynamic balance in female basketball players with DKV defects. Therefore, it can be recommended that sports trainers benefit from these advantages by adding STOP-X training to routine basketball exercises.

Effect of Exhaustive Exercise on Lumbopelvic-Hip Complex Stability, Muscle Activity, and Movement Patterns

This study aimed to evaluate the effect of exhaustive exercise on lumbopelvic-hip complex (LPHC) muscle activity, stability, and single-leg squat kinematics. Twenty-two healthy participants (12 females, 23.5 ± 3.1 years) were recruited. LPHC stability was measured by number of errors committed during a seated trunk control test (STCT). Surface electromyography recorded muscle activity of rectus abdominis (RA), external oblique, internal oblique (IO), erector spinae, and gluteus medius during the STCT and single-leg squat, and was normalized to peak activity during the task. Two-dimensional motion analysis quantified frontal and sagittal plane kinematics of the trunk, hip, and knee. Following exhaustive exercise, STCT performance worsened (number of errors: pre: 5.5 (interquartile range (IQR) = 1.4-9.0), post: 8.0 (IQR = 3.6-11.3), p = 0.026.), RA activity increased during the single-leg squat (pre: 42.1 (IQR = 33.6-48.5)%, post: 61.1 (IQR = 39.4-156.7 %, p =.004), and participants displayed less hip and knee flexion (hip: pre: 72.4 ± 22.1°; post: 66.2 ± 22.5°, p =.049; knee: pre: 72.4 ± 15.4°; post: 67.4 ± 18.2°, p =.005). Full-body exhaustive exercise negatively affected isolated LPHC stability and resulted in greater RA activity during the single-leg squat. Hip and knee flexion decreased during a single-leg squat after exhaustive exercise which could indicate decreased athletic performance, but changes in the quality of movement during other tasks should be further investigated.

Reliability and Measurement Error of the Qualitative Analysis of Single Leg Loading (QASLS) Tool For Unilateral Tasks

Background

Movement quality assessment is popular within clinical and sporting practice, due to the contribution diminished or suboptimal movement quality is believed to have on musculoskeletal (MSK) injury risk. Various movement quality assessments exist, many are limited to bilateral or jumping movements evaluation. Qualitative analysis of single leg loading (QASLS) is a new clinical assessment tool for unilateral tasks that utilizes a dichotomous scoring system of ten questions relating to the segmental body regions of the trunk, lower and upper limb.

Purpose

To determine the intra and inter-rater, within- and between-session reliability of the QASLS tool during two unilateral movement tasks, and provide insight to measurement error and smallest detectable difference (SDD).

Study Design

Reliability Study.

Methods

Fifteen healthy females (mean age 19 years SD2; height 167 cm, +/- 6; weight 56 kg, +/- 6) completed two unilateral tasks, single leg squat (SLS) and single leg landing (SLL), within session data collection occurred on the same day, with between session data collection occurring seven days later. Tasks were scored with the QASLS tool via video playback. Intra-Class correlation coefficients (ICCk,3) were used to measure within and between session reliability, and Kappa coefficients and percentage of exact agreement (PEA%) were used to determine intra and inter-rater reliability. Standard error of measurement (SEM) and the SDD for the compound score of each limb was calculated.

Results

Within session reliability of QASLS scores was good (ICC = 0.82-0.86) for SLS and moderate (ICC = 0.67-0.87) for SLL. Between session reliability was moderate (ICC = 0.69-0.87) for SLS and excellent (ICC = 0.92-0.93) for SLL. SEM was less than 1 point, and SDD for compound score ranging from 1.0-2.5 points. Intra-rater agreement of compound QASLS score was near perfect (k = 0.85-100; PEA% 90-100%) and agreement of individual components was substantial- near perfect (k = 0.13-0.74; PEA% 78-100%). Inter-rater agreement for compound QASLS scores ranged from non-substantial (k = 0.13-0.74; PEA% 43.3-90%) for SLS and non-slight (k =0.03-0.17; PEA% 43.3-60%) for SLL.

Conclusions

The QASLS movement analysis tool can be used to analyze movement quality during two unilateral loading tasks with moderate to excellent within and between session reliability. PEA% was acceptable for inter-rater agreement, however rater education training is recommended to develop more acceptable levels of reliability.

Level of Evidence

3.

Comparison of postural sway in individuals with and without dynamic knee valgus

BACKGROUND

Dynamic knee valgus (DKV) is a multi-planar faulty movement pattern that can cause faulty postural control. The primary objective of this study is to investigate the differences in postural sway (PS) between individuals aged 18-30 years old diagnosed with and without DKV.

METHODS

In this cross-sectional study, 62 students (39 males and 23 females) with and without DKV (age: 24.58 ± 2.63 years) were selected and assigned to two groups by conducting the single-leg squat test in the screening stage. The Biodex balance system was then employed to compare the two groups in PS. Mann-Whitney U test was conducted to compare the groups in PS (p ≤ 0.05).

RESULTS

The study's findings indicate that individuals with DKV did not exhibit any significant differences, compared to those without, about the anterior-posterior stability index (with p values for both static and dynamic situations at 0.309 and 0.198, respectively), medial-lateral stability index (with p values for both static and dynamic situations at 0.883 and 0.500, respectively), and overall stability index (with p values for both static and dynamic situations at 0.277 and 0.086, respectively).

