The effect of anti-pronation foot orthoses on hip and knee kinematics and muscle activity during a functional step-up task in healthy individuals: A laboratory study

Background

Greater frontal and transverse plane hip and knee motion, and delayed gluteus medius and vastus medialis oblique activation have frequently been identified in patellofemoral pain syndrome populations, whilst prefabricated anti-pronation foot orthoses have been reported to reduce symptoms. The aim of the study was to evaluate the effects of such orthoses on hip and knee kinematics, gluteal and vasti muscle activity, kinematic and electromyographic interactions alongside correlations with specific clinical measures.

Methods

Eighteen asymptomatic individuals (11 male 7 female) had measures taken of static foot posture and ankle range of motion. Hip muscle activity and kinematics were measured using electromyography and an active motion capture system during a step-up task. Order of testing with or without orthoses was determined using a coin toss.

Findings

Between condition paired t-tests indicated significantly reduced peak hip adduction angles (1.56°, P < 0.05) and significantly reduced knee internal rotation (1.3°, P < 0.05) in the orthoses condition. Reduced ankle dorsiflexion range of motion correlated with a reduction in hip adduction following the orthoses intervention (r = 0.59, P = 0.013).

Interpretation

The effects of prefabricated orthoses may be partially explained by kinematic alterations that occur proximal to the foot in the kinetic chain. These clinically and biomechanically relevant effects appear more evident in those with reduced underlying ankle motion. Further research is indicated using a symptomatic population to explore the clinical relevance of these observations.     

Comparison of muscle activation levels and knee valgus between individuals with medial patellofemoral ligament reconstruction and healthy individuals during fatiguing step down task

BackgroundMedial patellofemoral ligament reconstruction becomes first-choice surgical procedure for patients with a history of lateral patellar dislocations but there is limited knowledge about neuromuscular activation patterns of individuals with a history of patellar dislocation who underwent medial patellofemoral ligament reconstruction.ObjectiveThe aim of this study was to compare muscle activation levels and knee valgus during step down performance test between individuals with a history of medial patellofemoral ligament reconstruction and healthy individuals.MethodsFifteen individuals with medial patellofemoral ligament reconstruction and 15 healthy individuals were included. Vastus medialis obliquus, vastus lateralis and gluteus medius muscle activation levels and knee valgus were measured during 60-s- step down performance test. Two-way repeated-measures of analysis of covariance was used for statistical analysis.FindingsCompared to the healthy individuals, individuals with medial patellofemoral ligament reconstruction showed lower vastus medialis obliquus (p = .04) and gluteus medius (p = .005) activation levels, and higher knee valgus (p = .002) in last period of the step down performance test.InterpretationSince the significant results were only observed in the fatiguing section of the test, endurance tests may provide more information about neuromuscular control of the individuals with history of medial patellofemoral ligament reconstruction. Future studies should investigate whether endurance exercises that target to improve vastus medialis obliquus and gluteus medius activity result in better clinical outcomes than conventional programs for individuals with medial patellofemoral ligament reconstruction.     

Improvements in kinematics,muscle activity and pain during functional tasks in females with patellofemoral pain following a single patterned electrical stimulation treatment

BackgroundIndividuals with patellofemoral pain present with altered hip muscle activation, faulty movement patterns, and pain during functional tasks. Examining new treatment options to address these impairments may better treat those with patellofemoral pain. The purpose of this study was to determine if patterned electrical stimulation to the lower extremity affects muscle activity, movement patterns, and pain following a single treatment.MethodsFifteen females with patellofemoral pain were randomized to receive a single 15-minute treatment of either a patterned electrical neuromuscular stimulation or a sham. Peak kinematics of the knee, hip, and trunk, electromyography and pain were examined pre and post-intervention during a single leg squat and lateral step-down task. Group means and pre/post reduced kinematic values were also plotted during the entire task with 90% confidence intervals to identify differences in movement strategies.FindingsNo baseline differences were found in peak kinematics between groups. No pre to post-intervention differences in peak knee, hip and trunk kinematics were found, however differences were seen when the quality of movement across the entire tasks was assessed. The electrical stimulation group had improved knee flexion and hip abduction during the lateral step-down. A significant improvement in gluteus medius activation following patterned electrical neuromuscular stimulation occurred during the step-down (P = 0.039). Significant pain improvements were also seen in both the single leg squat (P = 0.025) and lateral step-down (P = 0.006).InterpretationA single treatment of patterned electrical neuromuscular stimulation improved muscle activation, lower extremity kinematics during functional tasks, and pain.     

