Lower limb squat biomechanics and select clinical measures in chronic ankle instability.

BACKGROUND: Individuals with chronic ankle instability often present with clinical and biomechanical abnormalities, however squat biomechanics have not been investigated. The purpose of this study was to compare select clinical assessments and squat biomechanics between individuals with and without chronic ankle instability. METHODS: Fifteen individuals with chronic ankle instability and a matched control group were studied. A weight-bearing dorsiflexion lunge test, foot posture, and an in-line half-kneeling motor control test for core stability were assessed. Lower limb 3D bilateral and unilateral squat biomechanics were captured. Groups, limbs and squat tasks were compared using an alpha of 0.05. FINDINGS: Individuals with chronic ankle instability had less static weight-bearing dorsiflexion and failed the core stability test more frequently, but did not differ in foot morphology compared to the controls. When squatting, those with chronic ankle instability demonstrated reduced peak ankle dorsiflexion angles and moments in the involved limb (p < 0.04) during single limb squats and had interlimb differences in ankle dorsiflexion angle as well as hip and knee kinetics (p < 0.04) during double limb squats. In those with chronic ankle instability, there was less overall motion, but higher kinetic demands in single limb versus double leg squatting (p < 0.03). INTERPRETATION: Individuals with chronic ankle instability had impaired weight-bearing dorsiflexion and showed impaired core stability more often, which accompanied altered squatting mechanics in both variations. Within the limbs with chronic ankle instability, single limb squats showed lesser kinematic demands but higher kinetic demands than double limb squatting.

Modified Biering-Sorenson Protocol Changes Joint Contributions to Total Support in Individuals with a History of Anterior Cruciate Ligament Reconstruction During Drop Vertical Jump Landings.

BACKGROUND: There are persistent deficits of the proximal musculature in individuals with anterior cruciate ligament reconstruction. Previous research has shown that proximal musculature fatigue alters drop vertical jump performance in healthy individuals. It is unknown how proximal musculature fatigue will alter drop vertical jump performance in individuals who have undergone anterior cruciate ligament reconstruction. HYPOTHESIS/PURPOSE: The purpose of this study was to examine the effects of a proximal extensor musculature fatigue protocol on drop vertical jump landing biomechanics of individuals with a history of anterior cruciate ligament reconstruction using both single-joint parameters and total support moment analysis. STUDY DESIGN: Quasi-experimental pre-post laboratory experiment. METHODS: Nineteen participants with a history of unilateral anterior cruciate ligament reconstruction were recruited. Three-dimensional motion analysis was performed bilaterally during a drop vertical jump. Participants then completed a proximal extensor musculature fatigue protocol and immediately repeated the drop vertical jump task. Sagittal plane kinetics and kinematics were collected. Joint contributions to peak total support moment were calculated. A condition-by-limb repeated measures analysis of variance was performed to explore the effects of the fatigue protocol, using an alpha level of 0.05. RESULTS: There were no interactions observed for any parameters. However, the injured limb demonstrated less vertical ground reaction force (13%, p=0.013) and reduced peak dorsiflexion angle (2°, p=0.028) both before and after the protocol. After the fatigue protocol both limbs demonstrated reduced hip extensor contribution to peak total support moment (4%, p=0.035). CONCLUSIONS: Individuals with a history of anterior cruciate ligament reconstruction performed the drop vertical jump with an altered anti-gravity support strategy after the proximal extensor musculature fatigue protocol. The significant reduction in bilateral hip extensor contribution to peak total support moment suggests evidence of targeted fatigue. LEVEL OF EVIDENCE: III.

Three-dimensional joint kinematic and two-dimensional quality of movement comparison between lateral and forward step-downs.

