Peak Knee Valgus Moment Research Articles

The applied impact of ‘naïve’ statistical modelling of clustered observations of motion data in injury biomechanics research

ObjectivesAppropriate statistical analysis of clustered data necessitates accounting for within-participant effects to ensure results are repeatable and translatable to real-world applications. This study aimed to compare statistical output and injury risk interpretation differences from two statistical regression models built from a clinical movement sidestepping database. A “naïve” regression model, which does not account for within-participant effects, was compared with an appropriately applied mixed effects model. DesignComparative study. MethodsThree-dimensional unplanned sidestepping joint angle data (trunk, hip, and knee) from 35 males (112 observations) were used to model peak knee valgus moments and anterior cruciate ligament injury risk during the impact phase of stance. Both statistical models were cross-validated using a k-fold analysis. ResultsThe naïve regression returned inflated goodness of fit statistics (R2=0.50), which was evident following cross-validation (predicted R2=0.43). Following cross-validation, the mixed effects model (predicted R2=0.40) explained a similar amount of variance, despite containing three less predictors. The naïve model produced inaccurate parameter estimates, overestimating the effects of certain kinematic parameters by as much as 79 %. ConclusionsA regression model naïvely applied to clustered observations of sidestepping data resulted in erroneous parameter estimates and goodness of fit statistics which have the potential to mislead future research and real-world applications. It is important for sport and clinical scientists to use statistically appropriate mixed effects models when modelling clustered motion capture data for injury biomechanics research to protect the translatability of the findings.

The Effects of a Compression Garment on Lower Body Kinematics and Kinetics During a Drop Vertical Jump in Female Collegiate Athletes

Background:The use of compression garments has spread rapidly among athletes, largely because of marketing and perceived benefits. Upon review, it is unclear whether compression garments have a significant effect on performance and recovery, although they have been found to enhance proprioception. Further, it is reported that compression of the knee joint improves both dynamic and static balance. However, there is currently a paucity of data demonstrating the effects of compression garments on the biomechanical risk factors of knee-related injuries in female athletes.Purpose:To evaluate the ability of a directional compression garment to alter hip and knee kinematics and kinetics during a drop vertical jump (DVJ) in healthy college-aged female athletes.Study Design:Controlled laboratory study.Methods:A sample of 23 healthy female collegiate athletes (mean age, 19.6 ± 1.3 years) participating in jumping sports (volleyball, basketball, and soccer) was included in this analysis. Each athlete performed 2 sets of 3 DVJs with and without a directional compression garment. Three-dimensional hip and knee kinematics and kinetics were collected using a standard Helen-Hayes 29-marker set, which was removed and reapplied after the garment was fitted, as well as 8 visible-red cameras and 2 force platforms. Each participant was tested in a single session.Results:Hip abduction range of motion was significantly reduced from 12.6° ± 5.5° to 10.2° ± 4.6° (P = .002) while performing DVJs without and with the compression garment, respectively. No statistically significant differences between conditions were found in peak hip abduction, knee valgus range of motion, peak valgus, peak hip abduction moment, and peak knee valgus moment.Conclusion:The results of this study show that wearing compression garments does have minimal effects on lower body mechanics during landing from a DVJ, partially supporting the idea that compression garments could acutely alter movement patterns associated with the knee injury risk. However, further research should focus on muscle activation patterns and adaptations over time.Clinical Relevance:The use of specifically designed compression garments could aid in the prevention of knee injuries by inducing changes in jumping mechanics.

Age Influences Biomechanical Changes After Participation in an Anterior Cruciate Ligament Injury Prevention Program