Effects of hip and trunk muscle strengthening on hip function and lower limb kinematics during step-down task

BackgroundStrengthening of the hip and trunk muscles has the potential to change lower limb kinematic patterns, such as excessive hip medial rotation and adduction during weight-bearing tasks. This study aimed to investigate the effect of hip and trunk muscles strengthening on hip muscle performance, hip passive properties, and lower limb kinematics during step-down task in women.MethodsThirty-four young women who demonstrated dynamic knee valgus during step-down were divided into two groups. The experimental group underwent three weekly sessions of strengthening exercises for eight weeks, and the control group continued their usual activities. The following evaluations were carried out: (a) isokinetic maximum concentric and eccentric work of hip lateral rotators, (b) isokinetic hip passive torque of lateral rotation and resting transverse plane position, and (c) three-dimensional kinematics of the lower limb during step-down.FindingsThe strengthening program increased concentric (P < 0.001) and eccentric (P < 0.001) work of hip lateral rotators, and changed hip resting position toward lateral rotation (P < 0.001). The intervention did not significantly change hip passive torque (P = 0.089, main effect). The program reduced hip (P = 0.002), thigh (P = 0.024) and shank (P = 0.005) adduction during step-down task. Hip, thigh and knee kinematics in transverse plane and foot kinematics in frontal plane did not significantly modify after intervention (P ≥ 0.069, main effect).InterpretationHip and trunk strengthening reduced lower limb adduction during step-down. The changes in hip maximum work and resting position may have contributed to the observed kinematic effects.     

The role of muscle strength & activation patterns in patellofemoral pain

BackgroundTo investigate the extent to which quadriceps muscle activation and strength are responsible for patellofemoral pain.MethodsA pain on–off switch system synchronized with a force transducer and surface electromyography was utilized on 32 volunteer patellofemoral pain patients during maximal isometric and squat exercises.FindingsThere were 26 patients out of the 32 tested who complained of pain during the squat or isometric test, of these 20 subjects presented a significant advantage for the vastus lateralis compared to the vastus medialis obliquis activation and 12 patients had decreased quadriceps strength of the symptomatic compared to the non symptomatic leg. All patients who demonstrated weak vastus medialis obliquis activation during the isometric exercise possessed the same symptoms during the squat. On the other hand, 9 patients who showed diminished vastus medialis obliquis activation during the squat displayed equal activation between the vastus medialis obliquis and the vastus lateralis during the isometric task. With regard to the timing for the onset of muscle activation, there were only 4 patients who had a difference (P = 0.03) between the symptomatic (0.042 s) and non-symptomatic legs (0.011 s).InterpretationCauses for patellofemoral pain vary and are not necessarily a result of quadriceps strength deficit or vastus medialis obliquis activation weakness. Patellofemoral pain patients who possess lower vastus medialis obliquis activation compared to the vastus lateralis do not necessarily have quadriceps weakness while patients presenting with quadriceps strength deficits do not always have an imbalance between vastus medialis obliquis and vastus lateralis activation.     

