Knee Valgus Moment Research Articles

Targeting associated mechanisms of anterior cruciate ligament injury in female community-level athletes

This study aims to determine if biomechanically informed injury prevention training can reduce associated factors of anterior cruciate ligament injury risk among a general female athletic population. Female community-level team sport athletes, split into intervention (n = 8) and comparison groups (n = 10), completed a sidestepping movement assessment prior to and following a 9-week training period, in which kinetic, kinematic and neuromuscular data were collected. The intervention group completed a biomechanically informed training protocol, consisting of plyometric, resistance and balance exercises, adjunct to normal training, for 15–20 min twice a week. Following the 9-week intervention, total activation of the muscles crossing the knee (n = 7) decreased for both the training (∆ −15.02%, d = 0.45) and comparison (∆ −9.68%, d = 0.47) groups. This decrease was accompanied by elevated peak knee valgus (∆ +27.78%, d = −0.36) and internal rotation moments (∆ +37.50%, d = −0.56) in the comparison group, suggesting that female community athletes are at an increased risk of injury after a season of play. Peak knee valgus and internal rotation knee moments among athletes who participated in training intervention did not change over the intervention period. Results suggest participation in a biomechanically informed training intervention may mitigate the apparent deleterious effects of community-level sport participation.

KNEE VALGUS ANGLE AND LOADING ACROSS COMMON ATHLETIC TASKS; REFERENCE VALUES AND GENDER DIFFERENCES IN A HEALTHY POPULATION

BackgroundAbnormal lower-limb mechanics during functional activities have been reported as being associated with several knee injuries. Hence it is important to develop screening tests to identify healthy individuals who may...

LOWER LEG BIOMECHANICS ASYMMETRIES DURING LANDING AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

BackgroundAsymmetries in knee motion have been identified as a risk factor for second anterior cruciate ligament (ACL)injury.ObjectiveTo investigate the kinematics and kinetics of knee joint and ground reaction force during...

BIOMECHANICAL ANALYSIS OF SINGLE-LEG SQUAT WITH ISOKINETIC AND CONSTANT RESISTIVE FORCE USING CONTROLLABLE EXERCISE EQUIPMENT

BackgroundWe have reported that a resistive single-leg squat (RSLS) exercise using exercise equipment that generates various resistance forces was effective for increasing the load on the gluteus medius and preventing...

Biomechanical Effects of an Injury Prevention Program in Preadolescent Female Soccer Athletes

Background: Anterior cruciate ligament (ACL) injuries are common, and children as young as 10 years of age exhibit movement patterns associated with an ACL injury risk. Prevention programs have been shown to reduce injury rates, but the mechanisms behind these programs are largely unknown. Few studies have investigated biomechanical changes after injury prevention programs in children. Purpose/Hypothesis: To investigate the effects of the F-MARC 11+ injury prevention warm-up program on changes to biomechanical risk factors for an ACL injury in preadolescent female soccer players. We hypothesized that the primary ACL injury risk factor of peak knee valgus moment would improve after training. In addition, we explored other kinematic and kinetic variables associated with ACL injuries. Study Design: Controlled laboratory study. Methods: A total of 51 female athletes aged 10 to 12 years were recruited from soccer clubs and were placed into an intervention group (n = 28; mean [±SD] age, 11.8 ± 0.8 years) and a control group (n = 23; mean age, 11.2 ± 0.6 years). The intervention group participated in 15 in-season sessions of the F-MARC 11+ program (2 times/wk). Pre- and postseason motion capture data were collected during preplanned cutting, unanticipated cutting, double-leg jump, and single-leg jump tasks. Lower extremity joint angles and moments were estimated using OpenSim, a biomechanical modeling system. Results: Athletes in the intervention group reduced their peak knee valgus moment compared with the control group during the double-leg jump (mean [±standard error of the mean] pre- to posttest change, –0.57 ± 0.27 %BW×HT vs 0.25 ± 0.25 %BW×HT, respectively; P = .034). No significant differences in the change in peak knee valgus moment were found between the groups for any other activity; however, the intervention group displayed a significant pre- to posttest increase in peak knee valgus moment during unanticipated cutting (P = .044). Additional analyses revealed an improvement in peak ankle eversion moment after training during preplanned cutting (P = .015), unanticipated cutting (P = .004), and the double-leg jump (P = .016) compared with the control group. Other secondary risk factors did not significantly improve after training, although the peak knee valgus angle improved in the control group compared with the intervention group during unanticipated cutting (P = .018). Conclusion: The F-MARC 11+ program may be effective in improving some risk factors for an ACL injury during a double-leg jump in preadolescent athletes, most notably by reducing peak knee valgus moment. Clinical Relevance: This study provides motivation for enhancing injury prevention programs to produce improvement in other ACL risk factors, particularly during cutting and single-leg tasks.

