Frontal Plane Knee Motion Research Articles

Examining movement asymmetries during three single leg tasks using interlimb and single subject approaches

Purposes: To examine whether healthy individuals displayed asymmetric trunk and lower extremity kinematics in the frontal and sagittal planes using both interlimb and single subject models. MethodsTrunk, pelvis, and lower extremity kinematic waveforms were analyzed bilaterally during the single leg squat (SLS), forward step down (FSD), and lateral step down (LSD). Participants identified task specific preferred and non-preferred legs based on perceived stability for interlimb analyses. Movement patterns were also analyzed with a single subject approach that included Fisher's exact tests to assess whether asymmetries were related to the task. ResultsParticipants were found to have increased pelvic drop on the non-preferred leg during the LSD from 41 to 77% of the movement (p = 0.01). No other bilateral differences were found for interlimb analyses. Single subject analyses indicated that no task had a greater probability of finding or not finding asymmetries. Associations were found between the FSD and SLS for frontal plane hip (p < 0.01) and knee motion (p < 0.01). ConclusionsInterlimb analyses can be influenced by intraparticipant movement variability between preferred and non-preferred legs. Movement asymmetries during single leg weightbearing are likely task dependent and a battery of tests is necessary for assessing bilateral differences.

Comparison of Three Single Leg Weightbearing Tasks with Statistical Parametric Mapping

The single leg squat (SLS), forward step down (FSD), and lateral step down (LSD) are clinically reliable movement screens for identifying motion imbalances. The current understanding for the kinematic profiles of each task is limited to discrete time points such as peak knee flexion. However, analyses of the entire movement would better aid clinicians when selecting the appropriate task for rehabilitation or movement screen purposes. The current study used Statistical Parametric Mapping to ascertain differences in the kinematic waveforms for the entire duration of each task. The trunk, pelvis, hip, and knee were analyzed in the sagittal and frontal planes. Data for each variable and task were analyzed from 0–100% of the movement. Primary findings indicated that the FSD provoked a greater magnitude of knee abduction than the SLS and LSD from 26–66% of the movement. The SLS generated the greatest amounts of trunk, pelvic, and hip flexion for the entirety of the movement. The LSD elicited the least amount of ipsilateral trunk lean (90–100%). Thus, the FSD may be optimal for assessing frontal plane knee motion as a screen for injury risk, while the SLS has potential to place increased sagittal plane demand on the muscles of the hip.

Preliminary brain-behavioral neural correlates of anterior cruciate ligament injury risk landing biomechanicsusing a novelbilateral leg press neuroimaging paradigm.

Anterior cruciate ligament (ACL) injury risk reduction strategies primarily focus on biomechanical factors related to frontal plane knee motion and loading. Although central nervous system processing has emerged as a contributor to injury risk, brain activity associated with the resultant ACL injury-risk biomechanics is limited. Thus, the purposes of this preliminary study were to determine the relationship between bilateral motor control brain activity and injury risk biomechanics and isolate differences in brain activity for those who demonstrate high versus low ACL injury risk. Thirty-one high school female athletes completed a novel, multi-joint leg press during brain functional magnetic resonance imaging (fMRI) to characterize bilateral motor control brain activity. Athletes also completed an established biomechanical assessment of ACL injury risk biomechanics within a 3D motion analysis laboratory. Knee abduction moments during landing were modelled as a covariate of interest within the fMRI analyses to identify directional relationships with brain activity and an injury-risk group classification analysis, based on established knee abduction moment cut-points. Greater landing knee abduction moments were associated with greater lingual gyrus, intracalcarine cortex, posterior cingulate cortex and precuneus activity when performing the bilateral leg press (all z > 3.1, p < .05; multiple comparison corrected). In the follow-up injury-risk classification analysis, those classified as high ACL injury-risk had greater activity in the lingual gyrus, parietal cortex and bilateral primary and secondary motor cortices relative to those classified as low ACL injury-risk (all z > 3.1, p < .05; multiple comparison corrected). In young female athletes, elevated brain activity for bilateral leg motor control in regions that integrate sensory, spatial, and attentional information were related to ACL injury-risk landing biomechanics. These data implicate crossmodal visual and proprioceptive integration brain activity and knee spatial awareness as potential neurotherapeutic targets to optimize ACL injury-risk reduction strategies.

Lower Extremity Kinematics of the Y-Balance Test in Healthy and ACL Injured Adolescent Females.