OBJECTIVES: While lateral and forward step-down tasks are commonly used, they may have different kinematic and performance demands that could influence clinical assessment and rehabilitation. Therefore, the purpose of this study was to compare 3D lower extremity kinematics and 2D quality of movement between the tasks. DESIGN: Cross-sectional comparative study. SETTING: Research laboratory. PARTICIPANTS: Thirty healthy adults (18 females, age = 23.2 ± 1.4 years, BMI = 23.9 ± 2.2 kg/m2). MAIN OUTCOME MEASURES: Participants underwent 3D and 2D motion analysis. 3D variables were peak hip, knee, and ankle angles. Dichotomous clinical criteria were used for 2D assessment. An alpha level of 0.05 was used for statistical analyses. RESULTS: In the sagittal plane, the forward step-down averaged 7° more knee flexion (p < 0.001, d = 2.30) and 4° more ankle dorsiflexion (p < 0.001, d = 1.72), but 2° less hip flexion (p = 0.001, d = 0.64). In the frontal plane, forward step-downs averaged 1° more hip adduction (p = 0.006, d = 0.54) and 1° more ankle eversion (p < 0.001, d = 1.04). The forward step-down elicited 2D movement faults more often (p = 0.003). CONCLUSIONS: The increased knee flexion and ankle dorsiflexion demands of the forward step-down were accompanied by increases in frontal plane aberrations. The forward step-down may be more challenging for individuals with reduced tolerance to loaded knee flexion and/or limited ankle mobility.

Trunk Muscle Endurance in Individuals With and Without a History of Anterior Cruciate Ligament Reconstruction.

ABSTRACT: Werner, DM and Barrios, JA. Trunk muscle endurance in individuals with and without a history of anterior cruciate ligament reconstruction. J Strength Cond Res 35(1): 118-123, 2021-Anterior cruciate ligament (ACL) rupture is one of the most common knee injuries and often leads to surgery. Second injury after an ACL reconstruction (ACLR) is a major risk after rehabilitation, and may be linked to persistent postoperative deficits in muscular strength and endurance. Trunk muscle endurance has not been well studied after ACLR. Therefore, the purpose of this study was to compare trunk endurance using the established McGill testing battery in 20 individuals who had previously undergone ACLR at least 1 year before with 20 controls matched for sex frequency, limb dominance, age, body mass index, and activity level. Four static positional holds to failure were performed in random order, with time in seconds recorded as the primary dependent variable. Mann-Whitney U tests using an alpha level of 0.05 were conducted comparing hold times for all positions between groups. Effect sizes were also calculated between groups. Deficits in trunk extension endurance were observed in the surgical group. The results of this study suggest that contemporary rehabilitation schemes after ACLR do not fully address trunk endurance deficits. Health care professionals delivering postoperative rehabilitation after ACLR may consider direct assessment of trunk endurance and targeted exercise training to address potential deficits.

Multi-segment foot model reveals distal joint kinematic differences between habitual heel-toe walking and non-habitual toe walking.

Toe walking is observed in pathological populations including cerebral palsy, stroke, and autism spectrum disorder. To understand pathological toe walking, previous studies have analyzed non-habitual toe walking. These studies found sagittal plane deviations between heel-toe and toe walking at the hip, knee, and ankle. Further investigation is merited as toe walking may involve altered biomechanics at more distal joints, such as the midtarsal joint. The purpose of this study was to examine biomechanical differences between rearfoot strike walking (RFSW) and non-rearfoot strike walking (NRFSW) in the midfoot and ankle. We hypothesized that during NRFSW, midtarsal kinematics would diverge from those during RFSW in all three cardinal planes and ankle kinematics would display increased supination. Twenty-four healthy females walked overground with both walking patterns. Motion capture, electromyography (EMG), and force plate data were collected. A validated multi-segment foot model was used with mean difference waveform analyses to compare walking conditions during stance. Significantly different kinematics were found in all three planes for the midtarsal and ankle joint during NRFSW. The NRFSW midtarsal joint exhibited increased plantarflexion, eversion, and adduction with the largest differences occurring at initial contact and in the sagittal plane. The NRFSW ankle exhibited increased supination at initial contact and during early stance. These findings indicate that toe walking alters both distal and proximal foot joint kinematics in multiple planes. This may further the understanding of altered biomechanics during toe walking while providing a basis for future analyses of pathological gait.

The patterning of local variability during the acquisition of a novel whole-body continuous motor skill in young adults.