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.

Effect of ACL Graft Type on Side-Step Cutting in Young Athletes

Objectives:Due to the slightly higher re-tear rate for ACL reconstruction (ACLR) with hamstring (HT) versus patellar tendon (PT), differences in movement strategies were assessed during side-step cutting in young athletes with recent ACLR to determine if graft type affected post-operative motion.Methods:Dominant limbs from 21 athletes without lower extremity injury or previous surgery (age 14.9 ± 2.0 years) and 26 limbs with recent (5.1-8.0 months post-operative) unilateral ACLR were included, 18 with HT grafts (age 16.6 ± 3.7 years) and 8 with PT (age 16.7 ± 1.2 years). Lower extremity 3-dimensional data was recorded during the deceleration phase (initial contact to maximum knee flexion) of a 45° cut. Group differences were assessed using analysis of variance with Bonferroni post-hoc tests.Results:The HT group had a slower approach velocity than controls (2.9 vs. 3.5 m/s; p=0.006) with intermediate velocity in the PT group (3.2 m/s). Both the HT and PT groups had lower peak ground reaction force (GRF) compared to controls (HT: 2.0 body weights, PT: 2.2 BW, Control: 2.8 BW; p≤0.02), along with lower peak knee flexion moments (HT: 1.4 Nm/kg, PT: 1.3 Nm/kg, Control: 2.2 Nm/kg; p=0.002). The PT group had less power absorption at the knee than controls (0.3 vs. 0.7 Nm/kg; p=0.07), while the HT group had more at the hip (0.4 vs. 0.1 Nm/kg; p=0.04). The HT group also had higher peak hip flexion (HT: 65.8°, PT: 53.9°, Control: 55.1°; p≤0.06) and hip sagittal plane excursion (HT: 9.4°, PT: 3.6°, Control: 2.8°; p≤0.05) than the PT and control groups. The HT group had lower peak knee valgus moments than controls (0.05 vs. 1.2 Nm/kg; p=0.01) as well as a greater range of frontal plane pelvic (8.2° vs. 3.4°; p=0.03) and hip (7.6° vs. 3.0°; p=0.05) motion. The PT group had intermediate values for valgus moment (0.8 Nm/kg) and pelvic (4.9°) and hip (3.3°) excursion.Conclusion:While both ACLR groups showed reduced GRFs and knee flexion moments compared with controls, the HT group demonstrated greater adaptations proximally with increased hip flexion and frontal plane pelvic and hip excursion. The lower frontal and sagittal plane hip motion in the PT group may be due to anterior knee pain associated with PT grafts. Since the HT group exhibited movement adaptations, but no observable pathologic movement patterns, such as increased knee valgus moment, other factors likely account for the observed higher re-tear rate in HT vs. PT ACLR.