CONCLUSION

Though several possible factors could contribute to the lack of significant differences in postural sway between individuals with and without DKV, such as measurement tool differences, variable sensitivity in postural stability tests, and differences in movement variability and test stance, we recommend analyzing postural sway in more functional tasks and with different methodological patterns in future studies. Such research could help develop targeted interventions for individuals with DKV and offer a better understanding of the relationship between postural control and DKV.

Comparison of the Frontal Plane Projection Angle and the Dynamic Valgus Index to Identify Movement Dysfunction in Females with Patellofemoral Pain

Background

Clinicians typically measure the knee frontal plane projection angle (FPPA) during a single-leg squat to identify females with patellofemoral pain (PFP). A limitation of this measure is minimal attention to movement of the pelvis on the femur that can create knee valgus loading. The dynamic valgus index (DVI) may be a better assessment.

Hypothesis/Purpose

The purpose of this study was to compare the knee FPPA and DVI between females with and without PFP and determine if the DVI better identified females with PFP than the knee FPPA.

Study Design

Case-control.

Methods

Sixteen females with and 16 without PFP underwent 2-dimensional motion analysis when performing five trials of a single-leg squat. The average peak knee FPPA and peak DVI were analyzed. Independent t-tests determined between-group peak knee FPPA and peak DVI differences. Receiver operating characteristic (ROC) curves determined the area under the curve (AUC) scores for sensitivity and 1 - specificity of each measure. Paired-sample area difference under the ROC curves was conducted to determine differences in the AUC for the knee FPPA and DVI. Positive likelihood ratios were calculated for each measure. The significance level was p < 0.05.

Results

Females with PFP exhibited a higher knee FPPA (p = 0.001) and DVI (p = 0.015) than controls. AUC scores were .85 (p = 0.001) and .76 (p = 0.012) for the knee FPPA and DVI, respectively. Paired-sample area difference under the ROC curves showed a similar (p = 0.10) AUC for the knee FPPA and DVI. The knee FPPA had 87.5% sensitivity and 68.8% specificity; the DVI had 81.3% sensitivity and 81.0% specificity. Positive likelihood ratios for the knee FPPA and DVI were 2.8 and 4.3, respectively.

Conclusion

The DVI during a single-leg squat may be another useful tool for discriminating between females with and without PFP.

Level of Evidence

3a.

Are proximal and distal neuromuscular parameters able to predict hip and knee frontal plane kinematics during single-leg landing?

OBJECTIVE

To determine if proximal and distal neuromuscular parameters (EMG amplitude and median frequency - MDF) can predict frontal plane kinematics during single-leg landing.

STUDY DESIGN

Cross sectional study.

SETTING

Laboratory.

PARTICIPANTS

Fifteen participants (7 female) performed six single-leg landings with measures of frontal plane kinematics and EMG obtained 230 ms after first foot contact, totalizing 90 landings.

MAIN OUTCOME MEASURES

(i) 2D hip adduction [hip ADD] and knee frontal plane projection angle [knee FPPA]; (ii) EMG amplitude and MDF of gluteus medius [GMed], tensor fascia latae [TFL], peroneus longus [PL] and tibialis anterior [TA].

RESULTS

We observed that MDF of TA was a significant predictor of hip ADD (p = 0.037; β = -0.049 Hz; R²c = 0.30). Also, MDF of PL was significant predictor of knee FPPA (p = 0.043; β = 0.042 Hz; R²c = 0.37). Hip muscles and EMG amplitude parameters were not considered predictors of frontal plane kinematics.

CONCLUSION

The firing frequency of ankle muscles predicted the variance of hip and knee frontal plane kinematics during single-leg landing.

Asymmetries in Two-Dimensional Trunk and Knee Kinematics During a Single-Leg Drop Landing Post Anterior Cruciate Ligament Reconstruction

The purpose of this study was to compare interlimb asymmetries in trunk and knee kinematics during a single-leg drop landing between athletes 9 months post anterior cruciate ligament reconstruction (post-ACLR) and healthy athletes using two-dimensional analysis. Thirty-three recreational athletes (12 post-ACLR and 21 healthy) participated in the study. Participants post-ACLR showed significantly higher limb symmetry indices in peak trunk flexion (144.0%, SE drop landing kinematics: 22.7%) when compared to healthy participants (100.6%, SE: 10.5%; z = 2.17, p = .03) and lower limb symmetry indices in peak knee flexion (85.3%, SE: 3.6%) when compared to healthy participants (98.0%, SE: 3.3%; z = −2.43, p = .01). Two-dimensional analyses of a single-leg drop landing is a clinically applicable tool that can identify interlimb asymmetries in peak trunk flexion and peak knee flexion kinematics in athletes greater than 9 months post-ACLR when compared to healthy athletes.

Análisis cinemático del ángulo de proyección frontal de rodilla en 2D: enfoque metodológico

La evaluación cinemática del comportamiento del miembro inferior en tres dimensiones (3D) requiere el uso de alta tecnología, formación especializada y laboratorios que no se ajustan a las demandas del ámbito clínico y deportivo. La valoración del APFR (ángulo de proyección frontal de rodilla)en dos dimensiones (2D) ha mostrado consistentemente su validez, objetividad y confiabilidad al ser comparada con la metodología de análisis en 3D para la detección del valgo dinámico asociado al incremento de torques externos de aducción y rotación interna de cadera durante la ejecución de tareas funcionales que exigen control muscular excéntrico. El valgo dinámico ha mostrado ser un predictor de lesión del ligamento cruzado anterior y de síndrome de dolor patelofemoral, especialmente en mujeres. La detección oportuna y el seguimiento del comportamiento cinemático con instrumentos de bajo costo, poca complejidad y un nivel de experticia básico utilizando análisis en 2D, se perfila como estrategia de valoración importante en el entrenamiento deportivo y el abordaje clínico para la prevención y rehabilitación de lesiones de rodilla asociados a estos desórdenes del movimiento. Por tanto, esta revisión narrativa pretende proveer de conocimientos esenciales para la correcta valoración, interpretación y análisis del APFR en Fisioterapeutas y Profesionales del Deporte.

