前交叉韧带断裂并半月板损伤的生物力学分析

目的探讨前交叉韧带断裂并半月板损伤的生物力学。方法随机抽取24侧正常男性新鲜膝关节标本,取材时间均在死亡后1 h,分为前交叉韧带(ACL)完整组、前内侧束断裂组(AMB断裂组)、后内侧束断裂组(PLB断裂组)、ACL全断组(全断组)。观察膝关节不同角度下各组内侧半月板后角应变情况。结果膝伸直0°,全断组后角应变高于其他组,差异有统计学意义(P0.05),AMB断裂组和ACL完整组比较差异未见统计学意义(P0.05)。膝屈曲30°,全断组后角应变高于其他组,差异有统计学意义(P0.05);PLB断裂组后角应变高于完整组和AMB断裂组,差异有统计学意义(P0.05)。膝屈曲60°,全断组后角应变高于PLB断裂组和完整组,差异有统计学意义(P0.05);AMB断裂组后角应变高于完整组、PLB组,差异有统计学意义(P0.05)。膝屈曲90°,全断组后应角应变高于完整组、PLB组和AMB组,差异有统计学意义(P0.05)。结论 ACL前交叉韧带断裂对半月板损伤有一定的影响,会造成其生物力学的改变。     

铁饼运动员旋转开始阶段肩关节急性损伤的生物力学分析

目的:采用问卷调查法和三维运动生物力学分析法,了解国家优秀女子铁饼运动员旋转开始阶段肩关节可能出现的运动损伤及其呈现的生物力学特点。方法:2004-06/07发放调查问卷14份,调查14名国家健将级优秀女子铁饼运动员肩关节损伤构成比。2005-03采用近景动态立体摄影的测量方法,用两台有电子快门的进口松下摄像机,对运动员现场比赛、训练进行定点拍摄,拍摄频率为50Hz。再采用爱捷运动录像快速反馈分析系统,进行图像采样和数据计算,获取生物力学指标,重点分析女子铁饼运动员旋转开始阶段肩关节可能出现的运动损伤及其呈现的生物力学特点。结果:①14份问卷全部收回,有效率100%。通过对问卷的分析,发现国家健将级优秀女子铁饼运动员肩关节损伤构成比最高的是肱二头肌长头肌肌腱损伤(34%),其次是肩袖损伤23%,肩锁关节扭伤及脱位、脱位与半脱位(盂肱关节)、三角肌拉伤、其他分别占14%,3%,5%,18%。②旋转开始阶段肩关节的生物力学指标:右脚离地瞬间,肩髋角度45°、拉引角度126°、肩轴角度2°,左肩速度为2.65m/s、右肩速度为0.98m/s;左脚离地瞬间,肩髋角度27°、拉引角度150°、肩轴角度-12°、左肩速度为1.98m/s、右肩速度为1.99m/s。结论:旋转开始阶段,由于女子铁饼运动员拉引角增加幅度相对较大,肱二头肌长头肌腱损伤构成比最高,拉引角增加幅度大可能是造成肱二头肌的长头肌腱损伤的重要因素。     

篮球运动员膝关节损伤调查及力学分析

目的：调查参加大学生篮球联赛的部分高校篮球代表队运动员膝关节患病情况、揭示篮球运动员膝关节损伤的内在机制，为篮球训练、教学、比赛中运动损伤的治疗与康复提供理论依据。方法：采用问卷调查法对武汉6所高校，18支男队，6支女队，共计420名运动员（男330人，女90人，年龄18～26岁，平均21岁)从运动生物力学角度对其膝关节损伤的几种常见类型进行调查分析。结果：总患病人数200人，总患病率为47．6％；急性损伤44人(21．9％)；慢性损伤156人(78．1％)，为篮球运动员膝关节损伤的主要类型。结论：膝关节损伤主要与其运动生物力学特点、运动性疲劳以及运动员选材有关，科学的训练与选材能有效减少篮球运动员膝关节损伤。     

