Increasing hip and knee flexion during a drop-jump task reduces tibiofemoral shear and compressive forces: implications for ACL injury prevention training

Relationship between Kinesiophobia and Dynamic Postural Stability after Anterior Cruciate Ligament Reconstruction: A Prospective Cohort Study

INTRODUCTION

 Anterior cruciate ligament (ACL) injuries in young, active patients generally require ACL reconstruction (ACLR) to restore mechanical and postural stability. The fear of movement or reinjury (kinesiophobia) has become increasingly recognized in the post-ACLR population; however, the association between restoration of postural stability and kinesiophobia remains largely unknown. The purpose of this study was to investigate changes in mean Tampa Scale of Kinesiophobia-11 (TSK-11), dynamic motion analysis (DMA) scores, and time on the testing platform, as well as any correlation between TSK-11 and mean overall and individual translational and rotational DMA scores during the first 12 months following ACLR.

DESIGN

 Cohort study.

METHODS

 Patients undergoing ACLR were prospectively enrolled and dynamic postural stability and kinesiophobia based on the TSK-11 were collected within 2 days prior to surgery and at 6 and 12 months following ACLR. Dynamic postural stability was quantified by calculating a DMA score, with score calculated in three translational (anterior/posterior [AP], up/down [UD], medial/lateral [ML]) and three rotational (left/right [LR], flexion/extension, and internal/external rotation) independent planes of motions. Correlations between DMA and TSK-11 scores at each time point were analyzed.

RESULTS

 A total of 25 patients meeting inclusion criteria were analyzed. Mean overall DMA and TSK-11 scores increased with each successive testing interval. At 6-month follow-up, a weakly positive association between TSK-11 and DMA scores was appreciated based on overall DMA, AP, UD, ML, and LR. At 12 months, a moderately positive correlation was appreciated between TSK-11 and the translational, but not rotational, planes of motion.

CONCLUSIONS

 Following ACLR, lower level of kinesiophobia were found to be moderately associated with improved dynamic stability, especially in the translation planes of motion.

Hamstrings vibration reduces tibiofemoral compressive force following anterior cruciate ligament reconstruction

Individuals who have undergone anterior cruciate ligament reconstruction (ACLR) are at greater risk of developing knee osteoarthritis (OA). This elevated risk of knee OA is associated with high tibiofemoral (TF) compressive force, due to a combination of low knee flexion angles and increased co-contraction of the hamstrings and quadriceps during limb loading. Prolonged vibration of the hamstrings fatigues the intrafusal muscle fibers, which reduces autonomic reflexive excitation of the hamstrings and alleviates reciprocal inhibition to the quadriceps. The aim of this study was to examine the effect of prolonged hamstrings vibration on TF compressive force in individuals who have undergone ACL reconstruction. Fourteen participants with unilateral ACLR and 14 participants without knee injury performed a single-leg drop-land task before and after prolonged (20 min) vibration of the hamstrings. Peak TF compressive force, knee flexion angle, and hamstrings/quadriceps co-contraction were calculated during the deceleration phase of the drop-land task before and after vibration. The ACLR group experienced an 18% decrease in TF compressive force, a 32% increase in knee flexion angle, and a 38% decrease in hamstrings/quadriceps co-contraction after hamstrings vibration. There was no difference in any of the parameters in the noninjured group after vibration. These data suggest that acute prolonged hamstrings vibration has the potential to mitigate TF compressive force, which may protect the knee joint in the long term. Clinical significance: The results of this research are expected to lead to improved clinical care for ACLR patients because it holds promise for mitigating altered joint mechanics and perhaps slowing down the onset of posttraumatic knee osteoarthritis.

Lower-extremity kinematics and kinetics differ based on drop vertical jump variation: An assessment of methodology for a return-to-play protocol using motion analysis

BACKGROUND

The drop vertical jump (DVJ) is commonly used in return-to-play evaluations to assess movement quality and risk during a dynamic task. However, across biomechanics literature, a multitude of DVJ variations have been used, influencing the generalizability and potential interpretation of the reported findings.

RESEARCH QUESTION

The purpose of this study was to identify differences in lower extremity kinematics and kinetics between DVJ variations that differ based on horizontal jump distance, verbal instructions, and the use of a jump target.

METHODS

A single-group repeated measures design was used in a laboratory setting. Twenty participants were tested, and three-dimensional angles and moments of the pelvis, hip, knee, and ankle were computed. Wilcoxon signed rank tests were performed to determine differences between DVJ variations.

