Effects of knee bracing on the functional performance of patients with anterior cruciate ligament reconstruction

OBJECTIVE: To compare the functional performance of subjects with unilateral anterior cruciate ligament (ACL) reconstruction. DESIGN: Cross-sectional comparative clinical trial. SETTING: A physical therapy outpatient department. SUBJECTS: Thirty-one subjects with unilateral ACL reconstruction for more than 5 months. INTERVENTION: Patients under 3 bracing conditions: (1) DonJoy Brace, (2) mechanical placebo brace, or (3) no brace. Running and turning 10 times on a 22-meter figure-8 runway, and running and jumping (and landing) on a semicircular path. MAIN OUTCOME MEASURES: Speed of running and turning, speed of running and jumping, and accuracy of landing after the jump. RESULTS: Subjects performed similarly in conditions 1 and 2 in all the tests, but the speeds of running and turning were significantly slower in conditions 1 and 2 than condition 3 (p =.008--.000). Results of the run and jump tests were not different among all conditions. CONCLUSION: Knee bracing may not improve functional performance of subjects 5 months after ACL reconstruction. The use of such a brace could actually slow down running and turning, irrespective of the mechanical constraints of the brace. These functional outcomes need to be noted when such a brace is used on this group of subjects.     

Assessment of functional knee bracing: an in vivo three-dimensional kinematic analysis of the anterior cruciate deficient knee

OBJECTIVE: To describe three-dimensional tibial and femoral movements in vivo and examine the effect of a brace on knee kinematics during moderate to intense activity. DESIGN: Skeletal kinematics of anterior cruciate ligament deficient knees was measured with and without braces during moderate to intense activity. BACKGROUND: Invasive markers implanted into the tibia and femur are the most accurate means to directly measure skeletal motion and may provide a more sensitive measure of the differences between brace conditions. METHODS: Steinmann traction pins were implanted into the femur and tibia of four subjects having a partial or complete anterior cruciate ligament rupture. Non-braced and braced conditions were randomly assigned and subjects jumped for maximal horizontal distance to sufficiently stress the anterior cruciate ligament. RESULTS: Intra-subject peak vertical force and posterior shear force were generally consistent between conditions. Intra-subject kinematics was repeatable but linear displacements between brace conditions were small. Differences in angular and linear skeletal motion were observed across subjects. Bracing the anterior cruciate ligament deficient knee resulted in only minor kinematic changes in tibiofemoral joint motion. CONCLUSION: In this study, no consistent reductions in anterior tibial translations were observed as a function of the knee brace tested. Relevance. Investigations have reported that knee braces fail when high loads are encountered or when load is applied in an unpredictable manner. Questions remain regarding tibiofemoral joint motion, in particular linear displacements. The pin technique is a means for direct skeletal measurement and may provide a more sensitive measure of the differences between brace conditions.     

Effects of functional knee bracing on muscle-firing patterns about the chronic anterior cruciate ligament-deficient knee

OBJECTIVE: To examine the effects of functional knee bracing on the muscle-firing patterns about the chronic anterior cruciate ligament (ACL)-deficient knee in successful brace users. DESIGN: Cross-sectional comparative clinical trial. SETTING: Motion analysis laboratory. PARTICIPANTS: Ten active individuals with unilateral, isolated, chronic (>18mo postinjury), ACL-deficient knees who subjectively reported improved function with a functional knee bracing. INTERVENTION: Each subject completed 3 single-leg hop maneuvers on their ACL-deficient knee with and without their knee brace while surface electromyographic activity was recorded from the quadriceps, hamstring, and gastrocnemius muscles. MAIN OUTCOME MEASURES: Muscle onset latency. RESULTS: Brace use significantly delayed the average onset of vastus lateralis activation before landing (123+/-47ms vs 109+/-30ms, P<.001), though significant interindividual variations existed. Bracing significantly altered the onset latency in 1 or more muscles in 9 of 10 subjects. In 4 subjects, a favorable change in the firing pattern was seen, whereas only 1 subject exhibited an unfavorable change. Without bracing, 5 of the 10 subjects fired the hamstrings or gastrocnemius muscles first; with bracing, 7 of 10 fired these muscles first. CONCLUSIONS: Brace use in this population did not consistently result in more favorable muscle firing patterns during the single-leg hop maneuver. Interindividual responses to brace use indicate the need for further research to investigate the multiple strategies that may exist to stabilize the ACL-deficient knee. In the meantime, functional knee brace use among ACL-deficient patients remains empirical.     

