不同外侧楔形矫形鞋垫对内侧间室膝骨性关节炎患者步态的影响

目的:通过比较早期内侧间室膝骨性关节炎患者在佩戴传统与新型外侧楔形角矫形鞋垫(LW)后步行过程中所产生的下肢生物力学变化及差异,探讨新型设计的LW在早期内侧间室骨关节炎康复治疗中的应用价值。方法:采用英国Vicon三维步态分析系统配合Kislter测力台分别测评30例早期内侧间室型膝骨性关节炎患者在佩戴传统LW(楔形角5°)、新型带足弓支撑的LW(楔形角5°)及无佩戴任何矫形器(测试过程中均穿标准鞋)3种不同条件下的下肢关节运动学、动力学及时间空间参数变化。结果:相较于未佩戴任何矫形鞋垫情况,佩戴2种LW后膝关节载荷(膝关节内翻力矩,膝关节内翻角冲量)均显著降低(P<0.05)。此外,佩戴传统的LW后患者步行过程中踝关节外翻角度、外翻力矩及地面反作用力内侧方向较其他2种方式明显增加(P<0.05),而佩戴新型LW后下肢前进角度较其他2种方式显著增加(P<0.05)。结论:两种不同设计的LW均有助于缓解早期内侧间室型膝骨性关节炎患者运动过程中的膝关节载荷,且未见明显差异。但相较于传统外侧楔形矫形鞋垫,带有足弓支撑设计的矫形鞋垫佩戴后更为舒适,且不会引起踝关节内侧应力的增加。     

Static and dynamic biomechanics of foot orthoses in people with medial compartment knee osteoarthritis

OBJECTIVE: Gait biomechanics (knee adduction moment, center of pressure) and static alignment were investigated to determine the mechanical effect of foot orthoses in people with medial compartment knee osteoarthritis. DESIGN: Repeated measures design in which subjects were exposed to three conditions (normal footwear, heel wedge and orthosis) in random order. BACKGROUND: The knee adduction moment is an indirect measure of medial compartment loading. It was hypothesized that the use of a 5 degrees valgus wedge and 5 degrees valgus modified orthosis would shift the center of pressure laterally during walking, thereby decreasing the adduction moment arm and the adduction moment. METHODS: Peak knee adduction moment and center of pressure excursion were obtained in nine subjects with medial compartment knee OA during level walking using an optoelectric system and force plate. Static radiographs were taken in 12 subjects using precision radiographs. RESULTS: There was no difference between conditions in static alignment, the peak adduction moment or excursion of the center of pressure in the medial-lateral direction. No relationship was found between the adduction moment and center of pressure excursion in the medial-lateral plane. The displacement of the center of pressure in the anterior-posterior direction, measured relative to the laboratory coordinate system, was decreased with the orthosis compared to the control condition (P=0.036) and this measure was correlated with the adduction moment (r=0.45, P=0.019). CONCLUSIONS: The proposed mechanism was not supported by the findings. The reduction in the center of pressure excursion in the anterior-posterior direction suggests that foot positioning was altered, possibly to a toe-out position, while subjects wore the orthoses. Based on the current findings, we hypothesize that toe-out positioning may reduce medial joint load. RELEVANCE: Knee Osteoarthritis is the most common cause of chronic disability amongst seniors. Developing inexpensive, non-invasive treatment strategies for this large population has potential to impact health care costs, quality of life and clinical outcomes.     