Background: The prevalence of anterior cruciate ligament (ACL) injuries increases during maturation and peaks during late adolescence. Previous studies suggested an age-related association between participation in injury prevention programs and reduction of ACL injury. However, few studies have investigated differences in biomechanical changes after injury prevention programs between preadolescent and adolescent athletes. Purpose/Hypothesis: The purpose was to investigate the influence of age on the effects of the FIFA Medical and Research Centre (F-MARC) 11+ injury prevention warm-up program on differences in biomechanical risk factors for ACL injury between preadolescent and adolescent female soccer players. It was hypothesized that the ACL injury risk factors of knee valgus angle and moment would be greater at baseline but would improve more after training for preadolescent athletes than adolescent athletes. It was further hypothesized that flexor-extensor muscle co-contraction would increase after training for both preadolescent and adolescent athletes. Study Design: Controlled laboratory study. Methods: Institutional Review Board–approved written consent was obtained for 51 preadolescent female athletes aged 10 to 12 years (intervention: n = 28, 11.8 ± 0.8 years; control: n = 23, 11.2 ± 0.6 years) and 43 adolescent female athletes aged 14 to 18 years (intervention: n = 22, 15.9 ± 0.9 years; control: n = 21, 15.7 ± 1.1 years). The intervention groups participated in 15 in-season sessions of the F-MARC 11+ program 2 times per week. Pre- and postseason motion capture data were collected during 4 tasks: preplanned cutting, unanticipated cutting, double-legged jump, and single-legged jump. Lower extremity joint angles and moments were estimated through biomechanical modeling. Knee flexor-extensor muscle co-contraction was estimated from surface electromyography. Results: At baseline, preadolescent athletes displayed greater initial contact and peak knee valgus angles during all activities when compared with the adolescent athletes, but knee valgus moment was not significantly different between age groups. After intervention training, preadolescent athletes improved and decreased their initial contact knee valgus angle (–1.24° ± 0.36°; P = .036) as well as their peak knee valgus moment (–0.57 ± 0.27 percentage body weight × height; P = .033) during the double-legged jump task, as compared with adolescent athletes in the intervention. Compared with adolescent athletes, preadolescent athletes displayed higher weight acceptance flexor-extensor muscle co-contraction at baseline during all activities (P < .05). After intervention training, preadolescent athletes displayed an increase in precontact flexor-extensor muscle co-contraction during preplanned cutting as compared with adolescent intervention athletes (0.07 ± 0.02 vs –0.30 ± 0.27, respectively; P = .002). Conclusion: The F-MARC 11+ program may be more effective at improving some risk factors for ACL injury among preadolescent female athletes than adolescent athletes, notably by reducing knee valgus angle and moment during a double-legged jump landing. Clinical Relevance: ACL prevention programs may be more effective if administered early in an athlete’s career, as younger athletes may be more likely to adapt new biomechanical movement patterns.

Can Repeated Ponseti Management for Relapsed Clubfeet Produce the Outcome Comparable With the Case Without Relapse? A Clinical Study in Term of Gait Analysis.

The prevention and treatment of relapsed clubfoot remained challenging tasks. There were controversies as to treatment options and management, such as complete subtalar release, application of an Ilizarov external frame, or repeated Ponseti method; and different options were available in different treatment centers. This study was designed to evaluate the clinical outcome of relapsed clubfeet treated by repeated Ponseti method in comparison with the cases without relapse in term of gait analysis and to clarify the clinical efficacy of repeated Ponseti method in treating the relapsed clubfeet. Thirty-seven patients (53 feet) were retrospectively identified from our database according to the inclusion and exclusion criteria. Among the 37 patients, 17 cases (25 relapsed clubfeet) were assigned to group I, whereas 20 cases (28 clubfeet without relapse) were assigned to group II. Clinical examination, gait analysis, and kinematic gait deviation criteria from Texas Scottish Rite Hospital for Children were used for evaluation. There was statistically significant difference in the parameters of foot length, stride length, and single limb support time (%gait cycle) between the 2 groups (P<0.05). No statistically significant difference was found in the kinematic parameters of total hip, knee, and ankle excursion, peak knee and ankle flexion and extension, and internal foot progression (P>0.05). There was no statistically significant difference in peak hip, knee, and ankle flexion moment, peak knee valgus moment, and peak ankle power (P>0.05). No statistically significant difference was found in equinus and calcaneus gait, increased ankle dorsiflexion, foot drop, and internal foot progression angle (P>0.05). Repeated Ponseti method for relapsed clubfeet can yield good or excellent clinical results. We recommend repeated Ponseti method as the treatment choice for relapsed clubfeet in the early stage. Level III-retrospective comparative study.

Do Neuromuscular Dentistry-Designed Mouthguards Enhance Dynamic Movement Ability in Competitive Athletes?