BackgroundAdolescent females are at significant risk for sustaining an ACL injury. The Y-Balance Test (YBT) is frequently used to evaluate neuromuscular control and lower extremity function. However, few studies have quantified 2D lower extremity kinematics during performance of the YBT, and there is an absence of kinematic data specific to at-risk adolescent females.PurposeTo examine lower extremity joint kinematics during execution of the YBT by healthy and ACL-injured adolescent females.Study DesignProspective cohort.MethodsTwenty-five healthy and ten ACL-injured (mean time from injury 143 days) adolescent females were assessed using the YBT. Sagittal and frontal plane knee and ankle motion was video recorded during execution of the YBT anterior reach movement. Ankle dorsi-flexion, knee flexion, and knee valgus angles were quantified via kinematic analysis. ANOVAs with a post hoc Bonferroni correction were used to compare YBT scoring (%LL) and kinematic data between groups. Pearson product-moment correlations determined the relationship between kinematic data and YBT scoring.ResultsHealthy and ACL-injured subjects demonstrated similar YBT scores and lower extremity kinematic data. Healthy subjects demonstrated a weak positive correlation between ankle dorsiflexion and YBT scoring, and a weak negative correlation between knee valgus and YBT scoring. These relationships did not exist for ACL-injured subjects. Kinematic data for both groups also demonstrated a large degree of variability, regardless of YBT score.ConclusionsAdolescent females frequently utilize a variety of lower extremity movement strategies when performing a functional movement task, and scoring on the YBT offers limited insight regarding lower extremity joint kinematics and ACL-injury risk in a physically active adolescent female population.Level of EvidenceLevel 3.

Effects of prolonged load carriage on angular jerk of frontal and sagittal knee motion

BackgroundDuring training, service members routinely walk with heavy body borne loads for long periods of time. These loads alter knee biomechanics and may produce jerky knee motions that reportedly increase joint loading and risk of musculoskeletal injury. Yet, it is unknown if service members use jerky knee motions during prolong walking with body borne load. Research questionTo quantify the effects of body borne load and duration of walking on the jerkiness of sagittal and frontal plane knee motion. MethodsEighteen participants had angular jerk of knee motion quantified while they walked (1.3 m/s) for 60-min with three body borne loads (0, 15, and 30 kg). Peak and cost of angular jerk for sagittal and frontal plane knee motion was quantified and submitted to a repeated measures linear model to test the main effects and interaction of load (0, 15, and 30 kg) and time (0, 15, 30, 45, and 60 min). ResultsBody borne load increased peak and cost of angular jerk for sagittal plane knee motion up to 35 % and 110 %, respectively, and frontal plane knee motion up to 20 % and 51 %, respectively (all p<0.001), while jerk cost of frontal plane knee motion (p=0.001) increased 31 % after walking 45 min. SignificanceBody borne load produced large (between 20 % and 110 %), incremental increases in angular jerk for both sagittal and frontal plane knee motion; whereas, duration of walking led to a 31 % increase in jerkiness of frontal plane knee motion. Service members who often walking for long periods of time with heavy body borne loads may have greater risk of developing musculoskeletal injury and disease due to large increases in jerky knee motions.

Quantifying varus thrust in knee osteoarthritis using wearable inertial sensors: A proof of concept

BackgroundVarus thrust during walking, visualized as excessive frontal plane knee motion during weight acceptance, is a modifiable risk factor for progression of knee osteoarthritis. However, visual assessment does not capture thrust severity and quantification with optical motion capture is often not feasible. Inertial sensors may provide a convenient alternative to optical motion capture. This proof-of-concept study sought to compare wearable inertial sensors to optical motion capture for the quantification of varus thrust. MethodsTwenty-six participants with medial knee osteoarthritis underwent gait analysis at self-selected and fast speeds. Linear regression with generalized estimating equations assessed associations between peak knee adduction velocity or knee adduction excursion from optical motion capture and peak thigh or shank adduction velocity from two inertial sensors on the lower limb. Relationships between inertial measures and peak external knee adduction moment were assessed as a secondary aim. FindingsBoth thigh and shank inertial sensor measures were associated with the optical motion capture measures for both speeds (P < 0.001 to P = 0.020), with the thigh measures having less variability than the shank. After accounting for age, sex, body mass index, radiographic severity, and limb alignment, thigh adduction velocity was also associated with knee adduction moment at both speeds (both P < 0.001). InterpretationAn inertial sensor placed on the mid-thigh can quantify varus thrust in people with medial knee osteoarthritis without the need for optical motion capture. This single sensor may be useful for risk screening or evaluating the effects of interventions in large samples.