RESULTS

Reduced knee flexion at initial contact and greater knee extensor moments across the descent phase were observed with increased horizontal jump distance. Additionally, both verbal instructions and a jump target influenced movement strategies at the pelvis, hip, and knee. Ground reaction forces were found to be similar across conditions and jump height following the first landing increased with a target.

SIGNIFICANCE

Although subtle, the biomechanical differences observed between task variations emphasize the importance of standardizing motion analysis protocols for research and clinical decision-making. Given the findings of the current study, the authors recommend using the Half Height variation in patients treated for a knee injury as it will likely be the most indicative of movement quality.

Bilateral lower extremity gait and function after unilateral total ankle arthroplasty: a case report

BACKGROUND

End-stage ankle osteoarthritis is one of the leading causes of chronic disability in North America. The main purpose of this case report was to describe the functional recovery of a person following total ankle arthroplasty (TAA) surgery using the INFINITY™ system for end stage osteoarthritis of the left ankle.

CASE DESCRIPTION

We report a case of a 55-year-old male who had attempted conservative management for end stage ankle osteoarthritis in his left ankle but ultimately elected to undergo TAA using The INFINITY™ Total Ankle System. He not only had significant left ankle pain limiting his daily function, but also had developed severe right knee pain. We performed gait analysis both before and 6 months after his TAA surgery to examine the sagittal and frontal-plane motions of bilateral ankle, knee, and hip joints during gait.

OUTCOMES

At 6 months post-surgery, the patient demonstrated a 44-point improvement in his Foot and Ankle Outcome questionnaire scores as well as an increase in both left knee and left ankle motion in the sagittal and frontal planes. Kinematic deviations in the left ankle, hip, and knee joints during gait also reduced post-surgery. Despite improvement in his left ankle and overall function, the participant's right knee pain and altered kinematics of the right limb during gait worsened after surgery.

DISCUSSION

Interventions, either before or after ankle surgery, should consider bilateral lower extremities simultaneously in order to optimize patient care and minimize future secondary complications for individuals with unilateral ankle osteoarthritis.

Knee Joint Contact Forces during High-Risk Dynamic Tasks: 90° Change of Direction and Deceleration Movements

Pivoting sports expose athletes to a high risk of knee injuries, mainly due to mechanical overloading of the joint which shatters overall tissue integrity. The present study explored the magnitude of tibiofemoral contact forces (TFCF) in high-risk dynamic tasks. A novel musculoskeletal model with modifiable frontal plane knee alignment was developed to estimate the total, medial, and lateral TFCF developed during vigorous activities. Thirty-one competitive soccer players performing deceleration and 90° sidestepping tasks were assessed via 3D motion analysis by using a marker-based optoelectronic system and TFCF were assessed via OpenSim software. Statistical parametric mapping was used to investigate the effect of frontal plane alignment, compartment laterality, and varus-valgus genu on TFCF. Further, in consideration of specific risk factors, sex influence was also assessed. A strong correlation (R = 0.71 ÷ 0.98, p < 0.001) was found between modification of compartmental forces and changes in frontal plane alignment. Medial and lateral TFCF were similar throughout most of the tasks with the exception of the initial phase, where the lateral compartment had to withstand to higher loadings (1.5 ÷ 3 BW higher, p = 0.010). Significant sex differences emerged in the late phase of the deceleration task. A comprehensive view of factors influencing the mediolateral distribution of TFCF would benefit knee injury prevention and rehabilitation in sport activities.

Angular Velocities and Linear Accelerations Derived from Inertial Measurement Units Can Be Used as Proxy Measures of Knee Variables Associated with ACL Injury