A hierarchy in functional muscle roles at the knee is influenced by sex and anterior cruciate ligament deficiency

BackgroundSex-related neuromuscular differences have been linked to greater risk of anterior cruciate ligament injuries in females. Despite this, it remains unclear if sex-related differences are present after injury. This study sought to determine if sex differences are present in the functional roles of knee joint muscles in an anterior cruciate ligament deficient population.MethodsAn isometric, weight-bearing, force-generation protocol required injured and healthy males and females to modulate ground reaction forces. Electromyography was used to classify the functional role of 10 lower limb muscles in their contribution to knee joint stability during various loading directions. These roles were compared between the four groups at 12 loading directions using a directional analysis.FindingsFunctional muscle roles were different between groups, except for injured males and healthy females. Healthy males had either joint actuators or specific joint stabilisers, but no general stabilisers; the vastus medialis and lateralis of injured males and healthy females were classified as general stabilisers while injured females added the gluteus medialis and medial gastrocnemius as general stabilisers.InterpretationA population-based hierarchy in functional muscle roles was discovered. Healthy males demonstrated the most specific muscle roles, which can be viewed as more adaptive to variable loading conditions. The more generalised stabilisation strategies seen in injured males and females would alter joint loading which may be detrimental to the knee joint health over time. In summary, (1) these injuries alter muscle roles; (2) these alterations are sex-specific; (3) rehabilitation might be optimised if sex-differences are considered.     

Gait of subjects with anterior cruciate ligament deficiency

An inter-limb comparison of ten subjects with unilateral anterior cruciate ligament (ACL) deficiency was undertaken in several areas. Isokinetic muscle testing was carried out at joint angular velocities of 60, 180 and 300/s. Each subject was videotaped at 200 Hertz while running on a treadmill at a recreational jogging pace, and kinematics were calculated. Electromyographic data were collected from the vasti lateralis and biceps femoris muscles during running. Isokinetic muscle testing revealed a significant quadriceps deficit in the ACL-deficient limb. During jogging, normalized electromyographic profiles showed increased quadriceps activity during a 200 ms period centred on footstrike. Earlier electromyographic activity was observed from the biceps femoris of the ACL-deficient limbs shortly after footstrike. It was concluded that even during straight line running, an activity not usually thought to affect individuals with ACL deficiency, compensatory techniques may be observed.     

Effect of a functional knee brace on knee flexion and extension strength after anterior cruciate ligament reconstruction

OBJECTIVES: To investigate the effect of a knee brace on knee flexion and extension muscular strength of patients after anterior cruciate ligament (ACL) reconstruction and to evaluate whether the effect of the brace depends on patient symptoms and muscular strength. DESIGN: Repeated measures. SETTING: A university-based outpatient orthopedic clinic and musculoskeletal assessment laboratory. PARTICIPANTS: Twenty-seven patients (14 women, 13 men; mean age, 28+/-11 y) having undergone arthroscopically assisted ACL reconstruction by using a semitendinosus and gracilis autograft. INTERVENTION: A custom-fit ACL functional knee brace. MAIN OUTCOME MEASURES: The brace effect was calculated as the change in peak torque observed with the brace, expressed as a percentage of peak torque observed without the brace, during isokinetic concentric knee flexion and extension movements performed at 90 degrees /s. Patient symptoms were quantified by using a disease-specific health-related quality of life questionnaire. RESULTS: Knee flexion strength decreased significantly with the brace (mean brace effect=-7.3%, P<.05). The brace effect during knee flexion varied considerably (-52% to 47%) and was significantly related to peak torque observed without the brace (r=-.50, P<.01). All other comparisons and correlations were not significant. CONCLUSIONS: These findings suggest that brace effects depend on patient strength. A brace may inhibit knee flexion strength of stronger patients, yet result in no change or even improvements in strength of weaker patients. Future research is required to further elucidate which patients may derive most benefit or detriment from bracing.     

A systematic review of bracing following reconstruction of the anterior cruciate ligament

Objectives

To determine whether the use of a postoperative knee brace following reconstruction of the anterior cruciate ligament (ACL) affects clinical outcomes.

Data sources

The electronic databases AMED, Cinahl, Cochrane database, Embase, Medline (via Ovid), Physiotherapy Evidence Database (PEDro) and Pubmed were searched from their inception to August 2006. A manual search of pertinent specialist journals and the reference lists of identified articles was also performed.