INFLUENCE OF LOWER EXTREMITY STATIC ALIGNMENT ON DYNAMIC KNEE VALGUS IN ADOLESCENTS FOLLOWING ACL RECONSTRUCTION

Background:Dynamic limb valgus, particularly high knee abduction moments, are a known risk factor for anterior cruciate ligament (ACL) injury. High knee abduction moments may result from poor static anatomic limb alignment, faulty biomechanics, or a combination of both. The distinction is important because anatomic limb alignment is difficult to change, while dynamic factors can be addressed through neuromuscular or biomechanical training.Hypothesis/Purpose:This study assessed the influence of static (lower extremity anatomic alignment) and dynamic (kinematic and kinetic) factors on external knee abduction moments during side-step cutting in uninjured adolescent athletes.Methods:This retrospective study included 43 adolescents with recent unilateral ACL reconstruction (mean age 15.3 years, SD 2.0, range 10-21; 17/43 female; 3-12 months post-surgery, mean 6.5, SD 2.1). Frontal plane hip to ankle imaging (EOS) was used to measure mechanical axis deviation (perpendicular distance from the center of the femoral condyles to the mechanical axis line connecting the center of the femoral head to the center of the talar dome) and tibial-femoral angle. Femoral anteversion was measured during physical examination. 3D motion capture provided lower extremity kinematics and kinetics during quiet standing and during the loading phase (initial contact to peak knee flexion) of an anticipated 45° side-step cut, with 2-3 trials per limb averaged for analysis. Relationships among imaging, static motion capture, and dynamic motion capture measures were investigated using correlation, and backward stepwise linear regression was used to evaluate potential predictors of average dynamic knee abduction moment.Results:Dynamic knee abduction moment was best predicted by a combination of dynamic measures: knee and hip abduction, external knee rotation, lateral trunk lean towards the planting foot, and ankle inversion during cutting (Table 1.1). Although EOS frontal plane tibial-femoral angle was correlated with dynamic knee abduction moment (r=0.24, p=0.02), no static/anatomic variables entered the model once the dynamic measures were included.Conclusion:Knee abduction moments during side-step cutting were related to dynamic factors reflecting frontal plane trunk, hip, knee, and ankle motion, as well as external knee rotation. Static (anatomic) lower limb alignment did not influence knee abduction moments once these dynamic factors were considered. Knee abduction moments and ACL injury risk are therefore not dictated by anatomic alignment and can be altered through neuromuscular/biomechanical training.Table 1.1.Multivariable prediction of average knee abduction moment during cutting (R2=0.69) βPDynamic ankle eversion-0.35<0.001Dynamic knee external rotation0.69<0.001Dynamic hip abduction0.180.004Dynamic trunk contralateral lean0.170.007Dynamic knee abduction0.39<0.001

Visual Biofeedback and Changes in Lower Extremity Kinematics in Individuals With Medial Knee Displacement.

Increased frontal-plane knee motion during functional tasks, or medial knee displacement, is a predictor of noncontact anterior cruciate ligament injury and patellofemoral pain. Intervention studies that resulted in a reduced risk of knee injury included some form of feedback to address aberrant lower extremity movement patterns. Research on integrating feedback into single-legged tasks and the ability to train 1 task and test another is limited. To determine if adding real-time visual biofeedback to common lower extremity exercises would improve single-legged landing mechanics in females with medial knee displacement. Cohort study. University laboratory. Twenty-four recreationally active females with medial knee displacement were randomized to a visual-biofeedback group (n = 12; age = 19.75 ± 0.87 years, height = 165.32 ± 8.69 cm, mass = 62.41 ± 8.91 kg) or a control group (n = 12; age = 19.75 ± 0.97 years, height = 166.98 ± 6.89 cm, mass = 59.98 ± 6.24 kg). Individuals in the feedback group viewed a real-time digital model of their body segments generated by Microsoft Kinect. The skeletal model changed color according to the knee-abduction angle of the test limb during the exercise tasks. Participants completed 3 trials of the single-legged drop vertical jump (SL-DVJ) while triplanar kinematics at the trunk, hip, knee, and ankle were collected via 3-dimensional motion capture. The feedback and control groups completed lower extremity exercises with or without real-time visual biofeedback, respectively. After the intervention, participants completed 3 additional trials of the SL-DVJ. At baseline, the feedback group had 3.83° more ankle eversion than the control group after initial contact. After the intervention, the feedback group exhibited 13.03° more knee flexion during the flight phase of the SL-DVJ and 6.16° less knee abduction after initial contact than the control group. The feedback group also demonstrated a 3.02° decrease in peak knee-abduction excursion compared with the baseline values (P = .008). Real-time visual biofeedback immediately improved faulty lower extremity kinematics related to knee-injury risk. Individuals with medial knee displacement adjusted their movement patterns after a single training session and reduced their medial knee motion during a dynamic task.

