Neuromuscular adaptations in older males and females with knee osteoarthritis during weight-bearing force control

Background

Females exhibit significantly greater incidence, prevalence, and severity of osteoarthritis (OA) compared to males. Despite known biological, morphological, and functional differences between males and females, there has been little sex-related investigation into sex-specific biomechanical and neuromuscular responses to OA.

Effects of increased step width on frontal plane knee biomechanics in healthy older adults during stair descent

BackgroundPeak internal knee abduction moment is a common surrogate variable associated with medial compartment knee loading. Stair descent has been shown to yield a greater peak knee abduction moment compared to level-walking. Changes in step width (SW) may lead to changes in frontal plane lower extremity limb alignment in the frontal plane and alter peak knee abduction moment. The purpose of this study was to investigate the effects of increased SW on frontal plane knee biomechanics during stair descent in healthy older adults.MethodsTwenty healthy adults were recruited for the study. A motion analysis system was used to obtain three-dimensional lower limb kinematics during testing. An instrumented 3-step staircase with two additional customized wooden steps was used to collect ground reaction forces (GRF) data during stair descent trials. Participants performed five stair descent trials at their self-selected speed using preferred, wide (26% leg length), and wider (39% leg length) SW.ResultsThe preferred normalized SW in older adults during stair descent was 20% of leg length. Wide and wider SW during stair descent reduced both first and second peak knee adduction angles and abduction moments compared to preferred SW in healthy adults.ConclusionsIncreased SW reduced peak knee adduction angles and abduction moments. The reductions in knee abduction moments may have implications in reducing medial compartment knee loads during stair descent.     

Influence of the instrumented force shoe on gait pattern in patients with osteoarthritis of the knee

Osteoarthritis (OA) of the knee is associated with alterations in gait. As an alternative to force plates, instrumented force shoes (IFSs) can be used to measure ground reaction forces. This study evaluated the influence of IFS on gait pattern in patients with knee OA. Twenty patients with knee OA walked in a gait laboratory on IFS and control shoes (CSs). An optoelectronic system and force plate were used to perform 3D gait analyses. A comparison of temporal-spatial gait parameters, kinematics, and kinetics was made between IFS and CS. Patients wearing IFS showed a decrease in walking velocity and cadence (8%), unchanged stride length, an increase in stance time (13%), stride time (11%) and step width (14%). No differences were found in knee adduction moment or knee kinematics. Small differences were found in foot and ankle kinematics (2–5°), knee transverse moments (5%), ankle frontal (3%) and sagittal moments (1%) and ground reaction force (1–6%). The gait of patients with knee OA was only mildly influenced by the IFS, due to increased shoe height and weight and a change in sole stiffness. The changes were small compared to normal variation and clinically relevant differences. Importantly, in OA patients no effect was found on the knee adduction moment.     

A comparison of tibiofemoral and patellofemoral alignment during a neutral and valgus single leg squat: an MRI study

BackgroundThe etiology of anterior knee pain is not well understood. Recently, excessive hip adduction and internal rotation have been cited as possible factors. However, how these altered hip mechanics affect the patellofemoral joint is still unclear.ObjectiveTo compare the three-dimensional tibiofemoral and patellofemoral alignment between a neutral squat and one performed with increased hip adduction and internal rotation. We aimed to examine the relationships between the three-dimensional tibiofemoral and patellofemoral alignment during a neutral and valgus squat. Finally, we aimed to determine the relationship between two-dimensional and three-dimensional measures of patellofemoral alignment.Methods10 healthy subjects were recruited for this study. Knee and patellar kinematics in a neutral squat and one performed with hip adduction and internal rotation were measured using a open, upright, magnetic resonance imaging unit. Both single leg squats were performed at 30° of knee flexion.ResultsThere was a significant correlation between knee external rotation and lateral patellar translation, and between knee abduction and lateral patellar translation. Moderate relationships were found between the 2D and 3D measures but these were not statistically significant.ConclusionThe valgus squat resulted in greater knee external rotation in all subjects. Although mean patellar mechanics were not different in the valgus squat, lateral patellar translation increased as knee external rotation increased. Lastly, 2D measures of patellofemoral alignment only provide moderately fair surrogates for 3D measures.     