An immediate effect of custom-made ankle foot orthoses on postural stability in older adults

BackgroundFoot and ankle problems are highly prevalent fall risks in the elderly. Ankle foot orthoses designed to stabilize the foot and ankles have been studied within specific patient groups, but their efficacy with a less restrictive elderly population is unknown. This study investigated if custom-made ankle foot orthoses improve postural stability in older adults.MethodsThirty ambulatory older adults averaged 73 (standard deviation = 6.5) years completed Romberg's balance (eyes-open/eyes-closed), functional reach, and Timed Up and Go tests while wearing validated kinematic sensors. Each test was completed in standardized shoes with and without bilateral orthoses. Additionally, barefoot trials were conducted for the Romberg's and functional reach tests.FindingsCompared to the barefoot and ‘shoes alone’ conditions, the orthoses reduced center of mass sway on average by 49.0% (P = 0.087) and 40.7% (P = 0.005) during eyes-open balance trials. The reduction was amplified during the eyes-closed trials with average reductions of 65.9% (P = 0.000) and 47.8% (P = 0.004), compared to barefoot and ‘shoes alone’ conditions. The orthoses did not limit functional reach distance nor timed-up and go completion times. However, the medial-lateral postural coordination while reaching was improved significantly with orthoses compared to barefoot (14.3%; P = 0.030) and ‘shoes alone’ (13.5%; P = 0.039) conditions.InterpretationAnkle foot orthoses reduced postural sway and improved lower extremity coordination in the elderly participants without limiting their ability to perform a standard activity of daily living. Additional studies are required to determine if these benefits are retained and subsequently translate into fewer falls.     

Roll-over shapes of the ankle–foot and knee–ankle–foot systems of able-bodied children

BackgroundThe roll-over shape is the effective rocker shape that a lower limb system conforms to during a step. The roll-over shape concept has been explored in detail in adults and has been successfully used in the design, evaluation, and alignment of lower limb prostheses and orthoses. No such analysis exists for the pediatric population. Therefore, the purpose of this study was to investigate the ankle–foot and knee–ankle–foot roll-over shapes in able-bodied children, values that could serve as tools for design and evaluation of lower limb pediatric prostheses and orthoses.MethodsThis study describes a multi-center retrospective review of existing motion analysis data (n = 153 from three centers). Roll-over shapes were calculated by transforming center of pressure data from a laboratory-based coordinate system into two body-based coordinate systems. Roll-over shapes were then characterized using a circular arc model. Best-fit radii of roll-over shapes for children in three age groups (3–7 years, 8–11 years, and 12–17 years) were compared using the Kruskal–Wallis test.FindingsNo significant changes were found in roll-over shape radii between the three age groups (P = 0.54 for ankle–foot roll-over shape radii; P = 0.12 for knee–ankle–foot roll-over shape radii). The weighted mean of median radii for ankle–foot and knee–ankle–foot roll-over shapes from the three centers were approximately 22% and 17% of body stature, values similar to those seen in adults.InterpretationChildren produce nearly circular knee–ankle–foot roll-over shapes at a young age that are similar to those seen in adults when scaled by body stature.     

Kinematic and kinetic gait deviations in males long after anterior cruciate ligament reconstruction

BackgroundBiomechanical deviations long (approx. 5 years) after anterior cruciate ligament reconstruction have not been quantified in males, despite their distinct risk profile as compared to females. These deviations can indicate altered joint loading during chronic, repetitive motions.MethodsCross-sectional study, comparing kinematic and kinetic variables between 15 male anterior cruciate ligament reconstructed patients and 15 healthy controls. During walking and running gait, measurements were taken of impact dynamics, knee and hip sagittal plane angles and moments, and knee varus angles and adduction moments.FindingsComparing affected limbs to control limbs, significantly lower maximum (P = 0.001) and initial (P = 0.003) loading rates were found during running, but not in walking. Hip angles were lower for affected limbs of patients compared to the control group (P = 0.039) in walking, but not during running. Between-limb comparisons showed important differences in symmetry of the affected patients. Maximum force during running was higher in the unaffected limb (P = 0.015), which was linked with a higher loading rate (P = 0.008). Knee flexion angle was reduced by 2° on average for the affected limb during running (P = 0.010), and both walking and running knee and hip moments showed differences. Knee varus angle showed a 1° difference during walking (P < 0.001), but not during running. Knee adduction moment was significantly lower (more valgus) during both walking and running.InterpretationMale anterior cruciate ligament reconstructed patients demonstrate persistent, clinically important gait asymmetries and differences from healthy controls long after surgery in kinematics, kinetics, and impact biomechanics.     