Given the high rates of both primary and secondary anterior cruciate ligament (ACL) injuries in multidirectional field sports, there is a need to develop easily accessible methods for practitioners to monitor ACL injury risk. Field-based methods to assess knee variables associated with ACL injury are of particular interest to practitioners for monitoring injury risk in applied sports settings. Knee variables or proxy measures derived from wearable inertial measurement units (IMUs) may thus provide a powerful tool for efficient injury risk management. Therefore, the aim of this study was to identify whether there were correlations between laboratory-derived knee variables (knee range of motion (RoM), change in knee moment, and knee stiffness) and metrics derived from IMUs (angular velocities and accelerations) placed on the tibia and thigh, across a range of movements performed in practitioner assessments used to monitor ACL injury risk. Ground reaction forces, three-dimensional kinematics, and triaxial IMU data were recorded from nineteen healthy male participants performing bilateral and unilateral drop jumps, and a 90° cutting task. Spearman's correlations were used to examine the correlations between knee variables and IMU-derived metrics. A significant strong positive correlation was observed between knee RoM and the area under the tibia angular velocity curve in all movements. Significant strong correlations were also observed in the unilateral drop jump between knee RoM, change in knee moment, and knee stiffness, and the area under the tibia acceleration curve (r_s = 0.776, r_s = -0.712, and r_s = -0.765, respectively). A significant moderate correlation was observed between both knee RoM and knee stiffness, and the area under the thigh angular velocity curve (r_s = 0.682 and r_s = -0.641, respectively). The findings from this study suggest that it may be feasible to use IMU-derived angular velocities and acceleration measurements as proxy measures of knee variables in movements included in practitioner assessments used to monitor ACL injury risk.

Effects of a soccer-specific vertical jump on lower extremity landing kinematics

Anterior cruciate ligament (ACL) injury frequently occurs in female soccer athletes during deceleration movements such as landings. In soccer, landings mostly occur following jumping headers. Little research has been done to determine the mechanics that follow and how they compare to standard drop vertical jumps (DVJ). The purpose of this study was to analyze differences in kinematics between the DVJ and the soccer-specific vertical jump (SSVJ) in female soccer athletes to better assess the sport-specific risk for ACL injury. A secondary aim was to compare second landings (L2) to first landings (L1). Eight female recreational soccer athletes performed DVJs and SSVJs initiated from a 31 ​cm height. Motion capture was performed during landings and data were analyzed using repeated-measures ANOVA. SSVJs produced less peak hip flexion (p ​= ​0.03) and less peak knee flexion (p ​= ​0.002) than DVJs. SSVJs also demonstrated increased ankle plantarflexion at initial contact (IC) than DVJs (p ​= ​0.005). L2s produced less peak hip (p ​= ​0.007) and knee flexion (p ​= ​0.002) than L1s. SSVJs and L2s displayed a more erect landing posture than the DVJs and L1s at the hip and knee, a known ACL risk factor. The significant results between jump styles show that the SSVJ displays mechanics that are different from the DVJ. The SSVJ may be a better sport-specific screening tool for ACL injury mechanisms than the DVJ in soccer athletes as it has a more direct translation to the sport.

Construction and Simulation of Biomechanical Model of Human Hip Joint Muscle-Tendon Assisted by Elastic External Tendon by Hill Muscle Model

Based on the Hill muscle model (HMM), a biomechanical model of human hip muscle tendon assisted by elastic external tendon (EET) was preliminarily established to investigate and analyze the biomechanical transition between the hip joint (HJ) and related muscle tendons. Using the HMM, the optimal muscle fiber length and muscle force scaling variables were introduced by means of constrained optimization problems and were optimized. The optimized HMM was constructed with human parameters of 170 cm and 70 kg. The biomechanical model simulation test of the hip muscle tendon was performed in the automatic dynamic analysis of mechanical systems (ADAMS) software to analyze and optimize the changes in the root mean square error (RMSE), biological moment, muscle moment distribution coefficient (MDC), muscle moment, muscle force, muscle power, and mechanical work of the activation curves of the hip major muscle, iliopsoas muscle, rectus femoris muscle, and hamstring muscle under analyzing the optimized HMM and under different EET auxiliary stiffnesses from the joint moment level, joint level, and muscle level, respectively. It was found that the trends of the output joint moment of the optimized HMM and the biological moment of the human HJ were basically the same, r² = 0.883 and RMSE = 0.18 Nm/kg, and the average metabolizable energy consumption of the HJ was (243.77 ± 1.59) J. In the range of 35%∼65% of gait cycle (GC), the auxiliary moment showed a significant downward trend with the increase of EET stiffness, when the EET stiffness of the human body was less than 200 Nm/rad, the biological moment of the human HJ gradually decreased with the increase of EET stiffness, and the MDC of the iliopsoas and hamstring muscles gradually decreased; when the EET stiffness was greater than 200 Nm/rad, the increase of the total moment of the extensor muscles significantly increased, the MDC of the gluteus maximus and rectus muscles gradually increased, and the gluteus maximus and hamstring muscle moments and muscle forces gradually increased; the results show that the optimized muscle model based on Hill can reflect the law of human movement and complete the simulation test of HJ movements, which provides a new idea for the analysis of energy migration in the musculoskeletal system of the lower limb.

