Lower extremity energy absorption and biomechanics during landing, part II: frontal-plane energy analyses and interplanar relationships

The influence of soccer-specific exercise on isokinetic angle-specific thigh musculature strength in female soccer players

This study assessed the influence of soccer-specific exercise on thigh musculature strength in female soccer players. Eight amateur female soccer players (age 24 ± 6 years; height 163 ± 8 cm; mass 68 ± 11 kg) participated in the study. Participants completed the female match simulation-90 (FEMS-90), replicating a 90-minute match. Isokinetic strength assessments of the concentric knee extensors (conKE), concentric knee flexors (conKF), eccentric knee extensors (eccKE) and eccentric knee flexors (eccKF) for the dominant lower limb were conducted at 60°∙s-1 where conventional ratios (CR) and dynamic control ratios (DCR) were determined. All strength data were expressed as angle-specific torque (AST). A Bayesian approach identified a 66-78% probability that AST of all muscle actions were lower post SSEP, and a 57-66% probability of a difference that CRAST and DCRAST were lower post SSEP across all angles. The results of this study provides unique insight into how female soccer players respond to soccer match-play, and may have implications for potential injury risk, exercise prescription and recovery. Moreover, given the prevalence and burden of knee ligament injuries in female soccer players, this study provides insight into thigh musculature strength acutely responds following simulated match-play.

Lower extremity energy absorption in individuals with lower extremity musculoskeletal injury history during functional tasks: A scoping review

BACKGROUND

Recent evidence has utilized energetic absorption as an alternative method to evaluate biomechanical profiles associated with lower extremity injury risk. The aim of scoping review is to summarize the literatures that utilized energetic analysis in individuals with lower extremity injury history during functional tasks.

METHODS

A literature search, conducted in August 2023, involved four databases-PubMed, SPORTDiscus, Scopus, and Web of Science. A manual search was performed to identify additional articles.

FINDINGS

Among the 17 included studies, we identified 11 and 6 articles investigated lower extremity energetic absorption in individuals with anterior cruciate ligament reconstruction and chronic ankle instability history during jump-related tasks, receptively. Individuals with anterior cruciate ligament reconstruction displayed a reduction of energetic absorption in the involved knee, coupled with increased energetic absorption in the involved hip, as compared to the uninvolved limb or the reference group. The findings in those with chronic ankle instability were varied. Most studies suggested that individuals with chronic ankle instability displayed a compensatory movement pattern to off-load their ankle joint, while concurrently increasing energy absorbed at the knee joint compared to the reference group. Conversely, one study suggested that individuals with chronic ankle instability might rely more on their ankle joint for energy absorption.

INTERPRETATION

Our findings indicated that both individuals with anterior cruciate ligament reconstruction and chronic ankle instability displayed a distinctive compensatory strategy during landing. This strategy is characterized by increasing energy dissipation on the proximal joints, compensating for a reduction on the distal joint to dissipate less energy.

Development of a Real-Time Single-Leg Hop Movement Quality Assessment to Identify Lower-Extremity Biomechanical Risk Factors

CONTEXT

The single-leg hop is based solely on performance with no measure of movement quality. The purpose of this study was to (1) develop a real-time screening tool to capture single-leg functional performance and movement quality and (2) to provide preliminary validation (criterion validity) of a trained clinician's real-time movement quality assessment with 3D kinematics.

STUDY DESIGN

Cross-sectional.

METHODS

Fifty-nine adolescent athletes volunteered (15.2 [1.1] y, 165.8 [9.2] cm, and 61.5 [13.9] kg, 51 females and 8 males). Each participant performed 3 trials of the single-leg hop on their dominant leg. A 3-dimensional inertial measurement system was used to capture knee joint kinematics. A movement quality checklist for use during a single-leg hop (movement quality single-leg hop) was developed to score biomechanical errors based on lower-extremity injury risk factors. Four criteria were developed for the checklist: (1) knee valgus, (2) foot rotation, (3) lateral trunk flexion, and (4) erect posture. An independent t test was conducted for each dependent variable (knee flexion displacement and knee abduction displacement) by each independent variable (movement category presence of (1) lateral trunk flexion, (2) knee valgus, (3) foot rotation, and (4) erect posture/sound during landing [yes or no]). The alpha level was set at α < .05 for all analyses.

RESULTS

Knee flexion displacement was significantly decreased (P < .001, mean difference 9.40 [1.88]) and knee abduction displacement was significantly increased (P < .001, mean difference 9.41 [0.47]) for those who had knee valgus documented by the clinician. In additional, for those with visually documented erect posture/sound of landing, there was a significant decrease in knee flexion displacement (P < .001, mean difference 10.13 [2.34]).

CONCLUSION

The movement quality single-leg hop checklist has shown promising preliminary validation (criterion validity) for clinicians to assess movement quality. Increased knee abduction and decreased knee flexion are common risk factors associated with knee injuries and this clinician friendly real-time checklist may highlight individuals who are at risk of sustaining a knee injury.

