The immediate effects of foot orthoses on hip and knee kinematics and muscle activity during a functional step-up task in individuals with patellofemoral pain

BackgroundEvidence shows that anti-pronating foot orthoses improve patellofemoral pain, but there is a paucity of evidence concerning mechanisms. We investigated the immediate effects of prefabricated foot orthoses on (i) hip and knee kinematics; (ii) electromyography variables of vastus medialis oblique, vastus lateralis and gluteus medius during a functional step-up task, and (iii) associated clinical measures.MethodsHip muscle activity and kinematics were measured during a step-up task with and without an anti-pronating foot orthoses, in people (n = 20, 9 M, 11 F) with patellofemoral pain. Additionally, we measured knee function, foot posture index, isometric hip abductor and knee extensor strength and weight-bearing ankle dorsiflexion.FindingsReduced hip adduction (0.82°, P = 0.01), knee internal rotation (0.46°, P = 0.03), and decreased gluteus medius peak amplitude (0.9 mV, P = 0.043) were observed after ground contact in the ‘with orthoses’ condition. With the addition of orthoses, a more pronated foot posture correlated with earlier vastus medialis oblique onset (r = − 0.51, P = 0.02) whilst higher Kujala scores correlated with earlier gluteus medius onset (r = 0.52, P = 0.02).InterpretationAlthough small in magnitude, reductions in hip adduction, knee internal rotation and gluteus medius amplitude observed immediately following orthoses application during a task that commonly aggravates symptoms, offer a potential mechanism for their effectiveness in patellofemoral pain management. Given the potential for cumulative effects of weight bearing repetitions completed with a foot orthoses, for example during repeated stair ascent, the differences are likely to be clinically meaningful.     

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.     

Determination of patellofemoral pain sub-groups and development of a method for predicting treatment outcome using running gait kinematics

BackgroundNot all patients with patellofemoral pain exhibit successful outcomes following exercise therapy. Thus, the ability to identify patellofemoral pain subgroups related to treatment response is important for the development of optimal therapeutic strategies to improve rehabilitation outcomes. The purpose of this study was to use baseline running gait kinematic and clinical outcome variables to classify patellofemoral pain patients on treatment response retrospectively.MethodsForty-one individuals with patellofemoral pain that underwent a 6-week exercise intervention program were sub-grouped as treatment Responders (n = 28) and Non-responders (n = 13) based on self-reported measures of pain and function. Baseline three-dimensional running kinematics, and self-reported measures underwent a linear discriminant analysis of the principal components of the variables to retrospectively classify participants based on treatment response. The significance of the discriminant function was verified with a Wilk's lambda test (α = 0.05).FindingsThe model selected 2 gait principal components and had a 78.1% classification accuracy. Overall, Non-responders exhibited greater ankle dorsiflexion, knee abduction and hip flexion during the swing phase and greater ankle inversion during the stance phase, compared to Responders.InterpretationThis is the first study to investigate an objective method to use baseline kinematic and self-report outcome variables to classify on patellofemoral pain treatment outcome. This study represents a significant first step towards a method to help clinicians make evidence-informed decisions regarding optimal treatment strategies for patients with patellofemoral pain.     

Influence of a knee brace intervention on perceived pain and patellofemoral loading in recreational athletes