The relationship between kinesiophobia and biomechanics in anterior cruciate ligament reconstructed females

OBJECTIVE

Kinesiophobia has been associated with deleterious biomechanical alterations during dual-limb landing tasks in anterior cruciate ligament (ACL) reconstructed females, however, no research has yet investigated single-limb tasks related to ACL injury. The aim of this investigation was to examine the relationship between kinesiophobia and biomechanics during a series of dual and single-limb functional tasks associated with ACL injury risk.

DESIGN

Cross-sectional study.

PARTICIPANTS

Fifteen females (age = 22.67 ± 2.58yrs, height = 1.65 ±0 .05m, mass = 65.28 ± 10.36 kg) with a history of ACL reconstruction (time post surgery = 3.40 ±0 .74yrs) were recruited for this investigation.

MAIN OUTCOME MEASURES

Kinesiophobia, measured via the Tampa Scale of Kinesiophobia (TSK-11). Kinematics and muscle activation were measured during three functional tasks: the drop jump (DJ), single-limb hop (SLH), and single-limb landing (SLL).

RESULTS

For the DJ task, there was a strong negative correlation between kinesiophobia and knee flexion (r = -.592, p = .20) and between kinesiophobia and trunk flexion (r = -0.724, p = .002). For the SLH task, there was a strong positive correlation between kinesiophobia and hip flexion (r = 0.560, p = .03).

CONCLUSIONS

These findings indicate that kinesiophobia is associated with movement alterations years after completion of ACL reconstruction and rehabilitation.

Effects of foot progression angle on knee mechanics during an anticipated cutting task: A statistical parametric mapping approach

Cutting is considered a "high-risk" movement for anterior cruciate ligament (ACL) injuries. It has been established that sex differences exist during cutting, placing females at greater ACL injury risk. Foot progression angle (FPA) during landing has been shown to influence lower extremity mechanics, yet little is known how FPA influences mechanics during cutting. The purpose of this study was to compare two FPA conditions during cutting between males and females. Twenty-four males and females were tested using two FPA conditions: toe-in 15° (TI15) and toe-out 15° (TO15). Right knee joint kinematic and kinetic variables were measured using a motion capture system and force plate. Five successful trials were collected and compared between FPA conditions. One-dimensional statistical parametric mapping was used to assess changes in knee mechanics between males and females over the entire stance phase. The only sex × FPA effect found was knee flexion angle. Females cutting at TI15 had decreased knee flexion angle compared TO15 (p = 0.019). Significant sex main effects included knee abduction and rotation angles, and knee flexion and rotation moments. Significant FPA main effects included knee flexion, abduction and rotation angles. The results show cutting with a toe-in FPA of 15° is enough to induce changes in knee abduction angle while cutting with 15° toe-out FPA influenced knee flexion and rotation angles. These data suggest that different cutting FPAs may be influential on known ACL injury risk variables. However, more research is warranted on cutting FPA before FPA is targeted as part of ACL injury prevention protocols.

Trunk Angle Modulates Feedforward and Feedback Control during Single-Limb Squatting

Trunk positioning and unexpected perturbations are high-risk conditions at the time of anterior cruciate ligament injury. The influence of trunk positioning on motor control responses to perturbation during dynamic performance is not known. We tested the influence of trunk position on feedforward and feedback control during unexpected perturbations while performing a novel single-limb squatting task. We also assessed the degree that feedforward control was predictive of feedback responses. In the flexed trunk condition, there were increased quadriceps (p < 0.026) and gluteus medius long-latency reflexes (p < 0.001) and greater quadriceps-to-hamstrings co-contraction during feedforward (p = 0.017) and feedback (p = 0.007) time bins. Soleus long-latency reflexes increased more than 100% from feedforward muscle activity regardless of trunk condition. Feedforward muscle activity differentially predicted long-latency reflex responses depending on the muscle (R²: 0.47-0.97). These findings support the concept that trunk positioning influences motor control responses to perturbation and that feedback responses may be invariant to the feedforward control strategy.

Estimation of vertical ground reaction force parameters during athletic tasks using 2D video

BACKGROUND

Given that elevated vertical ground reaction forces (vGRF) have been reported to contribute to various lower-extremity injuries, there is a need for a practical method to characterize movement behavior that is representative of elevated impact forces.

RESEARCH QUESTION

Can images obtained from 2D video be used to predict vGRF parameters during athletic tasks? Specifically, we sought to determine whether the 2D thigh angle obtained at peak knee flexion could be used to predict the peak vGRF and vGRF impulse during single limb and double limb landings and movements that involve a change of direction.