Strength and clinical test combinations enhance predictions of sagittal and frontal plane biomechanics in single-leg landing

OBJECTIVES

To determine whether clinical screening tests can predict lower limb joint kinematics and kinetics outcomes eliciting anterior cruciate ligament (ACL) injury risk in single-leg landings.

DESIGN

Cross-sectional study.

SETTING

Laboratory research.

PARTICIPANTS

Twenty-six professional male futsal athletes.

MAIN OUTCOME MEASURES

Participants completed the Modified Star Excursion Balance Test (mSEBT), Lateral Step Down (LSD), Lunge, Hop tests, and isometric strength tests for clinical screening of lower extremity injury risk and performed single-leg landings to assess lower extremity 3D kinematics and kinetics outcomes.

RESULTS

mSEBT, LSD, and isometric strength were the more important tests when constructing the prediction models. The predictive power of clinical tests for screening injury risk significantly increases when combined with strength measurements (p = 0.005, f2 = 0.595). We discerned 11 biomechanical predictions, six explicitly related to the sagittal plane's biomechanics. Some predictions were leg-dependent, with muscle strength tests predominantly predicting biomechanical outcomes of the preferred leg.

CONCLUSION

Combining clinical screening tests with strength measures enhances ACL injury risk factors prediction during single-leg landings. Clustering at least two tests improves prediction accuracy, aiding injury prevention planning and decision-making.

Establishing Phase Definitions for Jump and Drop Landings and an Exploratory Assessment of Performance-Related Metrics to Monitor During Testing

ABSTRACT

Harry, JR, Simms, A, and Hite, M. Establishing phase definitions for jump and drop landings and an exploratory assessment of performance-related metrics to monitor during testing. J Strength Cond Res 38(2): e62-e71, 2024-Landing is a common task performed in research, physical training, and competitive sporting scenarios. However, few have attempted to explore landing mechanics beyond its hypothesized link to injury potential, which ignores the key performance qualities that contribute to performance, or how quickly a landing can be completed. This is because a lack of (a) established landing phases from which important performance and injury risk metrics can be extracted and (b) metrics known to have a correlation with performance. As such, this article had 2 purposes. The first purpose was to use force platform data to identify easily extractable and understandable landing phases that contain metrics linked to both task performance and overuse injury potential. The second purpose was to explore performance-related metrics to monitor during testing. Both purposes were pursued using force platform data for the landing portion of 270 jump-landing trials performed by a sample of 14 NCAA Division 1 men's basketball players (1.98 ± 0.07 m; 94.73 ± 8.01 kg). The proposed phases can separate both jump-landing and drop-landing tasks into loading, attenuation, and control phases that consider the way vertical ground reaction force (GRF) is purposefully manipulated by the athlete, which current phase definitions fail to consider. For the second purpose, Pearson's correlation coefficients, the corresponding statistical probabilities ( α = 0.05), and a standardized strength interpretation scale for correlation coefficients (0 < trivial ≤ 0.1 < small ≤ 0.3 < moderate ≤ 0.5 < large ≤ 0.7 < very large) were used for both the group average (i.e., all individual averages pooled together) and individual data (i.e., each individual's trials pooled together). Results revealed that landing time, attenuation phase time, average vertical GRF during landing, average vertical GRF during the attenuation phase, average vertical GRF during the control phase, vertical GRF attenuation rate, and the amortization GRF (i.e., GRF at zero velocity) significantly correlated with landing performance, defined as the ratio of landing height and landing time ( R ≥ ± 0.58; p < 0.05), such that favorable changes in those metrics were associated with better performance. This work provides practitioners with 2 abilities. First, practitioners currently assess jump capacity using jump-landing tests (e.g., countermovement jump) with an analysis strategy that makes use of landing data. Second, this work provides preliminary data to guide others when initially exploring landing test results before identifying metrics chosen for their own analysis.

Role of ankle dorsiflexion in sports performance and injury risk: A narrative review

The objective of this literature review is to understand the role of ankle dorsiflexion range of motion in sports performance and the risk of injuries. The ankle harmonizes the interaction between the body and the supporting surface through adjusting to the supporting surface and handling forces to contribute effectually to different functional activities. Ankle dorsiflexion is an essential construct in many sport-specific skills. Ankle dorsiflexion is associated with activation of brain areas involved in movement preparation, sensory integration, motor planning/execution, balance, and visuomotor coordination. Ankle dorsiflexion was associated with enhanced activation of deep core and quadriceps muscles. Decreased ankle dorsiflexion is linked to compensations and altered kinetics and kinematics that can potentially affect sports performance and increase the chances of sustaining injuries. It is vindicated to consider more focus on ankle dorsiflexion range of motion in research studies, sports-related pre-season screening, clinical examination, injury rehabilitation, and return-to-sports judgment.