Does the 2D Frontal Plane Projection Angle Predict Frontal Plane Knee Moments during Stepping, Landing, and Change of Direction Tasks?

Background

Although dynamic knee valgus can be visually identified using the 2D frontal plane projection angle (FPPA), the validity of the FPPA in terms of predicting frontal plane knee kinematics has been questioned. The biomechanical utility of the FPPA may lie in its ability to predict frontal plane knee moments.

Hypothesis/Purpose

The purpose of the current study was to comprehensively evaluate the ability of the FPPA to predict the frontal plane knee kinetics (peak moment, average moment, and moment at peak knee flexion) across a wide range of tasks (stepping, landing, and change of direction).

Design

Crossover Study Design.

Methods

Three-dimensional lower-extremity kinetics and 2D video were obtained from 39 healthy athletes (15 males and 24 females) during execution of six tasks (step down, drop jump, lateral shuffle, deceleration, triple hop, side-step-cut). Linear regression analysis was performed to determine if the 2D FPPA at peak knee flexion predicted frontal plane knee moment variables during the deceleration phase of each task (peak moment, average moment, moment at peak knee flexion).

Results

The FPPA was found to significantly predict the peak frontal plane knee moment for two tasks (deceleration and side-step-cut, R2 = 12% to 25%), average frontal plane knee moment for five tasks (drop jump, shuffle, deceleration, triple hop, side-step-cut, R2 = 15% to 40%), and frontal plane knee moment at peak knee flexion for five tasks (drop jump, shuffle, deceleration, triple hop, side-step-cut, R2 = 16% to 45%).

Conclusion

An increased FPPA (medial knee collapse) predicted increased knee valgus moments (or decreased knee varus moments) during landing and change of direction tasks (but not stepping). However, the predictive ability of the FPPA was weak to moderate.

The association and reliability of the frontal plane projection angle during the lateral step down test on knee function in patients with patellofemoral pain

BACKGROUND

The lateral step-down test is used by physical therapists (PT) to identify movement faults in patients with patellofemoral pain (PFP). The FPPA is a measure of knee valgus and PTs have access to open source video analysis software and high quality smart phones and video cameras to implement 2D video analysis into practice. The purpose of our study was to determine the reliability of PTs measuring the frontal plane projection angle (FPPA) during the lateral step-down test, and to determine if the FPPA was associated with pain, self-reported knee function and fear of movement.

METHODS

Twenty-two subjects (mean age[SD] = 27.8 [6.6] years, females n = 14, males n = 8) with PFP were analyzed by six PTs using 2D video analysis software. The FPPA was measured during the lateral step down test. Numeric Pain Rating Scale (NPRS), Anterior Knee Pain Scale (AKPS) and the Tampa Scale of Kinesiophobia (TSK) were collected. Intraclass correlation (ICC) was used to assess for PT measurement reliability. Correlations between outcomes were calculated using Spearman correlation coefficient and standard error of measurement (SEM) and minimal detectable change (MDC) were reported.

RESULTS

Reliability amongst PTs measuring the FPPA was good (ICC [95 %CI] = 0.85 [0.72-0.93]; SEM = 3.33°, MDC = 9.20°). There were no significant correlations (p > 0.05) between FPPA and NPRS(ρ = -0.046), AKPS(ρ = 0.066), or TSK(ρ = -0.204).

CONCLUSIONS

Although reliability measuring FPPA was good, the large SEM and MDC associated with this measurement may limit its clinical utility in those with PFP.

Association between Selected Screening Tests and Knee Alignment in Single-Leg Tasks among Young Football Players

This study aimed to examine the relationship between knee valgus in the frontal plane projection angle (FPPA) during single-leg squat (SLS), single-leg landing (SLL), and other selected clinical tests in young athletes. Forty-three young healthy elite football players (age: 13.2 (1.7) years) that were regularly training in a local sports club participated in the study. The FPPA was assessed using 2D video analysis. The screening tests included the passive single-leg raise (PSLR), hip external and internal rotation (hip ER and IR), sit and reach test, weight-bearing lunge test (WBLT), modified star excursion balance test (mSEBT), countermovement jump (CMJ), single-leg hop for distance (SLHD), and age peak height velocity (APHV). There was a significant positive relationship between the knee valgus angles in the SLS test and the sit and reach test (r = 0.34) and a negative relationship with the hip ER ROM (r = −0.34) (p < 0.05). The knee valgus angles in the SLL were negatively associated with the hip IR (r = −0.32) and ER ROM (r = −0.34) and positive associated with the WBLT (r = 0.35) and sit and reach test (r = 0.33) (p < 0.05). Linear regression analysis showed that the results of the hip ER ROM and sit and reach tests were independent predictors of the FPPA in the SLS test (r2 = 0.11, p = 0.03 and r2 = 0.12, p = 0.02, respectively). The conducted study showed that individuals with more hip range of motion, more spine flexion extensibility, and less ankle dorsiflexion ROM may be more likely to experience high degrees of knee valgus in FPPA.

