膝内侧骨关节炎患者膝关节功能与不稳定性的关系

背景：膝内侧骨关节炎患者身体缺陷与骨性关节炎发展的关系尚不清楚。 目的：调查膝内侧骨关节炎患者的身体功能和膝关节不稳定性,探讨二者间的关系。 方法：纳入诊断性膝内侧骨关节炎患者104例,采用膝关节日常生活活动评估量表衡量膝关节不稳,功能的自我评估采用膝伤和骨性关节炎结果评分,应用计时爬梯试验评估基于体能的身体功能,并进行放射影像学评估。 结果与结论：不同程度膝关节不稳患者的内侧松弛度、外侧松弛度、对线角度、标准化最大随意等长收缩及爬梯时间比较差异无显著性意义(P > 0.05)。但不同程度膝关节不稳患者在疼痛、症状、日常生活活动、运动和膝关节相关生活质量子集得分方面差异有显著性意义(P < 0.05)。在膝内侧骨关节炎患者中,自报膝关节不稳与内侧松弛度、股四头肌无力、内翻对线无直接联系。     

骨水泥型与非骨水泥型全膝关节置换后的步态差异

背景：全膝关节置换已经被证明是一种有效治疗膝骨性关节炎的方法,但是不同类型的全膝关节置换假体固定方式术后所产生的膝关节下肢生物力学差异至今仍不明确。 目的：通过三维步态分析骨水泥固定和非骨水泥固定两种不同的全膝关节置换术后患者的膝关节生物力学差异。 方法：分别选取骨水泥型全膝关节置换以及非骨水泥型全膝关节置换患者各16例,通过测力台以及三维步态分析系统比较2组患者术前以及术后3个月的膝关节生物力学变化并进行对比。 结果与结论：与手术前相比两组患者术后步速及步长均明显增加,支撑相在整个步态周期中的百分比明显减小, 膝关节屈在支撑相及摆动相中最大屈曲角度均明显增加,膝关节外翻角度增加。两种患者术后膝关节内翻角度以及膝关节内收力矩均明显减小。提示,骨水泥型与非骨水泥型全膝关节置换术均能有效改善膝骨性关节炎患者的步行能力以及下肢关节功能,两者间未见明显生物力学差异。     

硅网支具对前交叉韧带损伤及膝关节稳定性的影响

文题释义： 硅网支具：由弹性硅网制成；相较普通支具，硅网支具的弹性网状结构可以吸收冲击并将峰值负载从膝盖痛的区域移除，减少膝关节压力，纠正髌骨轨迹，还可以减少膝关节疼痛，增强功能，提高生活质量。 膝骨关节炎：是一种以关节软骨退行性变和关节炎症为特征的慢性骨关节疾病, 主要临床表现为慢性疼痛和关节活动障碍, 严重影响患者生活质量。膝骨关节炎是由机械、遗传和环境因素引起的复杂多因素疾病, 也是关节中最常见的疾病, 许多环境因素如激素、饮食、感染、创伤、酒精摄入和接触烟草烟雾等，都会增加骨关节炎的患病风险, 年龄是其独立危险因素。 背景：在缓慢步行情况下硅网支具被证明可以改善膝关节力学，但大部分的研究缺乏运动情况下支具对膝关节影响的数据支撑。 目的：通过3个设计动作模拟快速运动过程中容易诱发膝关节损伤的跳跃、急停、旋转等因素，探索硅网支具是否可为膝关节提供稳定支撑，并为前交叉韧带损伤防护提供数据支撑。 方法：选取12名健康志愿者分别在穿戴支具和没有穿戴支具的情况下进行屈膝下蹲、单腿跳和转向跳3个动作，将反射标记放置在受试者脚、小腿、大腿和骨盆上，应用Qualisys三维运动捕捉系统获取膝关节运动学数据，比较膝关节在是否穿戴支具情况下进行运动的差异。试验方案于2018-08-08经贵州医科大学附属医院伦理委员会审核批准，批号为2018661。 结果与结论：进行各项运动时，膝关节在矢状面、冠状面和水平面的角度和角速度差异有显著性意义。穿戴支具时膝关节外翻和内旋角度均有所下降，且在单腿跳和转向跳动作中效果最为显著。穿戴支具时膝关节在水平面外旋角速度显著下降。提示穿戴支具能影响膝关节在冠状面和水平面运动力学，说明膝关节支具在动态运动过程中可以有效控制膝关节稳定性；穿戴支具可以改善膝关节峰值外翻角速度和外旋角速度的控制，有助于预防前交叉韧带损伤或帮助前交叉韧带缺陷患者。 ORCID: 0000-0002-2254-8494(荆晓伟) 中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程     