Radiographic analysis using the hip-to-calcaneus line and its association with lower limb joint kinetics in varus knee osteoarthritis

BackgroundThis study aimed to (1) determine whether the hip to ankle (HA) line or hip to calcaneus (HC) line better reflects knee coronal plane kinetics, (2) to examine whether the HC line reflects ankle coronal plane kinetics, and (3) to evaluate the radiological and biomechanical aspects of ankle in varus knee osteoarthritis (OA).MethodsFull-length, postero-anterior radiographs (hip-to-calcaneus radiographs) were taken and gait analysis was performed in 21 varus knee OA patients. The %HA where the HA lines pass through the tibial plateau, and the %HC and the mechanical ankle joint axis point (MAJAP), where the HC line passes through the tibial plateau and tibial plafond, respectively, were calculated. Knee adduction angular impulse (KAAI) and ankle inversion angular impulse (AIAI) were collected as kinetic data. Finally, we divided the patients into two groups with and without ankle OA, and compared each parameter between both groups.ResultsThe %HA and %HC were correlated with KAAI (%HA; r = -0.68, P = 0.001, %HC; r = -0.81, P < 0.001, respectively) and MAJAP was correlated with AIAI (r = -0.55, P = 0.009). MAJAP was significantly smaller, and KAAI and AIAI were significantly larger in the ankle OA group.ConclusionsRadiographic analysis using the HC line was more strongly correlated to knee joint kinetics than the HA line and was also correlated to ankle joint kinetics. Assessing lower limb alignment using the HC line could be useful to evaluate the knee and ankle joints for varus knee OA.     

Altered biomechanics in bilateral total knee replacement patients during stair negotiation

BackgroundMany total knee replacement (TKR) patients need to have a contralateral knee replacement. Biomechanical differences between first and second replaced limbs of bilateral TKR have not been examined during stair negotiation. Additionally, it is unknown whether hip and ankle biomechanics of bilateral patients are altered. We examined hip, knee, and ankle biomechanics of first and second replaced limbs bilateral patients, as well as replaced and non-replaced limbs of unilateral patients, during stair ascent and descent.MethodsEleven bilateral TKR patients (70.09 ± 5.41 years, 1.71 ± 0.08 m, 91.78 ± 13.00 kg) and 15 unilateral TKR patients (64.93 ± 5.11 years, 1.75 ± 0.09 m, 89.18 ± 17.55 kg) were recruited. Patients performed three to five trials of stair ascent and descent. The second step, during ascent, was the step of interest when analyzing each limb. A 2 × 2 (limb × group) analysis of variance was performed to determine differences between limbs and groups.ResultsDuring ascent, bilateral patients exhibited decreased peak loading-response knee extension (KEM) and push-off plantarflexion moments. Unilateral replaced limb KEM was lower than non-replaced limbs. During descent, bilateral patients descended the staircase significantly slower, had lower peak loading-response vertical ground reaction force and KEM, and push-off KEM. Bilateral patients had higher peak loading-response hip extension and push-off plantarflexion moments, and increased knee adduction ROM, compared with unilateral TKA patients.ConclusionsBilateral patients exhibited similar hip, knee, and ankle joint moments between first and second replaced limbs. Substantial differences in hip, knee, and ankle biomechanics during stair negotiation in bilateral patients compared with unilateral patients may indicate a more complex adaptation strategy present in these patients.     

A new biomechanical model for the functional assessment of knee osteoarthritis

The severity of symptoms in osteoarthritis (OA) of the knee can be difficult to assess. A new method for assessing medial compartment OA of the knee is proposed. The purpose of this study was to determine if a relationship exists between the severity of OA and single limb stance knee adduction moment (SSKAM). Fourteen patients with medial compartment OA of the knee were tested and compared with 14 age-matched volunteers. WOMAC OA index scores were documented. Biomechanical data were collected from a single Kistler force platform and a six-camera ProReflex motion analysis system, and the knee adduction moments were calculated. A significant difference in the maximum, minimum and mean adduction moments was found between the two groups, and a correlation of r=0.66 for WOMAC physical function subscale, r=0.63 for the WOMAC pain subscale and r=0.63 for the sum of the subscales and mean SSKAM was found. Single limb stance adduction moments provide additional, objective information in the assessment of medial compartment OA of the knee. It may be useful in the selection of patients for surgery and for evaluating various treatment modalities for medial compartment OA of the knee.     