There is increasing evidence that movement variability during motor skill acquisition plays a functional role. Specifically, initial variability might represent exploration of the possible motor space for solutions and error identification. Following practice, individuals might exploit a reduced amount of motor solutions to execute the task. While this variability pattern has been supported during discrete upper limb and multi-finger force tasks, there is a paucity of evidence for continuous whole-body motor tasks. Therefore, the purpose of this study was to characterize the role of variability during the acquisition of a whole-body continuous motor task across practice sessions in young adults. Twelve young adults aged 18-35-years participated in this study. Subjects practiced a novel, sagittal plane task, the kettlebell swing, using an online training video. We conducted an uncontrolled manifold analysis to partition local variability of the configuration of the kettlebell and body segments based on their impact on the position of the center-of-mass (COM) in the sagittal plane. Our results demonstrated that following initial practice, variability that did not affect the COM position remained elevated, suggesting sustained exploration of motor solutions. Following multiple practice sessions, variability related to motor solutions decreased, potentially indicating exploitation. The results from this study support the proposal that young adults initially utilize a range of motor solutions when acquiring a whole-body motor skill, followed by exploitation of stereotypic movement.

Surface Electromyography of the Internal and External Oblique Muscles During Isometric Tasks Targeting the Lateral Trunk.

CONTEXT: Tasks that activate the lateral trunk muscles are clinically relevant in athletic and rehabilitation programs. However, no electromyography studies have compared tasks aimed at lateral trunk muscle activation. OBJECTIVE: To compare the activation magnitudes of the internal and external obliques between 4 tasks targeting recruitment of the lateral trunk muscles, including the proposal of a novel assessment. DESIGN: Comparative laboratory study. SETTING: University-based biomechanics laboratory. PARTICIPANTS: Sixty-three participants (35 females, age = 23.6 [2.0] y, height = 1.72 [0.10] m, mass = 70.7 [14.4] kg, body mass index = 23.6 [2.86] kg/m2). INTERVENTION(S): Surface electromyography data were recorded bilaterally from the internal and external obliques while the participants performed 2 maximum voluntary contraction tasks followed by 4 isometric tasks. The isometric tasks included feet-elevated side-supported, trunk-elevated side-unsupported, lateral plank, and side-lying hip abduction. MAIN OUTCOME MEASURES: Maximum voluntary contraction-normalized and integrated muscle activities were calculated for targeted and nontargeted muscles in each task. A side-by-task analysis of variance with Bonferroni correction was conducted. RESULTS: The trunk-elevated side-unsupported task strongly activated the internal (199% maximum voluntary contraction) and external (103%) oblique muscles. The feet-elevated side-supported task strongly activated the internal obliques (205%) but not the external obliques (55%). The lateral plank task successfully activated the internal (107%) and external (72%) obliques, but not at the highest levels of the tested tasks. The side-lying hip abduction task was the least effective at activating either the internal (48%) or external (20%) obliques. CONCLUSIONS: We recommend the novel trunk-elevated side-unsupported task for assessing lateral trunk muscle performance. For independent exercise, we recommend the lateral plank task, unless arm or shoulder pathologies are present, whereby the feet-elevated side-supported task may be favorable.

In-Line Half-Kneeling as a Motor Control Test of Core Stability: Known-Groups Validity and Reliability.

Context: Core stability is considered critical for the successful execution of rehabilitative and athletic tasks. Although no consensus definition exists, different components related to core stability have been identified. An important component is the domain of motor control. There are few clinical tests assessing the motor control component of core stability (MCCS). Objective: To evaluate the interrater reliability and known-groups validity of a novel test of MCCS, the in-line half-kneeling test. The test is aimed at assessing MCCS by challenging the ability to maintain a static position with minimized contributions from the distal extremities over a minimized base of support. Design: Cross-sectional group comparison study. Setting: Laboratory. Patients or Other Participants: A total of 75 participants (25 individuals with a history of anterior cruciate ligament reconstruction, 25 uninjured Division 1 collegiate athletes, and 25 uninjured controls) were recruited from a university community. Intervention: Participants were video recorded while performing the in-line half-kneeling test for 120 seconds bilaterally. Three observers independently viewed each video to determine if individuals broke form during each test using 2 dichotomous criteria. Main Outcome Measures: Cohen's kappa was used to assess interrater reliability, and chi-square tests of independence were used to compare break rates between groups. Results: Good-to-excellent interrater reliability (.732-.973) was seen between the 3 observers. Chi-square tests of independence revealed different break rates between all 3 groups. Compared to break rate for the reference control group (11/25-44%), those with a history of anterior cruciate ligament reconstruction broke at a higher rate (18/25-72%), whereas the uninjured collegiate athletes broke at a lower rate (4/25-16%). Conclusions: The in-line half-kneeling test is a reliable test between raters that can differentiate between groups expected to differ in MCCS.