篮球运动员膝关节损伤调查及力学分析

目的:调查参加大学生篮球联赛的部分高校篮球代表队运动员膝关节患病情况,揭示篮球运动员膝关节损伤的内在机制,为篮球训练、教学、比赛中运动损伤的治疗与康复提供理论依据。方法:采用问卷调查法对武汉6所高校,18支男队,6支女队,共计420名运动员(男330人,女90人,年龄18～26岁,平均21岁)从运动生物力学角度对其膝关节损伤的几种常见类型进行调查分析。结果:总患病人数200人,总患病率为47.6%;急性损伤44人(21.9%);慢性损伤156人(78.1%),为篮球运动员膝关节损伤的主要类型。结论:膝关节损伤主要与其运动生物力学特点、运动性疲劳以及运动员选材有关,科学的训练与选材能有效减少篮球运动员膝关节损伤。     

优秀女子标枪运动员最后用力阶段肘关节生物力学分析及运动损伤调查

目的:采用横断面问卷调查优秀女子标枪运动员肘关节运动损伤情况,采用生物力学分析法分析其最后用力阶段肘关节的数据变化及其相关原因。方法:2004-05/12发放调查问卷36份,调查36名国家级、健将级女子标枪运动员肘关节损伤情况。2005-05采用近景动态立体摄影的测量方法,用两台有电子快门的进口松下摄像机,对运动员现场比赛、训练进行定点拍摄,拍摄频率为50Hz。再采用爱捷运动录像快速反馈分析系统,进行图像采样和数据计算,获取生物力学指标。重点分析最后用力阶段右肘角、右肘速度等指标。结果:36份问卷全部收回,问卷填写完整有效。①36名优秀女子标枪运动员肘关节损伤发生率为89%,其中因技术不正确占11%,因负荷安排不当占31%,因疲劳占29%,因准备活动不足占19%,其他占10%。②女子标枪运动员肘关节损伤构成比最高的是尺侧副韧带损伤,为41%,其次是肱骨上髁屈肌附着点或屈肌拉伤,为17%,再次是尺骨鹰嘴骨折为13%,肱骨骨折、桡侧副韧带损伤和其他损伤分别为11%,9%,9%。③最后用力阶段肘关节的生物力学指标:左脚着地瞬间,平均右肘角度为(112±4)°,右肘平均速度为(6.64±0.86)m/s;标枪出手瞬间,右肘角均值为(149±3)°,右肘平均速度为(8.65±1.32)m/s。结论:①掷标枪运动要求肘关节在高速运动中精确完成由屈曲到伸展的反关节运动,而超过正常的力及重复性微细损伤的积累或由于运动员肩关节柔韧性以及肘部力量不足等原因,通常导致肘关节损伤。②女子标枪运动员肘关节较易出现尺侧副韧带损伤和肱骨上髁屈肌附着点或屈肌拉伤。     

男子铁饼运动员最后用力阶段肩关节急性损伤的生物力学分析

目的:分析造成运动损伤的技术性因素,减少铁饼运动员的运动损伤,提高运动成绩。方法:选取第八届全运会前16名男子铁饼运动员和河北省中学生运动会前16名男子铁饼运动员作为研究对象,采用近景动态立体摄影进行拍摄,采用爱捷运动录像解析系统分析获得运动学数据。对32名运动员进行问卷调查,统计多年参加训练发生的运动损伤资料,分析并找出铁饼运动员肩部急性损伤的生物力学原因。结果:32名铁饼运动员的统计数据全部纳入结果分析。国家组运动员肱二头肌长头肌肌腱损伤、肩袖损伤、肩锁关节扭伤脱位以及三角肌拉伤构成比与省级组比较,差异有显著性意义(P<0.05)。国家组运动员在最后用力加速阶段铁饼出手时左、右肩速为(2.59±0.56,3.70±0.56)m/s,省级组左、右肩速为(1.50±0.39,3.40±0.87)m/s,两组比较有显著性差异(P<0.05)。结论:最后用力初始阶段、肩髋角减小、右侧投掷臂后留、拉引角达到最小值、胸部肌群预先拉长到最大程度,是发生肩关节三角肌拉伤的主要技术因素;右肩速的大幅度上升,是发生肩袖损伤的重要因素。     