佩带膝外翻支具膝骨关节炎患者膝关节的生物力学变化

背景：佩带膝关节外翻矫形器已被证明是一种可以有效减轻内侧间室膝骨关节炎患者疼痛的方法,但是佩带矫形器后的膝关节所产生的运动学以及动力学变化至今尚不明确。目的：观察内侧间室膝骨关节炎患者佩带膝关节矫形器前后的膝关节运动学以及动力学参数变化,便于为将来设计新型膝关节矫形器提供依据。方法：纳入20例内侧间室膝骨关节炎患者,分别通过三维步态分析系统和测力板对其在佩带膝外翻矫形器及不佩带膝外翻矫形器两种情况步行中的运动学及动力学参数进行采集,并进行对比。结果与结论：相比未佩带膝关节外翻支具,佩带膝关节外翻支具后患者在步行过程中膝关节内收力矩明显减小,与此同时膝关节内翻角度明显减小,外翻角度明显增加（P均〈0.05）,膝关节在步行过程中的最大屈曲角度以及时间空间参数差异无显著性意义。提示膝关节外翻矫形器可有效地通过增加内侧间室膝骨关节炎患者膝关节在步行过程中的外翻角度减小内翻角度从而降低膝内侧间室所承受的压力,与此同时纠正膝关节非正常对线。     

The use of a lateral wedge insole to reduce knee loading when ascending and descending stairs in medial knee osteoarthritis patients

Background

Stair climbing is a challenging task to the elderly being the task with the first complaint in patients with mild to moderate knee osteoarthritis. Stair climbing results in around six times more compressive load transmitted through the knee joint than walking on level ground. The purpose of this study was to assess whether lateral wedge insoles would reduce medial compartment knee loading when ascending and descending stairs in patients with medial knee osteoarthritis.

Methods

Eight patients with medial knee osteoarthritis were tested in random order with and without a pair of 5° off-the-shelf lateral wedge insoles for two separate activities (stair ascent and stair descent). Kinematic and kinetic data were collected for the lower extremity using a sixteen camera motion capture system and two force plates. Primary outcome measures were the external knee adduction moment and the knee adduction angular impulse.

Findings

During stair ascent and descent, lateral wedge insoles significantly (P < 0.05) reduced the 1st peak external knee adduction moment in early stance (ascent 6.8%, descent 8.4%), the trough in mid stance (ascent 13%, descent 10.7%), 2nd peak in the late stance (ascent 15%, descent 8.3%) and the knee adduction angular impulse compared to the control (standard shoe) with large effect sizes (0.75–0.95).

Interpretation

In this first study on stairs, lateral wedge insoles consistently reduced the overall magnitude of medial compartment loading during stair ascent and descent. Further research is needed to determine the relationship of this with clinical results when ascending and descending stairs with lateral wedge insoles.     

The effect of functional knee brace design and hinge misalignment on lower limb joint mechanics

BACKGROUND: Knee bracing has been shown to alter lower limb joint mechanics, which may protect the anterior cruciate ligament. The effect of brace alignment and brace type, however, remains largely unknown. This study was conducted to determine whether the use of a functional knee brace, the type of brace used or its alignment relative to the knee causes biomechanical alterations to gait. METHODS: Ten healthy participants took part in two walking conditions (aligned brace and misaligned brace) for two different types of brace (sleeve brace with bilateral hinges and hinge-post-shell). A non-braced condition was included as a baseline measure. Three-dimensional kinematics and force platform data were used to calculate the joint intersegmental forces and net joint moments of the ankle, knee and hip. FINDINGS: In comparison to non-braced walking, the shell brace in its aligned position significantly reduced the peak ankle plantarflexor moment. There was a decreased peak knee flexion angle with both the aligned shell and sleeve braces. The shell brace in its aligned position significantly increased peak knee adduction and reduced peak knee internal rotation. INTERPRETATION: In this sample of healthy participants, functional knee bracing failed to alter lower limb mechanics in such a way that would reduce the force transmitted to the anterior cruciate ligament. In addition, although there were brace induced changes in lower limb kinematics with 2cm of distal hinge misalignment, it is unlikely that hinge misalignment of this magnitude is detrimental to an uninjured knee joint during walking.     