Midtarsal locking, the windlass mechanism, and running strike pattern: A kinematic and kinetic assessment.

Changes in running strike pattern affect ankle and knee mechanics, but little is known about the influence of strike pattern on the joints distal to the ankle. The purpose of this study was to explore the effects of forefoot strike (FFS) and rearfoot strike (RFS) running patterns on foot kinematics and kinetics, from the perspectives of the midtarsal locking theory and the windlass mechanism. Per the midtarsal locking theory, we hypothesized that the ankle would be more inverted in early stance when using a FFS, resulting in decreased midtarsal joint excursions and increased dynamic stiffness. Associated with a more engaged windlass mechanism, we hypothesized that a FFS would elicit increased metatarsophalangeal joint excursions and negative work in late stance. Eighteen healthy female runners ran overground with both FFS and RFS patterns. Instrumented motion capture and a validated multi-segment foot model were used to analyze midtarsal and metatarsophalangeal joint kinematics and kinetics. During early stance in FFS the ankle was more inverted, with concurrently decreased midtarsal eversion (p < 0.001) and abduction excursions (p = 0.003) but increased dorsiflexion excursion (p = 0.005). Dynamic midtarsal stiffness did not differ (p = 0.761). During late stance in FFS, metatarsophalangeal extension was increased (p = 0.009), with concurrently increased negative work (p < 0.001). In addition, there was simultaneously increased midtarsal positive work (p < 0.001), suggesting enhanced power transfer in FFS. Clear evidence for the presence of midtarsal locking was not observed in either strike pattern during running. However, the windlass mechanism appeared to be engaged to a greater extent during FFS.

2D AND 3D KINEMATICS DURING LATERAL STEP-DOWN TESTING IN INDIVIDUALS WITH ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION.

BACKGROUND: The lateral step-down test is an established clinical evaluation tool to assess quality of movement in patients with knee disorders. However, this test has not been investigated in individuals after anterior cruciate ligament reconstruction (ACLR) in association with quantitative 3D motion analysis. PURPOSES: The purpose of this study was to determine the strength of association between visually-assessed quality of movement during the lateral step-down test and 3D lower limb kinematics in patients with history of ACLR. A second purpose was to compare kinematics between subgroups based on the presence or absence of faulty alignments during the task. The final purpose was to compare visually-assessed quality of movement scores between box heights during lateral step-down testing. METHODS: Twenty subjects at least one year status post-ACLR (18 females, age of 24.5 ± 4.6 years and body mass index of 23.4 ± 2.3 kg/m2) performed the lateral step-down test unilaterally on the surgical limb atop four and six inch boxes. A board-certified orthopedic physical therapist scored overall quality of movement during the lateral step-down test using established criteria during 2D video playback. Lower limb kinematics were simultaneously collected using 3D motion capture. An alpha level of 0.05 was used for all statistical treatments. RESULTS: Overall 2D quality of movement score significantly correlated (r =0.47-0.57) with 3D hip adduction and hip internal rotation across box heights. Across box heights, the presence of faulty pelvic alignment differentiated a subgroup exhibiting less peak knee flexion, and the presence of faulty knee alignment differentiated a subgroup exhibiting greater peak hip adduction. The six inch box elicited worse quality of movement compared to the four inch box. CONCLUSIONS: These results suggest that visually-assessed quality of movement is associated with several kinematic variables after ACLR. 2D movement deviations at the pelvis appear to consistently relate to less knee flexion, and 2D deviations at the knee appear to suggest greater hip adduction. Generally, poorer quality of movement was observed for the six inch box height. Clinically, these data suggest that interventions targeting hip abductor and knee extensor strength and neuromuscular control may be useful in the presence of poor quality of movement during lateral step-down testing. LEVEL OF EVIDENCE: 2b.

Single-limb drop landing biomechanics in active individuals with and without a history of anterior cruciate ligament reconstruction: A total support analysis.