胫骨平台内翻角在预测单纯膝内侧间室骨关节炎患者股骨后髁角中应用的可行性

目的探讨测量胫骨平台内翻角(PTA)预测单纯膝内侧间室骨关节炎患者股骨后髁角(PCA)的可行性。方法回顾性研究。纳入2018年1月—2019年12月哈尔滨医科大学附属第一医院拟行膝关节置换手术的72例单侧单纯膝内侧间室骨关节炎患者的临床资料,其中男7例、女65例,年龄49~80(66.5±14.35)岁,身高155~180(164.3±11.23)cm。72例患者患侧膝均呈内翻畸形,内翻角为10.6°±1.36°。收集患者术前负重位下肢全长X线片与膝关节CT影像资料,在X线片以及冠状位CT图片上测量患者双侧膝关节的PTA、PCA,统计分析患侧、健侧的PTA、PCA差异,采用Pearson相关分析法分别分析患侧、健侧的PTA与PCA之间的相关性。结果72例患者健侧PTA、PCA值分别为3.23°±0.79°、4.64°±1.13°,患侧PTA、PCA值分别为8.39°±1.99°、4.71°±1.15°。健侧PTA明显小于患侧,差异有统计学意义(t=18.916,P<0.01),而健侧与患侧PCA间差异无统计学意义(P>0.05)。Pearson相关分析结果显示,患侧、健侧PTA和PCA均无相关性(r健侧=0.144、r患侧=0.109,P值均>0.05)。结论对于单纯膝内侧间室骨关节炎患者,健侧与患侧的PCA值比较无明显差异,而PTA值则随内侧间室磨损程度的加重而增大,PCA与PTA之间并不存在明显的相关性。术前测量PTA用于预测PCA的方法不可行。     

膝骨关节炎女性伸膝肌力、步态时空参数与峰值膝关节屈曲/内收力矩关系

背景：已有研究表明膝骨关节炎患者的膝关节力矩会发生改变，但对于力矩变化与伸膝肌力及步态时空参数之间的相关性报道较少。目的：探索女性膝骨关节炎患者伸膝肌力及步态时空参数与峰值膝关节屈曲/内收力矩之间的相关性。方法：选取2022年2-8月在北京积水潭医院贵州医院住院治疗的20例单膝患病女性膝骨关节炎患者作为膝骨关节炎组，另外选取20例无肌肉骨骼疾病的女性健康人作为对照组。利用Biodex等速仪测量60 (°)/s向心伸膝肌力，并采用意大利BTS红外运动捕捉系统和测力台采集步态时空参数和峰值膝关节屈曲力矩和膝关节内收力矩。通过Pearson相关性分析探索肌力、步态时空参数和峰值膝关节内收力矩和膝关节屈曲力矩的关联，并进一步将与膝关节力矩显著相关的变量纳入多元逐步回归分析。结果与结论：(1)与对照组相比，膝骨关节炎组60 (°)/s向心伸膝肌力、步速、步频、步长以及峰值膝关节屈曲力矩均更低(P <0.05)；(2)Pearson相关性分析结果显示60 (°)/s向心伸膝肌力、步速、步频、步长与峰值膝关节屈曲力矩呈正相关，与峰值膝关节内收力矩呈负相关，差异有显著性意义(P <0.05...     