Deficits in Sagittal and Frontal Plane Mechanics during Drop Jump in Young Athletes with Recent Anterior Cruciate Ligament Reconstruction

Objectives:While the vertical drop jump (VDJ) is an established predictor of ACL injury risk, most studies have focused on frontal and transverse plane assessment in young adult athletes. This study assessed sagittal as well as frontal plane biomechanics during VDJ in adolescent athletes following recent anterior cruciate ligament reconstruction (ACLR).Methods:29 limbs with unilateral ACLR (69% female, mean age 15.8 ± 1.6 years, 5 to 12 months post-surgery), 29 contralateral non-operative limbs, and 19 control limbs (53% female, mean age of 15.5 ± 1.8 years) were evaluated during VDJ. Lower extremity three-dimensional kinematic and kinetic data from initial contact to peak knee flexion were compared among groups using analysis of variance with Bonferroni post-hoc tests.Results:The operative limbs had significantly lower peak ground reaction forces (GRF) than both control and contralateral limbs (ACLR: 1.7 body weights (BW), Contralateral: 2.1 BW, Control: 2.1 BW; p≤0.01) along with lower average external knee flexion moments (ACLR: 0.7Nm/kg, Contralateral: 0.9Nm/kg, Control: 1.1Nm/kg; p≤0.05) and reduced power absorption at the knee (ACLR: 0.9Nm/kg, Contralateral: 1.5Nm/kg, Control: 1.2Nm/kg; p≤0.01). Operative limbs had lower peak knee flexion (ACLR: 96.8°; Contralateral: 100.7°; p=0.001) and knee flexion excursion (ACLR: 75.0°, Contralateral: 82.5°; p=0.003) than contralateral limbs, but did not differ from controls in these measures. Both operative and non-operative limbs had greater peak hip flexion (ACLR: 98.9°, Contralateral: 99.8°, Control: 83.5°; p≤0.006), hip flexion excursion (ACLR: 60.8°, Contralateral: 65.6°, Control: 49.6°; p=), and power absorption at the hip (ACLR: 1.0Nm/kg, Contralateral: 1.2Nm/kg, Control: 0.7Nm/kg; p<0.03) compared with controls. In the coronal plane, both the operative and non-operative limbs demonstrated higher peak knee valgus moments compared to controls (ACLR: 0.5Nm/kg, Contralateral: 0.4Nm/kg, Control: 0.2Nm/kg; p≤0.02) and utilized less hip ab/adduction range (ACLR: 1.7°, Contralateral: 1.9°, Control: 6.1°; p≤0.003) though there were no differences in knee valgus angles (p≥0.31) or excursion (p≥0.52).Conclusion:Lower GRF and less energy absorbed at the knee during VDJ suggests a landing strategy that shifts loading from the post-surgical knee to the hip and contralateral limb. The frontal plane knee deficits in both the operative and non-operative limbs may place the limb at an elevated risk for future injury or re-injury. Avoidance of loading the reconstructed knee and residual deficits in frontal plane hip and knee control on either limb may indicate lack of readiness to return to full activity after recent ACLR.

Biomechanical Analysis Of A Single-leg Squat With Isokinetic Resistive Force By A Novel Exercise Equipment