BACKGROUND: The purpose of this study was to characterize the magnitude and distribution of the total support moment during single-limb drop landings in individuals after anterior cruciate ligament reconstruction compared to a control group. METHODS: Twenty participants after reconstruction and twenty control participants matched on sex, limb dominance and activity level were recruited. Motion analysis was performed during a single-limb drop landing task. Total support moment was determined by summing the internal extensor moments at the ankle, knee, and hip. Each relative joint contribution to the total support moment was calculated by dividing each individual contribution by the total support moment. Data were captured during a landing interval that started at initial contact and ended at the lowest vertical position of the pelvis. Data were then time-normalized and indexed at 25, 50, 75, and 100% of the landing interval. FINDINGS: No between-group differences for total support moment magnitude were observed. At both 75% and 100% of the landing, the relative contribution of the knee joint was lower in those with a history of surgery (p<0.001). At the same instances, the relative contribution to the total support moment by the hip joint was greater in those with a history of surgery (p=0.004). INTERPRETATION: In active participants after anterior cruciate ligament reconstruction, relative contributions to anti-gravity support of the center of mass shifted from the knee to the hip joint during single-limb landing, which became evident towards the end of the landing interval.

Effects of incremental ambulatory-range loading on arch height index parameters.

Deformation of the medial longitudinal arch under body weight loading is often assessed using the Arch Height Index Measurement System. This system assesses change in arch height between sitting and standing, estimated to be 10% and 50% of body weight, respectively. However, body weight forces during ambulation exceed these loads, therefore limiting our understanding of arch deformation under ambulatory load ranges. Thus, the study aims were (1) to assess if sitting and standing arch height differed from that seen under 10% and 50% body weight using a force target-matching procedure, and (2) to quantify the assumed linearity of arch stiffness, measured statically, throughout an ambulatory load range. Established sitting and standing arch height measurements were taken from 25 healthy subjects, who also underwent testing from 10% to 120% body weight in sequential 10% increments. Arch deformation in sitting was less than for 10% body weight, whereas the standing and 50% condition did not differ. The incremental loading data revealed linear and curvilinear trends between arch deformation and loading through the ambulatory range, such that further deformation beyond that seen at 120% would be minimal using these procedures. These data suggest that sitting arch loads and deformation are less than those seen at 10% body weight, which affects known parameters such as arch stiffness. Further, the curvilinear trend in the arch height data suggests that most arch deformation occurs in the ambulatory load range for a healthy foot.

Three-dimensional hip and knee kinematics during walking, running, and single-limb drop landing in females with and without genu valgum.

BACKGROUND: Dynamic knee valgus in females has been associated with various knee pathologies. Abnormal 3D hip and knee kinematics contribute prominently to this presentation, and these may become more aberrant with more demanding tasks. Underlying genu valgus may also accentuate such kinematics, but this effect has never been tested. Therefore, the purpose of this study was to compare 3D hip and knee kinematics during walking, running, and single-limb drop landing in females with and without genu valgus malalignment. We expected abnormal kinematics to become more evident in the valgus subjects as task demands increased. METHODS: Eighteen healthy females with genu valgum and 18 female controls with normal alignment underwent 3D motion analysis while performing walking, running, and single-limb drop-landing trials. Sagittal, frontal, and transverse plane hip and knee kinematics were compared between groups across tasks using analyses of variance and between-group effect sizes. FINDINGS: Group differences did not generally increase with higher forces. The valgus females demonstrated decreased hip flexion (ES=0.72-0.88) and increased knee abduction (ES=0.87-1.47) across the tasks. During running and single-limb drop landing, they showed increased knee external rotation (ES=0.69-0.73). Finally, during walking, the valgus females showed increased hip adduction (ES=0.69). INTERPRETATION: These results suggest that females with genu valgus alignment utilize aberrant hip and knee mechanics previously associated with dynamic valgus in the literature, but that these pathomechanics do not generally worsen with rising task demands. Healthy females that present with genu valgus may be natively at elevated risk for knee pathology.

The dose-response relationship between lateral foot wedging and the reduction of knee adduction moment.