Sex-specific hip osteoarthritis-associated gait abnormalities: Alterations in dynamic hip abductor function differ in men and women

BackgroundHip osteoarthritis results in abnormal gait mechanics, but it is not known whether abnormalities are the same in men and women. The hypothesis tested was that gait abnormalities are different in men and women with hip osteoarthritis vs. sex-specific asymptomatic groups.Methods150 subjects with mild through severe radiographic hip osteoarthritis and 159 asymptomatic subjects were identified from an Institutional Review Board-approved motion analysis data repository. Sagittal plane hip range of motion and peak external moments about the hip, in all three planes, averaged from normal speed walking trials, were compared for men and women, with and without hip osteoarthritis using analysis of variance.FindingsThere were significant sex by group interactions for the external peak hip adduction and external rotation moments (P = 0.009–0.045). Although asymptomatic women had peak adduction and external rotation moments that were respectively 12% higher and 23% lower than asymptomatic men (P = 0.026–0.037), these variables did not differ between men and women with hip osteoarthritis (P ≥ 0.684). The osteoarthritis vs. asymptomatic group difference in the peak hip adduction moment was 45% larger in women than in men. The osteoarthritis vs. asymptomatic group difference in the peak hip external rotation moment was 55% larger for men than for women (P < 0.001). Sex did not influence the association between radiographic severity and gait variables.InterpretationNormal sex differences in gait were not seen in hip osteoarthritis. Sex-specific adaptations may reflect different aspects of hip abductor function. Men and women with hip osteoarthritis may require different interventions to improve function.     

Neuromechanical gait adaptations in women with joint hypermobility — An exploratory study

BackgroundJoint hypermobility is known to be associated with joint and muscle pain, joint instability and osteoarthritis. Previous work suggested that those individuals present an altered neuromuscular behavior during activities such as level walking. Therefore, the aim of this study was to explore the differences in ground reaction forces, temporal parameters and muscle activation patterns during gait between normomobile and hypermobile women, including symptomatic and asymptomatic hypermobile individuals.MethodsA total of 195 women were included in this cross-sectional study, including 67 normomobile (mean 24.8 [SD 5.4] years) and 128 hypermobile (mean 25.8 [SD 5.4] years), of which 56 were further classified as symptomatic and 47 as asymptomatic. The remaining 25 subjects could not be further classified. Ground reaction forces and muscle activation from six leg muscles were measured while the subjects walked at a self-selected speed on an instrumented walkway. Temporal parameters were derived from ground reaction forces and a foot accelerometer. The normomobile and hypermobile groups were compared using independent samples t-tests, whereas the normomobile, symptomatic and asymptomatic hypermobile groups were compared using one-way ANOVAs with Tukey post-hoc tests (significance level = 0.05).FindingsSwing phase duration was higher among hypermobile (P = 0.005) and symptomatic hypermobile (P = 0.018) compared to normomobile women. The vastus medialis (P = 0.049) and lateralis (P = 0.030) and medial gastrocnemius (P = 0.011) muscles showed higher mean activation levels during stance in the hypermobile compared to the normomobile group.InterpretationHypermobile women might alter their gait pattern in order to stabilize their knee joint.     

Gluteal muscle activation during running in females with and without patellofemoral pain syndrome

Background

Hip and knee joint motion in the transverse and frontal plane during running may increase patellofemoral joint stress and contribute to the etiology of patellofemoral joint pain. We evaluated the association between these kinematics and the magnitude and timing of gluteus medius and maximus activity during running in females with patellofemoral pain. We also compared the magnitude and timing of gluteal muscle activity during running between females with and without patellofemoral pain.