个体化开放楔形胫骨高位截骨治疗内侧间室膝骨关节炎的优势

文题释义：开放楔形胫骨高位截骨：是一种治疗内侧间室膝骨关节炎合并膝内翻的保膝术式。通过胫骨近端内侧切口,在水平面、冠状面双截骨后,进行楔形撑开、钢板固定。其治疗意义在于将内翻的下肢力线转移至相对正常的膝外侧,以缓解内侧症状,延长关节寿命,延缓骨关节炎进展,甚至避免关节假体置换。 个体化力线矫形：根据膝骨关节炎的多阶段性,针对不同退变程度的膝内侧间室,施行不同的力线矫形方案。通过术前规划截骨后的楔形撑开角度或距离,可以将内翻的下肢力线矫正至中线或偏外侧,以达到临床治疗效果。 背景：开放楔形胫骨高位截骨对于内侧间室膝骨关节炎合并膝内翻患者疗效明确,但目前关于力线矫正点的选择仍以Fujisawa点作为参考,个体化力线矫形是否能获得更优越的临床疗效？ 目的：探讨开放楔形胫骨高位截骨术中个体化下肢力线矫形治疗内侧间室膝骨关节炎的短期疗效。 方法：选择2016年6月至2018年5月无锡市人民医院骨科因内侧间室膝骨关节炎行开放楔形胫骨高位截骨治疗的46例患者。根据X射线片、MRI综合评估患膝并划分退变等级(Ⅰ-Ⅲ级),其中Ⅰ,Ⅱ级患者随机分为个体化组及对照组,每组16例;14例Ⅲ级患者作为Fujisawa组。个体化组轻度退变Ⅰ级矫正下肢力线至胫骨平台50%点,中度退变Ⅱ级矫正至胫骨平台外侧55%点;对照组、Fujisawa组均矫正力线至62.5%点。测量评估术后下肢力线,比较术前、术后膝关节活动度、股胫角、胫骨近端内侧角;随访术前及术后3,6,12个月患膝的美国特种外科医院评分、西安大略和麦克马斯特大学骨关节炎指数,比较患者术后综合满意度的自评分。结果与结论：①所有患者均获得12个月随访;②3组下肢力线矫形结果满意,术后膝关节活动度、胫骨近端内侧角较术前明显增加,股胫角明显减少(P < 0.05);③随着随访时间延长,3组患者的美国特种外科医院评分显著增加,西安大略和麦克马斯特大学骨关节炎指数显著减少,组内不同时点差异有显著性意义(P < 0.05);个体化组术后3,6个月美国特种外科医院评分高于对照组,西安大略和麦克马斯特大学骨关节炎指数低于对照组,差异有显著性意义(P < 0.05);个体化组及对照组术后12个月美国特种外科医院评分、西安大略和麦克马斯特大学骨关节炎指数差异无显著性意义(P > 0.05);④所有患者对手术矫形效果满意,个体化组术后综合满意评分高于对照组,差异有显著性意义(P < 0.05);⑤结果表明,个体化开放楔形胫骨高位截骨通过准确地力线矫形,有利于膝关节早期功能恢复,提升患者满意度。 ORCID: 0000-0003-0566-2858(俞颖豪) 中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程     