Increased external knee valgus moment is a major factor in noncontact anterior cruciate ligament injury. Gluteal muscle activity is important for preventing excessive hip adduction motion and external knee valgus moment. To increase gluteal muscle activity during single-leg support, we devised a resistive single-leg squat (RSLS) exercise using a novel isokinetic exercise machine (ERIK ). RSLS is a closed kinetic chain exercise where the support leg performs a single-leg squat while sliding the opposite leg laterally against a resistive force. PURPOSE: To reveal the biomechanical and electromyographic (EMG) characteristics of the support leg during RSLS compared with those of a common single-leg squat (SLS). METHODS: Six asymptomatic female college students participated in this study. Participants performed RSLS and SLS. In RSLS, the movement speed of ERIK was 0.25 m/s and the reaching length was 80% of the SMD(spina malleollar distance). A motion capture system and force plate were used for motion analysis, and the support leg joint moments were calculated. Surface electrodes recorded EMG of support leg muscles. Average EMG amplitude during descent phase in both tasks was normalized by that during maximum voluntary contraction. The Wilcoxon signed-rank test was used for statistical analysis. RESULTS: In RSLS, hip adduction angle was significantly smaller (3.2±2.3° vs. 12.2±3.7°, p<0.05) and hip abduction angle was significantly larger (11.9±2.9° vs. 1.3±4.1°, p<0.05) than those in SLS. Motion patterns of the hip joint differed between RSLS and SLS. As descent motion progressed, hip abduction angle increased in RSLS, while hip adduction angle increased in SLS. External valgus moment occurred in 5 participants during SLS (0.2±0.2 Nm/kg) but in only 1 participant during RSLS. EMG activity of the gluteus medius was significantly higher in RSLS than in SLS (85±17% vs. 60±17%, p<0.05), as was that of the adductor longus muscle (35±18% vs. 23±13%, p<0.05). CONCLUSION: RSLS against isokinetic force with ERIK increased the load on the gluteus medius, and the alternate hip joint motion pattern seemed effective for preventing external knee valgus moment on the support leg. Supported by JSPS KAKENHI Grant No. 25282192.

Comparison of lateral shuffle and side-step cutting in young recreational athletes

This study compared three-dimensional (3-D) hip and knee kinematics and kinetics between lateral shuffle and side-step cutting movements to determine whether the simpler lateral shuffle movement can be used in place of cutting to assess knee injury risk. A total of 78 patients (52 female) and 34 controls (16 female) aged 8–19 years performed lateral shuffle and 45° side-step cutting movements. Hip and knee kinematics and kinetics between initial contact and peak knee flexion were calculated using the Plug-in-Gait model and compared between activities using Pearson's correlation and paired t-tests. Peak knee valgus angle correlated strongly (r=0.86, p<0.0001), while minimum (r=0.25, p=0.0001) and peak hip abduction (r=0.24, p=0.0003), and peak hip internal rotation (r=0.33, p<0.0001) correlated only weakly between the two activities. Peak external knee valgus moment (r=0.32, p<0.0001) and average external knee (r=0.42, p<0.0001) and hip (r=0.37, p<0.0001) flexion moments correlated weakly to moderately between activities. Subjects were more internally rotated (3.6°, p<0.0001) and less abducted (16.7° and 17.3° for minimum and maximum, p<0.0001) at the hip during cutting, with higher hip (0.12, p<0.0001) and lower knee (−0.02, p=0.0001) non-dimensional flexion moments. These results suggest that the lateral shuffle movement may be useful for evaluating knee valgus, particularly during initial visual assessment. However, the lateral shuffle may not be challenging enough to reveal poor neuromuscular control over hip ab/adduction and rotation, necessitating follow-up assessment of cutting, ideally using 3-D motion analysis.

Analysis of Jumping-Landing Manoeuvers after Different Speed Performances in Soccer Players.

PurposeRunning at high speed and sudden change in direction or activity stresses the knee. Surprisingly, not many studies have investigated the effects of sprinting on knee’s kinetics and kinematics of soccer players. Hence, this study is aimed to investigate indices of injury risk factors of jumping-landing maneuvers performed immediately after sprinting in male soccer players.MethodsTwenty-three collegiate male soccer players (22.1±1.7 years) were tested in four conditions; vertical jump (VJ), vertical jump immediately after slow running (VJSR), vertical jump immediately after sprinting (VJFR) and double horizontal jump immediately after sprinting (HJFR). The kinematics and kinetics data were measured using Vicon motion analyzer (100Hz) and two Kistler force platforms (1000Hz), respectively.ResultsFor knee flexion joint angle, (p = 0.014, η = 0.15) and knee valgus moment (p = 0.001, η = 0.71) differences between condition in the landing phase were found. For knee valgus joint angle, a main effect between legs in the jumping phase was found (p = 0.006, η = 0.31), which suggests bilateral deficit existed between the right and left lower limbs.ConclusionIn brief, the important findings were greater knee valgus moment and less knee flexion joint angle proceeding sprint (HJFR & VJFR) rather than no sprint condition (VJ) present an increased risk for knee injuries. These results seem to suggest that running and sudden subsequent jumping-landing activity experienced during playing soccer may negatively change the knee valgus moment. Thus, sprinting preceding a jump task may increase knee risk factors such as moment and knee flexion joint angle.