BackgroundThe current investigation aimed to investigate the effects of an intervention using knee bracing on pain symptoms and patellofemoral loading in male and female recreational athletes.MethodsTwenty participants (11 males & 9 females) with patellofemoral pain were provided with a knee brace which they wore for a period of 2 weeks. Lower extremity kinematics and patellofemoral loading were obtained during three sport specific tasks, jog, cut and single leg hop. In addition their self-reported knee pain scores were examined using the Knee injury and Osteoarthritis Outcome Score. Data were collected before and after wearing the knee brace for 2 weeks.FindingsSignificant reductions were found in the run and cut movements for peak patellofemoral force/pressure and in all movements for the peak knee abduction moment when wearing the brace. Significant improvements were also shown for Knee injury and Osteoarthritis Outcome Score subscale symptoms (pre: male = 70.27, female = 73.22 & post: male = 85.64, female = 82.44), pain (pre: male = 72.36, female = 78.89 & post: male = 85.73, female = 84.20), sport (pre: male = 60.18, female = 59.33 & post: male = 80.91, female = 79.11), function and daily living (pre: male = 82.18, female = 86.00 & post: male = 88.91, female = 90.00) and quality of life (pre: male = 51.27, female = 54.89 & post: male = 69.36, female = 66.89).InterpretationMale and female recreational athletes who suffer from patellofemoral pain can be advised to utilise knee bracing as a conservative method to reduce pain symptoms.     

The effect of a rotator cuff tear and its size on three-dimensional shoulder motion

BackgroundRotator cuff-disease is associated with changes in kinematics, but the effect of a rotator cuff-tear and its size on shoulder kinematics is still unknown in-vivo.MethodsIn this cross-sectional study, glenohumeral and scapulothoracic kinematics of the affected shoulder were evaluated using electromagnetic motion analysis in 109 patients with 1) subacromial pain syndrome (n = 34), 2) an isolated supraspinatus tear (n = 21), and 3) a massive rotator cuff tear involving the supraspinatus and infraspinatus (n = 54). Mixed models were applied for the comparisons of shoulder kinematics between the three groups during abduction and forward flexion.FindingsIn the massive rotator cuff-tear group, we found reduced glenohumeral elevation compared to the subacromial pain syndrome (16°, 95% CI [10.5, 21.2], p < 0.001) and the isolated supraspinatus tear group (10°, 95% CI [4.0, 16.7], p = 0.002) at 110° abduction. Reduced glenohumeral elevation in massive rotator cuff tears coincides with an increase in scapulothoracic lateral rotation compared to subacromial pain syndrome (11°, 95% CI [6.5, 15.2], p < 0.001) and supraspinatus tears (7°, 95% CI [1.8, 12.1], p = 0.012). Comparable differences were observed for forward flexion. No differences in glenohumeral elevation were found between the subacromial pain syndrome and isolated supraspinatus tear group during arm elevation.InterpretationThe massive posterosuperior rotator cuff-tear group had substantially less glenohumeral elevation and more scapulothoracic lateral rotation compared to the other groups. These observations suggest that the infraspinatus is essential to preserve glenohumeral elevation in the presence of a supraspinatus tear. Shoulder kinematics are associated with rotator cuff-tear size and may have diagnostic potential.     

Superior-inferior position of patellar component affects patellofemoral kinematics and contact forces in computer simulation

BackgroundAnterior knee pain has been reported as a major postoperative complication after total knee arthroplasty, which may lead to patient dissatisfaction. Rotational alignment and the medial-lateral position correlate with patellar maltracking, which can cause knee pain postoperatively. However, the superior-inferior position of the patellar component has not been investigated. The purpose of the current study was to investigate the effects of the patellar superior-inferior position on patellofemoral kinematics and kinetics.MethodsSuperior, central, and inferior models with a dome patellar component were constructed. In the superior and inferior models, the position of the patellar component translated superiorly and inferiorly, respectively, by 3 mm, relative to the center model. Kinematics of the patellar component, quadriceps force, and patellofemoral contact force were calculated using a computer simulation during a squatting activity in a weight-bearing deep knee bend.FindingsIn the inferior model, the flexion angle, relative to the tibial component, was the greatest among all models. The inferior model showed an 18.0%, 36.5%, and 22.7% increase in the maximum quadriceps force, the maximum medial patellofemoral force, and the maximum lateral patellofemoral force, respectively, compared with the superior model.InterpretationSuperior-inferior positions affected patellofemoral kinematic and kinetics. Surgeons should avoid the inferior position of the patellar component, because the inferior positioned model showed greater quadriceps and patellofemoral force, resulting in a potential risk for anterior knee pain and component loosening.     