Review methods

All English-language, human subject, controlled clinical trials that compared the effects of wearing a knee brace with not wearing a brace for 1 day to 3 months following ACL reconstruction were included. Two reviewers extracted the data independently from the included studies, and assessed the methodological quality of the literature using the PEDro scoring system.

Results

Seven papers comprising of 390 ACL reconstructions were included. There were no significant longer-term differences in outcomes between patients who wore knee braces and those who did not. The methodological assessment of the literature revealed a number of limitations, including not blinding assessors, not performing a power calculation to determine the sample size, and not concealing subject allocation.

Conclusions

There appeared to be no significant longer-term differences in clinical outcomes between patients who wore postoperative knee braces and those who did not. Areas for further study are suggested, most notably to assess this topic using more rigorous randomised controlled trial methodologies.     

Bilateral accommodations to anterior cruciate ligament deficiency and surgery

OBJECTIVE To determine bilateral lower extremity joint accommodations during gait in anterior cruciate ligament deficient subjects and uninjured controls. DESIGN: Gait testing of 10 chronic anterior cruciate ligament deficient subjects prior to and 3 months following reconstructive surgery, and 10 uninjured controls. BACKGROUND: It is possible that bilateral joint accommodations could occur as a result of anterior cruciate ligament injury and in response to surgical repair. Few studies have investigated bilateral joint accommodations to anterior cruciate ligament injury and there is little consistency in the reported results. METHODS: Bilateral lower extremity kinematic and kinetic data were collected from 12 walking trials and inverse dynamics calculations were made to estimate bilateral knee and hip joint angle, moment, and power patterns during the stance phase of gait. RESULTS: Control subjects exhibited asymmetrical hip but symmetrical knee joint moment and power patterns. In contrast, the anterior cruciate ligament deficient subjects exhibited symmetrical hip and asymmetrical knee joint moment and power patterns prior to and following reconstructive surgery. CONCLUSIONS: Gait asymmetry in healthy subjects should not be considered pathological. In addition, chronic anterior cruciate ligament injury results in joint specific, bilateral lower extremity accommodations in gait mechanics. These accommodations persist 3 months following surgical repair.     

Effect of functional bracing, quadriceps and hamstrings on anterior tibial translation in anterior cruciate ligament insufficiency: a preliminary study.

Anterior tibial translation was measured in six patients with anterior cruciate ligament insufficiency. The tests were done in 15, 45, and 90 degrees of knee flexion, partly with activated quadriceps or hamstrings, and partly with subjects wearing a 4-point functional DonJoy brace. The translation was evaluated with a computerized electrogoniometer (Acufex KSS). The anterior tibial translation was significantly reduced by use of the hamstrings in all three degrees of knee flexion. The effect of the 4-point brace was only significant in 15 and 45 degrees of flexion. The quadriceps did not reduce the anterior tibial translation.     

Single-leg assessment of postural stability and knee functional outcome two years after anterior cruciate ligament reconstruction

ObjectiveTo analyse postural stability and the single-leg hop for distance in subjects 2 years after anterior cruciate ligament reconstruction (ACLR), in comparison with an age- and activity-matched control group.Design and settingSubjects reported to a sports medicine or athletic training research laboratory for testing.SubjectsTwenty-six subjects having undergone ACLR and 26 age- and activity-matched controls were selected to participate in this study. An arthroscopically-assisted, central, one-third bone-patellar tendon procedure was used to repair the ACLs.MeasurementsOne-leg stance postural stability was measured with the NeuroCom Balance Master^® platform system. We recorded the single-leg hop for distance as an objective measure of function.ResultsWe found a significant difference (p < 0.05) between the ACLR and control subjects in terms of the one-leg stance sway velocity (knee fully extended) on the operated side.ConclusionsAfter ACLR (mean time postoperatively: 24 ± 1 months), single-leg hop for distance score was normal, when compared with the contralateral limb. Our results indicate that 2 years after surgery, single-limb postural stability in the ACLR group differed significantly from that in the control group. The persistence of poor stability control may be correlated to an impairment in proprioception.     