The influence of sole wedges on frontal plane knee kinetics, in isolation and in combination with representative rigid and semi-rigid ankle-foot-orthoses

BACKGROUND: In earlier stages of knee osteoarthritis orthotic treatments with knee orthoses or modified footwear are often considered. Although the load reducing effects of knee orthoses have been well established, wearing modified footwear would be more comfortable for the patient and less encumbering. The effect of modified footwear on the frontal load of the knee is controversial. This article describes the effect of medial or lateral shoe wedges alone or together with two different types of ankle-stabilizing orthoses. METHODS: The effect on frontal knee loading was measured during standing and walking with medially and laterally placed wedges under the sole of the shoe. The wedges were also combined with two types of orthotic devices - an Ankle-Foot-Orthosis that was rigid in the frontal plane but allowed unrestricted sagittal plane motion and an ankle support that was semi-rigid in the frontal plane. Joint loading of 10 healthy persons (mean (standard deviation): age 34 (9) years, height 178 (4)cm, mass 73 (9)kg) was investigated by means of a special measuring device that accurately determines static loads (Lasar Posture) and with instrumented gait analysis (Vicon/Kistler). FINDINGS: Using a lateral wedge under the sole of the shoe (without orthotic support) showed no significant reduction in the mean maximal knee moment in the frontal plane. Adding an Ankle-Foot-Orthosis that is rigid in the frontal plane resulted in significant reduction in the maximal frontal moment from 0.54 Nm/kg to 0.38Nm/kg (p0.01). Using a medial wedge, without and with Ankle-Foot-Orthosis, produced a significant increase in the maximal frontal moment to 0.59 Nm/kg (p0.05) or 0.67 Nm/kg (p0.01), respectively. INTERPRETATION: These results suggest that the application of a sole wedge significantly influences frontal knee loading when used in combination with an Ankle-Foot-Orthosis that is rigid in the frontal plane.     

Lateral wedge insoles for medial knee osteoarthritis: effects on lower limb frontal plane biomechanics

Background

Lateral wedges reduce the peak knee adduction moment and are advocated for knee osteoarthritis. However some patients demonstrate adverse biomechanical effects with treatment. Clinical management is hampered by lack of knowledge about their mechanism of effect. We evaluated effects of lateral wedges on frontal plane biomechanics, in order to elucidate mechanisms of effect.

Methods

Seventy three participants with knee osteoarthritis underwent gait analysis with and without 5° lateral wedges. Frontal plane parameters at the foot, knee and hip were evaluated, including peak knee adduction moment, knee adduction angular impulse, center of pressure displacement, ground reaction force, and knee-ground reaction force lever arm.

Findings

Lateral wedges reduced peak knee adduction moment and knee adduction angular impulse (− 5.8% and − 6.3% respectively, both P < 0.001). Although reductions in peak moment were correlated with more lateral center of pressure (r = 0.25, P < 0.05), less varus malalignment (r values 0.25-0.38, P < 0.05), reduced knee-ground reaction force lever arm (r = 0.69, P < 0.01), less hip adduction (r = 0.24, P < 0.05) and a more vertical frontal plane ground reaction force vector (r = 0.67, P < 0.001), only reduction in knee-ground reaction force lever arm was significantly predictive in regression analyses (B = 0.056, adjusted R² = 0.461, P < 0.001).

Interpretation

Lateral wedges significantly reduce peak knee adduction moment and knee adduction angular impulse. It seems a reduced knee-ground reaction force lever arm with lateral wedges is the central mechanism explaining their load-reducing effects. In order to understand why some patients do not respond to treatment, future evaluation of patient characteristics that mediate wedge effects on this lever arm is required.     

膝骨关节炎生物力学参数的研究进展

膝骨关节炎是老年人常见的慢性退行性疾病,其发生与发展与生物力学因素密切相关。膝关节受力受到关节形态、下肢力线、肌肉的主动收缩、外部负荷、软组织牵拉等不同因素的影响。由于体内测量限制,基于运动分析技术的生物力学参数被广泛应用于临床研究。目前应用较多的生物力学参数包括膝关节内收力矩、膝关节内收冲量、膝关节屈曲力矩、内翻延伸等。充分研究膝骨关节炎发生发展过程中膝关节生物力学参数的变化,对疾病的病因探究、诊断、干预及治疗均有重要意义。     

Individual selection of gait retraining strategies is essential to optimally reduce medial knee load during gait

Background

The progression of medial knee osteoarthritis seems closely related to a high external knee adduction moment, which could be reduced through gait retraining. We aimed to determine the retraining strategy that reduces this knee moment most effective during gait, and to determine if the same strategy is the most effective for everyone.