METHODS

2D sagittal plane video and vGRFs were obtained simultaneously from 39 participants (15 males and 24 females) during 5 athletic tasks (drop jump, lateral shuffle, deceleration, triple hop, side-step-cut). Linear regression analysis was performed to determine if the 2D thigh angle at peak knee flexion predicted the first peak of the vGRF and vGRF impulse during the deceleration phase of each task.

RESULTS

The 2D thigh angle predicted the peak vGRF for all tasks except cutting (R² = 0.17 to 0.47, all p < 0.01). However, the 2D thigh angle predicted the vGRF impulse for all 5 tasks (R² = 0.13 to 0.39, all p < 0.025).

SIGNIFICANCE

An increased 2D thigh angle (which is representative of increased hip and knee flexion) was able to predict lower peak vGRFs and vGRF impulse during athletic tasks. The 2D thigh angle is a potential clinical method to characterize movement behavior that may expose individuals to high impact forces.

Kinetic changes associated with extended knee landings following anterior cruciate ligament reconstruction in females

OBJECTIVES

To determine the relationship between knee flexion excursion symmetry and lower extremity kinematics, kinetics, and muscle, joint, and ligament forces in females 1-3 years after ACL reconstruction.

DESIGN

Cross-sectional.

SETTING

Laboratory.

PARTICIPANTS

Twenty-one, college-aged females.

MAIN OUTCOME MEASURES

Lower extremity kinetics and kinematics, including estimated muscle, tibiofemoral, and ligament forces were assessed using 3D motion analysis and a musculoskeletal modeling approach. Participants demonstrating greater than 10% asymmetry in knee flexion excursion were classified as landing with an "extended knee". Group and between-limb differences were compared.

RESULTS

Ten participants were classified as landing with an "extended knee" on the involved limb, while eleven exhibited a symmetric landing pattern. Participants landing with an "extended knee" demonstrated reduced knee extension moment and quadriceps force in the involved limb (p < 0.05).

CONCLUSIONS

These findings indicate that an "extended knee" landing pattern was associated with reduced knee extension moment and quadriceps muscle force in females 1-3 years after ACL reconstruction. This may represent an altered strategy that clinicians may choose to identify and address during rehabilitation.

Asymmetries in Dynamic Valgus Index After Anterior Cruciate Ligament Reconstruction: A Proof-of-Concept Study

Individuals with anterior cruciate ligament reconstruction (ACLR) are at a higher risk for subsequent anterior cruciate ligament (ACL) tears. Risk factors for ACL injuries likely involve a combination of anatomical, biomechanical, and neuromuscular factors. Dynamic knee valgus has been indicated as a possible biomechanical factor for future ACL injuries. Given that knee valgus is often accompanied by contralateral pelvic drop during single-leg activities, a dynamic valgus index (DVI) that quantifies combined kinematics of the knee and hip in the frontal plane has recently been developed. As the premise of asymmetrical DVI between limbs in the ACLR population has not been examined, this cross-sectional study was conducted with the aim to compare DVI between individuals with ACLR and healthy controls. Videos were taken for 12 participants with ACLR and 20 healthy controls when they performed single-leg hopping. One-way ANOVA revealed a higher DVI in the injured limb of the ACLR group when compared to their non-injured limb and to the healthy limb of the control group. As our data showed increased DVI in the injured limb of the ACLR group, the DVI approach accounting for hip and knee kinematics may be used to identify frontal plane movement deficits during single-leg hopping in individuals with ACLR.

Ankle Dorsiflexion Affects Hip and Knee Biomechanics During Landing

BACKGROUND

Restricted ankle dorsiflexion range of motion (DFROM) has been linked to lower extremity biomechanics that place an athlete at higher risk for injury. Whether reduced DFROM during dynamic movements is due to restrictions in joint motion or underutilization of available ankle DFROM motion is unclear.

HYPOTHESIS

We hypothesized that both lesser total ankle DFROM and underutilization of available motion would lead to high-risk biomechanics (ie, greater knee abduction, reduced knee flexion).