Quantitative analysis of anterior cruciate ligament instability

The purpose of this study was to quantify end-feel by evaluating instantaneous stiffness and change in stiffness of the tibiofemoral joint. Normal (n = 26), anterior cruciate ligament (ACL) deficient (n = 6), and posterior cruciate ligament (PCL) deficient (n = 2) subjects were tested using the KT 2000 knee ligament arthrometer. Analogue force and displacement data were digitized, filtered, and calibrated. Force-displacement curves in the region of anterior tibial displacement were approximated using 5th degree polynomial functions. Stiffness and change in stiffness were determined analytically by the first and second derivatives of these functions. Subjects with confirmed ACL deficiency had lower values for stiffness and change in stiffness in the region of the curves believed to be indicative of ACL function, compared to contralateral knees and control subjects. RELEVANCE: First and second derivatives of tibiofemoral force-displacement curves give the stiffness and the change in stiffness respectively for anterior displacement of the tibia relative to the femur. This information concerning knee stability in vivo may be useful for diagnosis and follow-up.     

膝关节前交叉韧带的发育与结构生理

目的:交叉韧带是膝关节内的核心性稳定结构,了解其发育和结构生理以便对膝关节内韧带损伤的修复及其功能恢复提供系统的理论指导。资料来源:通过计算机检索medline1960-01/2004-08和Elsevier数据库1998-01/2004-08与膝关节前交叉韧带相关的文章,检索词“anteriorcruciateligament,kneejoint,dissection,限定文章语言种类为English。资料选择:纳入标准:①观察类文献。②解剖观察对比类文章,观察例数在20例以上的文献。排除标准:①综述文献。②Meta分析。③同一研究。资料提炼:共收集到关于膝关节前交叉韧带胚胎学发生、组织细胞结构、解剖结构、血液供应分布及神经支配等相关文献29篇,总结了符合条件的17篇文献中的观点。排除综述文献、Meta分析及陈旧文献12篇。资料综合:仅采纳观察实验的客观结论,不引用其推导结论。结论:交叉韧带是关节内滑膜在人体发育中退化过程中的产物,具有多种纤维胶原成分和极为复杂的三维空间构像。血液供应和神经分布复杂,在对交叉韧带损伤的治疗中应该充分考虑该二项因素的修复。     

Electromyographic biofeedback and recovery of quadriceps femoris muscle function following anterior cruciate ligament reconstruction

The purpose of this study was to compare the effects of biofeedback-facilitated exercise with exercise alone on the recovery rate of quadriceps femoris muscle function following anterior cruciate ligament (ACL) reconstruction. Functional measures included 1) a dynamometric test of quadriceps femoris muscle isometric peak torque during the 12th postoperative week and 2) the number of days post-operatively that a patient achieved full active extension of the knee. Twenty-two patients with acute ACL injury were randomly assigned to a Treatment (biofeedback) Group (n = 11) or a Control (nonfeedback) Group (n = 11) during the first therapy session one week after reconstructive surgery. After the patients had completed the 12-week exercise program, the quadriceps femoris muscle isometric peak torque in the operative limb was compared with that in the nonoperative limb at three angles (90 degrees, 60 degrees, and 45 degrees) of extension. An analysis of variance revealed significant differences between the Treatment and Control Groups at all three angles. Mean recovery time was calculated for each group, and a t test for independent samples indicated a significant difference between the groups. These results demonstrate that the addition of biofeedback to muscle strengthening exercises facilitates the rate of recovery of quadriceps femoris muscle function following ACL reconstruction.     

人工韧带重建与膝关节前交叉韧带的运动损伤

目的:总结膝关节前交叉韧带的结构、功能,损伤的力学机制和特点及其缺损后的人工韧带重建研究现状,为人工韧带的临床应用提供依据.方法:以"膝关节,前交叉韧带,人工韧带,重建"为关键词,用计算机检索维普数据库和Medline数据库,按纳入和排除标准,对文献进行筛选,共纳入31篇文章.重点对以下3个方面进行了探讨:①前交叉韧带的结构和功能?②前交叉韧带运动损伤机制和特点?③前交叉韧带运动缺损后人工韧带的重建?结果:前交叉韧带由胶原纤维组成,对膝关节的内旋和胫骨的伸直活动起稳定性作用,限制胫骨前移及过度伸展,对膝内侧的稳定、膝伸直位时胫骨旋转活动限制作用.在一些扭转、斜切、急停等动作较多的运动中容易发生损伤,诸多研究表明LARS人工韧带重建前交叉韧带效果与其他移植物相比具有显著优势.结论:前交叉韧带在膝关节的稳定当中起着重要作用,但也是极易发生损伤的部位.当前对于前交叉韧带缺损的治疗比较认可的方法是LARS人工交叉韧带重建.它具有创伤小、早期即可从事运动等优势,同时也存在医疗费用高等不足.     