Methods

Thirty-seven healthy participants underwent 3D gait analysis. After normal walking was recorded, participants received verbal instructions on four gait strategies (Trunk Lean, Medial Thrust, Reduced Vertical Acceleration, Toe Out). Knee adduction moment and strategy-specific kinematics were calculated for all conditions.

Findings

The overall knee adduction moment peak was reduced by Medial Thrust (− 0.08 Nm/Bw·Ht) and Trunk Lean (− 0.07 Nm/Bw·Ht), while impulse was reduced by 0.03 Nms/Bw·Ht in both conditions. Toeing out reduced late stance peak and impulse significantly but overall peak was not affected. Reducing vertical acceleration at initial contact did not reduce the overall peak. Strategy-specific kinematics (trunk lean angle, knee adduction angle, first peak of the vertical ground reaction force, foot progression angle) showed that multiple parameters were affected by all conditions. Medial Thrust was the most effective strategy in 43% of the participants, while Trunk Lean reduced external knee adduction moment most in 49%. With similar kinematics, the reduction of the knee adduction moment peak and impulse was significantly different between these groups.

Interpretation

Although Trunk Lean and Medial Thrust reduced the external knee adduction moment overall, individual selection of gait retraining strategy seems vital to optimally reduce dynamic knee load during gait.     

Effect of a lateral wedge on joint moments during gait in subjects with recurrent ankle sprain

This study assessed the biomechanic effects of wearing a lateral wedge on the subtalar joint moment during gait in athletes with and without an unstable lateral ankle. A crossover design was applied whereby 50 collegiate males walked with two different wedges: a 0 degrees control wedge and a 6 degrees lateral wedge. We investigated frontal plane angles and moments at the subtalar joint and the knee joint, as well as ground reaction forces and center of pressure excursion. Moments were derived using a three-dimensional inverse dynamics model of the lower extremity. The 6 degrees lateral wedge significantly increased the subtalar joint valgus moment (P < 0.001) and reduced the knee joint varus moment (P < 0.001) when compared with no wedge. The differences between wedge conditions were associated with a laterally shifted location of the center of pressure during stance phase. However, there were diverse, sometimes reversed effects with the wedge among the athletes with an unstable lateral ankle. These results indicate that biomechanical indications and limitations of lateral wedges in unstable lateral ankles should be analyzed in more detail, possibly leading to new guidelines for the use of such foot orthoses.     

Sagittal plane joint loading is related to knee flexion in osteoarthritic gait

Background

High mechanical loading has been consistently linked with medial tibiofemoral osteoarthritis, and is considered to play a central role in the pathogenesis of the disease. Evidence from healthy adults indicates that knee flexion kinematics may influence knee load. The purpose of this study therefore, was to investigate the association between knee flexion kinematics and indicators of joint loading during walking (peak moments and vertical ground reaction force), in individuals with medial tibiofemoral osteoarthritis.

Methods

In this cross-sectional study, 89 participants with painful medial tibiofemoral osteoarthritis completed three-dimensional walking gait analysis to measure stance phase ground reaction forces, knee joint moments, and knee flexion kinematics.

Findings

In stepwise regression, greater knee flexion excursion was associated with higher peak vertical ground reaction force, accounting for 10% of its variance (B = 0.62 [95% CI 0.34, 0.89], P < 0.001). Greater peak knee flexion was associated with a higher flexion moment, accounting for 44% of its variance (B = 0.12 [95% CI 0.09, 0.15], P < 0.001). No association was found between the knee adduction moment and knee flexion kinematics during walking.

Interpretation

Our data suggest that greater knee flexion is associated with higher joint loads in the sagittal plane (i.e. a higher peak knee flexion moment). However, knee flexion kinematics were not associated with the knee adduction moment — a proxy measure of medial compartment knee load. Thus, high knee flexion should be considered an undesirable gait characteristic with respect to knee load in individuals with medial tibiofemoral osteoarthritis.     