Methods

Twenty females with patellofemoral pain and twenty females without knee pain participated in this study. Three-dimensional running kinematics, gluteus medius and gluteus maximus onset time, activation duration, mean activation level, and peak activation level were recorded simultaneously. Gluteal muscle timing and activation level were compared between groups using independent t-tests. The association of gluteal muscle activation parameters running kinematics in females with patellofemoral pain was quantified using Pearson correlation coefficients.

Findings

Females with patellofemoral pain demonstrated delayed (P = 0.028, effect size = 0.76) and shorter (P = 0.01, effect size = 0.88) gluteus medius activation than females without knee pain during running. The magnitude and timing of gluteus maximus activation was not different between groups. Greater hip adduction and internal rotation excursion was correlated with later gluteus medius and gluteus maximus onset, respectively.

Interpretation

Neuromuscular control differences of the gluteal muscles appear to exist among females with patellofemoral pain during running. Interventions to facilitate earlier activation of these muscles may be warranted among females with patellofemoral pain who demonstrate altered running kinematics.     

COMPARISON OF HIP AND KNEE STRENGTH AND NEUROMUSCULAR ACTIVITY IN SUBJECTS WITH AND WITHOUT PATELLOFEMORAL PAIN SYNDROME

Purpose/Background:

Historically, patellofemoral pain syndrome (PFPS) has been viewed exclusively as a knee problem. Recent findings have suggested an association between hip muscle weakness and PFPS. Altered neuromuscular activity about the hip also may contribute to PFPS; however, more limited data exist regarding this aspect. Most prior investigations also have not concurrently examined hip and knee strength and neuromuscular activity in this patient population. Additional knowledge regarding the interaction between hip and knee muscle function may enhance the current understanding of PFPS. The purpose of this study was to compare hip and knee strength and electromyographic (EMG) activity in subjects with and without PFPS.

Methods:

Eighteen females with PFPS and 18 matched controls participated in this study. First, surface EMG electrodes were donned on the gluteus medius, vastus medialis, and vastus lateralis. Strength measures then were taken for the hip abductors, hip external rotators, and knee extensors. Subjects completed a standardized stair-stepping task to quantify muscle activation amplitudes during the loading response, single leg stance, and preswing intervals of stair descent as well as to determine muscle onset timing differences between the gluteus medius and vastii muscles and between the vastus medialis and vastus lateralis at the beginning of stair descent.

Results:

Females with PFPS demonstrated less strength of the hip muscles. They also generated greater EMG activity of the gluteus medius and vastus medialis during the loading response and single leg stance intervals of stair descent. No differences existed with respect to onset activation of the vastus medialis and vastus lateralis. All subjects had a similar delay in gluteus medius onset activation relative to the vastii muscles.

Conclusion:

Rehabilitation should focus on quadriceps and hip strengthening. Although clinicians have incorporated gluteus medius exercise in rehabilitation programs, additional attention to the external rotators may be useful.Level of Evidence: 4     

Male and female gluteal muscle activity and lower extremity kinematics during running

Background

Patellofemoral pain is one of the most common lower extremity overuse injuries in runners and is significantly more common in females. This study evaluated differences in the timing and magnitude of gluteal muscle activity as well as hip and knee joint frontal and transverse plane kinematics between male and female runners in the context of this gender bias.

Methods

Twenty healthy male and 20 healthy female runners were participants. Three-dimensional lower extremity kinematics, and gluteus medius and gluteus maximus muscle activation were recorded using motion analysis and electromyography as subjects ran at 3.7 m/s (+/−5%). Comparisons of hip and knee joint kinematic and gluteus muscle activation data were made using independent t-tests (α = 0.05).

Findings

Females ran with 40% greater peak gluteus maximus activation level (P = 0.028, effect size = 0.79) and 53% greater average activation level (P = 0.013, effect size = 0.93) than males. Female runners also displayed greater hip adduction (P = .001, effect size = 1.20) and knee abduction (P = 0.011, effect size = 0.87) angles at initial contact, greater hip adduction at peak vertical ground reaction force (P < 0.001, effect size = 1.31), and less knee internal rotation excursion than males (P = 0.035, effect size = 0.71).