Lean muscle volume of the thigh has a stronger relationship with muscle power than muscle strength in women with knee osteoarthritis

BackgroundThigh lean muscle and intramuscular fat have been implicated in the impairment of physical function observed in people with knee osteoarthritis. We investigated the relationships of quadriceps and hamstrings intramuscular fat fraction and lean muscle volume with muscle power and strength, controlling for neuromuscular activation, and physical performance in women with knee OA.MethodsWomen (n = 20) 55 years or older with symptomatic, radiographic knee osteoarthritis underwent a 3.0T magnetic resonance imaging scan of the thigh of their most symptomatic knee. Axial fat-separated images were analyzed using software to quantify intramuscular fat and lean muscle volumes of the quadriceps and hamstrings. To quantify strength and power of the knee extensors and flexors, participants performed maximum voluntary isometric contraction and isotonic knee extensions and flexions, respectively. Electromyography of the quadriceps and hamstrings was measured. Participants also completed five physical performance tests.FindingsQuadriceps and hamstrings lean muscle volumes were related to isotonic knee extensor (B = 0.624; p = 0.017) and flexor (B = 1.518; p = 0.032) power, but not knee extensor (B = 0.001; p = 0.615) or flexor (B = 0.001; p = 0.564) isometric strength. Intramuscular fat fractions were not related to isotonic knee extensor or flexor power, nor isometric strength. No relationships were found between intramuscular fat or lean muscle volume and physical performance.InterpretationMuscle power may be more sensitive than strength to lean muscle mass in women with knee osteoarthritis. Thigh lean muscle mass, but neither intramuscular nor intermuscular fat, is related to knee extensor and flexor power in women with knee osteoarthritis.     

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.     

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.     

Patellar taping alters knee kinematics during step descent in individuals with a meniscal injury: An exploratory study

BackgroundMeniscus lesions are common musculoskeletal knee injuries which often lead to pain, limitation and compensations during functional tasks, such as descending stairs. This study investigated the effect of patellar taping with tension and without tension on three-dimensional (3D) kinematics of the knee during a slow step descent task in patients with meniscal lesions.MethodsTen patients diagnosed with a meniscal lesion, confirmed by magnetic resonance imaging, underwent five, step descent movements at slow speed under three different conditions: 1) no taping; 2) tension-free taping; and 3) patellar taping with medial tension. 3D kinematic data were recorded from the injured knee using an eight-camera infrared Vicon motion analysis system. Maximum and minimum angle values and total range of motion (maximum/minimum value) in three movement planes during single-limb stance were compared using a repeated measure ANOVA.FindingsResults showed a significant increase in the maximum and minimum angle value in the sagittal plane (mean differences = 2.4° and 4.2°, respectively) and a decrease in the transverse plane (− 6.3° and − 2.2°, respectively) for the patellar taping condition compared to the no taping condition. A decreased rotational angle range when comparing the patellar taping to the no taping (− 4.1°) and tension-free taping (− 3.1°) conditions was also observed. These changes remained significant when pain was considered as a covariate in the analysis. The tension applied to the patellar tape played a role in controlling the sagittal and transverse plane step-down movement among patients in our study.InterpretationThese results support the use of patellar taping with a medially oriented tension to help to reduce the transversal plane movement of the knee in this population and they bring new light to the taping effect.     