Chronic ankle instability modifies proximal lower extremity biomechanics during sports maneuvers that may increase the risk of ACL injury: A systematic review

The biomechanical changes in the lower extremity caused by chronic ankle instability (CAI) are not restricted to the ankle joint, but also affect the proximal joints, increasing the risk of joint injury. This study aimed to systematically review the research on CAI and lower extremity angle and movements during side-cutting, stop jumping, and landing tasks, to provide a systematic and basic theoretical basis for preventing lower extremity injury. Literature published from exception to April 2022 were searched in the PubMed, Web of Science, and SPORTDiscus databases using the keywords of "chronic ankle instability," "side-cut," "stop jump," and "landing." Only studies that compared participants with chronic ankle instability with healthy participants and assessed lower extremity kinetics or kinematics during side-cutting, stop jumping, or landing were included. The risk of bias assessment was conducted using a modified version of the Newcastle-Ottawa checklist. After title, abstract, and full text screening, 32 studies were included and the average score of the quality evaluation was 7 points (range 6-8). Among them five studies were related to the side-cut task, three studies were the stop-jump task, and twenty-four studies were related to landing. Although the results of many studies are inconsistent, participants with CAI exhibit altered lower extremity proximal joint movement strategies during side cut, stop jump, and landings, however, such alterations may increase the risk of anterior cruciate ligament injury.

The influence of angle-specific torque of the knee flexors and extensors on the angle-specific dynamic control ratio in professional female soccer players

The purpose of this study was to assess whether dynamic torque ratios (DCR) from isokinetic strength assessments of eccentric knee flexors (eccKF) and concentric knee extensors (conKE) display differences when stratified into specific angle-specific DCR (DCR_AST) groups. Fifty-two professional female soccer players (age 21.30 ± 4.44 years; height 166.56 ± 5.17 cm; mass 61.55 ± 5.73 kg) from the English Women's Super League completed strength assessments of both lower limbs on an isokinetic dynamometer at 60°∙s^-1. Angle-specific torque (AST) were used to calculate DCR_AST to create sub-groups using clustering algorithms. The results identified for the dominant side that the Medium DCR_AST group elicited significantly higher conKE AST when compared to Low and High DCR_AST groups at increased knee extension (P ≤ 0.05). For the non-dominant side, the High DCR_AST group had significantly higher and lower eccKF and conKE AST compared to the Low DCR_AST group at increased knee extension (P ≤ 0.05). This study highlights that the inclusion of AST data may subsequently help practitioners to prescribe exercise that promotes strength increases at targeted joint angles. In turn, these approaches can be used to help reduce injury risk, identify rehabilitation responses and help inform return to play.

Adolescent Athletes Demonstrate Inferior Objective Profiles at the Time of Return to Sport After ACLR Compared With Healthy Controls

Background:

Athletes display persistent muscle deficits and altered limb-loading mechanics at the time of return to sport (RTS) after anterior cruciate ligament reconstruction (ACLR).

Purpose:

To compare an objective profile of adolescent athletes at RTS after ACLR to matched healthy controls.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Included were 124 participants; 62 patients who underwent ACLR (15.4 ± 1.7 years) and 62 healthy controls (15.3 ± 1.7 years). Motion capture and force plates were used to capture joint motions during jump landing (JL) and single-limb squat (SLS) tasks. Energy absorption contribution (EAC) was calculated, and repeated-measures analysis of variance was used to assess for EAC differences between groups. Participants completed an International Knee Documentation Committee (IKDC) Subjective Knee Form, and isokinetic quadriceps and hamstring strength testing was performed on each limb. Independent t tests were run to examine age, height, weight, and IKDC scores as well as compare differences between groups for quadriceps and hamstring strength.

Results:

A significant group × joint interaction was found for JL (P < .001) and SLS (P < .001). For JL, patients who underwent ACLR utilized significantly greater hip (P < .001) and significantly less knee (P < .001) EAC on the surgical limb compared with controls. During SLS, patients who underwent ACLR utilized significantly greater hip (P < .001) and significantly less knee (P < .001) EAC on the surgical limb compared with controls. The ACLR cohort demonstrated lower IKDC scores (P < .001) and significantly lower quadriceps strength on the surgical limb (P < .001) than controls. There were no differences in surgical limb hamstring strength between the ACLR cohort and healthy controls (P = .701).

Conclusion:

Compared with matched healthy controls, the participants who underwent ACLR in this study demonstrated an inferior objective profile at RTS, consisting of deficits in surgical limb loading, self-reported outcomes, and strength.