Predictors of Frontal Plane Knee Moments During Side-Step Cutting to 45 and 110 Degrees in Men and Women: Implications for Anterior Cruciate Ligament Injury.

To compare frontal plane knee moments, and kinematics and kinetics associated with knee valgus moments between cutting to 45 and 110 degrees, and to determine the predictive value of kinematics and ground reaction forces (GRFs) on knee valgus moments when cutting to these angles. Also, to determine whether sex differences exist in kinematics and kinetics when cutting to 45 and 110 degrees. Cross-sectional study. Laboratory setting. Forty-five (20 females) healthy young adult soccer athletes aged 16 to 23 years. Kinematic and kinetic variables were compared between randomly cued side-step cutting maneuvers to 45 and 110 degrees. Predictors of knee valgus moment were determined for each task. Kinematic variables: knee valgus angle, hip abduction, and internal rotation angles. Kinetic variables: vertical, posterior, and lateral GRFs, and knee valgus moment. Knee valgus moments were greater when cutting to 110 degrees compared with 45 degrees, and females exhibited greater moments than males. Vertical and lateral GRFs, hip internal rotation angle, and knee valgus angle explained 63% of the variance in knee valgus moment during cutting to 45 degrees. During cutting to 110 degrees, posterior GRF, hip internal rotation angle, and knee valgus angle explained 41% of the variance in knee valgus moment. Cutting tasks with larger redirection demands result in greater knee valgus moments. Similar factors, including shear GRFs, hip internal rotation, and knee valgus position contribute to knee valgus loading during cuts performed to smaller (45 degrees) and larger (110 degrees) angles. Reducing vertical and shear GRFs during cutting maneuvers may reduce knee valgus moments and thereby potentially reduce risk for anterior cruciate ligament injury.

Motor learning strategies in basketball players and its implications for ACL injury prevention: a randomized controlled trial

PurposeAdding external focus of attention (EF, focus on the movement effect) may optimize current anterior cruciate ligament (ACL) injury prevention programmes. The purpose of the current study was to investigate the effects of an EF, by a visual stimulus and an internal focus, by a verbal stimulus during unexpected sidestep cutting in female and male athletes and how these effects remained over time.MethodsNinety experienced basketball athletes performed sidestep cutting manoeuvres in three sessions (S1, S2 and S3). In this randomized controlled trial, athletes were allocated to three groups: visual (VIS), verbal (VER) and control (CTRL). Kinematics and kinetics were collected at the time of peak knee frontal plane moment.ResultsMales in the VIS group showed a larger vertical ground reaction force (S1: 25.4 ± 3.1 N/kg, S2: 25.8 ± 2.9 N/kg, S3: 25.2 ± 3.2 N/kg) and knee flexion moments (S1: −3.8 ± 0.9 Nm/kg, S2: −4.0 ± 1.2 Nm/kg, S3: −3.9 ± 1.3 Nm/kg) compared to the males in the VER and CTRL groups and to the females in the VIS group (p < 0.05). Additionally, the males in the VIS group reduced knee valgus moment and the females in the VER group reduced knee varus moment over time (n.s.).ConclusionMale subjects clearly benefit from visual feedback. Females may need different feedback modes to learn a correct movement pattern. Sex-specific learning preferences may have to be acknowledged in day by day practice. Adding video instruction or feedback to regular training regimens when teaching athletes safe movement patterns and providing individual feedback might target suboptimal long-term results and optimize ACL injury prevention programmes.Level of evidenceI.