Asymmetric knee loading at heel contact during walking in patients with unilateral knee replacement

Increased load on the knee joint by excessive levels of impact forces during initial contact has been suggested to lead to knee osteoarthritis (OA). Asymmetric loading after knee replacement may also relate to the development of OA in the contralateral limb, therefore this study investigated the heel strike transient vertical force and subsequent lower extremity kinematic, kinetic and spatio-temporal parameters during level walking between the operated and the contralateral limbs in patients 12 months following unilateral knee replacement. A six camera motion analysis system with a force plate was used to investigate the differences between limbs in the heel strike transient vertical GRF and its relative timing, and hip, knee and ankle angles and moments at initial contact, as well as spatio-temporal parameters during the stance phase of walking in 19 subjects with unilateral knee replacement. Paired t tests showed a significant difference in the contralateral limb relative to the operated limb in the heel strike transient magnitude (p=0.03), hip moment (p=0.01), knee moment (p=0.02) and ankle moment (p=0.03). No significant differences were found for the joint angles at heel contact or the spatio-temporal parameters (p>0.05). The heel strike transient magnitude was lower for the operated limb with no differences in the spatio-temporal parameters or the joint angles at initial contact between the limbs. Differences in the hip, knee and ankle moments were also found indicating an asymmetric loading of the impact force at initial contact on the lower extremity. The current findings may indicate an asymmetric loading on the knee joint and therefore may be clinically relevant in patients undergoing unilateral knee replacement.     

Age-related changes in kinematics of the knee joint during deep squat

Researchers frequently use the deep knee squat as a motor task in order to evaluate the kinematic performance after total knee arthroplasty. Many authors reported about the kinematics of a normal squatting motion, however, little is known on what the influence of aging is. Twenty-two healthy volunteers in various age groups (range 21-75 years) performed a deep knee squat activity while undergoing motion analysis using an optical tracking system. The influence of aging was evaluated with respect to kinematics of the trunk, hip, knee and ankle joints. Older subjects required significantly more time to perform a deep squat, especially during the descending phase. They also had more knee abduction and delayed peak knee flexion. Older subjects were slower in descend than ascend during the squat. Although older subjects had a trend towards less maximal flexion and less internal rotation of the knee compared to younger subjects, this difference was not significant. Older subjects also showed a trend towards more forward leaning of the trunk, resulting in increased hip flexion and anterior thoracic tilt. This study confirmed that some aspects of squat kinematics vary significantly with age, and that the basic methodology employed here can successfully detect these age-related trends. Older subjects had more abduction of the knee joint, and this may indicate the load distribution of the medial and lateral condyles could be different amongst ages. Age-matched control data are therefore required whenever the performance of an implant is evaluated during a deep knee squat.     

Biomechanical effectiveness of a distraction–rotation knee brace in medial knee osteoarthritis: Preliminary results

BackgroundNon-pharmacological therapies are recommended for the care of knee osteoarthritis patients. Unloader knee braces provide an interesting functional approach, which aims to modulate mechanical stress on the symptomatic joint compartment. We aimed to confirm the biomechanical effects and evaluate functional benefits of a new knee brace that combines a valgus effect with knee and tibial external rotation during gait in medial osteoarthritis patients.MethodsTwenty patients with unilateral symptomatic medial knee osteoarthritis were included and they performed two test sessions of 3D gait analysis with and without the brace at the initial evaluation (W0) and after 5 weeks (W5) of wearing the brace. VAS-pain, satisfaction scores, WOMAC scores, spatio-temporal gait parameters (gait speed, stride length, stance and double stance phases, step width), and biomechanical data of the ipsilateral lower limb (hip, knee, ankle and foot progression angles) were recorded at each session.ResultsVAS-pain and WOMAC significantly decreased at W5. Walking speed was not significantly modified by knee bracing at W0, but increased significantly at W5. Knee adduction moments and foot progression angles significantly decreased in the terminal stance and push off, respectively, with bracing at W0 and W5. Lower-limb joint angles, moments and powers were significantly modified by wearing the brace at W0 and W5.ConclusionThis new knee brace with distraction–rotation effects significantly alters knee adduction moments and foot progression angles during gait, which might lead to significant functional gait improvements and have carry-over effects on pain at the short term in osteoarthritis patients (< 2 months).Level of Evidence: level IV.     