Energy Absorption Contribution Deficits in Participants Following Anterior Cruciate Ligament Reconstruction: Implications for Second Anterior Cruciate Ligament Injury

Context: Lower-extremity loading patterns change after anterior cruciate ligament reconstruction (ACLR). However, there is limited research regarding energy absorption contribution (EAC) of athletes following ACLR who reinjure their ACL and those who do not. EAC can be utilized as a measure of joint loading during tasks. Design: Cross-sectional study. Methods: Three groups of individuals (13 in each group) with matched age, sex, height, weight, and sports were enrolled. Data were collected at time of return-to-sport testing for the 2 ACLR groups. An 8-camera 3D motion capture system with a sampling rate of 120 Hz and 2 force plates capturing at 1200 Hz were used to capture joint motions in all 3 planes during a double-limb jump landing. Results: Participants in the ACLR no reinjury and ACLR reinjury groups had significantly greater hip EAC (55.8 [21.5] and 56.7 [21.2]) compared with healthy controls (19.5 [11.1]), P < .001 and P < .001, respectively. The ACLR no reinjury and ACLR reinjury groups had significantly lower knee EAC (24.6 [22.7] and 27.4 [20.8]) compared with healthy controls (57.0 [12.2]), P < .001 and P < .001, respectively. However, the ACLR reinjury group had significantly lower ankle EAC (15.9 [4.6]) than healthy controls (23.5 [6.6]), whereas there was no statistical difference between the ACLR no reinjury group (19.7 [7.8]) and healthy controls. Conclusions: Athletes who had a second ACL injury after ACLR, and those without second ACL injury, appear to have similar hip, knee, and ankle joint loading of the surgical limb at return-to-sport testing. Nevertheless, joint loading patterns were significantly different from healthy controls. The study suggests that EAC as a measure of joint loading during a double-limb jump landing at time of return to sport may not be a strong predictor for second injury following ACLR.

Lower extremity energy absorption strategies at different phases during single and double-leg landings with knee valgus in pubertal female athletes

Dynamic knee valgus (DKV) malalignment affects the biomechanical characteristic during sports activities. This cross-sectional study was conducted to evaluate mechanical energy absorption (MEA) strategies at initial contact (IC) and total landing (TL) phases during single-leg landing (SLL), and double-leg landing (DLL). Twenty-eight female athletes with DKV (age 10-14) were invited. MEA analysis of lower extremity joints was done in sagittal and frontal motion planes employing 8 Vicon motion capture cameras and 2 Kistler force plates. Statistical analysis was done using IBM Statistics (version24) by Bivariate Pearson Correlation Coefficient test. Knee extensors MEA during SLL (IC: P = 0.008, R = 0.522/TL: P < 0.001, R = 0.642) and DLL (IC: P < 0.001, R = 0.611/TL: P = 0.011, R = 0.525), and knee abductors during SLL (IC: P = 0.021, R = 0.474) were positively correlated with increased DKV angle. Ankle plantar flexors during SLL (TL: P = 0.017, R = - 0.477) and DLL (TL: P = 0.028, R = - 0.404), and hip extensors during SLL (TL: P = 0.006, R = - 0.5120) were negatively correlated with increased DKV angle. Compensated MEA in knee extensors was correlated with less ankle plantar flexion MEA during SLL (IC: P = 0.027, R = - 0.514/TL: P = 0.007, R = - 0.637) and DLL (IC: P = 0.033, R = - 00.412/TL: P = 0.025, R = - 0.485). These outcomes indicated a knee-reliant MEA strategy in female athletes with DKV during puberty, putting them at higher risks of ACL injuries during landing.

Limb dominance influences energy absorption contribution (EAC) during landing after anterior cruciate ligament reconstruction

OBJECTIVE

To determine the role of limb dominance on energy absorption contribution (EAC) during a jump landing (JL) task at return to sport (RTS) after ACL-R.

DESIGN

Cross-sectional study.

SETTING

Clinical Research Laboratory.

PARTICIPANTS

One hundred eight participants (age = 16.19 ± 1.74, Height = 172.25 ± 9.96 cm, Weight = 72.61 ± 15.48 kg).

MAIN OUTCOME MEASURES

Participants were grouped into two groups: those who injured their dominant limb ACL (D-ACL) and those who injured their non-dominant limb ACL (ND-ACL). A multiple analysis of variance (MANOVA) was used to assess for between group differences in EAC across the three joints.

RESULTS

In the surgical limb, D-ACL demonstrated smaller hip (D-ACL = 32.23 ± 10.44%, ND-ACL = 69.68 ± 8.51%, p < 0.008) and greater knee (D-ACL = 45.86 ± 10.36%, ND-ACL = 9.41 ± 5.68%, p < 0.008) EAC than ND-ACL. In the non-surgical limb, D-ACL demonstrated greater hip (D-ACL = 62.59 ± 9.03%, ND-ACL = 25.95 ± 7.15%, p < 0.008), and smaller knee (D-ACL = 13.79 ± 5.57%, ND-ACL = 58.01 ± 7.86%, p < 0.008), EAC than ND-ACL.