Differences in lumbar spine and lower extremity kinematics during a step down functional task in people with and people without low back pain

BackgroundWhen functional movements are impaired in people with low back pain, they may be a contributing factor to chronicity and recurrence. The purpose of the current study was to examine lumbar spine, pelvis, and lower extremity kinematics during a step down functional task between people with and without a history of low back pain.MethodsA 3-dimensional motion capture system was used to analyze kinematics during a step down task. Total excursion of the lumbar spine, pelvis, and lower extremity segments in each plane were calculated from the start to end of the task. Separate analysis of variance tests (α = 0.05) were conducted to determine the effect of independent variables of group and plane on lumbar spine, pelvis, and lower extremity kinematics. An exploratory analysis was conducted to examine kinematic differences among movement-based low back pain subgroups.FindingsSubjects with low back pain displayed less lumbar spine movement than controls across all three planes of movement (P-values = 0.001–0.043). This group difference was most pronounced in the sagittal plane. For the lower extremity, subjects with low back pain displayed more frontal and axial plane knee movement than controls (P-values = 0.001). There were no significant differences in kinematics among movement-based low back pain subgroups.InterpretationPeople with low back pain displayed less lumbar region movement in the sagittal plane and more off-plane knee movements than the control group during a step down task. Clinicians can use this information when assessing lumbar spine and lower extremity movement during functional tasks, with the goal of developing movement-based interventions.     

Distinctions of introarticular force distribution between genesis-II posterior stabilized and cruciate retaining total knee arthroplasty: An intraoperative comparative study of 45 patients

BackgroundAlthough both the posterior stabilized and cruciate retaining total knee arthroplasty have been proven to effectively relieve pain and restore basic functions, the joint gap width during flexion was reported to be different due to the presence or absence of posterior cruciate ligament, which may lead to different intra-articular force distribution. In this study, we investigated the distinctions in intra-articular force distribution between the two types of TKA designs in patients with varus knee osteoarthritis.MethodsForty five patients (50 knees) with varus knee osteoarthritis were prospectively included, with each 25 knees receiving cruciate retaining and posterior stabilized total knee arthroplasty, respectively. With an intra-articular force measurement system, the intra-articular force distribution with knee flexion at 0°, 30°, 45°, 60°, 90°, and 120° were recorded in all patients.FindingsThe total force was similar for posterior stabilized and cruciate retaining knees at all flexion degrees. However, force in the medial compartment accounted for 59.8% –84.0% of total force in posterior stabilized knees, while 27.4% –65.7% in cruciate retaining knees. In cruciate retaining knees, no significant difference was found between forces in the two compartments at 30° flexion (P = 0.444), but force was significantly concentrated in the lateral side during 45° –120° flexion (P = 0.000– 0.028).InterpretationAlthough the entire intra-articular forces were similar between CR and PS knees at different flexion angles, medial part had higher force than lateral part when PS knee was used. The posterior cruciate ligament do a role in soft balance, and make the force more evenly distributed.     

The role of knee joint moments and knee impairments on self-reported knee pain during gait in patients with knee osteoarthritis

BackgroundThe association between high mechanical knee joint loading during gait with onset and progression of knee osteoarthritis has been extensively studied. However, less attention has been given to risk factors related to increased pain during gait. The purpose of this study was to evaluate knee joint moments and clinical characteristics that may be associated with gait-related knee pain in patients with knee osteoarthritis.MethodsSixty-seven participants with knee osteoarthritis were stratified into three groups of no pain (n = 18), mild pain (n = 27), or moderate/severe pain (n = 22) based on their self-reported symptoms during gait. All participants underwent three-dimensional gait analysis. Quadriceps strength, knee extension range of motion, radiographic knee alignment and self-reported measures of global pain and function were also quantified.FindingsThe moderate/severe pain group demonstrated worse global pain (P < 0.01) and physical function scores (P < 0.01) compared to the no pain and the mild pain groups. The moderate/severe pain group also walked with greater knee flexion moments during the midstance phase of gait compared to the no pain group (P = 0.02). Additionally, the moderate/severe pain group demonstrated greater varus knee malalignment (P = 0.009), which was associated with higher weight acceptance peak knee adduction moments (P = 0.003) and worse global pain (P = 0.003) and physical function scores (P = 0.006).InterpretationGreater knee flexion moment is present during the midstance phase of gait in patients with knee osteoarthritis and moderate/severe pain during gait. Additionally, greater varus malalignment may be a sign of increased global knee joint dysfunction that can influence many activities of daily living beyond gait.     