Reliability and Differences Between Sexes in Landing Mechanics when Performing the Lateral Bound Test

Background and Purpose

Anterior cruciate ligament injuries are prevalent among the athletic population, imposing a heavy economic burden, and the risk of re-injury. Most current biomechanical screening tasks are performed in the sagittal plane, and there is a need for more screening tools that assess sports specific movements in the frontal plane. The purpose of this study was to determine the reliability of and examine differences between sexes in the performance of the Lateral Bound Test (LBT).

Materials/Methods

Each subject performed three trials of a LBT which included jumping laterally from one leg over a hurdle and landing on the opposite leg. Two cameras were placed six feet from the landing marker. Maximum dynamic knee valgus using the frontal plane projection angle and knee flexion angle at initial contact and maximal knee flexion were measured upon landing leg using 2D video analysis software. Additionally, video of 10 individuals' trials were analyzed twice with one week between the analyses to obtain intra-rater reliability while 12 participants were retested one week later to determine test-retest reliability.

Results

Thirty healthy subjects, 16 males, 14 females participated. Intra-rater reliability was determined to be excellent for all variables (ICC>0.96). In contrast, the test-retest reliability had greater disparity. Test-retest reliability ranged from poor (ICC = 0.47) to excellent (ICC > 0.90). Significant differences existed between the sexes, including males being significantly taller, weighing more, and demonstrating greater bilateral dynamic knee valgus (p < 0.05). No significant differences existed between sexes for knee flexion angles.

Conclusion

The new LBT had excellent intra-rater reliability for assessing dynamic knee valgus and initial and maximum knee flexion angle when performing a functional movement in the frontal plane. Furthermore, males landed with more dynamic knee valgus than females which is contradictory to what has been observed with functional screening tools performed in the sagittal plane.

Level of Evidence

3b (reliability study).

Landing biomechanics deficits in anterior cruciate ligament reconstruction patients can be assessed in a non-laboratory setting

Landing biomechanics provide important information pertaining to second anterior cruciate ligament (ACL) injury risk in patients following ACL reconstruction (ACLR). While traditional motion analysis technologies are often impractical for use in non-laboratory settings, methods to assess landing biomechanics which are inexpensive, portable, and user-friendly have recently been developed and validated. The purpose of this study was to compare landing kinematics and kinetics between ACLR patients and uninjured controls in a non-laboratory setting. Sixteen ACLR patients (7 male/9 female, 6-12 months post-ACLR) and 16 gender-matched controls completed seven bilateral drop vertical jumps and seven unilateral drop landings on each limb. Plantar force was measured bilaterally using force sensing insoles and frontal and sagittal-plane knee kinematics were measured using two tablets, six reflective markers, and automated point tracking software. Plantar force impulse normalized symmetry index (NSI) and knee frontal plane projection angle (FPPA) range of motion were computed during bilateral landing, and knee flexion range of motion NSI was computed during unilateral landing and compared between groups using independent samples t tests. ACLR patients had larger NSIs (reflecting less symmetry) for plantar force impulse during bilateral landing (p < 0.001) and knee flexion range of motion during unilateral landing (p = 0.004). No between-group differences were observed for knee FPPA range of motion (p = 0.111). This study is an important step towards assessing landing biomechanics in non-research settings with the goal of providing quantitative injury risk metrics in a clinical setting that can be used for return to sport decision making.

Feasibility of Superimposed Neuromuscular Electrical Stimulation to the Gluteus Medius During a Resistance Training Program

CONTEXT

Gluteus medius (GMed) weakness is a common impairment seen across multiple lower-extremity pathologies. Greater GMed weakness is moderately associated with greater frontal plane motion, often termed dynamic knee valgus during functional tasks which may increase risk of lower-extremity injury. Neuromuscular electrical stimulation (NMES) superimposed to targeted muscles has emerged in clinical practice; however, NMES superimposed to the GMed in unknown. It is essential to assess the safety, credibility, and expectancy of NMES superimposed to the GMed prior to implementation in clinical practice. The objective of this study was to evaluate feasibility, safety, credibility, and expectancy of improvement with a 2-week intervention with or without NMES to the GMed in females with dynamic knee valgus.

DESIGN

Feasibility study.

METHODS

A total of 22 adult females with dynamic knee valgus (age = 21.8 [1.4] y, mass = 76.9 [18.8] kg, height = 1.7 [0.1] m) completed a 2-week intervention with NMES or a sham treatment superimposed to the GMed during all therapeutic exercises. Feasibility was assessed by recruitment and completion rate, while safety was assessed by the total number of adverse events. Treatment credibility and expectancy was assessed with the Credibility Expectancy Questionnaire. Mixed-measure analysis of variance were used for statistical analysis (P ≤ .05).

RESULTS

Recruitment was completed in 5 months with 100% completion rate and no adverse events. There was no difference in treatment credibility between groups (NMES = 23.7 [2.3], sham = 21.7 [3.4], P = .12); however, the NMES group demonstrated a greater expectancy score (NMES = 20.0 [3.8], sham = 15.9 [5.1], P = .045).

CONCLUSION

Resistance training with NMES superimposed to the GMed is a feasible and safe intervention that resulted in greater expectance of success. Clinicians may consider superimposing NMES to the gluteal muscles when addressing muscle weakness in individuals with dynamic knee valgus.

Relationship between lower limb EMG activity and knee frontal plane projection angle during a single-legged drop jump

OBJECTIVES

To assess a relationship between lower limb muscle activity and the frontal plane knee kinematics during a single-legged drop jump.

