Tibial Rotation Moments Research Articles

Commentary on “The deterministic condition for the ground reaction force acting point on the combined knee valgus and tibial internal rotation moments in the early phase of cutting maneuvers in female athletes”

Commentary on “The deterministic condition for the ground reaction force acting point on the combined knee valgus and tibial internal rotation moments in the early phase of cutting maneuvers in female athletes”

The deterministic condition for the ground reaction force acting point on the combined knee valgus and tibial internal rotation moments in early phase of cutting maneuvers in female athletes

BackgroundCombined knee valgus and tibial internal rotation (VL + IR) moments have been shown to stress the anterior cruciate ligament (ACL) in several in vitro cadaveric studies. To utilize this knowledge for non-contact ACL injury prevention in sports, it is necessary to elucidate how the ground reaction force (GRF) acting point (center of pressure (CoP)) in the stance foot produces combined knee VL + IR moments in risky maneuvers, such as cuttings. However, the effects of the GRF acting point on the development of the combined knee VL + IR moment in cutting are still unknown. MethodsWe first established the deterministic mechanical condition that the CoP position relative to the tibial rotational axis differentiates the GRF vector's directional probability for developing the combined knee VL + IR moment, and theoretically predicted that when the CoP is posterior to the tibial rotational axis, the GRF vector is more likely to produce the combined knee VL + IR moment than when the CoP is anterior to the tibial rotational axis. Then, we tested a stochastic aspect of our theory in a lab-controlled in vivo experiment. Fourteen females performed 60° cutting under forefoot/rearfoot strike conditions (10 trials each). The positions of lower limb markers and GRF data were measured, and the knee moment due to GRF vector was calculated. The trials were divided into anterior- and posterior-CoP groups depending on the CoP position relative to the tibial rotational axis at each 10 ms interval from 0 to 100 ms after foot strike, and the occurrence rate of the combined knee VL + IR moment was compared between trial groups. ResultsThe posterior-CoP group showed significantly higher occurrence rates of the combined knee VL + IR moment (maximum of 82.8%) at every time point than those of the anterior-CoP trials, as theoretically predicted by the deterministic mechanical condition. ConclusionThe rearfoot strikes inducing the posterior CoP should be avoided to reduce the risk of non-contact ACL injury associated with the combined knee VL + IR stress.

Association Between the Medial-Lateral Quadriceps and Hamstring Muscle Thickness and the Knee Kinematics and Kinetics During Single-Leg Landing.

Muscle thickness can influence the joint kinematics and/or kinetics during dynamic activities. The relationship between the muscle thickness of individual quadriceps and hamstrings or medial-to-lateral thigh muscle thickness ratio and the knee kinematics/kinetics with respect to anterior cruciate ligament (ACL) injury risk remains unclear. Higher medial-to-lateral thigh muscle thickness ratio would be associated with lower knee valgus angle/moment and lower tibial internal rotation angle/moment during single-leg landing. Cross-sectional. Level 4. Muscle thickness of the vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), and semitendinosus (ST) of 30 healthy participants (16 males and 14 females) were measured using ultrasound. Knee joint kinematics and kinetics during single-leg landing were obtained. Stepwise multiple regression analysis, a follow-up Fisher's r to z test to examine the sex as a moderator, and independent t tests to evaluate sex difference were performed. Both knee valgus moment (R2 = 0.466, P < 0.001) and tibial external rotation moment (R2 = 0.330, P < 0.001) at peak anterior tibial shear force during single-leg landing were negatively correlated with medial-to-lateral (ie, (VM+ST):(VL+BF)) thickness ratio regardless of sex, whereas medial-to-lateral thigh muscle thickness ratio was not correlated with knee valgus and tibial external rotation angles. Male participants exhibited higher (VM+ST):(VL+BF) thickness ratio than female participants (P = 0.005), and lower knee valgus moment (P = 0.04) and tibial external rotation moment (P = 0.05), as well. The knee joint moments in frontal and transverse planes during single-leg landing were associated with the medial-to-lateral thigh muscle thickness ratio; thus, the medial-lateral thigh muscle thickness could be a potential contributor to frontal and transverse plane knee joint loading during dynamic movement. Strength training that aims to selectively strengthen the medial/lateral thigh muscles might be considered in a new ACL injury prevention training program to alter the biomechanical parameters associated with ACL injuries.