CONCLUSION

After ACL-R, eccentric loading strategies during a JL task at RTS are different depending upon limb dominance. D-ACL demonstrated a greater knee loading strategy on the surgical side compared to ND-ACL.

Knee Kinematics During Landing: Is It Really a Predictor of Acute Noncontact Knee Injuries in Athletes? A Systematic Review and Meta-analysis

BACKGROUND

Although knee kinematics during landing tasks has traditionally been considered to predict noncontact knee injuries, the predictive association between noncontact knee injuries and kinematic and kinetic variables remains unclear.

PURPOSE

To systematically review the association between kinematic and kinetic variables from biomechanical evaluation during landing tasks and subsequent acute noncontact knee injuries in athletes.

STUDY DESIGN

Systematic review; Level of evidence, 2.

METHODS

Databases used for searches were MEDLINE, LILACS, IBECS, CINAHL, SPORTDiscus, SCIELO, IME, ScienceDirect, and Cochrane from database inception to May 2020. Manual reference checks, articles published online ahead of print, and citation tracking were also considered. Eligibility criteria included prospective studies evaluating frontal and sagittal plane kinematics and kinetics of landing tasks and their association with subsequent acute noncontact knee injuries in athletes.

RESULTS

A total of 13 studies met the eligibility criteria, capturing 333 acute noncontact knee injuries in 8689 participants. A meta-analysis revealed no significant effects for any kinematic and kinetic variable with regard to subsequent noncontact knee injuries.

CONCLUSION

No kinetic or kinematic variables from landing tasks had a significant association with acute noncontact knee injuries. Therefore, the role and application of the landing assessment for predicting acute noncontact knee injuries are limited and unclear, particularly given the heterogeneity and risk of bias of studies to date.

Can kinematic and kinetic differences between planned and unplanned volleyball block jump-landings be associated with injury risk factors?

INTRODUCTION

Injury prevention programs for athletes are still limited by a lack of understanding of specific risk factors that can influence injuries within different sports. The majority of studies on volleyball have not considered the movement patterns when moving in different directions or in planned and unplanned block jump-landings.

METHODS

This study investigated all planes mechanics between the lead and trail limb when moving in dominant and non-dominant directions, for both planned and unplanned jump-landings in thirteen semi-professional female volleyball players. Ankle, knee and hip joint kinematics, kinetics and joint stiffness were recorded.

RESULTS

Our results showed statistically significant differences between the lead limb and the trail limb in the hip flexion angles, moments and velocity; in the knee flexion angles, moments, stiffness, power and energy absorption and in the ankle dorsiflexion, power and energy absorption, showing a tendency where the lead limb has a higher injury risk than the trail limb. When considering planned versus unplanned situations, there were statistically significant differences in knee flexion angles, moments, power and energy absorption; and hip contact angle, flexion angular velocity and energy absorption, with musculoskeletal adaptations in the planned situations.

DISCUSSION

It appears that the role of the limb, either lead or trail, is more important than the limb dominance when performing directional jump-landings, with the lead limb having a higher implication on possible overuse injuries than the trail limb. Furthermore, planned movements showed a difference in strategy indicating greater implications to possible overuse injuries than in the unplanned situations which may be associated with more conscious thought about the movements.

CONCLUSION

Coaches should consider unilateral coordination training in both landing directions for the lead and trail limb, and should adapt training to replicate the competition environment, using unplanned situations to minimize asymmetries to might reduce injury risks.

Knee Forces During Landing in Men and Women

Sex differences in biomechanics may provide one explanation for the greater incidence of knee injuries in women, but few studies have compared internal forces. In this study, a musculoskeletal model was used to compare male and female, bilateral and unilateral landings based on motion capture and force plate data. Participants were classified as landing medially or laterally loaded based upon the mediolateral load share at the knee (bilateral: p < 0.001, η²=0.452; unilateral: p < 0.001, η² = 0.444). Knee kinematics and ground reaction forces were not different between the two groups (p > 0.05, η² = 0.001 - 0.059), but there were differences in muscular recruitment. Landing strategy did not appear to be dependent on sex. However, for both medially and laterally loaded bilateral landings men had greater gluteal (p = 0.017, η² = 0.085) and hamstrings forces (p < 0.001, η² = 0.183), whereas women had greater quadriceps forces (p = 0.004, η² = 0.116). This study demonstrates an association between muscular recruitment and medially loaded landings. Landing strategy seems to be a function of skill not sex; however, within a particular landing strategy there may be sex differences in muscular activation that contribute to the difference in injury rates.

Participants at three months post-operative anterior cruciate ligament reconstruction (ACL-R) demonstrate differences in lower extremity energy absorption contribution and quadriceps strength compared to healthy controls

BACKGROUND

The purpose of this study was to compare hip and knee energy absorption contribution (EAC) during a double limb squat (DLS) and quadriceps strength in patients three months post-operative ACL-R versus matched healthy controls.