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Nineteen active female athletes (age, 20.0 ± 1.3 years; height, 1.61 ± 0.06 m; mass, 67.0 ± 10.7 kg) participated. Maximal ankle DFROM (clinical measure of ankle DFROM [DF-CLIN]) was measured in a weightbearing position with the knee flexed. Lower extremity biomechanics were measured during a drop vertical jump with 3-dimensional motion and force plate analysis. The percent of available DFROM used during landing (DF-%USED) was calculated as the peak DFROM observed during landing divided by DF-CLIN. Univariate linear regressions were performed to identify whether DF-CLIN or DF-%USED predicted knee and hip biomechanics commonly associated with injury risk.

RESULTS

For every 1.0° less of DF-CLIN, there was a 1.0° decrease in hip flexion excursion (r² = 0.21, P = 0.05), 1.2° decrease in peak knee flexion angles (r² = 0.37, P = 0.01), 0.9° decrease in knee flexion excursion (r² = 0.40, P = 0.004), 0.002 N·m·N^-1·cm^-1 decrease in hip extensor work (r² = 0.28, P = 0.02), and 0.001 N·m·N^-1·cm^-1 decrease in knee extensor work (r² = 0.21, P = 0.05). For every 10% less of DF-%USED, there was a 3.2° increase in peak knee abduction angles (r² = 0.26, P = 0.03) and 0.01 N·m·N^-1·cm^-1 lesser knee extensor work (r² = 0.25, P = 0.03).

CONCLUSION

Lower levels of both ankle DFROM and DF-%USED are associated with biomechanics that are considered to be associated with a higher risk of sustaining injury.

CLINICAL RELEVANCE

While total ankle DFROM can predict some aberrant movement patterns, underutilization of available ankle DFROM can also lead to higher risk movement strategies. In addition to joint specific mobility training, clinicians should incorporate biomechanical interventions and technique feedback to promote the utilization of available motion.

Comparison of Knee and Hip Kinematics during Landing and Cutting between Elite Male Football and Futsal Players

To design an accurate sport injury prevention program, alterations in the knee and hip kinematic variables involved in injury mechanisms should be known. The main purpose of the current study was to compare knee and hip kinematic variables during landing and cutting among male football and futsal players, and to discuss them within an injury description frame. Twenty football (20.5 ± 2.1 years., 74.5 ± 6.9 kg and 1.79 ± 0.07 m) and twenty futsal players (20.3 ± 2.0 years., 73.5 ± 7.1 kg and 1.78 ± 0.07 m), with at least three years’ experience of playing in the Kerman Province League, participated in this study. Hip flexion, knee flexion and knee valgus angle during two main movements with risk of injury, such as landing and cutting, were measured using a motion capture system with passive markers at 120-Hz sampling frequency. Landing and cutting maneuvers were administered in as natural way as possible. Results showed significant differences in landing and cutting maneuvers between groups in hip flexion, knee flexion and knee valgus angle. Results indicated that footballers have less extension of hip and knee joints than futsal players in landing maneuvers, which may be due to the higher requirement of jumping−landing maneuvers when playing football. In cutting maneuvers, footballers showed less hip and knee flexion than futsal players, whereas the knee valgus angle in cutting maneuvers was lower in futsal players. More information on the injury mechanisms of landing and cutting in football and futsal are needed to improve the design of injury prevention programs.

Effect of Sand on Knee Load During a Single-Leg Jump Task: Implications for Injury Prevention and Rehabilitation Programs

Richardson, MC, Murphy, S, Macpherson, T, English, B, Spears, I, and Chesterton, P. Effect of sand on knee load during a single-leg jump task: implications for injury prevention and rehabilitation programs. J Strength Cond Res 34(11): 3164-3172, 2020-The purpose of the study was to determine potential differences in landing strategies and subsequent joint loads at the knee (knee abduction moment [KAM], anterior-posterior [AP] tibial translation, and total knee shear force) when jumping onto sand and firm ground from both a level surface and a 30-cm height. Firm ground would act as the control for the study. Seventeen subjects (age: 23.6 ± 3.7 years; body mass: 67.7 ± 10.3 kg; height: 168.5 ± 7.4 cm) performed 3 single-leg jumps on their dominant leg for each of the 4 conditions tested (ground level, sand level, ground height, and sand height). A repeated-measures design investigated the effect of sand on KAM, AP tibial translation, and total knee shear force. Data were analyzed using magnitude-based inferences and presented as percentage change with 90% confidence limits. Results indicated that sand had a clear beneficial effect on KAM, which was possibly moderate during a drop jump (30 cm) and possibly small from a level jump. Sand also had a possibly moderate beneficial effect on AP tibial translation from a level jump. The effect of sand on total knee shear force was unclear. These results suggest that sand may provide a safer alternative to firm ground when performing jump tasks commonly used in anterior cruciate ligament and patellofemoral joint injury prevention and rehabilitation programs. Sand may also allow for an accelerated rehabilitation program because jumping activities could potentially be implemented more safely at an earlier stage in the process.