BACKGROUND: Lateral foot wedges represent a biomechanical intervention aimed at reducing medial knee loads. However, the effects of varying wedge amounts on biomechanical variables and orthotic comfort have not been systematically studied. Further, arch height may influence the comfort of laterally wedged devices. Therefore, the primary purpose of this study was to examine the effect of incrementally increasing lateral wedge amounts on knee adduction moment parameters and subjective comfort. The secondary purpose was to relate arch height measures to the comfort of the devices. METHODS: Twenty-five healthy subjects underwent three-dimensional instrumented gait analysis testing using seven inclinations of lateral wedging (0°, 2°, 4°, 6°, 8°, 10°, 12°). Subjects reported comfort level for each orthotic condition. Arch heights were measured in standing and sitting, and rigidity index and stiffness were calculated. FINDINGS: The knee adduction moment decreased with wedge amounts up to 6°, but more aggressive amounts did not yield additional reductions. Comfort ratings did not change from baseline until wedge amounts exceeded 8°. In addition, arch height measures, arch rigidity index and stiffness did not relate to the comfort of the orthotic device regardless of the wedge amount. INTERPRETATION: Knee adduction moment decreased with mild wedge amounts while maintaining comfort. Wedge amounts greater than 6° yielded little additional mechanical benefit and amounts greater than 8° compromised comfort. It appears that 4°-6° of lateral wedging are optimal in regard to desirable biomechanical change and comfort level in healthy individuals.

A sex comparison of ambulatory mechanics relevant to osteoarthritis in individuals with and without asymptomatic varus knee alignment.

The prevalence of medial knee osteoarthritis is greater in females and is associated with varus knee alignment. During gait, medial knee osteoarthritis has been linked to numerous alterations. Interestingly, there has been no research exploring sex differences during walking in healthy individuals with and without varus alignment. Therefore, the gait mechanics of 30 asymptomatic individuals with varus knees (15 females) and 30 normally-aligned controls (15 females) were recorded. Gait parameters associated with medial knee osteoarthritis were analyzed with two-factor analyses of variance. In result, varus males exhibited the greatest peak knee adduction moments, while normal females showed the greatest peak hip adduction angles and pelvic drop excursions. By sex, females exhibited greater peak hip adduction angles and moments and greater pelvic drop excursion, but lesser peak knee adduction angles. By alignment type, varus subjects exhibited greater peak knee adduction angles and moments, midstance knee flexion angles and excursion, and eversion angles and lateral ground reaction forces, but lesser peak hip adduction angles. In conclusion, females generally presented with proximal mechanics related to greater hip adduction, whereas males presented with more knee adduction. Varus subjects demonstrated a number of alterations associated with medial knee osteoarthritis. The differential sex effects were far less conclusive.

Comparison of stance phase knee joint angles and moments using two different surface marker representations of the proximal shank in walkers and runners.

Efforts to compare different surface marker configurations in 3-dimensional motion analysis are warranted as more complex and custom marker sets become more common. At the knee, different markers can been used to represent the proximal shank. Often, two anatomical markers are placed over the femoral condyles, with their midpoint defining both the distal thigh and proximal shank segment ends. However, two additional markers placed over the tibial plateaus have been used to define the proximal shank end. For this experiment, simultaneous data for both proximal shank configurations were independently collected at two separate laboratories by different investigators, with one laboratory capturing a walking population and the other a running population. Common discrete knee joint variables were then compared between marker sets in each population. Using the augmented marker set, peak knee flexion after weight acceptance was less (1.2-1.7°, P < .02) and peak knee adduction was greater (0.7-1.4°, P < .001) in both data sets. Similarly, the calculated peak knee flexion moment was less by 15-20% and internal rotation moment was greater by 11-18% (P < .001). These results suggest that the calculation of knee joint mechanics are influenced by the proximal shank's segment endpoint definition, independent of dynamic task, investigator, laboratory environment, and population in this study.

Effect of specific gait modifications on medial knee loading, metabolic cost and perception of task difficulty.