The counteracting effect of the friction moment against the tibial rotational moment driven by the ground reaction force in an early stance phase of cutting maneuver among healthy male athletes

ABSTRACT The ground reaction force (GRF) is known to produce tibial internal rotation loading associated with the stress in the anterior cruciate ligament (ACL). However, it is unclear whether the friction moment (FM; the moment due to horizontal shoe-floor friction, acting around the vertical axis at the GRF acting point) facilitates or restrains the effect of GRF-driven tibial rotation loading during cutting. The 45° cutting motions with forefoot/rearfoot strikes were captured simultaneously with GRF and FM data from 23 healthy males. The FM- and GRF-driven tibial rotation moments were calculated. Time-series correlation between FM- and GRF-driven tibial rotation moments and the orientation relationship among those moment vectors was investigated. The FM-driven tibial rotation moment negatively correlated with the GRF-driven one within the first 10% of stance phase. The peak regression slope value was −0.34 [SD 0.33] for forefoot and −1.64 [SD 1.76] for rearfoot strikes, showing significant difference from zero (SPM one-sample t-test, p<0.05). The FM-driven tibial “external” rotation moment counteracted the GRF-driven tibial “internal” rotation moment within first 10% of the stance phase in most trials, suggesting that the FM-driven tibial rotation moment potentially diminishes the effect of GRF-driven one and may reduce ACL injury risk during cutting.

A comparison of gait characteristics between posterior stabilized total knee and fixed bearing unicompartmental knee arthroplasties

Background/ObjectiveAccording to previous studies, physiological gait pattern was found in unicompartmental knee arthroplasty (UKA) as compared to total knee arthroplasty (TKA) concerning the gait parameters including gait speed, cadence, and step length. However, little attention had been paid to the detailed kinematic and kinetic differences during gait between TKAs and UKAs. The aim of the present study was to investigate and to clarify the biomechanical differences between posterior stabilized TKAs and fixed bearing UKAs during walking MethodsA total of 28 patients participated in the present study. Fifteen patients who underwent TKA and thirteen patients who underwent UKA were enrolled. Gait analysis was done at an average of 12.9 months after surgery. The subjects performed level walking at a preferred speed. For each subject, three-dimensional kinematic, kinetic and ground reaction force data were recorded as well as clinical data including range of motion at the knee joint and plain radiographs. Differences of knee kinematics or kinetics were compared between TKAs and UKAs using two-tailed Mann Whitney U-test. ResultsOn physical examination, passive range motion was significantly smaller in TKAs than in UKAs, while femorotibial angle on plain radiographs was not significantly different on plain radiographs. In terms of kinematics, TKAs were more flexed at heel contact and less extended in mid-stance phase compared to UKAs in the sagittal plane, and total excursion of TKAs were also smaller than UKAs. Regarding knee kinetics, TKA patients had significantly less peak tibial internal rotation moment in terminal stance phase. In addition, peak knee adduction moment was significantly larger in UKAs than in TKAs, while peak knee flexion moment was not significantly different. ConclusionPosterior stabilized TKAs exhibited less peak tibial internal rotation moment, which is known as pivot shift avoidance gait, in the present study, compared to fixed bearing UKAs. TKAs had similar gait pattern to anterior cruciate ligament deficient knees, compared to UKAs even if patients with TKAs had no subjective pain during walking.

Association between ankle angle at initial contact and biomechanical ACL injury risk factors in male during self-selected single-leg landing

BackgroundIncreasing the ankle plantar-flexion angle at initial contact (IC) during landing reduces the impact features associated with landing, such as the vertical ground reaction force and loading rate, potentially affecting the risk of anterior cruciate ligament (ACL) injury. However, the relationships between the ankle plantar-flexion angle at IC and the previously identified biomechanical factors related to noncontact ACL injury have not been studied. Research questionThus, the purpose of this study was to determine whether significant relationships exist between the ankle plantar-flexion angle at IC and the biomechanical factors related to noncontact ACL injury. MethodsThe peak anterior tibial shear force, peak external knee valgus moment, peak knee valgus angle, and combined peak external knee valgus plus tibial internal rotation moments were measured in 26 individuals while performing self-selected, single-leg landing. Pearson correlation analyses were performed to assess the relationships between the ankle plantar-flexion angle at IC and the biomechanical factors mentioned above. ResultsThe greater ankle plantar-flexion angle at IC was related to smaller the peak knee valgus moment (r = −0.5, p = 0.009) and the combined peak knee valgus plus internal rotation moments (r = −0.58, p = 0.001). SignificanceThese results suggest that large ankle plantar-flexion angle at IC might be associated with lesser loading of the knee frontal plane and altering the self-selective ankle angle may result in biomechanical changes associated with ACL injury risk.

Analysis of Internal Knee Forces Allows for the Prediction of Rupture Events in a Clinically Relevant Model of Anterior Cruciate Ligament Injuries.