Short-term effects of a dedicated knee orthosis on knee adduction moment, pain, and function in patients with osteoarthritis

Fantini Pagani CH, Böhle C, Potthast W, Brüggemann G-P. Short-term effects of a dedicated knee orthosis on knee adduction moment, pain, and function in patients with osteoarthritis.

Objective

To analyze knee joint loading, subjective pain relief, and improvements in function in patients with osteoarthritis (OA) with the use of 2 orthosis adjustments.

Design

Patients were tested under 3 different conditions (without orthosis, orthosis at 4° valgus, and a neutral very flexible adjustment) in a crossover trial.

Setting

University gait analysis laboratory with 3-dimensional motion analysis and force platforms.

Participants

Patients (N=11) with a clinical and radiographic diagnosis of unilateral OA in the medial knee compartment.

Interventions

Patients wore a knee orthosis designed to unload the medial knee compartment for 4 weeks in 2 different adjustments (2 weeks in each adjustment).

Main Outcome Measures

Net knee adduction moment and net knee adduction angular impulse during the stance phase were analyzed by using inverse dynamics. Subjective pain relief, stiffness, and function improvement were evaluated using a questionnaire (Western Ontario and McMaster Universities Osteoarthritis Index). A 6-minute walk test and stair-climbing test also were performed.

Results

Both orthosis adjustments induced subjective pain relief and improvement in function compared with the condition without orthosis. Knee adduction moment was significantly decreased with both adjustments, whereas the decrease observed with the 4° valgus adjustment was significantly greater than the flexible adjustment (25% vs 12.5%). Compared with the condition without orthosis, changes in knee adduction angular impulse of 29% and 15% were found with 4° valgus and the neutral flexible orthosis, respectively. Time required for the stair-climbing activity was significantly decreased using the orthosis in 4° valgus adjustment compared with the condition without orthosis. No significant differences were observed among conditions during the 6-minute walk test.

Conclusions

Both orthosis adjustments were effective in decreasing symptoms; however, a decrease in knee loading was more effective using the 4° valgus adjustment, which could contribute to avoidance of disease progression.     

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

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

Comparison of peak knee adduction moment and knee adduction moment impulse in distinguishing between severities of knee osteoarthritis

Background

The peak knee adduction moment is a valid proxy for medial knee joint loading. However as it only measures load at one instance of stance, knee adduction moment impulse, a measure that takes into account both the magnitude and duration of the stance phase, may provide more comprehensive information. This study directly compared the abilities of peak knee adduction moment and knee adduction moment impulse to distinguish between knee osteoarthritis severities.

Methods

169 participants with medial knee osteoarthritis completed radiographic and magnetic resonance imaging, the Western Ontario and McMaster Universities Arthritis Index to assess pain and a three-dimensional gait analysis. Participants were classified using four dichotomous classifications: Kellgren–Lawrence grading, alignment, medial tibiofemoral bone marrow lesions, and pain.

Findings

When using Kellgren–Lawrence grade and alignment classifications, the area under the receiver operator curves were significantly greater for knee adduction moment impulse than for peak knee adduction moment. Based on analysis of covariance, knee adduction moment impulse was significantly different between Kellgren–Lawrence grade and alignment groups while peak knee adduction moment was not significantly different. Both peak knee adduction moment and knee adduction moment impulse distinguished between bone marrow lesion severities while neither measure was significantly different between pain severity groups.

Interpretations

Findings suggest knee adduction moment impulse is more sensitive at distinguishing between disease severities and may provide more comprehensive information on medial knee joint loading. Future studies investigating biomechanics of knee osteoarthritis should include knee adduction moment impulse in conjunction with peak knee adduction moment.     