DESIGN

Correlation study; SETTING: Functional Anatomy Laboratory.

PARTICIPANTS

35 healthy collegiate male athletes.

MAIN OUTCOME MEASURES

Muscle activity (%MVIC) of gluteus maximus, gluteus medius, biceps femoris, semitendinosus, vastus medialis quadriceps, vastus lateralis quadriceps, medial gastrocnemius and lateral gastrocnemius; peak knee frontal plane projection angle; and Pearson's correlation coefficients between muscle activity and peak knee frontal plane projection angle. All outcomes were assessed for both dominant and non-dominant limbs.

RESULTS

Significant correlations (r = 0.46-0.60, P < 0.05) were found between the muscle activities of the gluteus maximus, gluteus medius, biceps femoris, and semitendinosus, when compared to the knee frontal plane projection angle.

CONCLUSION

Gluteal muscles and hamstring muscles are associated with the peak knee frontal plane projection angle during a single-legged drop jump test. Thus, gluteal and hamstring muscle activities should be considered when developing rehabilitation or injury prevention programs.

Is Hip Muscle Strength Associated with Dynamic Knee Valgus in a Healthy Adult Population? A Systematic Review

This study aimed to systematically review research investigating the association between hip muscle strength and dynamic knee valgus (DKV). Four databases (MEDLINE, PubMed, CINAHL, and SPORTDiscus) were searched for journal articles published from inception to October 2020. Seven studies investigating the association between hip muscle strength and DKV using a two-dimensional motion analysis system in healthy adults were included. The relationship between hip abductor muscle strength and DKV was negatively correlated in two studies, positively correlated in two studies, and not correlated in three studies. The DKV was associated with reduced hip extensor muscle strength in two studies and reduced hip external rotator muscle strength in two studies, while no correlation was found in three and five studies for each muscle group, respectively. The relationship between hip muscle strength, including abductors, extensors, and external rotators and DKV is conflicting. Considering the current literature limitations and variable methodological approaches used among studies, the clinical relevance of such findings should be interpreted cautiously. Therefore, future studies are recommended to measure the eccentric strength of hip muscles, resembling muscular movement during landing. Furthermore, high-demand and sufficiently challenging functional tasks revealing lower limb kinematic differences, such as cutting and jumping tasks, are recommended for measuring the DKV.

Noncontact Knee Ligament Injury Prevention Screening in Netball: A Clinical Commentary with Clinical Practice Suggestions for Community-Level Players

Netball is a predominantly female team court-sport which is played worldwide. Netball is becoming more popular in the United States following its countrywide introduction to schools and community centers. A unique characteristic of netball is the footwork rule which restricts players to a one-step landing after catching the ball. Most netball landings are single-leg landings resulting in high vertical ground reaction forces and high skeletal tissue forces. Thus, high-risk landing events that have the biomechanical potential for injury occur frequently. Noncontact knee ligament injuries are common following a knee abduction collapse when landing. Because the consequences of noncontact knee ligament injury are profound, strategies are needed to mitigate the burden of such injury for players, teams, and society. The purpose of this clinical commentary is to demonstrate how theoretical principles, different types of research, and different levels of evidence underpin a rational clinical reasoning process for developing noncontact knee ligament injury prevention screening procedures in netball. The theoretical principles that are discussed in this commentary include injury control, the sequence of prevention, principles of screening in injury prevention, the multifactorial model of injury etiology, complex systems theory, and systems science. The different types of research that are reviewed include descriptive and analytic-observational studies. The different levels of evidence that are discussed include prospective studies, cross-sectional studies, and clinicians' own kinesiological modelling. Subsequently, an integrated approach to the evidence-informed development of noncontact knee ligament injury prevention screening procedures is presented. Clinical practice suggestions include a selection of evidence-informed screening tests that are quickly and easily implemented with netball players in local communities. The need for repeated screening at strategic timepoints across a season/year is explained. Sports physical therapists will find this commentary useful as an example for how to undertake clinical reasoning processes that justify the content of screening procedures contributing to noncontact knee ligament injury prevention in community-level netball.

LEVEL OF EVIDENCE

5.

The influence of kinesio taping on trunk and lower extremity motions during different landing tasks: implications for anterior cruciate ligament injury

Purpose

The purpose of the study was to investigate the influence of a 72-h KT application on trunk and lower extremity kinematics during different landing tasks.

Methods

Twenty-nine competitive male athletes participated in this study. The sum of knee valgus and lateral trunk lean, symmetry index (SI), and peak angles of lateral trunk lean, hip flexion, knee abduction and flexion were assessed for all participants during single-leg drop landing (SLDL), single-leg vertical drop jump (SLVDJ), vertical drop jump (DLVDJ), and double leg forward jump (DLFJ), at baseline and seventy-two hours following KT application.

Results

The KT application resulted in more knee flexion and abduction, sum of knee valgus and lateral trunk lean as compared with the non-KT condition during SLDL (P < 0.05). Nonetheless, there were no differences in SI, maximum angle of the lateral trunk lean during SLDL, SLVDJ, nor hip flexion, knee abduction, and flexion during DLVDJ, and DLFJ tasks (P > 0.05).

Conclusions

The research findings suggest that KT after 72-h application may improve knee abduction and sum of knee valgus and lateral trunk lean during SLDL, knee flexion during SLDL and SLVDJ in individuals displaying risky single-leg kinematics. Therefore, KT application may marginally improve high-risk landing kinematics in competitive male athletes.