关节镜术后等速训练对膝半月板损伤恢复的影响

背景:运动损伤后的康复训练是保持和减缓运动能力的重要途径,开展此领域的研究具有重要意义。目的:观察膝半月板损伤施以关节镜手术后,等速训练对膝关节功能恢复及关节周围肌肉力量的影响。设计:病例-对照观察。单位:辽宁警官高等专科学校警训系。对象:于2004-09/2005-01选择大连医科大学附属医院外科收治的单侧膝关节半月板急性损伤患者22例为观察对象。随机数字表法分为实验组和对照组,各11例。方法:实验组和对照组患者进行关节镜手术治疗,对照组进行常规封闭、理疗、按摩等方法恢复。实验组患者术后第2～4天开始功能恢复,3周后采用Cybex-6000型等速运动测试仪对患侧膝屈伸肌进行等速运动训练。主要观察指标:不同测试速度[60,120,180(°)/s]时的屈伸肌峰力矩、单次最大做功量、力矩加速能、平均功率。结果:纳入患者22例,均进入结果分析。①关节镜手术配合等速肌力训练后,膝关节运动范围加大,训练前患膝的最大屈曲角度为(132±25)°,训练后患膝的最大屈曲角度为(158±21)°,经配对t检验,两者差异有非常显著性意义(P<0.01)。而对照组手术后最大屈曲角度为(133±31)°,实验结束后最大屈曲角度为(139±34)°,差异无显著性意义(P>0.05)。且两组实验后差异有显著性意义(P<0.05)。②实验组膝屈伸肌峰力矩、单次最大做功量、力矩加速能及平均功率在60,120,180(°)/s的变化与对照组相比差异均有显著性意义(P<0.05)。结论:膝关节等速训练,可加速膝半月板损伤后的康复过程,对增加膝关节周围肌肉力量、保持膝关节的稳定性和运动能力均具有重要的意义。     

慢性非特异性腰痛髋部肌群肌力及腰部功能特征研究

目的:观察慢性非特异性腰痛(CNLBP)的髋部肌群肌力特征,并探讨其与腰部疼痛及功能的相关性。方法:选取CNLBP患者(CNLBP组)30例,30例正常健康人为对照组。评估CNLBP组疼痛侧、非疼痛侧与对照组右侧髋部肌群肌力。应用等速肌力测试系统(60°/s)测定2组髋屈曲、髋后伸、髋内收、髋外展、髋内旋和髋外旋肌群的峰力矩。采用视觉模拟评分(VAS)评估腰部疼痛,采用日本骨科协会(JOA)评分评估腰部功能。以峰力矩/体重评估髋部肌群肌力,并进行CNLBP组疼痛侧与非疼痛侧对比、两侧分别与对照组右侧对比。对CNLBP组髋部肌群肌力和腰部疼痛、功能进行相关性分析。结果:CNLBP组疼痛侧髋屈曲、髋外展、髋外旋肌群峰力矩/体重比值均低于非疼痛侧且低于对照组(P<0.05)。髋屈曲、髋外展肌群肌力与腰部疼痛程度具有中等程度相关性(P<0.05)。髋屈曲、髋外展、髋外旋肌群肌力与腰部功能评分有中等程度相关性(P<0.05)。结论:CNLBP患者存在疼痛侧髋屈曲、髋外展及髋外旋肌群肌力下降。以纠正髋部肌群肌力失衡为目标的康复训练对改善腰部疼痛及功能可能有积极作用。     