Background:A recently developed mechanical impact simulator induced an anterior cruciate ligament (ACL) rupture via the application of a combination of inverse dynamics–based knee abduction moment (KAM), anterior tibial shear force (ATS), and internal tibial rotation moment with impulsive compression in a cohort of cadaveric limbs. However, there remains an opportunity to further define the interaction of internal forces and moments at the knee and their respective influence on injury events.Purpose:To identify the influence of internal knee loads on an ACL injury event using a cadaveric impact simulator.Study Design:Controlled laboratory study.Methods:Drop-landing simulations were performed and analyzed on 30 fresh-frozen cadaveric knees with a validated mechanical impact simulator. Internal forces and moments at the knee joint center were calculated using data from a 6-axis load cell recorded on the femur during testing. Kinetic data from a total of 1083 trials that included 30 ACL injury trials were used as inputs for principal component (PC) analysis to identify the most critical features of loading waveforms. Logistic regression analysis with a stepwise selection was used to select the PCs that predicted an ACL injury. Injurious waveforms were reconstructed with selected PCs in logistic regression analysis.Results:A total of 3 PCs were selected in logistic regression analysis that developed a significant model (P < .001). The external loading of KAM was highly correlated with PC1 (ρ < –0.8; P < .001), which explained the majority (>69%) of the injurious waveforms reconstructed with the 3 selected PCs. The injurious waveforms demonstrated a larger internal knee adduction moment and lateral tibial force. After the ACL was ruptured, decreased posterior tibial force was observed in injury trials.Conclusion:These findings give us a better understanding of ACL injury mechanisms using 6-axis kinetics from an in vitro simulator. An ACL rupture was correlated with an internal knee adduction moment (external KAM) and was augmented by ATS and lateral tibial force induced by an impact, which distorted the ACL insertion orientation.Clinical Relevance:The ACL injury mechanism explained in this study may help target injury prevention programs to decrease injurious knee loading (KAM, ATS, and lateral tibial force) during landing tasks.

Rearfoot strikes more frequently apply combined knee valgus and tibial internal rotation moments than forefoot strikes in females during the early phase of cutting maneuvers

BackgroundAnterior cruciate ligament (ACL) injury often occurs during deceleration maneuvers in sports. Combined knee valgus and tibial internal rotation (VL + IR) moments have been recognized as a risk leading to ACL injury; however, it is unknown how the foot strike pattern (forefoot or rearfoot strike) affects the occurrence rate of the aforementioned combined knee moments during cutting maneuvers. Research questionTo test the hypothesis that rearfoot strikes rather than forefoot strikes show a significantly higher occurrence rate of the combined VL + IR moments during the early stance phase of a cutting maneuver. MethodsTwenty-four females performed 60° cutting maneuvers under rearfoot and forefoot strike conditions. Positional data of lower limb markers and ground reaction force (GRF) were collected. Knee varus/valgus and tibial internal/external rotation moments due to GRF were calculated and time-normalized (0–100 %) to the stance phase. The occurrence rates of combined VL + IR moments were compared between rearfoot and forefoot strike conditions throughout the stance (chi-squared test, p < 0.01). Furthermore, the time patterns of the two knee moments and the position of the GRF acting point were compared using the statistical parametric mapping paired t-test (p < 0.0125). ResultsRearfoot strikes more frequently produced combined VL + IR moments than forefoot strikes (maximum occurrence rates: 73.5 % vs. 27.8 %, p < 0.01) during the first 0–40 % of the stance. Both foot strikes consistently showed an increase in knee valgus moment soon after foot impact; however, rearfoot and forefoot strikes respectively applied opposite internal and external rotation moments during the first 0–7 % of stance (p < 0.0125), indicating that the GRF vector that generated knee valgus moment further applied tibial internal rotation moment when it acted posterior to the tibial rotation axis. SignificanceThe current results suggest that rearfoot strike in cuttings elevates the probability of ACL injury via combined VL + IR moments.

Multiplanar Loading of the Knee and Its Influence on Anterior Cruciate Ligament and Medial Collateral Ligament Strain During Simulated Landings and Noncontact Tears