Level of evidence

Level III.

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

OBJECTIVES

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.

DESIGN

Prospective cohort.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

A new method for assessing landing kinematics in non-laboratory settings

OBJECTIVES

1) Determine the concurrent validity of using automated 2D video analysis relative to 3D motion capture for assessing frontal and sagittal-plane knee kinematics during landing, 2) compare the accuracy of visually estimating joint center locations (2D Manual) with computing joint center locations using anatomical markers (2D Automatic), and 3) compare landing kinematics between a controlled laboratory setting and a non-laboratory setting.

DESIGN

Validity/repeatability study.

SETTINGS

Biomechanics research laboratory and non-laboratory athletic facility.

PARTICIPANTS

Thirty uninjured recreational athletes.

MAIN OUTCOME MEASURES

Peak knee flexion, knee flexion range of motion, peak knee frontal plane projection angle, and knee frontal plane projection angle range of motion during bilateral and unilateral landing were measured simultaneously in 3D using motion capture and in 2D using two low-cost video cameras during the first study session (biomechanics research laboratory), and in 2D only during the second study session (non-laboratory athletic facility).

RESULTS

There was good to excellent agreement between 3D motion capture and both 2D Manual (ICC = 0.86-0.99) and 2D Automatic (ICC = 0.89-0.99) video analysis methods. There was good to excellent agreement between data collected in a laboratory and non-laboratory setting (ICC = 0.75-0.95).

CONCLUSION

The methods introduced in this study are inexpensive, reliable, and feasible for use in non-laboratory settings.

Reliability of 3D measurement of pelvic and lower limb kinematics during two single leg landing tasks

Study aim: Three-dimensional (3D) motion analysis is one of the available methods used to evaluate body kinematics. The aim of this study was to assess the intrarater reliability of measurement of pelvic and lower limb kinematics during two single leg landing tasks using 3D motion analysis.

Material and methods: 19 healthy volunteers (8 women, 11 men, age 23.1 ± 2.8 years, weight 70.7 ± 9.2 kg, height 174.8 ± 6.7 cm) performed five repeated single leg hurdle hops (SLHH) (30 cm height) and five single leg drop landings (SLDL) from a box (40 cm height) in one measurement session with a 15-minute break and after marker replacement with 3D assessment. The intraclass correlation coefficient (ICC), standard error of measurement (SEM), and the smallest detectable differences (SDD) were used to examine the reliability of kinematic parameters during the landing phase.

Results: The average intrarater ICC for SLHH was 0.92 (SEM = 1.69°, SDD 4.68°) and for SLDL was 0.96 (SEM = 0.81°, SDD = 2.26°). After marker replacement ICC decreased to an average value of 0.81 (SEM = 2.05°, SDD 5.68°) for SLHH and 0.82 (SEM = 2.36°, SDD 6.53°) for SLDL.

Conclusions: Using the 3D method to evaluate pelvis and lower limb kinematics during single leg landing in one measurement session is a high reliability method for most parameters. Marker replacement is one of the factors that reduce the reliability of measures. When applying the SEM and SDD values, which the present paper contains, it is worth mentioning that the obtained results are caused by measurement error or they are due to individual issues.

Timing is everything: Dance aesthetics depend on the complexity of movement kinematics

What constitutes a beautiful action? Research into dance aesthetics has largely focussed on subjective features like familiarity with the observed movement, but has rarely studied objective features like speed or acceleration. We manipulated the kinematic complexity of observed actions by creating dance sequences that varied in movement timing, but not in movement trajectory. Dance-naïve participants rated the dance videos on speed, effort, reproducibility, and enjoyment. Using linear mixed-effects modeling, we show that faster, more predictable movement sequences with varied velocity profiles are judged to be more effortful, less reproducible, and more aesthetically pleasing than slower sequences with more uniform velocity profiles. Accordingly, dance aesthetics depend not only on which movements are being performed but on how movements are executed and linked into sequences. The aesthetics of movement timing may apply across culturally-specific dance styles and predict both preference for and perceived difficulty of dance, consistent with information theory and effort heuristic accounts of aesthetic appreciation.

Comparison of Drop Jump and Tuck Jump Knee Joint Kinematics in Elite Male Youth Soccer Players: Implications for Injury Risk Screening

CONTEXT

Despite the popularity of jump-landing tasks being used to identify injury risk factors, minimal data currently exist examining differences in knee kinematics during commonly used bilateral jumping tasks. This is especially the case for rebounding-based protocols involving young athletes.

OBJECTIVE

To compare the frontal plane projection angles (FPPAs) during the drop vertical jump (DVJ) and tuck jump assessment (TJA) in a cohort of elite male youth soccer players of varying maturity status.

METHODS

A total of 57 male youth soccer players from an English championship soccer club participated in this study. Participants performed 3 trials of the DVJ and TJA, during which movement was recorded with 2-dimensional video cameras. FPPA for both right (FPPA-r) and left (FPPA-l) legs, with values <180° indicative of medial knee displacement.

RESULTS

On a whole-group level, FPPA-r (172.7° [7.4°] vs 177.2° [11.7°]; P < .05; effect size [ES] = 0.46) and FPPA-l (173.4° [7.3°] vs 179.2° [11.0°]; P < .05; ES = 0.62) were significantly greater for both limbs in the TJA compared with the DVJ; however, these differences were less consistent when grouped by maturity status. FPPA-r during the TJA was significantly and moderately greater in the circa-peak height velocity (PHV) group compared with the post-PHV cohorts (169.4° [6.4°] vs 175.3° [7.8°]; P < .05; ES = 0.49). Whole-group data showed moderate relationships for FPPA-r and FPPA-l between the TJA and DVJ; however, stronger relationships were shown in circa- and post-PHV players compared with the pre-PHV cohort.