Interpretation

Greater gluteus maximus activation levels during running may predispose females to earlier gluteus maximus fatigue, promoting altered lower extremity running kinematics thought to be associated with the etiology of patellofemoral pain. Gender differences in transverse and frontal plane hip and knee kinematics observed in this study may also contribute to the gender bias for patellofemoral pain among females.     

Surface electromyography and plantar pressure changes with novel gait training device in participants with chronic ankle instability

BackgroundRehabilitation is ineffective at restoring normal gait in chronic ankle instability patients. Our purpose was to determine if a novel gait-training device could decrease plantar pressure on the lateral column of the foot in chronic ankle instability patients.MethodsTen chronic ankle instability patients completed 30 s trials of baseline and gait-training walking at a self-selected pace while in-shoe plantar pressure and surface electromyography were recorded from their anterior tibialis, peroneus longus, medial gastrocnemius, and gluteus medius. The gait-training device applied a medially-directed force to the lower leg via elastic bands during the entire gait cycle. Plantar pressure measures of the entire foot and 9 specific regions of the foot as well as surface electromyography root mean square areas were compared between the baseline and gait-training conditions using paired t-tests with a priori level of significance of p ≤ 0.05.FindingsThe gait-training device decreased pressure time integrals and peak pressures in the lateral midfoot (p = 0.003 and p = 0.003) and lateral forefoot (p = 0.023 and p = 0.005), and increased pressure time integrals and peak pressures for the total foot (p = 0.030 and p = 0.017) and hallux (p = 0.005 and p = 0.002). The center of pressure was shifted medially during the entire stance phase (p < 0.003 for all comparisons) due to increased peroneus longus activity prior to (p = 0.002) and following initial contact (p = 0.002).InterpretationThe gait-training device decreased pressure on the lateral column of the foot and increased peroneus longus muscle activity. Future research should analyze the efficacy of the gait-training device during gait retraining for chronic ankle instability.     

Quantity and Quality of the Lower Extremity Muscles in Women with Knee Osteoarthritis

The objective of the study described here was to compare lower extremity muscle quantity and quality between individuals with and those without knee osteoarthritis (OA). Twenty-one women with knee OA (mild, n = 8; severe, n = 13) and 23 healthy patients participated. Ultrasonography was used to measure muscle thickness (MT) and echo intensity (EI) of the rectus femoris, vastus intermedius, vastus lateralis, vastus medialis, biceps femoris, gluteus maximus, gluteus medius, gastrocnemius, soleus and tibialis anterior. MTs of the vastus medialis and vastus intermedius were smaller, and EIs of the vastus medialis, vastus intermedius, gluteus medius and tibialis anterior were larger, in the severe OA group compared than in the healthy group. Compared with the healthy group, the mild OA group had decreased MT and enhanced EI. Changes in quality and quantity occurring with knee OA progression differed among muscles. In the vastus medialis, change was observed from an earlier stage.     

Increased internal femoral torsion can be regarded as a risk factor for patellar instability — A biomechanical study

BackgroundIncreased internal femoral torsion is regarded as a risk factor for patellar instability. Biomechanical investigations confirming this hypothesis are missing.MethodsEight fresh-frozen cadaver knees were tested on a specially designed simulator. Patellar motion and patellofemoral pressure were evaluated for 0°, 10°, and 20° of increased internal and external femoral torsion with native and with transected medial patellofemoral ligaments used to simulate patellar instability. A regression analysis was used for statistical analysis.FindingsIn native medial patellofemoral ligaments, there were no significant changes in mean or peak pressures for any torsional states (P ≥ 0.07). At 20° increased internal femoral torsion, there was a significant center of force shift towards the lateral side (P = 0.01). Patellar shift was directed laterally at low knee flexion angles up to 30°. Lateral patellar tilt increased significantly at 10° and 20° of increased internal femoral torsion (P ≤ 0.004). In transected medial patellofemoral ligaments, mean pressure (P ≤ 0.005) and peak pressure (P ≤ 0.02) decreased significantly for all torsional states. There was a significantly greater lateral center of force shift with increased internal femoral torsion (P ≤ 0.04). Lateral patellar tilt increased significantly (P < 0.001). Patellar shift did not change significantly with increased internal femoral torsion (P ≥ 0.30).InterpretationIn a native medial patellofemoral ligament, 20° of increased internal femoral torsion can be regarded as a significant risk factor for patellar instability. With an insufficient medial patellofemoral ligament, 10° of increased internal femoral torsion already represents a significant risk factor.     