Comparison of Three-Dimensional Motion During Side-Step Cutting in Pediatric Athletes with Recent ACL Reconstruction and those with No ACL Surgical History

Objectives:This study assessed differences between pediatric athletes’ anterior cruciate ligament (ACL) reconstructed limb and non-reconstructed limb compared to limbs with no lower extremity surgical history during a side-step cut.Methods:28 limbs with an ACL reconstruction within the 12 months prior to testing (operative limbs), 28 contralateral limbs (non-operative limbs) and 56 limbs with no lower extremity surgical history (control limbs; 28 individuals) were included. Lower extremity kinematic and kinetic 3-dimensional data was recorded during the deceleration phase of a side-step cut. Outcomes were evaluated at initial foot contact and between initial foot contact and maximum knee flexion of the cutting limb. Differences between operative and non-operative limbs and control limbs were assessed using analysis of variance with Bonferroni post-hoc tests.Results:Operative limbs had higher peak hip adduction (-0.14° ± 7.3 vs. -6.1° ± 5.0, =0.01) and higher average external knee valgus moments (0.16 Nm/kg ± 0.50 vs. -0.21Nm/kg ± 0.58, p=0.02) compared to control limbs. In terms of shock absorption, operative limbs had lower peak ground reaction forces (23.2 N/kg ± 4.7 vs. 28.3 N/kg ± 5.8, p<0.0001) and peak ankle dorsiflexion (14.5° ± 7.5 vs. 20.0° ± 6.4, p=0.002) compared to control limbs with lower peak external knee flexor moments (1.4 Nm/kg ± 0.61 vs. 2.0 Nm/kg ± 0.63, p<0.0001) and less power absorption at the knee (0.38 Ws/kg ± 0.31 vs. 0.55Ws/kg ± 0.34, p=0.05) and ankle (0.43 Ws/kg ± 0.21 vs. 0.65 Ws/kg ± 0.41, p=0.01). Though non-operative limbs had less knee valgus (-1.0° ± 3.5 vs. 1.1° ± 3.3, p=0.04) at initial contact, they had higher peak knee valgus (3.6° ± 5.7 vs. 0.58° ± 4.1, p=0.04) and higher average external knee valgus moments (0.09 Nm/kg ±0.59 vs. -0.21Nm/kg ±0.58, p=0.06) compared to control limbs. Non-operative limbs also had less pelvic obliquity compared to control limbs (10.4° ± 5.8 vs. 14.6° ± 7.7, p=0.04). Lower peak ground reaction forces (24.5 N/kg ± 4.5 vs. 28.3 N/kg ± 5.8, p=0.005), increased power absorption at the hip (0.43 Ws/kg ± 0.48 vs. 0.15 Ws/kg ± 0.23, p=0.005), and decreased power absorption at the ankle (0.49 Ws/kg ± 0.23 vs. 0.65 Ws/kg ± 0.41, p=0.09) were seen in non-operative compared to control limbs.Conclusion:Limbs with ACL reconstruction exhibited poorer hip stability compared to control limbs. ACL reconstructed limbs also had less energy absorption at the knee and lower peak vertical ground reaction forces, likely reflecting an avoidance strategy when performing a cut using an ACL reconstructed limb. The uninjured, contralateral limbs of ACL reconstructed patients also demonstrated reduced ground reaction forces and altered neuromuscular control. These changes may reflect overall tentativeness in performing a cut but also suggest baseline suboptimal neuromuscular control that possibly lends insight into the increased risk of contralateral ACL tear seen in patients who have sustained an index ACL tear. It is also possible that the biomechanical strategies present on the operative side could be putting the non-operative limb at risk for injury. These findings support the need for ongoing research into rehabilitation protocols and return to sport timing and also support to existing injury prevention programs.