The Influence Of Concussion History On Landing Biomechanics In Adolescent Athletes: A Pilot Investigation.

Sport-related concussion (SRC) is now classified as a major public health concern affecting millions of athletes each year. Recent evidence suggests that previously concussed athletes are at greater risk for lower extremity (LE) injury beyond the resolution of traditional SRC assessment batteries. The current literature has yet to elucidate the biomechanical movement patterns of sport-specific activities that may provide rationale for LE injury risk following SRC. PURPOSE: To examine landing biomechanics in adolescent athletes who report a SRC history. METHODS: Three athletes with a SRC history (age: 11.3 ± 3.5 yrs; previous SRCs: 1.3 ± 0.6) and two athletes without a SRC history (age: 13.0 ± 4.2 yrs) completed drop-landings from 30 cm and 60 cm. Three dimensional kinematic data were measured via a 10-camera motion analysis system at 100 Hz, while kinetic data were collected at 1000 Hz with two adjacent force platforms. The preferred limb to initiate the drop-landing was used for data analysis in comparing landing mechanics between groups. Five landing trials were collected to ensure landing performance stability. The independent variables were group (concussion, control) and landing height (30, 60 cm), while the dependent variables included maximum vertical ground reaction force (vGRF), loading rate, and knee joint kinematic parameters during the landing tasks. RESULTS: Athletes with a previous SRC demonstrated a 7.9% increase (4.22 BWs vs 3.89 BWs) in maximum vGRF and 14.7% increase in loading rate (109.2 BWs / sec vs 93.2 BWs / sec) from the 60 cm height compared to control athletes. Additionally, previously concussed athletes demonstrated an 8.8 degrees (-4.9° vs 3.9°) and 11.2 degrees (-8.1° vs 3.1°) increase in knee abduction angle from the 30 cm and 60 cm heights compared to control athletes. Knee sagittal plane range of motion was decreased by 56.2% (52.0° vs 81.2°) from the 30 cm height and 30.3% (62.3° vs 81.1°) from the 60 cm height in athletes with a previous SRC. CONCLUSIONS: Preliminary analysis highlights that previously concussed adolescent athletes demonstrate landing mechanics that may increase LE injury risk. Specifically, athletes with a SRC history demonstrate sagittal and frontal plane knee motion during landings that are associated with greater risk of an anterior cruciate ligament injury.

Frontal Plane Projection Angle during Step Down Test in Subjects With and Without Patellofemoral Pain Syndrome

AbstractBackground: Patellofemoral Pain (PFP) is considered one of the most common forms of knee pain. Increased frontal-plane knee motion during dynamic activities may play a role in the development of PFP due to alterations in joint loading at the patellofemoral joint and increased stress on the peri-articular structures of the patella.Aim of Study: To determine if there is an alteration of the frontal plane projection angle during step down test in subjects with and without Patellofemoral Pain Syndrome (PFPS).Subjects and Methods: Forty participants, with age be-tween 18-35 years, 20 PFPS and 20 healthy control group. FPPA angle for both groups was measured by digital video camera and was analyzed by kinovea software for motion analysis during performing Step down test.Results: There was no significant difference in the median value of FPPA between the affected side in the PFPS group and the healthy group (p=0.72).Conclusion: PFPS is not linked to altered FFPA during step down task, this finding suggests that assessment of lower extremity kinematics in clinical practice need 3-D motion analysis not only one plane assessment.

Quantitative and qualitative assessment of frontal plane knee motion in males and females: A reliability and validity study