膝关节单髁置换术后膝关节登梯动作生物力学分析

目的 探讨内侧膝关节单髁置换（unicompartmental knee arthroplasty, UKA）手术对登楼梯时膝关节生物力学的影响。方法 9例接受固定平台内侧UKA骨关节炎患者,术前3周及术后（7±2）月对其进行登楼梯动作的生物力学测试。采用双平面X线装置收集患者UKA手术前后行走时的影像资料,健侧膝关节作为对照组。通过CT扫描建立股骨、胫骨三维模型,通过自动匹配软件,将股骨、胫骨3D模型与X线中股骨、胫骨相匹配并同步。测量股骨、胫骨3D模型运动力学参数,包括前后向移位、内外翻、旋转及内侧间室间隙、接触中心点及外侧间室间隙。结果 术前UKA侧膝关节较健侧内翻4.8°,术后UKA侧较术前外翻3.1°,术前UKA侧膝关节较健侧外旋4.4°,术前UKA侧内侧间室接触中心点较健侧后移2.5 mm（P<0.05）。外侧间隙UKA手术前后及与健侧相比无明显变化（P>0.05）。结论 UKA可以有效改善膝关节内外翻,同时能够恢复患侧膝关节旋转的生物力学特性,不影响外侧间室间隙的接触中心,但内外侧间室的接触中心仍有变化。     

不同硬度楔形鞋垫对膝关节内翻力矩的影响

目的研究不同硬度楔形鞋垫在步行状态下对膝关节内翻力矩的影响。方法 15名健康成年男性受试者穿着不同硬度楔形鞋垫进行步态测试,通过光学运动捕捉系统和地面测力板收集运动学和动力学数据,经Visual3D软件计算得出膝关节内翻力矩,分析在3种不同步行状况下(仅穿鞋、鞋中放入软、硬楔形鞋垫)膝关节内翻力矩峰值的差异。结果与较软的楔形鞋垫相比,较硬的楔形鞋垫可使膝关节内翻力矩的第1个峰值降低9.3%,第2个峰值降低9.7%,差异具有统计学意义。结论楔形鞋垫增加一定的硬度能更多降低膝关节内侧间室的压力,减轻关节面的磨损,从而可能缓解膝关节炎症状。     

膝骨性关节炎合并内翻畸形患者运动特征研究

为研究膝骨性关节炎合并内翻畸形患者术前生物力学群体特征,用于比较患者术前术后步态延续性及进行术后康复指导,本文采集9例患者水平行走和坐立-起身过程的步态,并进行骨肌多体动力学分析。本文研究结果显示,水平行走时试验组下肢运动功能减弱,试验组非手术侧膝关节平均活动范围为22.5°~71.5°,拟置换侧膝关节平均活动范围为24.4°~57.6°,而对照组膝关节平均活动范围为7.2°~62.4°。单侧膝内翻患者完成坐立-起身过程时的下肢地面反作用力对称度介于0.72~0.85,非手术侧下肢起主要支撑作用。双侧膝内翻患者坐立-起身时地面反作用力之和最小。尽管单侧膝内翻患者采用非手术侧下肢过量负载的代偿方式能完成术后日常活动,但长期过量负载容易增加非手术侧下肢膝关节罹患膝骨性关节炎风险。对膝骨性关节炎合并内翻畸形患者完成日常活动的运动学和生物力学特征进行研究,有助于从生物力学角度理解内翻膝的发病机制,对患者的术前评估、预防和术后恢复具有较强的临床指导意义。     

软组织平衡技术在维吾尔族膝外翻人工关节置换中的应用

背景：因地域环境和饮食习惯致使新疆本地维吾尔族肥胖和骨关节炎患者较多,目前进行人工膝关节置换的患者日益增多,软组织平衡技术在不同体质和民族患者的人工膝关节置换过程中应如何掌握和进一步应用成为许多学者关注的焦点。 目的：分析软组织平衡技术在新疆维吾尔族膝外翻患者人工全膝关节表面置换中的应用效果。 方法：2009年2月至2010年12月针对60例(72膝)重度膝骨关节炎伴一定程度膝外翻患者采用膝前外侧入路及个体化的软组织平衡方法行全膝关节表面置换。随访方式为门诊随访,拍X射线片测量股胫角(即股骨和胫骨解剖轴线夹角的补角);定期随访评估美国膝关节协会(KSS)临床评分及功能评分,以评估膝关节功能。 结果与结论：随访6-35个月,总计有57例患者获得随访。患者股胫角由置换前27.9°降至5.6°,KSS临床评分由置换前16.7 分提高到87.5分,KSS功能评分由置换前7.9分提高到85.2分。置换前及末次随访评分差异均有显著性意义(P < 0.01)。57例患者置换后外翻畸形均得到完全矫正,且关节稳定性良好。提示在重度膝骨关节炎伴一定程度外翻畸形的患者中,选择个体化的软组织平衡方案,可以有效矫正软组织失衡并获得较为满意的修复效果。中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程     

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.     