The purpose of this study was to examine the effect of a neuromuscular dentistry-designed mouthguard (NMDD) on dynamic movement ability. Forty-two competitive athletes (8 women, 21.9 ± 2.9 years, 66.8 ± 18.8 kg, 1.68 ± 0.11 m; 34 men, 22.8 ± 4.8 years, 77.4 ± 12.7 kg, 1.78 ± 0.08 m) with greater than 2 years' experience in their designated sport were enrolled in the study. Participants completed the Functional Movement Screen (FMS), modified Star Excursion Balance Test (mSEBT), and a single-leg landing (SLL) task. Each subject was tested with 3 separate mouthguard conditions in random order: (a) no mouthguard (NO), (b) over-the-counter boil-and-bite mouthguard (BB; Shockdoctor Gravity, (c) and an NMDD (Pure Power Elite). Data were analyzed using a repeated-measures analysis of variance for each variable. There were no differences between mouthguard conditions in each of the 7 individual components or composite FMS score (p > 0.05). No differences were seen in the anterior, posteromedial, or posterolateral movements of the mSEBT; overall composite score; or time-to-contact measurements (p > 0.05). The BB condition (2.16 Nm·kg) exhibited higher peak knee valgus moments (pKVM) on the right leg only when compared with the NMDD condition (1.95 Nm·kg; p = 0.003) but not the NO condition (2.09 Nm·kg; p = 0.7262) during the SLL task. No differences in pKVM were seen on the left leg (p = 0.324). In conclusion, an NMDD was not effective at enhancing or diminishing measures of dynamic movement ability compared with BB or NO conditions.

Visual Memory Influences the Effect of Soccer Ball Handling on Knee Valgus Angle while Cutting

BACKGROUND: Sports injuries remain a major concern for athletes despite ongoing efforts to improve screening and prevention methods. Recent research suggests that neurocognition may play a role in the neuromuscular control associated with injuries such as anterior cruciate ligament tears. Additionally, sport-specific tasks, such as dribbling a soccer ball, are integral to playing sports, but may also influence lower extremity mechanics. The relationship between neurocognitive ability and biomechanics during a sport specific cutting task has yet to be investigated. PURPOSE: To determine the relationship between neurocognition and the effect of soccer ball handling on lower extremity mechanics during a side-step task. METHODS: Fifteen healthy male collegiate soccer players (20.8 ± 2.0 yr; 1.77 ± 0.07 m; 77.0 ± 8.6 kg) participated in the study. Participants performed anticipated 45° run-to-cut trials while dribbling a soccer ball (BH) and without dribbling (NB) while 3D kinematics and kinetics were recorded. Approach speeds of NB trials were matched to those of BH trials. Peak knee valgus angle (pKValA) and moment for the plant leg were calculated. Participants also completed the ImPACT® neurocognitive assessment to evaluate visual and verbal memory, reaction time, and visual motor speed. Composite scores from the neurocognitive assessment were entered as candidate linear regression predictors for the change scores in lower extremity biomechanical parameters (i.e., BH – NB). Promising models with respect to adjusted-R2 and Mallow’s Cp were further evaluated for significance (α=0.05) through linear regression analysis. RESULTS: A one unit decrease in the visual memory composite score (i.e., worse visual attention, scanning, and/or visual learning) was associated with an increase in pKValA of 0.25° ± 0.07° during the BH task compared to the NB task (R2 = 45.8%, p = 0.006). CONCLUSION: The detrimental effect of soccer ball handling during a side-step cut movement on knee valgus was found to be influenced by athletes’ visual memory ability. These results may suggest that athletes with a diminished capacity for visual memory may be less able to maintain optimal biomechanics while accommodating the demands of sport-specific tasks that require visual attention.

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.

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.

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.

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.

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.

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.

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.

THE INFLUENCE OF HIP JOINT CONTROL ON KNEE JOINT VALGUS MOMENT IN YOUNG FEMALE ELITE ATHLETES

BackgroundBiomechanical investigations of sports-specific movements may yield information on which measures could be most efficient for prevention of Anterior Cruciate Ligament (ACL) injuries. High knee valgus moments have been related...