Femorotibial kinematics and load patterns after total knee arthroplasty: An in vitro comparison of posterior-stabilized versus medial-stabilized design

BackgroundFemorotibial kinematics and contact patterns vary greatly with different total knee arthroplasty (TKA) designs. Therefore, guided motion knee systems were developed to restore natural knee kinematics and make them more predictable. The medial stabilized TKA design is supposed to replicate physiological kinematics more than the posterior-stabilized TKA system. We conducted this study to compare a newly developed medial stabilized design with a conventional posterior-stabilized design in terms of femorotibial kinematics and contact patterns in vitro.MethodsTwelve fresh-frozen knee specimens were tested in a weight-bearing knee rig after implantation of a posterior stabilized and medial-stabilized total knee arthroplasty under a loaded squat from 20° to 120° of flexion. Femorotibial joint contact pressures in the medial and lateral compartments were measured by pressure sensitive films and knee kinematics were recorded by an ultrasonic 3-dimensional motion analysis system.FindingsThe medial stabilized design showed a reduction of medial femorotibial translation compared to posterior-stabilized design (mean 3.5 mm compared to 15.7 mm, P < 0.01). In the lateral compartment, both designs showed a posterior translation of the femur with flexion, but less in the medial stabilized design (mean 14.7 mm compared to 19.0 mm, P < 0.01). In the medial femorotibial compartment of medial stabilized design, we observed an enlarged contact area and lower peak pressure, in contrast in the lateral compartment there was a reduced contact area and an increased peak pressure.InterpretationWhile posterior-stabilized design enforces a medio-lateral posterior translation, the medial stabilized arthroplasty system enables a combination of a lateral translation with a medial pivot, which restores the physiological knee kinematics better.     

A sex comparison of reactive knee stiffness regulation strategies under cognitive loads

BackgroundSex differences may exist in cognitive faculties and neuromuscular strategies for maintaining joint stability. The purpose of this study was to assess whether preparatory and reactive knee stiffening strategies are affected differently in males and females exposed to sex-biased cognitive loads.Methods20 male and 20 female volunteers were tested for knee joint stiffness and quadriceps and hamstring muscle activation patterns throughout a rapid eccentric knee extension perturbation. Participants were tested under 3 cognitive loads (Benton's Judgment of Line Orientation; Symbol Digit modalities Test; and Serial 7's) and a control condition. Apparent knee joint stiffness and muscle activation amplitude and timing were quantified throughout the perturbation across the 4 conditions.FindingsReactive knee stiffness values were significantly less during the cognitive tasks compared to the control condition (Judgment of Line Orientation = 0.034 Nm/deg/kg, Symbol Digit Modalities Test = 0.037 Nm/deg/kg, Serial 7's = 0.037 Nm/deg/kg, control = 0.048 Nm/deg/kg). Females had greater normalized total apparent stiffness than males. The quadriceps muscles had faster and greater activation than the hamstring muscles; however, no group differences were observed. No overall differences in muscle activation (magnitude and timing) were found between the cognitive loading tasks.InterpretationCognitive loading may decrease the ability of healthy individuals to reactively stiffen their knee joint and appears to interfere with the normal stiffness regulation strategies. This may elucidate an extrinsic risk factor for non-contact knee ligament injury.     

The effect of wedge and tibial slope angles on knee contact pressure and kinematics following medial opening-wedge high tibial osteotomy