Re-evaluating the functional implications of the Q-angle and its relationship to in-vivo patellofemoral kinematics

BackgroundThe Q-angle is widely used clinically to evaluate individuals with anterior knee pain. Recent studies have questioned the utility of this measure and have suggested that a large Q-angle may not be associated with lateral patellofemoral translation, as often assumed. The objective of this study was to determine: 1) how accurately the Q-angle represents the line-of-action of the quadriceps and 2) if adding active quadriceps contraction or a bent knee position to the measurement of the Q-angle improves its reliability, accuracy, and association with patellofemoral kinematics.MethodsThe study included individuals diagnosed with chronic idiopathic patellofemoral pain and control subjects (n = 43 and n = 30 knees). Three measures of the clinical Q-angle (straight- and bent-knee with relaxed quadriceps and straight-knee with maximum isometric quadriceps contraction) were obtained with a goniometer and compared to a fourth MR-based measure of Q-angle. Patellofemoral kinematics were derived from dynamic cine-phase contrast images, acquired while subjects extended/flexed their knee from approximately 0° and 45°.FindingsThe Q-angle did not represent the line-of-action of the quadriceps. The average difference between each clinical and the MR-based Q-angle ranged from 5° to 8°. These differences varied greatly across subjects (range: − 28.5° to 3.9^o). Adding an active quadriceps contraction or a bent knee position, did not improve the reliability of the Q-angle. An increased Q-angle correlated to medial patellar displacement and tilt (r = 0.38—0.54, P < 0.001) in the cohort with anterior knee pain.InterpretationClinicians are cautioned against using the Q-angle to infer patellofemoral kinematics.     

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

BackgroundDynamic 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.MethodsEighteen 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.FindingsGroup 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).InterpretationThese 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.     

Comfort and midfoot mobility rather than orthosis hardness or contouring influence their immediate effects on lower limb function in patients with anterior knee pain

Background

Despite evidence for use of foot orthoses in the treatment of anterior knee pain, there is a paucity of research into their mechanisms of action. This study (i) determined the immediate lower limb kinematics and muscle activity adaptations, and (ii) evaluated the effect of individual's comfort and foot mobility.

Methods

Forty individuals diagnosed with anterior knee pain were measured for lower limb kinematics and electromyographic activity (via surface electrodes) while they jogged in three prefabricated contoured orthoses (hard, medium and soft) and a soft-flat orthosis. Subjects ranked orthoses in order of comfort.

Findings

Soft orthoses were more comfortable. No immediate adaptations in kinematics and electromyographic activity were observed when orthoses were added to shoes. There were few effects of perceived comfort and foot mobility, one being a significant interaction in frontal plane hip motion (Pillai's V = 0.089, P = 0.031) with the least comfortable orthosis producing the greatest relative adduction in those with mobile feet (0.54° (standard deviation 0.87)). Other main effects were a significant increase in vastus lateralis activity when wearing the least comfortable orthosis (6.94%, P = 0.007) and a delay in offset of medial gastrocnemius in individuals with less mobile feet (1.51%, P = 0.045).

Interpretation

It is becoming apparent that it is important to use more comfortable foot orthoses in a condition like anterior knee pain, where there is an associated increased hip adduction and vastus lateralis activity with least comfortable orthoses. Future research is needed to determine adaptations after ongoing wearing of orthoses.