Lower limb flexibility norms: some racial, gender and limb symmetrical considerations

The joint flexibility of the lower limb of 400 undergraduate students (200 males and 200 females) whose ages ranged between 20 and 25 years were measured with the standard goniometer. The measured range of motion were hip flexion, extension, abduction, adduction, medial and laterial rotation, knee flexion and ankle dorsiflexionn and plantarflexion. Overall it was found that Nigeria adults demonstrated more lower limb joints flexibility than those reported by the American Academy of Orthopaedic Surgeons (AAOS) (1963). Females exhibited higher flexibility in hip extension, adduction, medial and lateral rotation, ankle dorsiflexion and plantarflexion, but were lower in hip flexion and abduction as compared to males. For both sexes, only slight asymmetrical variation were observed in the joint measurements obtained for the right and left lower limbs. Our findings suggested that the application of universal joint flexibility norms for different racial groups may be clinically inappropriate. Thus flexibility norms may be specific to the racial population from which it was derived. It also alerts physical therapists on the need to discriminate joint mobilities between male and female patients. It is envisaged that the findings of this study will further assist physical therapists while assessing young adult patients who may suffer musculoskeletal dysfunction affecting the lower extremity. In treating a patient, the unaffected contra-lateral limb joint may validly be used as a standard for the affected one.     

Effect of footwear on the external knee adduction moment - A systematic review

ContextFootwear modifications have been investigated as conservative interventions to decrease peak external knee adduction moment (EKAM) and pain associated with knee osteoarthritis (OA).ObjectiveTo evaluate the literature on the effect of different footwear and orthotics on the peak EKAM during walking and/or running.MethodsA systematic search of databases resulted in 348 articles of which 33 studies were included.ResultsSeventeen studies included healthy individuals and 19 studies included subjects with medial knee OA. Quality assessment (modified Downs and Black quality index) showed an (average ± SD) of 73.1 ± 10.1%. The most commonly used orthotic was the lateral wedge, with three studies on the medial wedge. Lateral wedging was associated with decreased peak EKAM in healthy participants and participants with medial knee OA while there is evidence for increased peak EKAM with the use of medial wedges. Modern footwear (subjects' own shoe, “stability” and “mobility” shoes, clogs) were likely to increase the EKAM compared to barefoot walking in individuals with medial knee OA. Walking in innovative shoes (“variable stiffness”) decreased the EKAM compared to control shoes. Similarly, shoes with higher heels, sneakers and dress shoes increased EKAM in healthy individuals compared to barefoot walking.ConclusionsFurther development may be needed toward optimal footwear for patients with medial knee OA with the aim of obtaining similar knee moments to barefoot walking.     

Does increasing step width alter knee biomechanics in medial compartment knee osteoarthritis patients during stair descent?

BackgroundResearch shows that one of the first complaints from knee osteoarthritis (OA) patients is difficulty in stair ambulation due to knee pain. Increased step width (SW) has been shown to reduce first and second peak internal knee abduction moments, a surrogate variable for medial compartment knee joint loading, during stair descent in healthy older adults. This study investigates the effects of increased step width (SW) on knee biomechanics and knee pain in medial compartment knee OA patients during stair descent.MethodsThirteen medial compartment knee OA patients were recruited for the study. A motion analysis system was used to obtain three-dimensional joint kinematics. An instrumented staircase was used to collect ground reaction forces (GRF). Participants performed stair descent trials at their self-selected speed using preferred, wide, and wider SW. Participants rated their knee pain levels after each SW condition.ResultsIncreased SW had no effect on peak knee abduction moments and knee pain. Patients reported low levels of knee pain during all stair descent trials. The 2nd peak knee adduction angle and frontal plane GRF at time of 2nd peak abduction moment were reduced with increasing SW.ConclusionsThe findings suggest that increases in SW may not influence knee loads in medial compartment knee OA patients afflicted with low levels of knee pain during stair descent.     

Comparison of three knee braces in the treatment of medial knee osteoarthritis

BackgroundConservative orthotic treatments rely on different mechanisms, such as three-point bending systems or hinges forcing external rotation of the leg and knee stabilization, to alter the biomechanics of the lower limbs and thus reduce knee loading on the affected compartment in patients with knee osteoarthritis (KOA). No previous study had compared the effects of these mechanisms on external loading and leg kinematics in patients with KOA.MethodsTwenty-four patients with medial KOA (Kellgren–Lawrence grade II or III) wore three custom knee braces: a valgus brace with a three-point bending system (V3P-brace), an unloader brace with valgus and external rotation functions (VER-brace) and a functional knee brace used in ligament injuries (ACL-brace). Pain relief, comfort, lower extremity kinematics and kinetics during walking were compared with and without each knee brace.ResultsKnee pain was alleviated with all three braces (p < 0.01). The VER- and ACL-braces allowed a significant reduction in peak knee adduction moment (KAM) during terminal stance from 0.313 to 0.280 Nm/Bw1Ht (p < 0.001) and 0.293 to 0.268 (p < 0.05), respectively, while no significant reduction was observed with the V3P-brace (p = 0.52). Reduced knee adduction and lower ankle and knee external rotation were observed with the V3P-brace but not with the VER-brace. The ACL-brace did not modify lower limb kinematics.ConclusionsNo difference between the knee braces was found for pain reduction, discomfort or KAM. The VER-brace was slightly more comfortable, which could ensure better compliance with treatment over the long term.     