Biomechanical and neuromuscular comparison of single- and multi-planar jump tests and a side-cutting maneuver: Implications for ACL injury risk assessment

BACKGROUND

Non-contact anterior cruciate ligament (ACL) injuries are a major problem among adolescent female soccer and handball players. Therefore, the aim of this study was to examine if known biomechanical and neuromuscular ACL injury risk factors obtained from single-planar jump-landings and multi-planar side-jumps can resemble the demands of side-cutting maneuvers, a known high-risk ACL injury movement for this population.

METHODS

Twenty-four female soccer and handball players (mean ± SD: age: 17 ± 1 year; height: 172 ± 66 cm; mass: 67 ± 9 kg) performed a series of functional tasks including two single-planar jump-landings, two multi-planar side-jumps and a sports-specific side-cutting maneuver on their dominant leg. Frontal and sagittal plane knee and hip joint kinematics and kinetics were calculated from three-dimensional motion analysis, whereas hamstring and quadriceps muscle pre-activity levels were measured with surface electromyography.

RESULTS

The sports-specific side-cut was distinguished by more knee flexion at initial contact, greater abduction angles and external knee abduction moments, higher biceps femoris and semitendinosus muscle pre-activity levels than both the single-planar jump-landings and multi-planar side-jumps (p < .05). Whilst, poor-to-strong spearman rank correlation coefficients inconsistently were found for the biomechanical and neuromuscular ACL injury risk factors explored between the side-cut and the single-planar jump-landings (r_s = 0.01-0.78) and multi-planar side-jumps (r_s = 0.03-0.88) respectively.

CONCLUSION

Single-planar jump-landings and multi-planar side-jumps should be used with caution to test for non-contact ACL injury risk factors in adolescent female soccer and handball players, because they do not mimic the biomechanical nor neuromuscular demands of the most frequent injury situation.

Effects of Two Competitive Soccer Matches on Landing Biomechanics in Female Division I Soccer Players

Fatigue has been proposed to increase the risk of knee injury. This study tracked countermovement jump, knee isometric strength, and kinetics and kinematics in 8 female soccer players (experimental group) during an anticipated sidestep maneuver before and after two matches played over a 43-h period. Time points were: Before and after match 1 (T0 and T1), 12 h after the first match (T2), and immediately after the second match (T3). A control group participated only in practice sessions. Isometric knee extension strength decreased by 14.8% at T2 (p = 0.003), but knee flexion was not affected until T3, declining by 12.6% (p = 0.018). During the sidestep maneuver, knee joint degrees of flexion at initial contact was increased by 17.1% at T3, but maximum knee and hip angle at initial contact were unchanged. Peak resultant ground reaction force (GRF) increased by 12.6% (p = 0.047) at T3 (3.03 xBW) from 2.69 xBW at T0, while posterior GRF was significantly higher than T0 at all three subsequent time points (T1 = 0.82 ± 0.23 xBW, T2 = 0.87 ± 0.22 xBW, T3 = 0.89 ± 0.22 xBW). Anterior tibial shear force increased significantly (p = 0.020) at T3 (1.24 ± 0.12 xBW) compared to T1 (1.15 ± 0.13 xBW), an 8.8% increase. Lateral tibial shear force was significantly higher at both T1 (0.95 ± 0.20 xBW) and T3 (1.15 ± 0.38 xBW) compared to T0 (0.67 ± 0.25 xBW). These findings suggest that participation in a soccer match has significant effects on both physical performance parameters and kinetics/kinematics during a sidestep cut, but these can be more pronounced after a second match with short rest.

Tibiofemoral Joint Forces in Female Recreational Runners Vary with Step Frequency

PURPOSE

Elevated tibiofemoral joint (TFJ) contact forces have been linked to the development and progression of knee osteoarthritis. The primary objective of this study was to determine the association between peak TFJ shear and compression forces during running at different self-selected step frequencies (SF) in female recreational runners.

METHODS

Fifty-five healthy female recreational runners ran at 2.98 m·s on an instrumented treadmill. Peak TFJ anterior shear force, peak axial TFJ compression force, and peak medial compartment TFJ compression force were estimated using a musculoskeletal model with inputs from 3D joint kinematics and inverse dynamics calculations. Three SF groups were generated using tertiles, and differences between the groups were compared using one-way ANOVA (α = 0.05).