BackgroundThe aim was to determine reliability and validity of frontal plane projection angle (FPPA) and visual assessments (VA) in both males and females. MethodsFifty-four participants (30 females) performed lateral step-downs while kinematics were recorded by two-dimensional and three-dimensional analyses. Two raters viewed the videos, extracted images, and measured the FPPA (quantitative). Using the videos, the raters also categorized (qualitative VA) each participant's motion as demonstrating dynamic valgus (>10° valgus), dynamic varus (>10° varus), or no change. Reliability was assessed for FPPA and VA using intraclass correlation coefficients and Kappa, respectively. Validity was determined by comparing the FPPA to three-dimensional measures (Pearson correlations) and comparing the VA to both FPPA and standard reference 3D kinematics (Kappa). ResultsFPPA showed good-excellent reliability (ICC = 0.850–0.998). VA showed minimal–moderate reliability (κ = 0.370–0.766). The FPPA showed large correlations (r = −0.514–0.531) with hip adduction in both sexes but only a moderate relationship with knee abduction in males (r = 0.427–0.445). VA showed no-weak (κ = 0.153–0.475) and weak-moderate (κ = 0.455–0.698) agreement compared to FPPA and no-weak (κ = −0.300–0.183) and no-minimal (κ = −0.078–0.027) disagreement compared to the reference standard 3D kinematics in males and females, respectively. ConclusionThe quantitative FPPA is more reliable and valid than qualitative VA of frontal knee plane motion.

Jumping performance based on duration of rehabilitation in female football players after anterior cruciate ligament reconstruction

PurposeTo determine if female football players who had longer durations of rehabilitation, measured in months, after anterior cruciate ligament reconstruction would have lower tuck jump scores (fewer technique flaws) and smaller asymmetries during drop vertical jump landing.MethodsOne-hundred-and-seventeen female football players, aged 16–25 years, after primary unilateral ACL reconstruction (median 16 months, range 6–39) were included. Athletes reported the duration of rehabilitation they performed after anterior cruciate ligament reconstruction. Athletes also performed the tuck jump and drop vertical jump tests. Outcome variables were: tuck jump score, frontal plane knee motion and probability of peak knee abduction moment during drop vertical jump landing.ResultsThere was no difference in tuck jump score based on duration of rehabilitation (n.s.). No interaction (n.s.), difference between limbs (n.s.), or duration of rehabilitation (n.s.) was found for peak knee abduction moment during drop vertical jump landing. No interaction (n.s.) or difference between limbs (n.s.) was found for frontal plane knee motion, but there was a difference based on duration of rehabilitation (P = 0.01). Athletes with > 9 months of rehabilitation had more frontal plane knee motion (medial knee displacement) than athletes with < 6 months (P = 0.01) or 6–9 months (P = 0.03).ConclusionAs there was no difference in tuck jump score or peak knee abduction moment based on duration of rehabilitation, the results of this study press upon clinicians the importance of using objective measures to progress rehabilitation and clear athletes for return to sport, rather than time alone.Level of evidenceII.

An Analysis of Squat Mechanics Between Individuals With High and Low Strength Levels

Individuals with weak hip musculature may have compensatory hip and knee motion during common strengthening exercises, such as the back squat (BS), that elevate frontal plane joint loading. PURPOSE: The purpose of this study was to compare frontal plane squat mechanic.0s between strong and weak individuals during the BS. METHODS: Twenty-eight individuals (17 males and 11 females, 23.42±3.34 yrs., 1.72±0.09 m, 73.20±11.41 kg) who consistently performed the BS were recruited for this study, and were categorized into strong (n=14, 23.00±0.08yrs, 1.69±0.09m, 71.97±11.80kg) and weak (n=14, 23.86±3.86yrs, 1.76±0.08m, 74.43±11.32kg) groups using a median split of BS 1-repetition- maximum (1RM) normalized to body mass. This study required two visits, with the first being 1RM testing and the second consisting of a 3-dimensional assessment of squatting mechanics. During the second visit, participants performed 2 sets of 3 repetitions of the BS at 70% and 85% 1RM in a random order. The average of the second repetitions of each set was used for analysis. Dependent variables included the peak knee abduction angle and external moment, and peak hip adduction angle and external moment. 2 (group) x 2 (load) mixed model ANOVA was used to compare peak external knee abduction moments and angles, and peak external hip adduction moments and angles at 70% and 85% 1RM. RESULTS: Group x load interactions were not significant for peak knee abduction angles (F1,26=1.05, p=0.31) and moments (F1,26=0.61, p=0.44), or for peak hip adduction angles (F1,26=0.87, p=0.61) and moments (F1,26=0.11, p=0.79). There were also no main effects of load or group on any dependent variable. CONCLUSIONS: Results suggest that strong and weak individuals have similar frontal plane hip and knee mechanics during the BS at 70% and 85% 1RM. However, these loads were relatively similar, and loads greater than 85% 1RM are frequently used in exercise programs. Differences may also become evident during repetitions closer to failure. Future research should examine if compensatory frontal plane actions are found with greater resistance. Furthermore, all participants were trained regardless of group, and training status may influence the magnitude of frontal plane hip and knee motion during the BS.