Comparison of forward and backward walking in gait initiation

(0.41± 0.52Nm/kg) at landing phase. Sidestep cutting had peak valgusmoment (0.86± 0.35Nm/kg). Crossover cutting had peak varus moment (2.68± 0.43Nm/kg). Conclusion(s): High knee valgus moment during medial single leg hop at jumping phase, lateral single leg hop at landing phase and sidestep cutting maneuvers may increase ACL load and risk of injury. Medial and lateral single leg hop close to biomechanical property of actual sidestep cutting are more likely valid for predicting the risk of injury. Implications: Evaluations of knee valgus moment during medial, lateral single leg hop may produce effective ACL injury prevention programs in sports involving sidestep cutting.

Side-step Cutting In Pediatric Athletes With Recent Acl Reconstruction Compared To Those With No Acl Surgical History

PURPOSE: This study assessed differences between pediatric athletes’ anterior cruciate ligament (ACL) reconstructed limb and non-reconstructed limb compared to limbs with no lower extremity surgical history during a side-step cut. METHODS: 28 limbs with an ACL reconstruction within the 12 months prior to testing (operative limbs), 28 contralateral limbs (non-operative limbs) and 56 limbs with no lower extremity surgical history (control limbs; 28 individuals) were evaluated. Kinematic and kinetic data was recorded during the deceleration phase of a cut. Outcomes were evaluated at initial foot contact and between initial foot contact and maximum knee flexion of the cutting limb. Differences were assessed using analysis of variance. RESULTS: Operative limbs had higher peak hip adduction (p=0.01) and average external knee valgus moments (p=0.02) compared to control limbs. In terms of shock absorption, operative limbs had lower peak ground reaction forces (p<0.0001) and peak ankle dorsiflexion (p=0.002) compared to control limbs with lower peak external knee flexor moments (p<0.0001) and less power absorption at the knee (p=0.05) and ankle (p=0.01). Though non-operative limbs had lower knee valgus (p=0.04) at initial contact, they had higher peak knee valgus (p=0.04) and average external knee valgus moments compared to control limbs. Non-operative limbs also had less pelvic obliquity compared to control limbs (p=0.04). Lower peak ground reaction forces (p=0.005), increased power absorption at the hip (p=0.005), and decreased power absorption at the ankle (p=0.09) were seen in non-operative compared to control limbs. CONCLUSIONS: Limbs with ACL reconstruction exhibited poorer hip stability compared to control limbs. ACL reconstructed limbs also had less energy absorption at the knee and lower peak vertical ground reaction forces, likely reflecting an avoidance strategy when performing a cut. The uninjured, contralateral limbs of ACL reconstructed patients also demonstrated reduced ground reaction forces and altered neuromuscular control. These changes may reflect overall tentativeness in performing a cut but also suggest suboptimal neuromuscular control that possibly lends insight into the increased risk of contralateral ACL tear in patients who have sustained an index ACL tear. These findings support the need for ongoing research into rehabilitation protocols and return to sport timing.

Do exercises used in injury prevention programmes modify cutting task biomechanics? A systematic review with meta-analysis

ObjectiveSome injury prevention programmes aim to reduce the risk of ACL rupture. Although the most common athletic task leading to ACL rupture is cutting, there is currently no consensus on...

The effect of external ankle support on the kinematics and kinetics of the lower limb during a side step cutting task in netballers.