Background: Anterior cruciate ligament (ACL) tears and concomitant medial collateral ligament (MCL) injuries are known to occur during dynamic athletic tasks that place combinatorial frontal and transverse plane loads on the knee. A mechanical impact simulator that produces clinical presentation of ACL injury allows for the quantification of individual loading contributors leading to ACL failure. Purpose/Hypothesis: The objective was to delineate the relationship between knee abduction moment, anterior tibial shear, and internal tibial rotation applied at the knee and ACL strain during physiologically defined simulations of impact at a knee flexion angle representative of initial contact landing from a jump. The hypothesis tested was that before ACL failure, abduction moment would induce greater change in ACL strain during landing than either anterior shear or internal rotation. Study Design: Controlled laboratory study. Methods: Nineteen cadaveric specimens were subjected to simulated landings in the mechanical impact simulator. During simulations, external knee abduction moment, internal tibial rotation moment, and anterior tibial shear loads were derived from a previously analyzed in vivo cohort and applied to the knee in varying magnitudes with respect to injury risk classification. Implanted strain gauges were used to track knee ligament displacement throughout simulation. Kruskal-Wallis tests were used to assess strain differences among loading factors, with Wilcoxon each pair post hoc tests used to assess differences of magnitude within each loading. Results: Each loading factor significantly increased ACL strain (P < .005). Within factors, the high-risk magnitude of each factor significantly increased ACL strain relative to the baseline condition (P≤ .002). However, relative to knee abduction moment specifically, ACL strain increased with each increased risk magnitude (P≤ .015). Conclusion: Increased risk levels of each load factor contributed to increased levels of ACL strain during a simulated jump landing. The behavior of increased strain between levels of increased risk loading was most prevalent for changes in knee abduction moment. This behavior was observed in the ACL and MCL. Clinical Relevance: Knee abduction moment may be the predominant precursor to ACL injury and concomitant MCL injury. As knee abduction occurs within the frontal plane, primary preventative focus should incorporate reduction of frontal plane knee loading in landing and cutting tasks, but secondary reduction of transverse plane loading could further increase intervention efficacy. Constraint of motion in these planes should restrict peak ACL strain magnitudes during athletic performance.

Three dimensional knee kinematics and kinetics in ACL-deficient patients with and without medial meniscus posterior horn tear during level walking

BackgroundThe location of the meniscus tear has been reported to influence kinematics in anterior cruciate ligament deficient (ACLD) knees. Medial meniscus posterior horn tear (MMPHT) often occurred after ACL rupture. Whether MMPHT influences the kinematics and kinetics in ACLD knees has not been reported yet. Research questionThe purpose of this study was to investigate three-dimensional (3D) kinematics and kinetics in ACLD knees with and without MMPHT (ACLD + MMPHT, ACLDs) during level walking. MethodsFifteen patients with isolated unilateral ACLD, ten with unilateral ACLD + MMPHT, and twenty-two healthy controls underwent gait testing between January 2014 and December 2016. Participant characteristics, as well as gait parameters, were compared among control, ACLDs and ACLD + MMPHT knees. ResultsCompared to the healthy controls, the ACLD knees with and without MMPHT showed significant extension deficiency at maximum extension (flexion: ACLDs: 7.83 ± 4.3°, ACLD + MMPHT: 11.09 ± 7.8°, control: 3.12 ± 4.6°, p = 0.005) and lower extension moments during terminal stance phase of gait. Compared with the healthy controls, significantly increased external tibial rotation during pre-swing phase and lower rotation moments at terminal stance phase were observed in the ACLD + MMPHT knees, but not in the ACLDs knees. No significant differences in gait parameters were observed between ACLDs and ACLD + MMPHT knees during stance phase of walking. SignificanceThe ACLD knees with medial meniscus posterior horn tear exhibited extension deficiency, increased external tibial rotation, lower extension and internal rotation moments during the terminal stance phase compared to healthy control knees, presenting a combination of “stiffening gait” and “pivot shift gait” pattern. The ACLDs knees only presented extension deficiency and lower extension moments compared with healthy control knees, presenting a “stiffening gait”. Medial meniscus posterior horn tear did not significantly affect gait patterns during stance of walking in ACLD knees.

Investigation on the kinetic and kinematic characteristics of knee and ankle joints during simulated downhill walking: Implication for ACL injury risk

We investigated 3D kinematic and kinetic changes of knee and ankle during downhill walking as the slope angle increased and evaluated biomechanical injury risk factors related to non-contact ACL injury. Fifteen male subjects performed level walking and 15° and 25° downhill walking. For the kinetic and kinematic parameters, one-way ANOVA and post-hoc tests were performed at a significance level of 0.05. This study revealed significant differences in 3D knee and ankle kinematics and kinetics among 0°, 15° and 25° downhill walking. The peak posterior ground reaction force, the peak knee anterior force and the knee valgus moment (0° vs. 15°: p < 0.05; 0° vs. 25°: p < 0.05) in the early stance phase increased as the slope angle increased. The peak knee internal tibial rotation moments in the late stance also increased (0° vs. 15°: p < 0.05; 0° vs. 25°: p < 0.05; 15° and 25°: p < 0.05) as the slope angle increased. These results showed the risk for ACL injuries may be increased during downhill walking with a greater slope angle.