单侧全髋关节置换术后患者下肢三维运动力学特征分析

目的:分析单侧全髋关节置换术(THR)恢复期患者平地步行中下肢关节的三维运动学和动力学特征,指导后续和早期康复.方法:采用运动重建实验室检测病例数据库资料分析的方法,选择在本院关节外科行THR后5-10年的患者14例为实验组,14例相匹配的健康人为对照组.采用Vicon Nexus、AMTI检测下肢三维运动学和动力学,应用Polygon分析步态周期中髋、膝、踝关节三维运动学和动力学特征.结果:和对照组右侧下肢比较,术侧髋关节屈曲峰值力矩减小(P＜0.05),膝、踝关节屈曲峰值力矩增大(P＜0.05);峰值角度方面,术侧髋关节内收、内旋、外旋、后伸和膝关节内收以及踝关节内收、外展、内旋、外旋,差异有显著性意义(P＜0.05).术侧和健侧比较无显著性差异(P＞0.05).结论:髋关节置换术后恢复期患者,通过同侧膝关节和踝关节屈曲力矩增加代偿患髋屈曲力矩的降低;同时为防止植入物松动和向外脱位,步行中患髋过度外旋并发踝关节过度内旋.另外,健侧下肢产生了与患侧下肢相似的运动力学变化.     

髌韧带替代前交叉韧带重建术后股四头肌及guo绳肌等速测试结果

目的评价前交叉韧带(ACL)损伤经骨-髌韧带-骨(BPB)重建术后患侧及健侧膝关节股四头肌及腘绳肌的向心性收缩及离心性收缩功能的变化,重点观测作为协同保护前交叉韧带的腘绳肌拮抗性离心性收缩在不同运动速度及不同的关节位置下的功能变化.方法用Cybex-770型等速测试系统对30例陈旧性前交叉韧带损伤经关节镜行BPB替代ACL重建术后的患者进行患肢及健肢的股四头肌及腘绳肌的向心性和离心性收缩的肌肉功能进行测试.结果 显示在30°/s、60°/s、90°/s、120°/s的4组测试运动速度下患膝的股四头肌及在30°/s、60°/s、90°/s三组测试运动速度下患膝腘绳肌的向心性及离心性收缩的峰力矩都较健侧有明显下降,具显著性差异(P<0.05),而在120°/s运动速度下两下肢腘绳肌的向心性及离心性收缩峰力矩已无显著性差异.患肢腘绳肌离心性收缩与股四头肌向心性收缩的峰力矩之比(H/Q的E/C)及两者的向心性收缩峰力矩之比(H/Q的C/C)在4组运动速度下均大于健侧,具极显著性差异(P<0.01).随着运动速度的加大及膝关节的伸直两个比值逐步加大,H/Q的E/C比值在膝关节近伸直位时达到最高峰.结论前交叉韧带损伤BPB替代ACL重建术后患肢的股四头肌及腘绳肌都发生了废用性萎缩,但后者比前者恢复要快,术后2年在较快速运动下两侧腘绳肌的收缩功能已无明显差异,患侧肢体适应性地加强了作为保护前交叉韧带的动力装置腘绳肌的收缩功能,尤其是离心性收缩,随着运动速度的加快及膝关节的逐渐伸直至ACL最易损伤处这种保护反应达到最高峰.     

Biomechanical Changes During a 90º Cut in Collegiate Female Soccer Players With Participation in the 11+

BackgroundValgus collapse and high knee abduction moments have been identified as biomechanical risk factors for ACL injury. It is unknown if participation in the 11+, a previously established, dynamic warm-up that emphasizes biomechanical technique and reduces ACL injury rates, reduces components of valgus collapse during a 90º cut.Hypothesis/PurposeTo determine whether participation in the 11+ during a single soccer season reduced peak knee abduction moment and components of valgus collapse during a 90º cut in collegiate female soccer players.Study DesignProspective cohort studyMethodsForty-six participants completed preseason and postseason motion analysis of a 90º cut. During the season, 31 players completed the 11+ and 15 players completed their typical warm-up (control group). Peak knee abduction moment, components of valgus collapse (hip adduction, internal rotation, and knee abduction angles), and a novel measure of knee valgus collapse were analyzed with repeated-measures ANOVAs to determine differences between preseason and postseason. Smallest detectable change (SDC) and minimal important difference (MID) values were applied to contextualize results.ResultsThere was a significant main effect of time for non-dominant knee valgus collapse (p=0.03), but decreases in non-dominant knee valgus collapse only exceeded the SDC in the intervention team.ConclusionsClinically meaningful decreases in knee valgus collapse may indicate a beneficial biomechanical effect of the 11+. Participation in the 11+ may lower ACL injury risk by reducing valgus collapse during a 90º cut.Level of Evidence2b     

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.     