Effect of medial foot loading self-practice on lower limb kinematics in young individuals with asymptomatic varus knee alignment

BackgroundVarus alignment of the knee is a risk factor for developing knee osteoarthritis. Recently, voluntary shifting the plantar pressure distribution medially (medial foot loading) during gait has been found to reduce knee adduction angle during stance, which may lower the joint load. However, it is not yet known whether such effect would persist after long-term self-practice. This study aimed to determine whether medial foot loading can be an effective self-care protocol for reducing the knee adduction angle.MethodsEight subjects with asymptomatic varus knee alignment were trained on medial foot loading once in a laboratory, then carried out as self-practice for 8 weeks outside the laboratory. Spatiotemporal gait parameters and lower limb joint kinematics data were collected during natural walking prior to the training (baseline walking), during the practice session immediately after the initial training (trained walking), and during natural walking after the self-practice period (post-practice walking).ResultsParticipants walked significantly faster after the self-practice period with longer step length compared with the baseline. The knee adduction angle at initial contact, maximum angle during stance, and mean angle during a gait cycle were significantly decreased during both the trained and post-practice walking compared with baseline. The 8-week self-practice caused larger decrements in the three angles than the single training, but no significant differences were found between the two conditions.ConclusionsSelf-practice of medial foot loading walking could be an effective gait strategy to reduce the knee adduction angle. The effect could be sustained for individuals with asymptomatic varus knee alignment.     

正走和倒走的膝关节生物力学特征比较

目的 比较正走和倒走两种不同行走模式时膝关节的生物力学特征。方法 采用三维运动捕捉系统Vicon T40和测力台AMTI OR6-7采集并比较13名健康青年男性志愿者正走和倒走时的时间、空间、运动学和动力学参数。结果 与正走相比,倒走时的步速、步频和步幅均显著减小,跨步周期和支撑相所占百分比显著增加;在矢状面上,倒走时膝关节活动度、最大屈伸力矩较正走小;在冠状面上,倒走时膝关节内翻外展活动范围也较正走小,内翻力矩峰值在支撑早期较正走小,但在支撑晚期较正走大;地面反作用力在支撑早期较正走大,但在支撑晚期较正走小。结论 倒走和正走膝关节生物力学特征差异明显。与正走相比倒走在支撑相早期能减轻膝关节内侧间室的负荷,而倒走在支撑相晚期对膝关节负荷的影响则尚须进一步研究。     

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.     

Finite element analysis of unicompartmental knee arthroplasty

Concerns over accelerated damage to the untreated compartment of the knee following unicompartmental knee arthroplasty (UKA), as well as the relatively poor success rates observed for lateral as opposed to the medial arthroplasty, remain issues for attention. Finite element analysis (FEA) was used to assess changes to the kinematics and potential for cartilage damage across the knee joint in response to the implantation of the Oxford Mobile Bearing UKA. FE models of lateral and medial compartment arthroplasty were developed, in addition to a healthy natural knee model, to gauge changes incurred through the arthroplasty. Varus–valgus misalignments were introduced to the femoral components to simulate surgical inaccuracy or over-correction. Boundary conditions from the Stanmore knee simulator during the stance phase of level gait were used. AP translations of the tibia in the medial UKA models were comparable to the behaviour of the natural knee models (±0.6 mm deviation from pre-operative motion). Following lateral UKA, 4.1 mm additional posterior translation of the tibia was recorded than predicted for the natural knee. IE rotations of the medial UKA models were less consistent with the pre-operative knee model than the lateral UKA models (7.7° vs. 3.6° deviation). Varus misalignment of the femoral prosthesis was more influential than valgus for medial UKA kinematics, whereas in lateral UKA, a valgus misalignment of the femoral prosthesis was most influential on the kinematics. Resection of the cartilage in the medial compartment reduced the overall risk of progressive OA in the knee, whereas removing the cartilage from the lateral compartment, and in particular introducing a valgus femoral misalignment, increased the overall risk of progressive OA in the knee. Based on these results, under the conditions tested herein, both medial and lateral UKA can be said to induce kinematics of the knee which could be considered broadly comparable to those of the natural knee, and that even a 10° varus–valgus misalignment of the femoral component may not induce highly irregular kinematics. However, elevated posterior translation of the tibia in lateral UKA and large excursions of the insert may explain the higher incidence of bearing dislocation observed in some clinical studies.     