Strain Response of the Anterior Cruciate Ligament to Uniplanar and Multiplanar Loads During Simulated Landings

Background: Despite basic characterization of the loading factors that strain the anterior cruciate ligament (ACL), the interrelationship(s) and additive nature of these loads that occur during noncontact ACL injuries remain incompletely characterized. Hypothesis: In the presence of an impulsive axial compression, simulating vertical ground-reaction force during landing (1) both knee abduction and internal tibial rotation moments would result in increased peak ACL strain, and (2) a combined multiplanar loading condition, including both knee abduction and internal tibial rotation moments, would increase the peak ACL strain to levels greater than those under uniplanar loading modes alone. Study Design: Controlled laboratory study. Methods: A cadaveric model of landing was used to simulate dynamic landings during a jump in 17 cadaveric lower extremities (age, 45 ± 7 years; 9 female and 8 male). Peak ACL strain was measured in situ and characterized under impulsive axial compression and simulated muscle forces (baseline) followed by addition of anterior tibial shear, knee abduction, and internal tibial rotation loads in both uni- and multiplanar modes, simulating a broad range of landing conditions. The associations between knee rotational kinematics and peak ACL strain levels were further investigated to determine the potential noncontact injury mechanism. Results: Externally applied loads, under both uni- and multiplanar conditions, resulted in consistent increases in peak ACL strain compared with the baseline during simulated landings (by up to 3.5-fold; P ≤ .032). Combined multiplanar loading resulted in the greatest increases in peak ACL strain (P < .001). Degrees of knee abduction rotation (R2 = 0.45; β = 0.42) and internal tibial rotation (R2 = 0.32; β = 0.23) were both significantly correlated with peak ACL strain (P < .001). However, changes in knee abduction rotation had a significantly greater effect size on peak ACL strain levels than did internal tibial rotation (by ~2-fold; P < .001). Conclusion: In the presence of impulsive axial compression, the combination of anterior tibial shear force, knee abduction, and internal tibial rotation moments significantly increases ACL strain, which could result in ACL failure. These findings support multiplanar knee valgus collapse as one the primary mechanisms of noncontact ACL injuries during landing. Clinical Relevance: Intervention programs that address multiple planes of loading may decrease the risk of ACL injury and the devastating consequences of posttraumatic knee osteoarthritis.

Research-Based and Clinical Considerations for Effective Neuromuscular Training to Prevent Second Anterior Cruciate Ligament Injury

The second anterior cruciate ligament (ACL) injury after ACL reconstruction occurs at reported rates, ranging from 5-20 times greater than that of the primary injury, and results in significantly poorer patient outcomes. In athletes, most of the second ACL injuries occur within the first 2 years of return to sport. Significant functional impairments and deficits in neuromuscular control are frequently reported up to 2 years postreconstruction. Neuromuscular deficit-targeted neuromuscular training (NMT) alters high-risk biomechanics and reduces rates of primary ACL injury. Its efficacy in ACL-injured subjects is currently unknown. External loads during dynamic motion, specifically knee abduction moment, internal tibial rotation moment, and proximal anterior tibial shear force, especially in the lateral compartment, increase ACL strain. These factors are reportedly influenced by modifiable and nonmodifiable factors. ACL reconstruction subjects pose a unique challenge to clinicians and researchers due to the numerous confounding factors in identifying and addressing their risk of reinjury. However, they also may provide clinicians and researchers with a great deal of accessible, highly pertinent clinical, anatomical, and biomechanical information in the forms of medical images, charts, and rehabilitation notes. Thorough determination of postoperative biomechanical impairments, modifiable and nonmodifiable risk factors, and the effects of NMT on these factors aids in eventual reduction of second ACL injury rates. A properly structured and executed large-scale, multicenter trial to evaluate the biomechanical efficacy of NMT in the context of these factors would be invaluable both clinically and academically.

Preferential Loading of the ACL Compared With the MCL During Landing

Background: Strong biomechanical and epidemiological evidence associates knee valgus collapse with isolated, noncontact anterior cruciate ligament (ACL) injuries. However, a concomitant injury to the medial collateral ligament (MCL) would be expected under valgus collapse, based on the MCL’s anatomic orientation and biomechanical role in knee stability. Purpose/Hypothesis: The purpose of this study was to investigate the relative ACL to MCL strain patterns during physiological simulations of a wide range of high-risk dynamic landing scenarios. We hypothesized that both knee abduction and internal tibial rotation moments would generate a disproportionate increase in the ACL strain relative to the MCL strain. However, the physiological range of knee abduction and internal tibial rotation moments that produce ACL injuries are not of sufficient magnitude to compromise the MCL’s integrity consistently. Study Design: Controlled laboratory study. Methods: A novel in sim approach was used to test our hypothesis. Seventeen cadaveric lower extremities (mean age, 45 ± 7 years; 9 female and 8 male) were tested to simulate a broad range of landings after a jump under anterior tibial shear force, knee abduction, and internal tibial rotation at 25° of knee flexion. The ACL and MCL strains were quantified using differential variable reluctance transducers. An extensively validated, detailed finite element model of the lower extremity was used to help better interpret experimental findings. Results: Anterior cruciate ligament failure occurred in 15 of 17 specimens (88%). Increased anterior tibial shear force and knee abduction and internal tibial rotation moments resulted in significantly higher ACL:MCL strain ratios (P < .05). Under all modes of single-planar and multiplanar loading, the ACL:MCL strain ratio remained greater than 1.7, while the relative ACL strain was significantly higher than the relative MCL strain (P < .01). Relative change in the ACL strain was demonstrated to be significantly greater under combined multiplanar loading compared with anterior tibial shear force (P = .016), knee abduction (P = .018), and internal tibial rotation (P < .0005) moments alone. Conclusion: While both the ACL and the MCL resist knee valgus during landing, physiological magnitudes of the applied loads leading to high ACL strain levels and injuries were not sufficient to compromise the MCL’s integrity. Clinical Relevance: A better understanding of injury mechanisms may provide insight that improves current risk screening and injury prevention strategies. Current findings support multiplanar knee valgus collapse as a primary factor contributing to a noncontact ACL injury.