膝关节镜下前交叉韧带重建术的护理配合

目的探讨和总结膝关节镜下重建前交叉韧带的手术配合经验,以进一步提高配合水平。方法通过对15例自体韧带重建前交叉韧带的手术配合,总结配合要点、经验。结果本组患者术后平均15.0 d出院。无1例交叉感染,术后2个月Lysholm膝关节功能良好。结论充分的术前准备,严格执行无菌操作,准确熟练地配合手术,正确使用仪器和器械是手术成功的关键。     

Part 1. Innovations in treating anterior cruciate ligament deficiency

Orthopaedic clinicians and researchers have made great strides in understanding the intricacy of the anterior cruciate ligament (ACL). The number of ACL injuries is increasing with a more active population and more advanced diagnostic techniques. The ACL's importance for normal knee function has created a great need to find reconstructive techniques that will restore and maintain the complex motion of the knee.     

Gait perturbation response in chronic anterior cruciate ligament deficiency and repair

OBJECTIVE: To determine how chronic anterior cruciate ligament deficient and surgically repaired subjects react to unexpected forward perturbations during gait as compared to healthy controls. DESIGN: Gait testing of 10 chronic anterior cruciate ligament deficient subjects prior to and three months following reconstructive surgery, and 10 uninjured controls. BACKGROUND: The ability of an anterior cruciate ligament injured individual to react and maintain equilibrium during gait perturbations is critical for the prevention of reinjury. No studies have investigated how these individuals respond to unexpected perturbations during normal gait. METHODS: An unexpected forward perturbation was induced upon heel strike using a force plate capable of translational movement. RESULTS: Prior to surgery, the anterior cruciate ligament subjects exhibited a greater knee extensor moment in response to the perturbation compared to healthy controls. Following surgery, the anterior cruciate ligament injured subjects exhibited a static knee position and a sustained knee extensor moment throughout stance in response to the perturbation as compared to controls. CONCLUSIONS: These data suggest that chronic anterior cruciate ligament deficient subjects rely heavily on knee extensor musculature to prevent collapse in response to an unexpected perturbation. This same reactive response was more pronounced 3 months following surgery. RELEVANCE: The results suggest that, prior to and following surgery, chronic anterior cruciate ligament injured subjects respond differently than healthy controls to an unexpected perturbation during gait. Anterior cruciate ligament injured or repaired subjects do not reduce or avoid vigorous contraction of the quadriceps muscles when responding to gait perturbations.     

膝关节前交叉韧带重建的生物学及生物力学特性

目的通过总结前交叉韧带重建的生物学及生物力学特性,探讨早期锻炼对膝关节前交叉韧带重建后移植物愈合及膝关节运动功能恢复的作用.资料来源应用计算机检索MEDLINE1970-01/2004-01期间有关膝关节前交叉韧带重建及其生物力学特征的文献,检索词"anterior cruciate ligament,knee ioint,biomechanics",并限定文章语言种类为英文.资料选择对资料进行初审,选择有关膝关节前交叉韧带重建及其生物力学特征的文献,开始查找全文.选择随机对照类文章,当同一作者有多篇文章时,选择病例数最多的予以纳入;排除综述类及Mete分析类文章.质量评价主要考察资料的真实性,调查、实施过程是否严密.资料提炼共检索到46篇有关膝关节前交叉韧带重建及其生物力学特征的文章,29篇符合以上纳入标准,排除的17篇文章中,9篇为小样本分析,8篇为综述类或Mete分析类文章.资料综合通过了解正常前交叉韧带的生物力学特征制定重建措施及康复计划指导.重建后前交叉韧带动物实验提示膝关节运动功能恢复均不理想,而人体实验结果优于动物.随机对照实验表明,前交叉韧带重建后立即持重不增加膝关节的松弛性,反而有利于减轻髌骨疼痛.结论前交叉韧带损伤重建后固定膝关节,限制关节周围肌肉收缩活动,导致韧带、关节及周围肌肉运动功能受限.早期康复锻炼可以减轻疼痛,改善关节软骨代谢,防止关节囊挛缩,有助于重建后膝关节前交叉韧带运动功能的恢复.