The effects of a simulated occupational kneeling exposure on squat mechanics and knee joint load during gait

Occupational kneeling is associated with an increased risk for tibiofemoral knee osteoarthritis. Forces on the knee in the kneeling posture, as well as the greater incidence of meniscus tears among workers, likely contribute to the increased risk. We hypothesise that an additional mechanism may contribute – altered neuromuscular control due to prolonged high knee flexion. Forty participants (20 male, 20 female) completed an evaluation of gait and squatting before, immediately following, and 30 min following a 30 min simulated occupational kneeling exposure. An increase in the peak external knee adduction moment and a delay in vastus medialis activation onset during walking were observed post-kneeling, as well as increased frontal plane knee motion during squatting. This was the first investigation to find changes in high flexion transitions as a result of kneeling. Greater frontal plane knee motion may increase the risk for meniscal tears, and subsequently, knee osteoarthritis.Practitioner Summary: A 30 min simulated occupational kneeling exposure resulted in small but significant gait changes. The greatest effect was on frontal plane knee movement during squatting, which is especially relevant to occupations requiring frequent kneeling/squatting. This increased motion may indicate an increased risk of injury, which supports a link to knee osteoarthritis.

The Impact of Hip Abduction Elastic-Resisted Neuromuscular Feedback on Frontal Plane Knee Kinematics in Female Volleyball Athletes

**Background**: In female athletes, the knee is one of the most commonly injured areas of the body. Uncontrolled frontal plane knee motion or “valgus collapse” has been identified as a risk factor for knee injury. This movement pattern has been observed in cases of anterior cruciate ligament (ACL) tears in athletes and it has also been linked to the development of patellofemoral pain syndrome. While often seen during a body-weight squatting maneuver, the valgus collapse is magnified when the athlete either lands from a jump or attempts to accelerate into a jump. Knee injury prevention programs that emphasize knee separation have shown the ability to reduce the effect of the loss of valgus control and are associated with a decrease in knee injury risk. **Purpose**: The purpose of this study is to examine the impact of hip elastic-resisted neuromuscular feedback on frontal plane knee abduction during a counter jump maneuver. **Design**: Randomized, controlled repeated measure. **Methods**: In total, 20 female volleyball athletes (mean age, 16.4 +/- 1.6 years; age range, 15–18 years) were included in this study under the following condition: athletes should have had a pain-free dysfunctional squatting pattern with no signs of structural dysfunction. During a drop-jump test, the distance between the hips, knees, and ankles was measured via video analysis software. The separation distance between the knees (mid-patella width) and ankles (lateral malleolus width) was normalized by the hip separation (greater trochanter width) distance and measured at pre-landing, landing, and takeoff. Athletes were randomized into either a control group or a neuromuscular intervention group; a SquatGuide was used and variable resistance was manually applied to the distal femur to resist hip abduction by means of an elastic band. Before a volleyball practice session, the athletes in the neuromuscular intervention group performed 30 repetitions of a deep squat with variable resistance manually applied around the distal thighs; the SquatGuide was used to provide feedback on proper lower-quarter positioning. During this period, the control group did not participate in any activity. The jump landing characteristics of both groups were immediately re-examined before practice and again at 60 min at the conclusion of practice. **Results**: The means and standard deviations for the absolute distances (measures in centimeters) of knee and ankle separation and for the normalized knee and ankle separation were calculated. There was no corre- lation between the distance in the knee and ankle separation for each of the jump-land sequences. After squat training, statistically significant increases were found in the absolute distance (P < .001) and the nor- malized knee and ankle separation distance (P < .001) for all phases of the jump-land sequence, both imme- diately following the training and at 60 min after training.