RESULTS

Runners with an SF of ≥178 steps per minute demonstrated the lowest peak TFJ anterior shear force (P = 0.04), peak axial TFJ compression force (P = 0.01), and peak TFJ medial compartment compression forces (P = 0.01) compared with runners using lower SF.

CONCLUSION

Female recreational runners with low SF of ≤166 steps per minute experience greater TFJ contact forces. This study provides evidence of an association between SF and both shear and axial peak TFJ contact forces during running.

Abnormal Biomechanics at 6 Months Are Associated With Cartilage Degeneration at 3 Years After Anterior Cruciate Ligament Reconstruction

PURPOSE

To investigate the changes in landing biomechanics over a 3-year period and their correlation with cartilage degenerative changes in the medial tibiofemoral joint of the knee after anterior cruciate ligament reconstruction (ACLR) using magnetic resonance T1ρ mapping.

METHODS

Thirty-one anterior cruciate ligament-injured patients underwent magnetic resonance imaging of the injured knee before ACLR and 3 years after ACLR, as well as biomechanical analysis of a drop-landing task at 6 months and 3 years after ACLR. Sixteen healthy individuals were recruited and underwent knee magnetic resonance imaging and biomechanical assessment during a drop-landing task. T1ρ cartilage relaxation times were calculated for the medial femur and tibia.

RESULTS

ACLR patients exhibited increased peak vertical ground reaction force (VGRF), VGRF impulse, peak knee flexion moment (KFM), and KFM impulse from 6 months to 3 years (P < .001 for each). Although the ACLR knees showed significantly lower peak VGRF and KFM at 6 months (P < .001 for both) when compared with the controls, there were no significant differences at 3 years. At 3 years, ACLR patients showed higher T1ρ values over the medial femur (P < .001) and tibia (P = .012) when compared with their preoperative values and with healthy control values. Within the ACLR group, side-to-side differences in peak VGRF and sagittal knee biomechanics at 6 months were associated with increased T1ρ values from baseline to 3 years.

CONCLUSIONS

The results of this longitudinal study show that landing biomechanics are altered after ACLR but biomechanical abnormalities tend to recover at 3 years after ACLR. Differences in lower-extremity mechanics during a landing task at 6 months may be associated with cartilage degeneration at 3 years after anterior cruciate ligament injury and reconstruction.

LEVEL OF EVIDENCE

Level II, prospective trial.

Muscle Activation During ACL Injury Risk Movements in Young Female Athletes: A Narrative Review

Young, adolescent female athletes are at particular high risk of sustaining a non-contact anterior cruciate ligament (ACL) injury during sport. Through the last decades much attention has been directed toward various anatomical and biomechanical risk factors for non-contact ACL injury, and important information have been retrieved about the influence of external loading factors on ACL injury risk during given sports-specific movements. However, much less attention has been given to the aspect of neuromuscular control during such movements and only sparse knowledge exists on the specific muscle activation patterns involved during specific risk conditions. Therefore, the aim of this narrative review was (1) to describe anatomical aspects, strength aspects and biomechanical aspects relevant for the understanding of ACL non-contact injury mechanisms in young female athletes, and (2) to review the existing literature on lower limb muscle activation in relation to risk of non-contact ACL-injury and prevention of ACL injury in young female athletes. Studies investigating muscle activity patterns associated with sports-specific risk situations were identified, comprising cohort studies, intervention studies and prospective studies. Based on the retrieved studies, clear gender-specific differences in muscle activation and coordination were identified demonstrating elevated quadriceps activity and reduced hamstring activity in young female athletes compared to their male counterparts, and suggesting young female athletes to be at elevated risk of non-contact ACL injury. Only few studies (n = 6) examined the effect of preventive exercise-based intervention protocols on lower limb muscle activation during sports-specific movements. A general trend toward enhanced hamstring activation was observed during selected injury risk situations (e.g., sidecutting and drop landings). Only a single study examined the association between muscle activation deficits and ACL injury risk, reporting that low medial hamstring activation and high vastus lateralis activation prior to landing was associated with an elevated incidence of ACL-injury. A majority of studies were performed in adult female athletes. The striking paucity of studies in adolescent female athletes emphasizes the need for increased research activities to examine of lower limb muscle activity in relation to non-contact ACL injury in this high-risk athlete population.