EFFECT OF INJURY PREVENTION TRAINING ON KNEE MECHANICS IN FEMALE ADOLESCENTS DURING PUBERTY

Purpose/Background:

Female adolescents change their landing mechanics during puberty. It is unknown whether implementation of anterior cruciate ligament (ACL) injury prevention training reduces the loss of knee control in female athletes during puberty. The purpose of this study was to evaluate the effect of injury prevention training on dynamic knee alignment in female basketball players specifically when the knee mechanics were changing during puberty.

Methods:

Sixty female junior high school basketball players participated and were divided into two groups: a training group (n = 32) and a control group (n = 28). The training group underwent an injury prevention program for 6 months, whereas the control group maintained a regular training routine. The knee valgus motion and knee flexion range of motion during a drop vertical jump were measured before and after the training period. The probability of a high knee abduction moment (pKAM) was also evaluated using an ACL injury prediction algorithm.

Results:

The knee valgus motion was significantly increased in the control group (p < 0.001), whereas it did not change in the training group (p = 0.64). Similarly, the knee flexion range of motion was significantly decreased in the control group (p < 0.001), whereas it was not changed in the training group (p = 0.55). The pKAM was significantly increased in the control group (p < 0.001), but not in the training group (p = 0.06).

Conclusions:

Implementation of injury prevention training was effective in limiting the loss of knee control in female athletes during puberty. Lowering the risk of ACL injury might be possible in this population.

Level of Evidence:

2b     

Clinical correlates to laboratory measures for use in non-contact anterior cruciate ligament injury risk prediction algorithm

Background

Prospective measures of high knee abduction moment during landing identify female athletes at high risk for non-contact anterior cruciate ligament injury. Biomechanical laboratory measurements predict high knee abduction moment landing mechanics with high sensitivity (85%) and specificity (93%). The purpose of this study was to identify correlates to laboratory-based predictors of high knee abduction moment for use in a clinic-based anterior cruciate ligament injury risk prediction algorithm. The hypothesis was that clinically obtainable correlates derived from the highly predictive laboratory-based models would demonstrate high accuracy to determine high knee abduction moment status.

Methods

Female basketball and soccer players (N = 744) were tested for anthropometrics, strength and landing biomechanics. Pearson correlation was used to identify clinically feasible correlates and logistic regression to obtain optimal models for high knee abduction moment prediction.

Findings

Clinical correlates to laboratory-based measures were identified and predicted high knee abduction moment status with 73% sensitivity and 70% specificity. The clinic-based prediction algorithm, including (Odds Ratio: 95% confidence interval) knee valgus motion (1.43:1.30–1.59 cm), knee flexion range of motion (0.98:0.96–1.01°), body mass (1.04:1.02–1.06 kg), tibia length (1.38:1.25–1.52 cm) and quadriceps to hamstring ratio (1.70:1.06–2.70) predicted high knee abduction moment status with C statistic 0.81.

Interpretation

The combined correlates of increased knee valgus motion, knee flexion range of motion, body mass, tibia length and quadriceps to hamstrings ratio predict high knee abduction moment status in female athletes with high sensitivity and specificity.

Clinical Relevance

Utilization of clinically obtainable correlates with the prediction algorithm facilitates high non-contact anterior cruciate ligament injury risk athletes' entry into appropriate interventions with the greatest potential to prevent injury.     

Multicenter trial of motion analysis for injury risk prediction: lessons learned from prospective longitudinal large cohort combined biomechanical - epidemiological studies