CONCLUSIONS

Considering that the TJA exposed players to a larger FPPA and was sensitive to between-group differences in FPPA-r, the TJA could be viewed as a more suitable screen for identifying FPPA in young male soccer players.

Performance in dynamic movement tasks and occurrence of low back pain in youth floorball and basketball players

BACKGROUND

Prospective studies investigating risk factors for low back pain (LBP) in youth athletes are limited. The aim of this prospective study was to investigate the association between hip-pelvic kinematics and vertical ground reaction force (vGRF) during landing tasks and LBP in youth floorball and basketball players.

METHODS

Three-hundred-and-eighty-three Finnish youth female and male floorball and basketball players (mean age 15.7 ± 1.8) participated and were followed up on for 3 years. At the beginning of every study year the players were tested with a single-leg vertical drop jump (SLVDJ) and a vertical drop jump (VDJ). Hip-pelvic kinematics, measured as femur-pelvic angle (FPA) during SLVDJ landing, and peak vGRF and side-to-side asymmetry of vGRF during VDJ landing were the investigated risk factors. Individual exposure time and LBP resulting in time-loss were recorded during the follow-up. Cox's proportional hazard models with mixed effects and time-varying risk factors were used for analysis.

RESULTS

We found an increase in the risk for LBP in players with decreased FPA during SLVDJ landing. There was a small increase in risk for LBP with a one-degree decrease in right leg FPA during SLVDJ landing (HR 1.09, 95% CI 1.02 to 1.17, per one-degree decrease of FPA). Our results showed no significant relationship between risk for LBP and left leg FPA (HR 1.04, 95% CI 0.97 to 1.11, per one-degree decrease of FPA), vGRF (HR 1.83, 95% CI 0.95 to 3.51) or vGRF side-to-side difference (HR 1.22, 95% CI 0.65 to 2.27) during landing tasks.

CONCLUSIONS

Our results suggest that there is an association between hip-pelvic kinematics and future LBP. However, we did not find an association between LBP and vGRF. In the future, the association between hip-pelvic kinematics and LBP occurrence should be investigated further with cohort and intervention studies to verify the results from this investigation.

LEVEL OF EVIDENCE

Prognosis, level 1b.

Effect of Sand on Landing Knee Valgus During Single-Leg Land and Drop Jump Tasks: Possible Implications for ACL Injury Prevention and Rehabilitation

CONTEXT

Despite significant emphasis on anterior cruciate ligament injury prevention, injury rates continue to rise and reinjury is common. Interventions to reduce injury have included resistance, balance, and jump training elements. The use of sand-based jump training has been postulated as an effective treatment. However, evidence on landing mechanics is limited.

OBJECTIVE

To determine potential differences in landing strategies and subsequent landing knee valgus when performing single-leg landing (SLL) and drop jump (DJ) tasks onto sand and land, and to compare between both male and female populations.

DESIGN

A randomized repeated-measures crossover design.

SETTING

University laboratory.

PARTICIPANTS

Thirty-one participants (20 males and 11 females) from a university population.

INTERVENTIONS

All participants completed DJ and SLL tasks on both sand and land surfaces.

MAIN OUTCOME MEASURES

Two-dimensional frontal plane projection angle (FPPA) of knee valgus was measured in both the DJ and SLL tasks (right and left) for both sand and land conditions.

RESULTS

FPPA was lower (moderate to large effect) for SLL in sand compared with land in both legs (left: 4.3° [2.8°]; right: 4.1° [3.8°]) for females. However, effects were unclear (left: -0.7° [2.2°]) and trivial for males (right: -1.1° [1.9°]). FPPA differences for males and females performing DJ were unclear; thus, more data is required. Differences in FPPA (land vs sand) with respect to grouping (sex) for both SLL left (4.9° [3.0°]) and right (5.1° [4.0°]) were very likely higher (small)/possibly moderate for females compared with males.

CONCLUSIONS

The effects of sand on FPPA during DJ tasks in males and females are unclear, and further data is required. However, the moderate to large reductions in FPPA in females during SLL tasks suggest that sand may provide a safer alternative to firm ground for female athletes in anterior cruciate ligament injury prevention and rehabilitation programs, which involve a SLL component.

A descriptive report of the variability in 3D hip and knee kinematics during a single limb squat in women who have patellofemoral pain and visually classified dynamic knee valgus

Objective: To describe the variability in: (1) the contributions of 3D hip and knee kinematics to the dynamic knee valgus (DKV) movement pattern during a single limb squat in women with patellofemoral pain; and (2) the 3D strategies used to reduce DKV following an intervention.Methods: Secondary analysis of a feasibility study investigating a movement training intervention. In 23 participants, 2D knee frontal plane projection angles (FPPA) and 3D hip and knee frontal and transverse plane angles at peak knee flexion were calculated during a single limb squat at pre- and post-intervention, and the change in 2D and 3D angles computed. 3D angles at pre-intervention were summed for each participant to create cumulative bar graphs. Similar graphs were created for change in 3D angles. For visual comparison, graphs were ordered by increasing knee FPPA or change in knee FPPA.Results: The knee FPPA decreased from a mean of 7.2 degrees (SD: 7.1) to a mean of -8.9 degrees (SD: 8.9) following the intervention. A large portion of DKV, and change in DKV, was due to hip adduction and knee lateral rotation, yet participants with similar knee FPPA and change in knee FPPA displayed variation in all 3D components and change in 3D components.Conclusion: People who demonstrate similar observed movement patterns during a weight-bearing task may use different 3D strategies for execution.