The Relationship Between A New Test Of Trunk Control To Cutting Mechanics

Poor neuromuscular control of the trunk in laboratory studies has been identified as a significant risk factor for lower extremity injuries in females. To date few clinical tests have been developed that capture trunk control which have been compared to trunk and lower extremity control. Establishing the relationship between multidirectional trunk control and lower extremity control during a cutting task would serve as the first step in establishing a measure to identify females at risk for injury in a clinical setting. PURPOSE: To determine the association between a new seated trunk test and trunk and lower extremity kinematics during an unanticipated cutting task. METHODS:8 female subjects (20.9± 1.6 ages, 20.6 ± 2.0 BMI) with no prior lower extremity injuries performed an instrumented three dimensional assessment of an unanticipated cutting task. Visual 3D was used to analyze frontal plane trunk, hip, and knee kinematics at initial contact (IC). Subjects were asked to sit on a wobble board placed on a solid surface on a plinth with their feet approximately 0.1 m off the ground with their eyes closed. Errors were counted and averaged during the two 30 second trials. Errors included uncrossing the arms, opening eyes, or if the wobble board touched the plinth. Pearson Product Moment Correlations were calculated between kinematics at IC and the mean number of trunk errors. RESULTS: Mean frontal plane angles were trunk -1.1±1.8°, hip, -4.7±3.5°, knee 2.9±4.1° and the numbers of trunk errors were 1.7±1.5. A significant relationship was observed with errors and hip adduction (r=0.84, p=0.009). Significant associations were not observed at the trunk (r=0.23, p=0.578) and knee (r=-0.59, p=0.126). CONCLUSIONS: There was a significant relationship between greater hip adduction which is associated with numerous injuries to the errors on the seated trunk test. While not significant the relationship to the frontal plane knee motion did have a high r value indicating a strong relationship that may become significant with additional subjects. The lack of relationship to trunk mechanics could be due to a greater contribution of trunk rotation than frontal plane motion during cutting from the trunk. Future analysis will further assess this possibility.

Knee Abduction Affects Greater Magnitude of Change in ACL and MCL Strains Than Matched Internal Tibial Rotation In Vitro.

Anterior cruciate ligament (ACL) injures incur over USD 2 billion in annual medical costs and prevention has become a topic of interest in biomechanics. However, literature conflicts persist over how knee rotations contribute to ACL strain and ligament injury. To maximize the efficacy of ACL injury prevention, the effects of underlying mechanics need to be better understood. We applied robotically controlled, in vivo-derived kinematic stimuli to the knee to assess ligament biomechanics in a cadaver model. We asked: (1) Does the application of abduction rotation increase ACL and medial collateral ligament (MCL) strain relative to the normal condition? (2) Does the application of internal tibial rotation impact ACL strain relative to the neutral condition? (3) Does combined abduction and internal tibial rotation increase ligament strain more than either individual contribution? A six-degree-of-freedom robotic manipulator was used to position 17 cadaveric specimens free from knee pathology outside of low-grade osteoarthritis (age, 47 ± 8 years; 13 males, four females) into orientations that mimic initial contact recorded from in vivo male and female drop vertical jump and sidestep cutting activities. Four-degree rotational perturbations were applied in both directions from the neutral alignment position (creating an 8° range) for each frontal, transverse, and combined planes while ACL and MCL strains were continuously recorded with DVRT strain gauges implanted directly on each ligament. Analysis of variance models with least significant difference post hoc analysis were used to assess differences in ligament strain and joint loading between sex, ligament condition, or motion task and rotation type. For the female drop vertical jump simulation in the intact knee, isolated abduction and combined abduction/internal rotational stimuli produced the greatest change in strain from the neutral position as compared with all other stimuli within the ACL (1.5% ± 1.0%, p ≤ 0.035; 1.8% ± 1.3%, p ≤ 0.005) and MCL (1.8% ± 1.0%, p < 0.001; 1.6% ± 1.3%, p < 0.001) compared with all other applied stimuli. There were no differences in mean peak ACL strain between any rotational stimuli (largest mean difference = 2.0%; 95% confidence interval [CI], -0.9% to 5.0%; p = 0.070). These trends were consistent for all four simulated tasks. Peak ACL strain in the intact knee was larger than peak MCL strain for all applied rotational stimuli in the drop vertical jump simulations (smallest mean difference = 2.1%; 95% CI, -0.4% to 4.5%; p = 0.047). Kinematically constrained cadaveric knee models using peak strain as an outcome variable require greater than 4° rotational perturbations to elicit changes in intraarticular ligaments. Because combined rotations and isolated abduction produced greater change in strain relative to the neutral position for the ACL and MCL than any other rotational stimuli in this cadaver study, hypotheses for in vivo investigations aimed toward injury prevention that focuses on the reduction of frontal plane knee motion should be considered. Furthermore, reduced strain in the MCL versus the ACL may help explain why only 30% of ACL ruptures exhibit concomitant MCL injuries.

Relationship of Knee Motions With Static Leg Alignments and Hip Motions in Frontal and Transverse Planes During Double-Leg Landing in Healthy Athletes.