BACKGROUND: The metabolic cost and cognitive demand of altering natural gait have not been well studied. The purpose of this investigation was to assess three modified patterns - toe out, ipsilateral trunk lean and a medial weight shift at the foot - on the basis of 1) medial knee joint load reduction, 2) metabolic cost of performance and 3) subject perception of task difficulty. METHODS: 12 healthy individuals underwent 3 dimensional motion analysis and metabolic testing to assess the gait mechanics and energy expenditure of natural gait and the three experimental gait patterns, performed to a self-selected moderate degree. Walking speed was controlled. Perceived workload was assessed using the NASA Task Load Index. FINDINGS: Trunk lean significantly reduced first peak knee adduction moment (↓32%, P<0.001) as well as KAM impulse (↓35%, P<0.001), but was costly in terms of energy expenditure (↑11%, P<0.001) and perceived workload (↑1178%, P<0.001). A moderate toe-out pattern significantly reduced the second peak knee adduction moment (↓32%, P<0.001) and KAM impulse (↓14%, P=0.026), but had no effect on the first peak. Conversely, toe-out was least demanding in terms of additional energy expenditure (↑2%, P=0.001) and perceived workload (↑314%, P=0.001). Medial shift did not reduce knee adduction moment. INTERPRETATION: The prioritization of joint load reduction versus additional metabolic and cognitive demands could play a substantial role in the clinical decision making process of selecting a modified gait pattern.

Effects of medially wedged foot orthoses on knee and hip joint running mechanics in females with and without patellofemoral pain syndrome.

We examined the effects of medially wedged foot orthoses on knee and hip joint mechanics during running in females with and without patellofemoral pain syndrome (PFPS). We also tested if these effects depend on standing calcaneal eversion angle. Twenty female runners with and without PFPS participated. Knee and hip joint transverse and frontal plane peak angle, excursion, and peak internal knee and hip abduction moment were calculated while running with and without a 6° full-length medially wedged foot orthoses. Separate 3-factor mixed ANOVAs (group [PFPS, control] x condition [medial wedge, no medial wedge] x standing calcaneal angle [everted, neutral, inverted]) were used to test the effect of medially wedged orthoses on each dependent variable. Knee abduction moment increased 3% (P = .03) and hip adduction excursion decreased 0.6° (P < .01) using medially wedged foot orthoses. No significant group x condition or calcaneal angle x condition effects were observed. The addition of medially wedged foot orthoses to standardized running shoes had minimal effect on knee and hip joint mechanics during running thought to be associated with the etiology or exacerbation of PFPS symptoms. These effects did not appear to depend on injury status or standing calcaneal posture.

Mechanical effectiveness of lateral foot wedging in medial knee osteoarthritis after 1 year of wear.

The use of lateral foot wedging in the management of medial knee osteoarthritis is under scrutiny. Interestingly, there have been minimal efforts to evaluate biomechanical effectiveness with long-term use. Therefore, we aimed to evaluate dynamic knee loading (assessed using the knee adduction moment) and other secondary gait parameters in patients with medial knee osteoarthritis wearing lateral foot wedging at a baseline visit and after 1 year of wear. Three-dimensional gait data were captured in an intervention group of 19 patients with symptomatic medial knee osteoarthritis wearing their prescribed laterally wedged foot orthoses at 0 and 12 months. Wedge amounts were prescribed based on symptom response to a step-down test. A control group of 19 patients wearing prescribed neutral orthoses were also captured at 0 and 12 months. The gait of the intervention group wearing neutral orthoses was additionally captured. Walking speed and shoes were controlled. Analyses of variance were conducted to examine for group-by-time (between the groups in their prescribed orthoses) and condition-by-time (within the intervention group) interactions, main effects, and simple effects. We observed increased knee adduction moments and frontal plane motion over time in the control group but not the intervention group. Further, within the intervention group, the mechanical effectiveness of the lateral wedging did not decrease. In patients with medial knee osteoarthritis, the effects of lateral foot wedging on pathomechanics associated with medial knee osteoarthritis were favorable and sustained over time.

Dynamic versus radiographic alignment in relation to medial knee loading in symptomatic osteoarthritis.

Dynamic knee alignment is speculated to have a stronger relationship to medial knee loading than radiographic alignment. Therefore, we aimed to determine what frontal plane knee kinematic variable correlated most strongly to the knee adduction moment. That variable was then compared with radiographic alignment as a predictor of the knee adduction moment. Therefore, 55 subjects with medial knee OA underwent three-dimensional gait analysis. A subset of 21 subjects also underwent full-limb radiographic assessment for knee alignment. Correlations and regression analyses were performed to assess the relationships between the kinematic, kinetic and radiographic findings. Peak knee adduction angle most strongly correlated to the knee adduction moment of the kinematic variables. In comparison with radiographic alignment, peak knee adduction angle was the stronger predictor. Given that most epidemiological studies on knee OA use radiographic alignment in an attempt to understand progression, these results are meaningful.