亚洲蹲和西方蹲的下肢关节运动学和肌肉激活比较

目的分析比较亚洲蹲和西方蹲动作中下肢关节运动学和肌肉激活程度的差异。方法以11名健康成年人为研究对象,采用三维运动捕捉系统、测力台和表面肌电同步采集两种下蹲动作的运动学、动力学和肌肉激活信息,并通过OpenSim计算下肢肌力。结果在膝关节弯曲角度峰值时刻,亚洲蹲骨盆前倾,而西方蹲骨盆后倾;此外,与亚洲蹲相比,西方蹲具有显著较小的髋关节屈角、较大的膝关节屈角、较大的髋关节外展角和内旋角。在自重深蹲的下降期和上升期中,西方蹲的比目鱼肌力峰值均显著大于亚洲蹲,西方蹲的胫骨前肌力均显著小于亚洲蹲,峰值时刻未见统计学差异。结论在亚洲蹲中,胫骨前肌激活和近侧端关节前屈可能有利于稳定;而在脚跟抬起的西方蹲中,比目鱼肌激活显著,但两者近端肌肉激活模式相同。研究结果为临床深蹲康复方案制定或深蹲训练方式的选择提供理论指导。     

负重对行军士兵下肢步态特征的影响

目的评定负重行军对下肢步态产生的影响。方法采用随机交互设计,15名健康男性受试者进行4次步行,作训着装0、7.5、27、50kg,分别采用Vicon运动捕捉系统和AMTI测力台检测髋部、膝部和踝部运动学参数的变化。结果随着负重增加,周期性步频相对增加,步幅减小,基本上维持在恒定速度;左右髋关节屈角峰值、外旋角度峰值以及左右膝关节内收峰值受到影响较为明显,但关节运动幅度能够维持。左踝关节内翻角度峰值以及右踝关节外翻角度峰值同样受到影响;下肢左右膝、踝关节的力和力矩增加。结论在既定负荷范围内,负重增加,整体上下肢关节变化较为稳定,但下肢负荷增加,可潜在增加下肢损伤的风险。     

Influence of the Powers™ strap on pain and lower limb biomechanics in individuals with patellofemoral pain

BackgroundAbnormal biomechanics, especially hip internal rotation and adduction are known to be associated with patellofemoral pain (PFP). The Powers? strap was designed to decrease hip internal rotation and to thereby stabilise the patellofemoral joint.ObjectivesThis study aimed to investigate whether the Powers? strap influenced pain and lower limb biomechanics during running and squatting in individuals with PFP.MethodsTwenty-four individuals with PFP were recruited using advertisements that were placed at fitness centres. They were asked to perform a single leg squat task (SLS) and to run on an indoor track at their own selected speed during two conditions: with and without the Powers? strap. Immediate pain was assessed with the numeric pain rating scale. Three-dimensional motion and ground reaction force data were collected with 10 Qualisys cameras and three AMTI force plates.ResultsImmediate pain was significantly reduced with the Powers? strap (without the Powers? strap: 4.04 ± 1.91; with the Powers? strap: 1.93 ± 2.13). The Powers? strap condition significantly increased hip external rotation by 4.7° during the stance phase in running and by 2.5° during the single leg squat task. Furthermore, the external knee adduction moment during the SLS and running increased significantly.ConclusionThis study assessed the effect of the Powers? strap on lower limbs kinematics and kinetics in individual with PFP. The results suggest that the Powers? strap has the potential to improve abnormal hip motion. Furthermore, the Powers? strap demonstrated an ability to significantly reduce pain during functional tasks in patients with PFP.     