METHODS

Twenty-four ACL-R participants (Age = 15.5 ± 1.3 yrs; Ht = 1.66 ± .07 m; Mass = 66.3 ± 15.5 kg) were compared to 24 age, sex, limb, and activity-matched healthy controls (Age = 15.5 ± 1.2 yrs; Ht = 1.65 ± .08 m; Mass = 59.0 ± 9.8 kg). Lower extremity biomechanical data was collected at three months post-operative ACL-R during five consecutive DLS. EAC was calculated during DLS descent. Isokinetic quadriceps strength was collected at 60°/s. Normalized quadriceps peak torque (QUADS) was averaged across five trials. Independent t-tests examined differences in group hip and knee EAC during each task. Separate Pearson product-moment correlations examined the relationship between QUADS and hip and knee EAC during the DLS.

RESULTS

ACL-R demonstrated greater injured limb hip EAC (46.4 ± 16.0) than Healthy (31.7 ± 11.0) during a DLS (p = 0.001). ACL-R demonstrated less injured limb knee EAC (42.7 ± 14.6) than Healthy (60.6 ± 8.9) during DLS (p < 0.001). No differences were seen between uninjured limb hip (ACL-R = 0.0 ± 14.2; Healthy = 33.4 ± 9.1, p = 0.629) or knee (ACL-R = 56.9 ± 15.6; Healthy = 59.1 ± 9.8, p = 0.561) EAC and matched limbs. ACL-R injured limb QUADS was decreased compared to Healthy (ACL-R = 1.1 ± 0.5; Healthy = 2.0 ± 0.5, p < 0.001). No differences were seen in QUADS on the uninjured and matched limbs (ACL-R = 2.0 ± 0.6; Healthy = 1.9 ± 0.5, p = 0.894). There was a weak, negative correlation between injured limb QUADS and hip EAC (r = -0.471, p = 0.001) and moderate, positive correlation between injured limb QUADS and knee EAC (r = 0.615, p < 0.001).

CONCLUSIONS

ACL-R participants demonstrate different eccentric loading strategies during a DLS at three months postoperative compared to matched healthy controls.

Energy Absorption Contribution and Strength in Female Athletes at Return to Sport After Anterior Cruciate Ligament Reconstruction: Comparison With Healthy Controls

Background:

Female patients are more likely to suffer a second anterior cruciate ligament (ACL) injury after ACL reconstruction (ACLR) and return to sport (RTS) compared with healthy female controls. Few studies have examined the energy absorption contribution (EAC) that could lead to this subsequent injury.

Hypothesis:

The ACLR group would demonstrate an altered EAC between joints (hip, knee, and ankle) but no difference in quadriceps, hip abduction, or hip external rotation (ER) strength at the time of RTS.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

A total of 34 female participants (ACLR: n = 17; control: n = 17) were enrolled in the study and matched for age and activity level. Jump landing performance for the initial 50 milliseconds of landing of a lateral-vertical jump was assessed using a 10-camera 3-dimensional motion capture system and 2 force plates. Isokinetic quadriceps strength was measured using a Biodex machine, and hip abduction and ER isometric strength were measured using a handheld dynamometer. All values were normalized to the participant’s height and weight. A 1-way multivariate analysis of variance was used to assess between-group differences in the EAC at the hip, knee, and ankle. Two 1-way analyses of variance were used to independently examine quadriceps, hip abduction, and hip ER strength between the groups.

Results:

Significant differences in the EAC were found between the groups for the involved hip (P = .002), uninvolved hip (P = .005), and involved ankle (P = .023). There were no between-group differences in the EAC for the involved or uninvolved knee or the uninvolved ankle. Patients who underwent ACLR demonstrated significantly decreased quadriceps strength on the involved limb (P = .02) and decreased hip ER strength on both the involved (P = .005) and uninvolved limbs (P = .002). No significant strength differences were found between the groups for the uninvolved quadriceps or for involved or uninvolved hip abduction.

Conclusion:

At RTS, patients who underwent ACLR utilized a greater hip EAC bilaterally and a decreased involved ankle EAC during a lateral-vertical jump. Furthermore, quadriceps strength on the involved limb and hip ER strength of bilateral lower extremities remained decreased. This could place greater stress on the ACL graft and ultimately lead to an increased injury risk.

Normalization influences knee abduction moment results: Could it influence ACL-injury research, too?

OBJECTIVES

Normalization of joint moments to reduce anthropometric influences prior to making group comparisons is a widely-accepted practice. However, a seminal prospective study reported greater non-normalized knee abduction moment (KAM) in nine females who subsequently sustained an ACL injury. It is not clear if this finding may have been influenced by the fact that the ACL-injured females were on average 3.6cm taller and 2.4kg heavier than uninjured females.

DESIGN

Cross-sectional.