Effects of disease severity on response to lateral wedged shoe insole for medial compartment knee osteoarthritis

OBJECTIVE: To determine the effects of lateral wedged insoles on knee kinetics and kinematics during walking, according to radiographic severity of medial compartment knee osteoarthritis (OA). DESIGN: A prospective case control study of patients with medial compartment OA of the knee. SETTING: Gait analysis laboratory in a university hospital. PARTICIPANTS: Forty-six medial compartment knees with OA of 23 patients with bilateral disease and 38 knees of 19 age-matched healthy subjects as controls. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: We measured the peak external adduction moment at the knee during the stance phase of gait and the first acceleration peak after heel strike at the lateral side of the femoral condyles. Kellgren and Lawrence grading system was used for radiographic assessment of OA severity. RESULTS: The mean value of peak external adduction moment of the knee was higher in OA knees than the control. Application of lateral wedged insoles significantly reduced the peak external adduction moment in Kellgren-Lawrence grades I and II knee OA patients. The first acceleration peak value after heel strike in these patients was relatively high compared with the control. Application of lateral wedged insoles significantly reduced the first acceleration peak in Kellgren-Lawrence grades I and II knee OA patients. CONCLUSIONS: The kinetic and kinematic effects of wearing of lateral wedged insoles were significant in Kellgren-Lawrence grades I and II knee OA. The results support the recommendation of use of lateral wedged insoles for patients with early and mild knee OA.     

Knee dynamics during take-off and landing in spike jumps performed by volleyball players with patellar tendinopathy

[Purpose] Patellar tendinopathy is a common sports injury. The risk factors for this injury can be categorized as intrinsic, extrinsic, and dynamic. We examined the dynamic factors in this study. [Participants and Methods] The participants were volleyball players who were assigned to a patient group (n=6) if they had medial patellar tendinopathy in the left knee or to a control group (n=7) otherwise. The participants performed spike jumps, and their ground reaction force and three-dimensional kinematic data were recorded. Knee angle and moment data were extracted at the peak extension moment of take-off and landing. [Results] The two groups showed no differences in knee angles. A tendency for abduction/external rotation moments at take-off and landing on both sides was observed in the control group, while the patient group showed adduction and internal rotation moments at take-off and adduction moment at landing in the left (injured) knee. [Conclusion] The observed knee joint moments in the left (injured) knee of the patient group may have been involved in the pathophysiological mechanism underlying the development of patellar tendinopathy.     

Effects of laterally wedged insoles on knee and subtalar joint moments

OBJECTIVE: To assess the biomechanic effects of wearing a lateral wedge on the knee joint varus moment during gait in elders with and without knee osteoarthritis (OA). DESIGN: Crossover design whereby subjects walked under 2 different insole conditions: a 0 degrees control wedge and a 6 degrees lateral wedge. SETTING: A gait laboratory with 3-dimensional motion analysis and force platform equipment. PARTICIPANTS: Thirteen healthy subjects and 13 knee patients with OA. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Frontal plane angles and moments at the knee and subtalar joints, ground reaction forces, and center of pressure. Moments were derived by using a 3-dimensional inverse dynamics model of the lower extremity. RESULTS: The 6 degrees lateral wedge significantly reduced knee joint varus moment and increased subtalar joint valgus moment in both groups when compared with no wedge. All patients had a greater knee joint varus moment with a similar subtalar joint valgus moment compared with the people without OA. There were diverse, sometimes reversed effects with the insole among the patients. CONCLUSIONS: The 6 degrees lateral wedge did not consistently reduce the knee joint varus moment in patients with knee OA. The biomechanic indications and limitations of laterally wedged insoles should be confirmed by a larger study.     