Biomechanical Comparison Of Double Bundle Versus Single Bundle Anterior Cruciate Ligament Reconstruction Using Three Dimensional Gait Analysis

No differences were detected between anatomic SB and DB ACL reconstructed patients with regard overall tibio-femoral rotation and adduction moments. There has been a recent focus on surgical techniques that more closely approximate the anatomy of the anterior cruciate ligament (ACL). Double bundle techniques have gained popularity but are more surgically demanding, costly and may lead to more complex revision procedures. Outcome measures used in clinical studies may not be sensitive enough to detect a difference between the techniques, therefore more accurate in vivo studies are required. This study utilizes three dimensional gait analysis to compare two groups of patients having undergone either an anatomical single or double bundle ACL reconstruction. It is hypothesised that there will be no significant difference between the two groups with regard tibio-femoral rotation and knee adduction moments. Twenty-eight patients (14 SBACLR, 14 DBACLR) were assessed using a ten-camera Vicon system allowing three dimensional gait analysis. They were each required to perform four tasks: level walking, step descent and immediate pivot, jog and cut and hop and dodge The overall range of tibial rotation and knee adduction moments were recorded for the reconstructed and normal contralateral knee. Other outcome measures including KT-1000, IKDC score and functional hop tests were recorded and clinical tests such as a Lachman and pivot shift were performed. Patient demographics were similar for both groups and all patients were clinically stable and satisfied with their reconstructed knee (IKDC A or B). There were no significant differences for range of tibial rotation between the reconstructed and ACL intact limbs for either the DB or SB groups. Similarly there were no differences between DB and SB groups regarding adduction moments. This paper demonstrates that an anatomical single bundle ACL reconstruction, when compared to the normal contralateral knee, is able to control tibio-femoral rotation and adduction moments as well as a double bundle procedure. The key may be anatomical graft position, not the number of bundles.

The effect of frame rates on knee kinetics during landing and cutting

The analysis of knee kinematics and kinematics during high-risk movements associated with anterior cruciate ligament (ACL) injury is essential to studying the mechanism of ACL injury. Motion capture at low frame rates may not always detect the actual peak values during high-speed movements. However, the knee kinetic differences between various frame rate measurements during high-risk movements have not been reported. The purpose of this study was to investigate whether 3D knee kinetics would be measured differently between frame rates such as a high frame rate (1200 Hz), 400 Hz, 240 Hz and the popular low frame rate (120 Hz). Knee kinetics during a single-leg drop landing and side-step cutting under different frame rates were repeatedly measured and statistically compared. Peak knee valgus and tibial internal rotation moments measured at a popular low frame rate were significantly lower than those measured at the other frame rates of 400 Hz and 1200 Hz. The peak anterior and superior forces measured at the highest (1200 Hz) frame rate were significantly higher than those measured at any other frame rates. In addition, the variations in the peak kinetic values were significantly larger at the lowest frame rate capture and trended toward being smaller at the higher frame rates. In conclusion, significant differences in the knee kinetics between the frame rates suggest that the high frequency capturing increases the accuracy of the knee kinetics measurement for high risk maneuvers for the study of ACL injury.

Preferential Loading of the ACL Compared to the MCL during Landing: A Novel In Sim Approach Yields the Multi-Planar Mechanism of Dynamic Valgus during ACL Injury