METHODS

Peak KAM was identified in thirty-six females completing jump landings. A custom software program randomly divided participants into two groups that were compared on: (1) non-normalized KAM, (2) KAM normalized to body mass, and (3) KAM normalized to body height times weight a total of 500,000 times and the results categorically coded for statistical significance (α≤0.05). For the 10,591 iterations in which one group was 3-4cm taller and 2-3kg heavier, the agreement between results obtained using non-normalized versus normalized data were assessed using non-parametric analyses.

RESULTS

Despite moderate-strong agreement between the results obtained using non-normalized and normalized data (Κ=0.614-0.744), a significant effect of normalization on the interpretation of group differences in peak KAM was identified (p<0.001). In 30.4-41.9% of the cases in which non-normalized KAM was deemed significantly different between groups, no group differences were identified when using normalized KAM.

CONCLUSIONS

While it is unlikely the magnitude of the difference in non-normalized KAM identified prospectively in ACL-injured females was attributable solely to anthropometric differences, caution should be exercised when evaluating research findings reporting non-normalized KAM.

Weight-Bearing Dorsiflexion Range of Motion and Landing Biomechanics in Individuals With Chronic Ankle Instability

CONTEXT

People with chronic ankle instability (CAI) exhibit less weight-bearing dorsiflexion range of motion (ROM) and less knee flexion during landing than people with stable ankles. Examining the relationship between dorsiflexion ROM and landing biomechanics may identify a modifiable factor associated with altered kinematics and kinetics during landing tasks.

OBJECTIVE

To examine the relationship between weight-bearing dorsiflexion ROM and single-legged landing biomechanics in persons with CAI.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Fifteen physically active persons with CAI (5 men, 10 women; age = 21.9 ± 2.1 years, height = 168.7 ± 9.0 cm, mass = 69.4 ± 13.3 kg) participated.

INTERVENTION(S)

Participants performed dorsiflexion ROM and single-legged landings from a 40-cm height. Sagittal-plane kinematics of the lower extremity and ground reaction forces (GRFs) were captured during landing.

MAIN OUTCOME MEASURE(S)

Static dorsiflexion was measured using the weight-bearing-lunge test. Kinematics of the ankle, knee, and hip were observed at initial contact, maximum angle, and sagittal displacement. Sagittal displacements of the ankle, knee, and hip were summed to examine overall sagittal displacement. Kinetic variables were maximum posterior and vertical GRFs normalized to body weight. We used Pearson product moment correlations to evaluate the relationships between dorsiflexion ROM and landing biomechanics. Correlations (r) were interpreted as weak (0.00-0.40), moderate (0.41-0.69), or strong (0.70-1.00). The coefficient of determination (r(2)) was used to determine the amount of explained variance among variables.

RESULTS

Static dorsiflexion ROM was moderately correlated with maximum dorsiflexion (r = 0.49, r(2) = 0.24), ankle displacement (r = 0.47, r(2) = 0.22), and total displacement (r = 0.67, r(2) = 0.45) during landing. Dorsiflexion ROM measured statically and during landing demonstrated moderate to strong correlations with maximum knee (r = 0.69-0.74, r(2) = 0.47-0.55) and hip (r = 0.50-0.64, r(2) = 0.25-0.40) flexion, hip (r = 0.53-0.55, r(2) = 0.28-0.30) and knee (r = 0.53-0.70, r(2) = 0.28-0.49) displacement, and vertical GRF (-0.47- -0.50, r(2) = 0.22-0.25).

CONCLUSIONS

Dorsiflexion ROM was moderately to strongly related to sagittal-plane kinematics and maximum vertical GRF during single-legged landing in persons with CAI. Persons with less dorsiflexion ROM demonstrated a more erect landing posture and greater GRF.

Drop-Landing Performance and Knee-Extension Strength After Anterior Cruciate Ligament Reconstruction

CONTEXT

Individuals with a history of anterior cruciate ligament reconstruction (ACLR) are at greater risk of reinjury and developing early-onset osteoarthritis due to persistent abnormal joint loading. Real-time clinical assessment tools may help identify patients experiencing abnormal movement patterns after ACLR.

OBJECTIVE

To compare performance on the Landing Error Scoring System (LESS) between participants with ACLR and uninjured control participants and to determine the relationship between LESS score and knee-extension strength in these participants.

DESIGN

Controlled laboratory study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Forty-six recreationally active participants, consisting of 22 with ACLR (12 men, 10 women; age = 22.5 ± 5.0 years, height = 172.8 ± 7.2 cm, mass = 74.2 ± 15.6 kg, body mass index = 24.6 ± 4.0) and 24 healthy control participants (12 men, 12 women; age = 21.7 ± 3.6 years, height = 168.0 ± 8.8 cm, mass = 69.2 ± 13.6 kg, body mass index = 24.3 ± 3.2) were enrolled.