BackgroundExcessive knee valgus moments are considered to be a risk factor for non-contact injuries in female athletes. Knee injuries are highly prevalent in netballers and are significant in terms of cost and disability. The aim of the study was to identify if changes in external ankle support mechanisms effect the range of motion and loading patterns at the ankle and knee joint during a sidestep cutting manoeuvre in high performance netball players.MethodsNetballers with no previously diagnosed ankle or knee injury (n = 10) were recruited from NSW Institute of Sport netball programme. Kinematic and kinetic data were collected simultaneously using a 3-D Motion Analysis System and a force platform to measure ground reaction forces. Players performed repeated side step cutting manoeuvres whilst wearing a standard netball shoe, the same shoe with a lace-up brace and a high-top shoe.ResultsThe brace condition significantly reduced ankle joint ROM in the sagittal plane by 8.9° ± 2.4 when compared to the standard netball shoe (p = 0.013). No other significant changes were seen between conditions for either kinematic or kinetic data. All shoe conditions did however produce knee valgus moments throughout the cutting cycle that were greater than those considered excessive in the previous literature (0.59 Nm/kg-Bwt).ConclusionsThe results show that an external ankle support brace can be used to reduce the ROM at the ankle in the sagittal plane without affecting the loading of the joints of the lower limb. Internal varus moments generated at the knee during the task were however greater than values reported in the literature to classify excessive knee joint moments, regardless of the condition. All netballers exhibited lower extremity patterns and alignments previously associated with increased peak external valgus moments including; increasing hip abduction, peak hip flexion and internal rotation during early contact and high laterally directed ground reaction forces. Increased external valgus knee loads have been strongly linked to the development of non-contact injuries at the knee in female athletes and could highlight a potential mechanism for the development non-contact knee injuries in netballers performing side step cutting tasks.

The kinematic/kinetic differences of the knee and ankle joint during single-leg landing between shod and barefoot condition

Anterior cruciate ligament (ACL) injury often occurs among athletes during single-leg landing. Wearing shoes could alter lower extremity kinematics and kinetics and affect the risk of ACL injury. This study aimed to investigate knee and ankle kinematics and kinetics during single-leg landing in shod and barefoot conditions. Nineteen males performed single-leg landings by stepping off a 0.3-meter platform in shod and barefoot conditions. Three-dimensional lower limb kinetics and kinematics were calculated using a force plate and motion analysis system. The present study found that the peak knee valgus moment (p=0.024), peak anterior tibial translation (ATT) (p=0.022), and peak knee flexion angle (p<0.01) are greater during shod landing. In addition, the peak ankle inversion (p<0.01), peak eversion moment (p=0.032), and peak eversion angular velocity (p<0.01) were higher during shod landing. In conclusion, the increased knee valgus moment and ankle eversion moment suggest that shod conditions increase the risk of ACL injury; however, higher ATT and knee flexion angle during shod landing were not associated with increased risk of ACL injury. Further, the higher ankle movement in the coronal plane during shod conditions appears to increase the risk of ankle injury.

Effect of interventions on potential, modifiable risk factors for knee injury in team ball sports: a systematic review.

Knee injuries are one of the most common types of injuries in team ball sports, and prevention is crucial because of health and economic implications. To set up effective prevention programs, these programs must be designed to target potential, modifiable risk factors. In addition, it is essential to evaluate the effects of these prevention programs. The purpose of this study was to provide an overview of the effect of prevention programs on potential, modifiable risk factors for knee injuries in team ball sports. A systematic review was performed in PUBMED (1978 to December 2013), EMBASE (1973 to December 2013), and CINAHL (1992 to December 2013). The titles, abstracts, and full texts were analyzed according to predefined inclusion criteria to find relevant studies. Neuromuscular control training with plyometric and agility exercises with addition of instructions reduced knee valgus angles and moments in female athletes. Knee flexion angles and moments were enhanced by plyometric and resistance exercises with augmented feedback (verbal or video). The specificity of the exercises must match the task that needs to be improved. Hamstring/quadricep strength ratio and hamstring strength may be improved by isolated hamstring exercises. Various training components are required to reduce the risk of knee injury. Neuromuscular control training and the use of instructions/feedback (verbal or video) seem promising. However, attention should be given to the target populations and the specificity of the programs. More research is needed with respect to reducing risk factors in male athletes as well as in children.