BackgroundHigh tibial osteotomy is a surgical procedure to treat medial compartment osteoarthritis in varus knees. The reported success rates of the procedure are inconsistent, which may be due to sagittal plane alignment of the osteotomy. The objective of this study was to determine the effect of changing tibial slope, for a range of tibial wedge angles in high tibial osteotomy, on knee joint contact pressure location and kinematics during continuous loaded flexion/extension.MethodsSeven cadaveric knee specimens were cycled through flexion and extension in an Oxford knee-loading rig. The osteotomy on each specimen was adjusted to seven clinically relevant wedge and slope combinations. We used pressure sensors to determine the position of the centre of pressure in each compartment of the tibial plateau and infrared motion capture markers to determine tibiofemoral and patellofemoral kinematics.FindingsIn early knee flexion, a 5° increase in tibial slope shifted the centre of pressure in the medial compartment anteriorly by 4.5 mm (P ≤ 0.001), (from the neutral slope/wedge position). Increasing the tibial slope also resulted in the tibia translating anteriorly (P ≤ 0.001).InterpretationChanges to the tibial slope during high tibial osteotomy for all tested wedge angles shifted the centre of pressure in both the medial and lateral compartments substantially and altered knee kinematics. Tibial slope should be controlled during high tibial osteotomy to prevent unwanted changes in tibial plateau contact loads.     

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.     

Trunk and lower limb biomechanics during stair climbing in people with and without symptomatic femoroacetabular impingement

BackgroundFemoroacetabular impingement is a pathomechanical hip condition leading to pain and impaired physical function. It has been shown that those with femoroacetabular impingement exhibit altered gait characteristics during level walking and stair climbing, and decreased muscle force production during isometric muscle contractions. However, no studies to-date have looked at trunk kinematics or muscle activation during dynamic movements such as stair climbing in this patient population. The purpose of this study was to compare biomechanical outcomes (trunk and lower limb kinematics as well as lower limb kinetics and muscle activation) during stair climbing in those with and without symptomatic femoroacetabular impingement.MethodsTrunk, hip, knee and ankle kinematics, as well as hip, knee and ankle kinetics and muscle activity of nine lower limb muscles were collected during stair climbing for 20 people with clinical and radiographic femoroacetabular impingement and compared to 20 age- and sex-matched pain-free individuals.FindingsThose with femoroacetabular impingement ascended the stairs slower (effect size = 0.82), had significantly increased peak trunk forward flexion angles (effect size = 0.99) and external hip flexion moments (effect size = 0.94) and had decreased peak external knee flexion moments (effect size = 0.90) compared to the control group.InterpretationFindings from this study indicate that while those with and without femoroacetabular impingement exhibit many biomechanical similarities when ascending stairs, differences in trunk forward flexion and joint kinetics indicate some important differences. Further longitudinal research is required to elucidate the cause of these differences as well as the clinical relevance.     

Scapular asymmetry in participants with and without shoulder impingement syndrome; a three-dimensional motion analysis

BackgroundThis study analyzed the dynamic three-dimensional scapular kinematics and scapular asymmetry in participants with and without shoulder impingement syndrome.MethodsTwenty-nine participants with shoulder impingement syndrome, have been suffering from unilateral shoulder pain at the dominant arm lasting more than six weeks and thirty-seven healthy controls participated in the study. Scapular kinematics was measured with an electromagnetic tracking device during shoulder elevation in the sagittal plane. Data for bilateral scapular orientation were analyzed at 30°, 60°, 90°, and 120° of humerothoracic elevation and lowering. The symmetry angle was calculated to quantify scapular asymmetry throughout shoulder elevation.FindingsStatistical comparisons indicated that the scapula was more downwardly rotated (p < 0.001) and anteriorly tilted (p = 0.005) in participants with shoulder impingement syndrome compared to healthy controls. Side-to-side comparisons revealed that the scapula was more anteriorly tilted on the involved side of participants with shoulder impingement syndrome (p = 0.01), and the scapula was rotated more internally (p = 0.02) and downwardly (p = 0.01) on the dominant side of healthy controls. Although there were side-to-side differences in both groups, symmetry angle calculation revealed that the scapular movement was more asymmetrical for scapular internal and upward rotation in individuals with shoulder impingement syndrome when compared with healthy controls (p < 0.05).InterpretationThe findings of the study increase our knowledge and understanding of scapular alterations in symptomatic and asymptomatic populations, which creates biomechanical considerations for shoulder assessment and rehabilitation.