Excessive knee valgus and tibial external rotation relative to the femur during weight bearing motions, such as jump-landing, reportedly increases the risk of developing chronic knee pain, such as patellofemoral pain. Excessive deviations from normal ranges of several static lower extremity alignment measures and dynamic hip motions may also increase the risks for patellofemoral pain. To determine the relationship between lower extremity alignments and hip motions to frontal and transverse plane knee motions during double-leg landings. Correlational study. Laboratory. 69 healthy, competitive athletes (27 men, 42 women; height, 166.5 ± 9.5 cm; weight, 61.3 ± 9.9 kg; age, 20.7 ± 1.0 y) participated in this study. Prone and supine hip version, quadriceps angle, and tibiofemoral angle were measured. Frontal and transverse knee and hip angles at peak knee extensor moment during landing were calculated. 2 separate stepwise multiple regression analyses were conducted to predict frontal and transverse plane knee motions using 4 static lower extremity alignment measures and hip motions. Greater hip adduction and prone hip anteversion, and lesser hip internal rotation and supine hip anteversion, were related to greater knee valgus motions (R2 = .475, P < .01). Greater hip adduction was related to greater knee external rotation (R2 = .205, P < .01). Some targeted static lower extremity alignments and hip motions are associated with frontal and transverse knee motions. However, stronger relationships of hip motions with knee motions than static lower extremity alignments provided evidence that improving hip movements may help improve patellofemoral pain in those with lower extremity malalignments.

Can the Functional Movement Screen™ be used to capture changes in spine and knee motion control following 12 weeks of training?

ObjectiveTo examine whether objective measures of spine and frontal plane knee motion exhibited during Functional Movement Screen™ (FMS) task performance changed following a movement-guided fitness (MOV) and conventional fitness (FIT) exercise intervention. DesignSecondary analysis of a randomized controlled experiment. Before and after 12 weeks of exercise, participants' kinematics were quantified while performing the FMS and a series of general whole-body movement tasks. SettingBiomechanics laboratory. ParticipantsFifty-two firefighters were assigned to MOV, FIT, or a control (CON) group. Outcome measuresPeak lumbar spine flexion/extension, lateral bend and axial twist, and frontal plane knee motion. ResultsThe post-training kinematic changes exhibited by trainees while performing the FMS tasks were similar in magnitude (effect size < 0.8) to those exhibited by CON. However, when performing the battery of general whole-body movement tasks, only MOV showed significant improvements in spine and frontal plane knee motion control (effect size > 0.5). ConclusionsWhether graded qualitatively, or quantitatively via kinematic analyses, the FMS may not be a viable tool to detect movement-based exercise adaptations. Amendments to the FMS tasks and/or scoring method are needed before it can be used for reasons beyond appraising the ability to move freely, symmetrically, and without pain.

Greater Hip Extension but Not Hip Abduction Explosive Strength Is Associated With Lesser Hip Adduction and Knee Valgus Motion During a Single-Leg Jump-Cut.

Background:The relationships between hip abductor and extensor strength and frontal plane hip and knee motions that are associated with anterior cruciate ligament injury risk are equivocal. However, previous research on these relationships has evaluated relatively low-level movement tasks and peak torque rather than a time-critical strength measure such as the rate of torque development (RTD).Hypothesis:Females with greater hip abduction and extension RTD would exhibit lesser frontal plane hip and knee motion during a single-leg jump-cutting task.Study Design:Descriptive laboratory study.Methods:Forty recreationally active females performed maximal isometric contractions and single-leg jump-cuts. From recorded torque data, hip extension and abduction RTD was calculated from torque onset to 200 ms after onset. Three-dimensional motion analysis was used to quantify frontal plane hip and knee kinematics during the movement task. For each RTD measure, jump-cut biomechanics were compared between participants in the highest (high) and lowest (low) RTD tertiles.Results:No differences in frontal plane hip and knee kinematics were identified between high and low hip abduction RTD groups. However, those in the high hip extension RTD group exhibited lower hip adduction (high, 3.8° ± 3.0°; low, 6.5° ± 3.0°; P = .019) and knee valgus (high, –2.5° ± 2.3°; low, –4.4° ± 3.2°; P = .046) displacements during the jump-cut.Conclusion:In movements such as cutting that are performed with the hip in a relatively abducted and flexed position, the ability of the gluteus medius to control hip adduction may be compromised. However, the gluteus maximus, functioning as a hip abductor, may take on a pivotal role in controlling hip adduction and knee valgus motion during these types of tasks.Clinical Relevance:Training with a specific emphasis on increasing explosive strength of the hip extensors may be a means through which to improve frontal plane hip and knee control during high-risk maneuvers such as cutting.