Comparison of Landing Biomechanics Between Male and Female Dancers and Athletes, Part 2

Background: Fatigue is strongly linked to an increased risk of injuries, including anterior cruciate ligament (ACL) ruptures. Part 1 of this study identified differences in the biomechanics of landing from a jump between dancers and team athletes, particularly female athletes, which may explain the epidemiological differences in ACL injuries between dancers and team athletes and the lack of a sex disparity within dancers. However, it is not known if these biomechanical variables change differently between team athletes and dancers in the face of fatigue. Purpose/Hypothesis: The purpose of this study was to compare dancers’ and team athletes’ resistance to fatigue and its effect on the biomechanics of single-legged drop landings. The primary hypotheses were that dancers may be more resistant than team athletes to the onset of fatigue and/or may have different biomechanical responses than athletes in landing tasks once fatigue has been achieved. Study Design: Controlled laboratory study. Methods: Kinematics and kinetics were recorded as 40 elite modern and ballet dancers (20 men and 20 women) and 40 team sport athletes (20 men and 20 women; National Collegiate Athletic Association Division I-III) performed single-legged drop landings from a 30-cm platform before and after a fatigue protocol consisting of step-ups and vertical jumps. Unfatigued and fatigued joint kinematics and kinetics were compared between groups and sexes with multivariate analyses of variance, followed by pairwise t tests as appropriate. Results: Dancers took longer (P = .023) than team athletes to reach a similar state of fatigue. Multiple kinetic (eg, increased peak knee valgus moment; P < .001) and kinematic (eg, increased lateral and forward trunk flexion; P < .001 and P = .002, respectively) parameters of landing changed with fatigue, such that both fatigued dancers and athletes landed with mechanics that were more at risk for ACL injuries as compared with before fatigue. Conclusion: Dancers took significantly longer to reach fatigue than team athletes. Female athletes consistently exhibited landing patterns associated with a risk for ACL injuries when compared with the other 3 groups. Fatigue changed landing mechanics similarly in both dancers and athletes, such that all groups landed with worse alignment after being fatigued. Clinical Relevance: Dancers are more resistant to lower extremity fatigue than athletes, and this may partially explain the lower incidence of ACL injuries in both male and female dancers compared to team athletes. The extensive training in landing technique and daily practice that dancers undergo from a young age may be responsible for the higher levels of endurance.

Effects of Different Visual Stimuli on Postures and Knee Moments during Sidestepping

Evasive sidestepping during sports commonly results in noncontact anterior cruciate ligament injuries. Sidestepping in response to different simple visual stimuli has been studied previously but never investigated using quasi-game-realistic visual conditions. We compared the biomechanics of high-level and low-level soccer players when sidestepping in response to projected, three-dimensional defender(s) and the traditionally used planned and unplanned arrow stimuli. A three-dimensional motion analysis system captured the trunk and lower limb kinematics and ground reaction forces of 15 high-level and 15 low-level soccer players sidestepping in response to a one-defender scenario (1DS), two-defender scenario (2DS), arrow-planned condition (AP), and arrow-unplanned condition (AUNP). The temporal constraints imposed by the stimuli conditions resulted in increasing difficulty from AP, 1DS, 2DS, to AUNP. Selected joint kinematics and three-dimensional knee moments during the weight-acceptance phase of sidestepping were analyzed. Hip external rotation at initial foot contact was smaller when participants sidestepped in response to the projected defenders versus arrow conditions. Hip abduction was smallest in the AP, moderate in the defender scenarios, and largest in the AUNP. Peak knee valgus moments were 25% larger in the defender scenarios and 70% larger in the AUNP compared with the AP. High-level players exhibited decreased hip abduction and knee valgus moments in the 2DS compared with the low-level players. Compared with the arrow conditions, sidestepping in response to the defender(s) resulted in different postures and knee moments, which further differentiated between high-level and low-level players in the complex 2DS. These findings highlight the effects of stimuli realism and complexity on the visual-perceptual-motor skill of sidestepping, which has implications for anterior cruciate ligament injury prevention.

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.