Objectives:Strong biomechanical and epidemiologic evidence associates knee valgus collapse with isolated non-contact ACL injury. However, the predominance of isolated non-contact anterior cruciate ligament (ACL) injuries is challenging for clinicians and researchers to explain, as the medial collateral ligament (MCL) has been reported to be the primary restraint against knee valgus. The purpose of this study was to investigate the relative ACL to MCL strain patterns during physiologic simulations of a wide range of high-risk dynamic landing scenarios. We hypothesized that both knee abduction and internal tibial rotation moments would generate a disproportionate increase in ACL strain relative to MCL strain. However, the physiologic range of knee abduction and internal tibial rotation moments that produce ACL injuries would not be of sufficient magnitude to consistently compromise MCL integrity.Methods:A novel in sim approach was used to test our hypotheses. 17 cadaveric lower extremities (45 ± 7 years, 9 female & 8 male) were tested to simulate a broad range of landing conditions following a jump under anterior tibial shear, knee abduction and internal tibial rotation. Specimens were oriented to simulate lower extremity posture during ground strike while landing from a jump. Landing was simulated by applying an impulsive axial impact load (simulating ground reaction forces) under simulated muscle forces. ACL and MCL strains were quantified using DVRT displacement transducers arthroscopically placed across the ACL AM-bundle and sutured to the anterior/middle/posterior aspects of superficial MCL across the joint line. Specimens were tested until failure. Multiple paired and independent t-tests along with general linear models were used to investigate the changes in strain levels under each modes of loading. An extensively validated, detailed finite element model of the lower extremity was used to better interpret experimental findings.Results:ACL failure was generated in 15 of 17 specimens (88%). Increased anterior tibial shear force, and knee abduction and internal tibial rotation moments resulted in significantly higher ACL: MCL strain ratios (p<0.05) compared to landing under no applied external loads. Under all modes of single- and multi-planar loading, ACL: MCL strain ratio remained greater than 1.7, and relative ACL strain was significantly higher than relative MCL strain (p<0.003, Figure 1). Relative change in ACL strain was significantly greater under combined multi-planar loading compared to ACL strain under anterior tibial shear force (p=0.016), knee abduction (p=0.018) and internal tibial rotation (p<0.0005) moments alone.Conclusion:The tibiofemoral frontal plane loading mechanism has become a recent topic of debate as a contributing factor to non-contact ACL injuries. Both in vivo and video analyses studies indicate that increased knee abduction is associated with increased risk for ACL injury. The current findings demonstrates that while both the ACL and MCL resist knee valgus during landing, physiological magnitudes of the applied loads that lead to high ACL strain levels and injury were not sufficient to compromise MCL integrity. Further, these findings support multi-planar knee valgus collapse as a primary mechanism of non-contact ACL injury. This enhances our understanding of the non-contact ACL injury mechanism, and provides insight that can improve current risk screening and injury prevention strategies.

Clinically Relevant Injury Patterns After an Anterior Cruciate Ligament Injury Provide Insight Into Injury Mechanisms

Background: The functional disability and high costs of treating anterior cruciate ligament (ACL) injuries have generated a great deal of interest in understanding the mechanism of noncontact ACL injuries. Secondary bone bruises have been reported in over 80% of partial and complete ACL ruptures. Purpose: The objectives of this study were (1) to quantify ACL strain under a range of physiologically relevant loading conditions and (2) to evaluate soft tissue and bony injury patterns associated with applied loading conditions thought to be responsible for many noncontact ACL injuries. Study Design: Controlled laboratory study. Methods: Seventeen cadaveric legs (age, 45 ± 7 years; 9 female and 8 male) were tested utilizing a custom-designed drop stand to simulate landing. Specimens were randomly assigned between 2 loading groups that evaluated ACL strain under either knee abduction or internal tibial rotation moments. In each group, combinations of anterior tibial shear force, and knee abduction and internal tibial rotation moments under axial impact loading were applied sequentially until failure. Specimens were tested at 25° of flexion under simulated 1200-N quadriceps and 800-N hamstring loads. A differential variable reluctance transducer was used to calculate ACL strain across the anteromedial bundle. A general linear model was used to compare peak ACL strain at failure. Correlations between simulated knee injury patterns and loading conditions were evaluated by the χ2 test for independence. Results: Anterior cruciate ligament failure was generated in 15 of 17 specimens (88%). A clinically relevant distribution of failure patterns was observed including medial collateral ligament tears and damage to the menisci, cartilage, and subchondral bone. Only abduction significantly contributed to calculated peak ACL strain at failure (P = .002). While ACL disruption patterns were independent of the loading mechanism, tibial plateau injury patterns (locations) were significantly (P = .002) dependent on the applied loading conditions. Damage to the articular cartilage along with depression of the midlateral tibial plateau was primarily associated with knee abduction moments, while cartilage damage with depression of the posterolateral tibial plateau was primarily associated with internal tibial rotation moments. Conclusion: The current findings demonstrate the relationship between the location of the tibial plateau injury and ACL injury mechanisms. The resultant injury locations were similar to the clinically observed bone bruises across the tibial plateau during a noncontact ACL injury. These findings indicate that abduction combined with other modes of loading (multiplanar loading) may act to produce ACL injuries. Clinical Relevance: A better understanding of ACL injury mechanisms and associated risk factors may improve current preventive, surgical, and rehabilitation strategies and limit the risk of ACL and secondary injuries, which may in turn minimize the future development of posttraumatic osteoarthritis of the knee.