MAIN OUTCOME MEASURE(S)

Bilateral normalized knee-extension maximal voluntary isometric contraction (MVIC) torque (Nm/kg) and LESS scores were measured during a single testing session. We compared LESS scores between groups using a Mann-Whitney U test and the relationships between LESS scores and normalized knee-extension MVIC torque using Spearman ρ bivariate correlations.

RESULTS

The ACLR participants had a greater number of LESS errors (6.0 ± 3.6) than healthy control participants (2.8 ± 2.2; t44 = -3.73, P = .002). In ACLR participants, lower normalized knee-extension MVIC torque in the injured limb (ρ = -0.455, P = .03) was associated with a greater number of landing errors.

CONCLUSIONS

Participants with ACLR displayed more errors while landing. The occurrence of landing errors was negatively correlated with knee-extension strength, suggesting that weaker participants had more landing errors. Persistent quadriceps weakness commonly associated with ACLR may be related to a reduced quality of lower extremity movement during dynamic tasks.

What is normal? Female lower limb kinematic profiles during athletic tasks used to examine anterior cruciate ligament injury risk: a systematic review

BACKGROUND

It has been proposed that the performance of athletic tasks where normal motion is exceeded has the potential to damage the anterior cruciate ligament (ACL). Determining the expected or 'normal' kinematic profile of athletic tasks commonly used to assess ACL injury risk can provide an evidence base for the identification of abnormal or anomalous task performances in a laboratory setting.

OBJECTIVE

The objective was to conduct a systematic review of studies examining lower limb kinematics of females during drop landing, drop vertical jump, and side-step cutting tasks, to determine 'normal' ranges for hip and knee joint kinematic variables.

DATA SOURCES

An electronic database search was conducted on the SPORTDiscus(TM), MEDLINE, AMED and CINAHL (January 1980-August 2013) databases using a combination of relevant keywords.

STUDY SELECTION

Studies identified as potentially relevant were independently examined by two reviewers for inclusion. Where consensus could not be reached, a third reviewer was consulted. Original research articles that examined three-dimensional hip and knee kinematics of female subjects during the athletic tasks of interest were included for review. Articles were excluded if subjects had a history of lower back or lower limb joint injury or isolated data from the female cohort could not be extracted.

STUDY APPRAISAL AND SYNTHESIS METHODS

Two reviewers independently assessed the quality of included studies. Data on subject characteristics, the athletic task performed, and kinematic data were extracted from included studies. Studies were categorised according to the athletic task being examined and each study allocated a weight within categories based on the number of subjects assessed. Extracted data were used to calculate the weighted means and standard deviations for hip and knee kinematics (initial contact and peak values). 'Normal' motion was classified as the weighted mean plus/minus one standard deviation.

RESULTS

Of 2,920 citations, a total of 159 articles were identified as potentially relevant, with 29 meeting all inclusion/exclusion criteria. Due to the limited number of studies available examining double-leg drop landings and single-leg drop vertical jumps, insufficient data was available to include these tasks in the review. Therefore, a total of 25 articles were included. From the included studies, 'normal' ranges were calculated for the kinematic variables of interest across the athletic tasks examined.

LIMITATIONS

Joint forces and other additional elements play a role in ACL injuries, therefore, focusing solely on lower limb kinematics in classifying injury risk may not encapsulate all relevant factors. Insufficient data resulted in no normal ranges being calculated for double-leg drop land and single-leg drop vertical jump tasks. No included study examined hip internal/external rotation during single-leg drop landings, therefore ranges for this kinematic variable could not be determined. Variation in data between studies resulted in wide normal ranges being observed across certain kinematic variables.

CONCLUSIONS

The ranges calculated in this review provide evidence-based values that can be used to identify abnormal or anomalous athletic task performances on a multi-planar scale. This may be useful in identifying neuromuscular factors or specific muscular recruitment strategies that contribute to ACL injury risk.

The influences of sex and posture on joint energetics during drop landings

Previous observations suggest that females utilize a more erect initial landing posture than males with sex differences in landing posture possibly related to sex-specific energy absorption (EA) strategies. However, sex-specific EA strategies have only been observed when accompanied by sex differences in initial landing posture. This study (a) investigated the potential existence of sex-specific EA strategies; and (b) determined the influences of sex and initial landing posture on the biomechanical determinants of EA. The landing biomechanics of 80 subjects were recorded during drop landings in Preferred, Flexed, and Erect conditions. No sex differences in joint EA were identified after controlling for initial landing posture. Males and females exhibited greater ankle EA during Erect vs Flexed landings with this increase driven by 12% greater ankle velocity, but no change in ankle extensor moment. No differences in hip and knee EA were observed between conditions. However, to achieve similar knee EA, subjects used 7% greater mean knee extensor moment but 9% less knee angular velocity during Flexed landings. The results suggest that sex-specific EA strategies do not exist, and that the magnitude of knee joint EA can be maintained by modulating the relative contributions of joint moment and angular velocity to EA.