The knee adduction angle of the osteo-arthritic knee: A comparison of 3D supine,static and dynamic alignment

BackgroundEnd-stage knee osteoarthritis (OA) commonly results in knee arthroplasty. Three dimensional (3D) supine imaging is often used for pre-operative planning to optimise post-operative knee adduction angles (KAA). However, supine imaging may not represent loaded knee alignment. The aim of this study was to investigate differences in knee alignment under supine, static and dynamic conditions in healthy subjects and subjects with knee OA.MethodsNine healthy subjects and 15 subjects with end-stage knee OA were recruited. All subjects underwent supine imaging and motion capture during gait. KAAs were calculated from supine images (SUPINE), upright standing (STATIC) and at the first peak ground reaction force during gait (DYNAMIC), and were compared.ResultsKAAs were significantly higher (more varus) during gait compared with static (loaded and unloaded) in healthy subjects (p < 0.01) but not in subjects with knee OA. There was a good correlation between SUPINE and DYNAMIC for both healthy and OA subjects (R² > 0.58), with differences in the two relationships; healthy knees had a higher KAA during gait for any given KAA in the supine position, whereas OA knees that were valgus in imaging became more valgus during gait, and the opposite occurred for varus knees.ConclusionsFactors that may contribute to the noted differences between healthy and OA subjects include morphological changes in the joint as a result of OA, and gait compensation strategies in people with end-stage OA. Dynamic 3D motion capture provides important information about functional alignment that is not provided by supine imaging or static motion capture.Clinical RelevanceGait analysis may provide useful information to the surgeon during surgical planning of knee arthroplasties.     

Gait analysis of pre- and post-meniscectomy knee: a prospective study

Degenerative changes in the knee joint after meniscectomy are well known. Although likely to be due to changed biomechanics, there is no evidence in the literature to identify the underlying biomechanical alterations. The aim of this study was to analyse lower limb gait biomechanics before and after meniscectomy.

Ten patients who required partial medial meniscectomy for irreparable meniscal tear took part in motion analysis before surgery, then at 6 and 12 months post-operatively. A control group was also set up consisting of 10 healthy volunteers.

Joint kinematics did not show significant alterations between pre-operative and 6 month post-operative evaluations. However flexion increases at the hip, knee and ankle joint were observed in late swing and early stance phase 12 months after surgery. Hip and knee flexion–extension moments were affected with knee moment altered both before and after surgery. Before surgery and at 6 months after, the changes occurred mainly at the point of push off, while at 12 months they occurred during the swing phase. Hip flexion–extension moment had also changed 12 months after surgery.

When examining symmetry of gait patterns prior to surgery, there were differences between the flexion–extension moments of the healthy and of the injured knee at first impact and during late stance. After surgery, asymmetries were not more apparent at first impact, but in late stance phase a reduced knee extension moment in the injured limb was still present.

Before surgery, the joint kinematics were not greatly altered and changes were mainly due to pain. After partial meniscectomy, the pain disappeared and new joint responses were observed. These could be caused by the altered mechanics and/or through proprioceptive mechanisms.     

Contributions of muscles and external forces to medial knee load reduction due to osteoarthritis braces

BackgroundBraces for medial knee osteoarthritis can reduce medial joint loads through a combination of three mechanisms: application of an external brace abduction moment, alteration of gait dynamics, and reduced activation of antagonistic muscles. Although the effect of knee bracing has been reported independently for each of these parameters, no previous study has quantified their relative contributions to reducing medial knee loads.MethodsIn this study, we used a detailed musculoskeletal model to investigate immediate changes in medial and lateral loads caused by two different knee braces: OA Assist and OA Adjuster 3 (DJO Global). Seventeen osteoarthritis subjects and eighteen healthy controls performed overground gait trials in unbraced and braced conditions.ResultsAcross all subjects, bracing reduced medial loads by 0.1 to 0.3 times bodyweight (BW), or roughly 10%, and increased lateral loads by 0.03 to 0.2 BW. Changes in gait kinematics due to bracing were subtle, and had little effect on medial and lateral joint loads. The knee adduction moment was unaltered unless the brace moment was included in its computation. Only one muscle, biceps femoris, showed a significant change in EMG with bracing, but this did not contribute to altered peak medial contact loads.ConclusionsKnee braces reduced medial tibiofemoral loads primarily by applying a direct, and substantial, abduction moment to each subject's knee. To further enhance brace effectiveness, future brace designs should seek to enhance the magnitude of this unloader moment, and possibly exploit additional kinematic or neuromuscular gait modifications.