Our biodynamics laboratory group has conducted large cohort biomechanical-epidemiological studies targeted at identifying the complex interactions among biomechanical, biological, hormonal, and psychosocial factors that lead to increased risk of anterior cruciate ligament (ACL) injuries. The findings from our studies have revealed highly sensitive and specific predictors for ACL injury. Despite the high incidence of ACL injuries among young athletes, larger cohorts are needed to reveal the underlying mechanistic causes of increased risk for ACL injury. In the current study, we have outlined key factors that contribute to the overall success of multicenter, biomechanical-epidemiological investigations designed to test a larger number of athletes who otherwise could not be recruited, screened, or tested at a single institution. Twenty-five female volleyball players were recruited from a single high school team and tested at three biodynamics laboratories. All athletes underwent three-dimensional motion capture analysis of a drop vertical jump task. Kinematic and kinetic variables were compared within and among laboratories. Reliability of peak kinematic variables was consistently rated good-to-excellent. Reliability of peak kinetic variables was consistently rated goodto-excellent within sites, but greater variability was observed between sites. Variables measured in the sagittal plane were typically more reliable than variables measured in the coronal and transverse planes. This study documents the reliability of biomechanical variables that are key to identification of ACL injury mechanisms and of athletes at high risk. These findings indicate the feasibility of executing multicenter, biomechanical investigations that can yield more robust, reliable, and generalizable findings across larger cohorts of athletes.     

Limited hip and knee flexion during landing is associated with increased frontal plane knee motion and moments

Background

It has been proposed that female athletes who limit knee and hip flexion during athletic tasks rely more on the passive restraints in the frontal plane to deceleration their body center of mass. This biomechanical pattern is thought to increase the risk for anterior cruciate ligament injury. To date, the relationship between sagittal plane kinematics and frontal plane knee motion and moments has not been explored.

Methods

Subjects consisted of 58 female club soccer players (age range: 11–20 years) with no history of knee injury. Kinematics, ground reaction forces, and surface electromyography were collected while each subject performed a drop landing task. Subjects were divided into two groups based on combined sagittal plane knee and hip flexion angles during the deceleration phase of landing (high flexion and low flexion).

Findings

Subjects in the low flexion group demonstrated increased knee valgus angles (P = 0.02, effect size 0.27), increased knee adductor moments (P = 0.03, effect size 0.24), decreased energy absorption at the knee and hip (P = 0.02, effect size 0.25; and P < 0.001, effect size 0.59), and increased vastus lateralis EMG when compared to subjects in the high flexion group (P = 0.005, effect size 0.35).

Interpretation

Female athletes with limited sagittal plane motion during landing exhibit a biomechanical profile that may put these individuals at greater risk for anterior cruciate ligament injury.     

BIOMECHANICAL MEASURES DURING TWO SPORT-SPECIFIC TASKS DIFFERENTIATE BETWEEN SOCCER PLAYERS WHO GO ON TO ANTERIOR CRUCIATE LIGAMENT INJURY AND THOSE WHO DO NOT: A PROSPECTIVE COHORT ANALYSIS

Background:Decelerating and cutting are two common movements during which non-contact anterior cruciate ligament (ACL) injuries occur in soccer players. Retrospective video analysis of ACL injuries has demonstrated that players are often in knee valgus at the time of injury.Purpose:To determine whether prospectively measured components of valgus collapse during a deceleration and 90 ° cut can differentiate between collegiate women''s soccer players who go on to non-contact ACL injury.Design:Secondary analysis of prospectively collected data.Methods:51 NCAA women''s soccer players completed motion analysis of a deceleration and 90 ° before the competitive season. Players were classified as Injured (noncontact ACL injury during the season) or Uninjured at the end of the season. Differences between groups for peak hip adduction, internal rotation, and knee abduction angles, and knee valgus collapse were analyzed with a MANOVA.Results:Four non-contact ACL injuries were reported at the end of the season. There was a significant difference between groups for hip adduction angle during the 90 ° cut (p = 0.02) and deceleration (p = 0.03). Players who went on to ACL injury were in more hip adduction.Conclusions:Hip adduction angle is larger in players who go on to ACL injury than those who do not during two sport-specific tasks. The components of knee injury prevention programs that address proximal control and strength are likely crucial for preventing ACL injuries.Level of Evidence:2b     

Association between lower extremity posture at contact and peak knee valgus moment during sidestepping: implications for ACL injury