Test-retest reliability and minimum detectable change for various frontal plane projection angles during dynamic tasks

OBJECTIVE

Establish between-day test-retest reliability metrics for 2-dimensional frontal plane projection angles (FPPAs) during the lateral step-down (LSD), single-limb squat (SLS), single-limb landing (SLL), and drop vertical jump (DVJ).

DESIGN

Test-retest reliability study.

SETTING

University laboratory.

PARTICIPANTS

20 healthy adults (12 female, age = 23.60 ± 1.93 years old, body mass index = 24.26 ± 2.54 kg/m²) were tested on 2 separate occasions 7-14 days apart.

MAIN OUTCOME MEASURES

Intraclass correlation coefficients (ICC), standard errors of the measurement (SEM), and minimal detectable change (MDC) values across the LSD, SLS, SLL, and DVJ for the following body region variables: trunk, trunk on pelvis, pelvis, hip, thigh to vertical, knee, and shank to vertical.

RESULTS

There was moderate-to-substantial between-day test-retest reliability for nearly all body regions across all tasks (ICC = 0.65-0.96). SEM values varied across body regions and tasks (0.9-3.5°). MDCs were variable (2.3-9.8°). Of the body regions, MDCs were largest for the knee and hip. By task, MDCs were lowest for the LSD.

CONCLUSIONS

This study identified between-day test-retest reliability metrics for 2-dimensional FPPAs across a variety of body regions during commonly assessed clinical tasks. These data allow clinicians and researchers to more confidently assess true change between assessments or over time.

Are tibial angles measured with inertial sensors useful surrogates for frontal plane projection angles measured using 2-dimensional video analysis during single leg squat tasks? A reliability and agreement study in elite football (soccer) players

During single leg squats (SLS), tibial angle (TA) quantification using inertial measurement units (IMU) may offer a practical alternative to frontal plane projection angle (FPPA) measurement using 2-dimensional (2D) video analysis. This study determined: (i) the reliability of IMUs and 2D video analysis for TA measurement, and 2D video analysis for FPPA measurement; (ii) the agreement between IMU TA and both 2D video TA and FPPA measurements during single leg squats in elite footballers. 18 players were tested on consecutive days. Absolute TA (ATA) and relative TA (RTA) were measured with IMUs. ATA and FPPA were measured concurrently using 2D video analysis. Within-session reliability for all measurements varied across days (intraclass correlation coefficient (ICC) range = 0.27-0.83, standard error of measurement (SEM) range = 2.12-6.23°, minimal detectable change (MDC) range = 5.87-17.26°). Between-sessions, ATA reliability was good for both systems (ICCs = 0.70-0.74, SEMs = 1.64-7.53°, MDCs = 4.55-7.01°), while IMU RTA and 2D FPPA reliability ranged from poor to good (ICCs = 0.39-0.72, SEMs = 2.60-5.99°, MDCs = 7.20-16.61°). All limits of agreement exceeded a 5° acceptability threshold. Both systems were reliable for between-session ATA, although agreement was poor. IMU RTA and 2D video FPPA reliability was variable. For SLS assessment, IMU derived TAs are not useful surrogates for 2D video FPPA measures in this population.

Single leg squat ratings by clinicians are reliable and predict excessive hip internal rotation moment

BACKGROUND

Single leg squats are commonly used subjective assessments of general biomechanical function, injury risk, as a predictor for recovery and as an outcome measure of rehabilitation. While 3D motion capture is a useful tool for elite sports performance and research it is impractical for routine clinical use.

RESEARCH QUESTION

This cross-sectional study aims to: assess reliability and validity of clinicians' subjective ratings of single leg squats compared to 3D motion capture, and to identify whether performance predicts joint moments.

METHODS

22 healthy military volunteers were simultaneously recorded on video and 3D motion capture performing single leg squats. Videos were reviewed twice by 5 physiotherapists rating performance on a 0-5 scale assessing squat depth, hip adduction, pelvic obliquity, pelvic tilt and trunk flexion summated into a composite score.

RESULTS

Hip adduction and trunk flexion exhibited moderate to substantial inter- and intra-rater reliability (range κ = 0.408-0.699) other individual criteria were mostly fair (κ ≤ 0.4). Composite scores for inter-rater reliability were ICC_(1,1) = 0.419 and ICC_(1,κ) = 0.783 and intra-rater reliability were ICC_(1,1) = 0.672 and κ(w) = 0.526. Validity against 3D kinematics was poor with only 6/75 individually rated criteria reaching κ > 0.40. Correlation was found between composite scores and hip internal rotation moment (r_s = 0.571, p = 0.009).

SIGNIFICANCE

Repeated use of single leg squats by a single practitioner is supported. Comparisons between clinicians are unreliable but improved by average measures from multiple raters. Heterogeneous reliability across scoring components suggests a qualitative description of the criteria scored is less ambiguous than using composite scores in a clinical setting. Composite scores may be more useful for analysis at a population level. Poor validity against kinematic data suggests clinicians use additional information upon which they find agreement such as estimating kinetics. Correlation between hip internal rotation moment and subjective ratings may be such an example of clinicians trying to identify excessive abnormal loading.