Lower Extremity Joint Posture and Peak Knee Valgus Moment during Side-step Cutting Performed by Males and Females

[Purpose] To determine the associations between peak knee valgus moment and lower extremity joint angles at initial contact and at peak knee valgus moment during side-step cutting and to investigate their associations with gender. [Subjects and Methods] Twenty healthy subjects and twenty basketball players participated in this study. Three-dimensional kinematics and kinetics of hip, knee and ankle joints were recorded during a side-step cutting protocol by six video cameras and a forceplate. Associations between peak knee valgus moment and three-dimensional hip, knee and ankle joint angles were analyzed using Pearson's product moment correlation. [Results] Peak knee valgus moment was significantly associated with increased hip flexion, knee flexion, ankle inversion and ankle external rotation at initial contact and at peak knee valgus moment. With regard to gender, significant associations between peak knee valgus moment and hip, knee and ankle joint angles were found only in females. [Conclusion] The results provided data on lower extremity joint posture related to peak knee valgus moment during side-step cutting and indicate that females are more sensitive to increased peak knee valgus moment while performing side-step cutting.

Anterior Cruciate Ligament Stress In The Golf Swing: Frontal Plane Knee Moments On The Target Side Limb.

Frontal plane knee moments (FPKM) have been shown to be an important factor in the development and progression of knee injury and disease. Specifically, the external knee valgus moment has been identified as a risk factor for ACL injury. It is most likely the case that loads experienced by the knee during the golf swing are not large enough to make golf a risk factor for acute knee injury. However, golf swing loads may create small microtraumas to knee's soft tissues with each swing that could build up over time and result in significant macrotraumas. Since foot position can have an effect on the FPKM during gait, quantifying these loads in two different foot positions during the golf swing may provide further information about the relative stresses on the knee. PURPOSE: To quantify the FPKM during the golf swing in two different front foot set-up positions and to compare these loads to those in other sporting activities. METHODS: Participants were seven healthy golfers (5M, 21.3±3.1 years) who were all members of the University's Golf Team. Each participant performed five golf swings with the lead foot straight (STR) and with the lead foot externally rotated (EXT) while kinetic and kinematic data were collected. These data were used to calculate the FPKM. RESULTS: All subjects had a peak external knee valgus moment just prior to ball contact whose magnitude did not change with external rotation of the foot at set up (STR = 0.70 Nm/kg±0.12, EXT = 0.80 Nm/kg±0.19, p>0.05). Surprisingly, these loads are of similar magnitude to those calculated during a jump landing task (0.74±0.12Nm/kg) and during a side-step cutting maneuver (1.2±0.4Nm/kg) for female athletes who either went on to tear their ACL or were considered to be at high risk for ACL injury. CONCLUSIONS: Although generally considered a docile sport, the golf swing creates loads on the knee that are of similar magnitudes as jump landing and cutting. Sports that require jumping and cutting have an unpredictability factor that is not present in golf; however, the repeated nature of the golf swing during practice and play may lead to microtraumas that could build up over time and lead to knee injury/disease. This also may have implications in creating exercises and/or swing modifications to reduce the stress on the soft tissues of the knee during golf.

Loading characteristics of females exhibiting excessive valgus moments during cutting

Excessive knee valgus moments are considered a risk factor for non-contact anterior cruciate ligament injuries in female athletes, however, little is known about the biomechanical factors that contribute to this loading pattern. The purpose of this study was to compare lower extremity kinematics, foot position and ground reaction forces between female soccer players who demonstrate normal frontal plane moments at the knee with those who demonstrate excessive frontal plane moments at the knee during a cutting maneuver. Sixty-one female soccer players, 16 (2) years, participated. Three dimensional kinematics and ground reaction forces were recorded during a side-step cutting maneuver. Knee frontal plane moments were calculated with inverse dynamics equations and were used to classify subjects into normal (N=38) and excessive valgus moment (N=23) groups. Data revealed that the subjects with excessive valgus moments demonstrated an initial loading pattern that included greater laterally directed ground reaction forces (P<0.001, effect size 1.51), increased hip abduction (P=0.002, effect size 0.79), increased hip internal rotation (P=0.008, effect size 0.71) and a more internally rotated foot progression angle (P=0.04, effect size 0.55). Taken together, these variables explained 49% of the variance in peak knee valgus moment (R=.698, P<0.001). These results provide insight into potentially injurious loading strategies and support the premise that interventions designed to encourage loading of the lower extremity in a more neutral alignment may work to decrease frontal plane loading at the knee.