BACKGROUND. Knee valgus load during sports movement is viewed as an important predictor of non-contact anterior cruciate ligament injury risk, particularly in females. Formulating movement strategies that can reduce valgus loading during these movements therefore appears pertinent to reducing anterior cruciate ligament injury rates. With this in mind, the current study examined the relationship between peak valgus moment and lower extremity postures at impact during a sidestep cutting task. METHODS. Ten male and ten female NCAA athletes had initial contact three-dimensional hip, knee and ankle angles and subsequent knee valgus moment quantified during the execution of (n=10 trials) sidesteps. Peak valgus data were normalized to mass and height and tested for the main effect of gender (ANOVA, P<0.05). Intra-subject correlations between the eight initial joint angles and the normalized valgus moment were then conducted across the ten sidestepping trials. The ensuing slopes of regression were submitted to a two-sample t-test to determine whether mean slope values were significantly different from zero and for the main effect of gender (P<0.05). FINDINGS. Females had significantly larger normalized knee valgus moments than males. A greater peak valgus moment was associated with larger initial hip flexion and internal rotation, and with larger initial knee valgus angle. Peak knee valgus moment was more sensitive to initial hip internal rotation and knee valgus position in females. INTERPRETATION. Training of neuromuscular control at the hip joint may reduce the likelihood of anterior cruciate ligament injury via a valgus loading mechanism during sidestepping, especially in females.     

Loading characteristics of females exhibiting excessive valgus moments during cutting

BACKGROUND: Excessive knee valgus moments are considered a risk factor for non-contact anterior cruciate ligament injuries in female athletes, however, little is known about the biomechanical factors that contribute to this loading pattern. The purpose of this study was to compare lower extremity kinematics, foot position and ground reaction forces between female soccer players who demonstrate normal frontal plane moments at the knee with those who demonstrate excessive frontal plane moments at the knee during a cutting maneuver. METHODS: Sixty-one female soccer players, 16 (2) years, participated. Three dimensional kinematics and ground reaction forces were recorded during a side-step cutting maneuver. Knee frontal plane moments were calculated with inverse dynamics equations and were used to classify subjects into normal (N=38) and excessive valgus moment (N=23) groups. FINDINGS: Data revealed that the subjects with excessive valgus moments demonstrated an initial loading pattern that included greater laterally directed ground reaction forces (P<0.001, effect size 1.51), increased hip abduction (P=0.002, effect size 0.79), increased hip internal rotation (P=0.008, effect size 0.71) and a more internally rotated foot progression angle (P=0.04, effect size 0.55). Taken together, these variables explained 49% of the variance in peak knee valgus moment (R=.698, P<0.001). INTERPRETATION: These results provide insight into potentially injurious loading strategies and support the premise that interventions designed to encourage loading of the lower extremity in a more neutral alignment may work to decrease frontal plane loading at the knee.     

Kinetic and kinematic differences between first and second landings of a drop vertical jump task: Implications for injury risk assessments

Background

Though the first landing of drop vertical jump task is commonly used to assess biomechanical performance measures that are associated with anterior cruciate ligament injury risk in athletes, the implications of the second landing in this task have largely been ignored. We examined the first and second landings of a drop vertical jump for differences in kinetic and kinematic behaviors at the hip and knee.

Methods

A cohort of 239 adolescent female basketball athletes (age = 13.6 (1.6) years) completed drop vertical jump tasks from an initial height of 31 cm. A three dimensional motion capture system recorded positional data while dual force platforms recorded ground reaction forces for each trial.

Findings

The first landing demonstrated greater hip adduction angle, knee abduction angle, and knee abduction moment than the second landing (P-values < 0.028). The second landing demonstrated smaller flexion angles and moments at the hip and knee than the first landing (P-values < 0.035). The second landing also demonstrated greater side-to-side asymmetry in hip and knee kinematics and kinetics for both the frontal and sagittal planes (P-values < 0.044).

Interpretation

The results have important implications for the future use of the drop vertical jump as an assessment tool for anterior cruciate ligament injury risk behaviors in adolescent female athletes. The second landing may be a more rigorous task and provides a superior tool to evaluate sagittal plane risk factors than the first landing, which may be better suited to evaluate frontal plane risk factors.