膝内外翻畸形时髋臼负重顶区的生物力学变化

背景：膝内、外翻畸形改变了膝关节的形态,除影响膝关节的功能外,还可能改变相邻关节髋关节的生物力学行为,也就是髋臼与股骨头之间的力学传导. 目的：评价不同程度膝内、外翻畸形对髋臼负重顶区的生物力学影响. 方法：取成年男性鲜尸体下肢标本3个,剔除附着的肌肉组织,保留骨膜、韧带及关节囊,通过胫骨高位截骨模拟不同程度的膝内外翻畸形.标本分为中立位组、膝内翻10°组、膝内翻20°组、膝外翻10°组和膝外翻20°组.实验中骨盆的位置选择单足站立中立位.标本通过生物力学试验机加载至50 kg,采用压敏片技术测量髋臼顶负重区的负重面积、平均应力及峰值应力. 结果与结论：髋臼顶区中立位时股胫关节面负重面积为（6.33±0.12） cm2,平均应力（3.62±0.33） MPa,峰值应力为（4.58±0.20） MPa.当膝内、外翻达10°时,髋臼顶区负重面积减少,平均应力及峰值应力有明显的增加,但差异无显著性意义（P〉0.05）;当膝内、外翻达20°时髋臼负重面积显著减少,平均应力峰值及应力显著增加,差异有非常显著性意义（P 〈0.01）.结果提示：随膝内、外翻畸形程度的不同,髋臼负重顶区的负重面积、峰值应力及平均应力也发生变化,当膝内、外翻达20°时,负重面积显著减少,平均应力峰值及应力显著增加,这可能是膝内外翻畸形造成髋骨关节炎的病因之一.因此临床上应重视对膝骨关节炎内、外翻畸形患者的早期干预.     

Peak Biomechanical Variables During Bilateral Drop Landings: Comparisons Between Sex (Female/Male) and Fatigue (Pre-Fatigue/Post-Fatigue)

Background

Although anterior cruciate ligament (ACL) sprains usually occur during the initial phase of the landing cycle (less than 40° knee flexion), the literature has focused on peak values of knee angles, vertical ground reaction force (VGRF), and muscle activity even though it is unclear what occurs during the initial phase of landing.

Objectives

The objectives of this study were to determine the effects of sex (male and female) and fatigue (prefatigue/post-fatigue) on knee flexion angles at the occurrence of peak values of biomechanical variables [knee valgus angle, VGRF, and normalized electromyographic amplitude (NEMG) of the quadriceps and hamstring muscles] during a bilateral drop landing task.

Methods

Knee valgus angle, VGRF, and NEMG of the quadricep and hamstring muscles were collected during bilateral drop landings for twenty-nine recreational athletes before and after a fatigue protocol.

Results

Peak values of knee valgus, VGRF, and NEMG of medial and lateral hamstring muscles occurred during the late phase of the landing cycle (>40° of knee flexion). Females in the post-fatigue condition exhibited peak VGRF at significantly less knee flexion than in the pre-fatigue condition. Males in the post-fatigue condition exhibited peak lateral hamstring muscles NEMG at significantly higher knee flexion than in the pre-fatigue condition.

Discussion and Conclusion

Peak values of biomechanical variables that have been previously linked to ACL injury did not occur during the initial phase of landing when ACL injuries occur. No biomechanical variables peaked during the initial phase of landing; therefore, peak values may not be an optimal indicator of the biomechanical factors leading to ACL injury during landing tasks.     

Biomechanical comparison of frontal plane knee joint moment arms during normal and Tai Chi walking

[Purpose] Medial knee osteoarthritis, a degenerative joint disease, affects adults. The external knee adduction moment, a surrogate knee-loading measure, has clinical implications for knee osteoarthritis patients. Tai Chi is a promising intervention for pain alleviation in knee osteoarthritis; however, the characteristics of external knee adduction moment during Tai Chi have not been established. [Subjects and Methods] During normal and Tai Chi walking, a gait analysis was performed to compare the external knee adduction moment moment-arm characteristics and paired t-tests to compare moment-arm magnitudes. [Results] A significant difference was observed in the average lateral direction of moment-arm magnitude during Tai Chi walking (−0.0239 ± 0.011 m) compared to that during normal walking (−0.0057 ± 0.004 m). No significant difference was found between conditions in average medial direction of moment-arm magnitude (normal walking: 0.0143 ± 0.010 m; Tai Chi walking: 0.0098 ± 0.014 m). [Conclusion] Tai Chi walking produced a larger peak lateral moment-arm value than normal walking during the stance phase, whereas Tai Chi walking and normal walking peak medial moment-arm values were similar, suggesting that medial knee joint loading may be avoided during Tai Chi walking.Key words: Tai Chi gait, External knee adduction moment arm, Walking