In vivo kinematic comparison before and after mobile-bearing unicompartmental knee arthroplasty during high-flexion activities

BackgroundMany patients who undergo unicompartmental knee arthroplasty (UKA) have an expectation that their knee flexion would increase following its replacement. Additionally, the survival rate of mobile-bearing UKA (MB-UKA) is high. However, the effect on the patient's kinematics remains unknown. This study aimed to clarify the kinematic effect of MB-UKA knees during high-flexion activities by comparing the in vivo kinematics before and after surgery.MethodsA squatting motion was performed under fluoroscopic surveillance in the sagittal plane before and after MB-UKA. To estimate the spatial position and orientation of the knee, a two-dimensional/three-dimensional registration technique was used. The femoral rotation and varus–valgus angle relative to the tibia and anteroposterior (AP) translation of the medial and lateral side of the femur on the plane perpendicular to the tibial mechanical axis in each flexion angle were evaluated.ResultsRegarding the varus–valgus angle, the preoperative knees indicated a significant varus alignment compared with the postoperative knees from 10° to 60° of flexion. There were no significant differences in the femoral rotation angle, AP translation, and kinematic pathway before and after MB-UKA in the mid-flexion of the range of motion.ConclusionThere were differences between the varus–valgus knee kinematics before and after MB-UKA, from 10 to 60° of flexion, but no difference from midrange of flexion to deep flexion. In addition, the rotational knee kinematics before and after MB-UKA was not significantly different.     

Effect of lower limb malalignment in the frontal plane on transverse plane mechanics during gait in young individuals with varus knee alignment

BackgroundVarus knee alignment has been identified as a risk factor for the progression of medial knee osteoarthritis (OA). This study tested the hypothesis that not only frontal plane kinematics and kinetics but also transverse plane lower extremity mechanics during gait are affected by varus malalignment of the knee.MethodsEighteen, otherwise healthy children and adolescents with varus malalignment of the knee were studied to examine the association between static varus malalignment and functional gait parameters. Kinematic data were collected using a Vicon motion capture system (Vicon Motion Systems, Oxford, UK). Two AMTI force plates (Advanced Mechanical Technology, Inc., Watertown, MA, USA) were used to collect kinetic data.ResultsThe results indicated that changes in transverse plane mechanics occur concomitantly with changes in knee malalignment in the frontal plane. A mechanical consequence of varus knee malalignment is obviously an increased endorotation of the foot (internal foot placement) and an increased internal knee rotation (tibia rotation) during stance phase. The linear correlation between the maximum external knee adduction moment in terminal stance and the internal knee rotation in terminal stance (r = 0.823, p < 0.001) shows that this transverse plane gait mechanics is directly in conjunction with intrinsic compressive load on the medial compartment during gait.ConclusionsUnderstanding factors that influence dynamic knee joint loading in healthy, varus malaligned knees may help us to identify risk factors that lead to OA. Thus, three-dimensional gait analysis could be used for clinical prognoses regarding the onset or progression of medial knee OA.     

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.