Effect of Fatigue on Tibial Rotation After Single- and Double-Bundle Anterior Cruciate Ligament Reconstruction

Background: Fatigue is an extrinsic factor adversely affecting joint proprioception and neuromuscular response, thereby increasing anterior cruciate ligament (ACL) strain and injury risk. The effectiveness of the single- and double-bundle techniques for ACL reconstruction to control residual rotational knee laxity under fatigue has not been examined. Hypothesis: Fatigue results in a significant increase in tibial rotation angles and moments in both ACL-intact and single- and double-bundle ACL-reconstructed knees. The 2 groups with ACL-reconstructed knees will show no significant differences in tibial rotation angles and moments either pre- or postfatigue. Study Design: Controlled laboratory study. Methods: Twenty-four male patients who underwent successful single-bundle (n = 12) or double-bundle (n = 12) ACL reconstructions and 10 matched healthy controls were subjected to a standard lower limb muscle fatigue protocol using an isokinetic dynamometer. Three-dimensional motion analysis was used to measure tibial rotation and rotational knee moments in the pre- and postfatigue states, during a swinging maneuver on the weightbearing leg from a standing position with the knee in extension. Results: Tibial rotation of the single-bundle group significantly increased postfatigue (prefatigue 22° ± 10° vs 29° ± 15° postfatigue, P = .015). In contrast, the double-bundle group showed similar tibial rotation values pre- and postfatigue (16° ± 6° vs 18° ± 4°, P = .22). The double-bundle group showed a trend toward decreased tibial rotation values pre- and post-fatigue compared with controls (22 ± 4 and 23 ± 4) (P = .065 and .08, respectively). In the prefatigue state, rotational moments (N·mm/Kg) of the single-bundle (339 ± 148) and double-bundle (317 ± 97) groups were significantly lower than that of controls (465 ± 134) (P = .05 and .03, respectively). In the postfatigue state, an increase was observed in rotational moments of the single-bundle (388 ± 131) and double-bundle (408 ± 187) groups compared with prefatigue values, whereas a decrease was noted in the control group (411 ± 117). Conclusion: Single-bundle ACL-reconstructed knees demonstrate a reduced ability to resist rotational loads under fatigue. Double-bundle reconstructed knees had significantly better control of tibial rotation when fatigued. However, they demonstrate an excessive, yet not significant, reduction in tibial rotation compared with the intact knee, suggesting a possible overcorrection in rotational laxity.

Tibial Plateau Geometry Influences Lower Extremity Biomechanics During Landing

Background: Intersubject differences in lateral and medial posterior tibial plateau slope, coronal tibial slope (CTS), and medial tibial plateau depth (MTD) may influence one’s susceptibility for anterior cruciate ligament (ACL) injury. Understanding how these structural characteristics influence hip and knee joint biomechanics during weightbearing activity may advance our understanding of how tibial plateau geometry influences one’s injury risk potential. Purpose/Hypotheses: To determine the extent to which tibial plateau geometry is associated with frontal and transverse plane hip and knee joint biomechanics during the initial landing phase of a double-legged drop landing. Greater lateral tibial slope combined with lower medial/lateral tibial slope ratio would predict greater tibial internal rotation motion and moments. Lower CTS would predict greater hip adduction and knee valgus motion and reduced internal peak varus moments. These associations would be stronger when combined with a shallower MTD. Study Design: Descriptive laboratory study. Methods: Magnetic resonance scans of the knee were obtained on 23 female participants who were also assessed for hip and knee joint biomechanics during the initial landing phase of double-legged drop jumps. Results: Once controlling for the respective initial hip flexion or initial knee flexion angle at ground contact, lower CTS consistently predicted greater initial and peak hip adduction and knee valgus angles (R2 range, .212-.427, P < .027). Greater coronal and lateral tibial slope predicted greater hip internal rotation (femur relative to pelvis) at initial contact (R2 = .504) and greater CTS and lower medial/lateral tibial slope ratio predicted greater knee internal rotation (tibia relative to femur) excursions (R2 = .594, P = .001). Joint geometry was not associated with hip or knee peak joint moments. Conclusion: These data confirm substantial intersubject differences in tibial condylar geometry that are associated with intersubject differences in hip and knee motion patterns when landing from a jump. Clinical Relevance: The current findings may partially explain a female’s greater likelihood of demonstrating combined motion patterns of knee valgus and external rotation during landing. Although tibial geometry cannot be modified through training, these associations suggest that tibial geometry may have a substantial influence on tibiofemoral joint biomechanics when the knee is subjected to external loads and deserves further study in our understanding of ACL injury.