EMG profiles of knee joint musculature during walking: changes induced by anterior cruciate ligament deficiency

A tear of the anterior cruciate ligament (ACL) disrupts the delicate balance of static stabilizers of the knee, leading to significant alterations in joint kinematics. Little is known about the dynamic compensatory responses of the patient to these kinematic alterations. This lack of quantitative information on the muscle synergy patterns has limited the surgeon's ability to evaluate various operative and rehabilitative techniques. Twelve subjects with documented ACL deficiency for at least 1 year and 15 normal participants were studied. Each subject was asked to walk at free and fast speeds on a 12 m walkway. The right and left foot contact patterns and the linear envelopes from the surface electromyogram (EMG) patterns of the gastrocnemius, medial and lateral hamstrings, rectus femoris, and vastus lateralis were measured. Significant differences were found in the muscle synergy patterns during walking. During the swing-to-stance transition, the ACL-deficient subjects showed significantly less activity in the quadriceps and gastrocnemius muscles and more activity in the biceps femoris than in the normal group. During early swing, the vastus lateralis is more active than normal, and during midstance and terminal stance, the hamstrings appear to be less active than normal subjects. These dynamic compensatory mechanisms suggest that use of the hamstring tendons in reconstructive procedures may alter important compensatory mechanisms about the knee joint. Application of dynamic EMG techniques to the study of reconstructive procedures should provide additional information that will assist the clinician in the rational choice of a surgical procedure.     

Quadriceps and hamstrings muscle control in athletic males and females

The aim of this study was to investigate whether athletic males and females have differences in their quadriceps and hamstrings muscle control strategies. Twenty‐four people (12 males, 12 females) active in level I activities volunteered to participate. The subjects' muscle control strategies were studied using electromyography and a target matching protocol that assesses one's ability to produce force with control. The degree of control exhibited in the subjects' quadriceps and hamstrings muscle activation strategies was evaluated by calculating specificity indices for each muscle using circular statistics. Females displayed significantly lower specificity than males in their vastus medialis (p < 0.001), rectus femoris (p = 0.044), and lateral hamstrings (p = 0.001) muscle activity patterns, but similar specificity in their vastus lateralis and medial hamstrings activity patterns. Females also used a significantly higher magnitude of vastus lateralis (p < 0.001) and vastus medialis (p < 0.001) muscle activity than males to achieve the same relative force level. These findings indicate athletic males and females have differences in their knee muscle control strategies. © 2008 Orthopaedic Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:800–808, 2008     

Muscle reflexes during gait elicited by electrical stimulation of the posterior cruciate ligament in humans.

We investigated the influence of electrical stimulation of the posterior cruciate ligament (PCL) on the motoneuron pool of the thigh and calf muscle during gait. The study group comprised eight young men without any history of injury to the knee joints. Multistranded teflon-insulated stainless steel wires were inserted into the PCL guided by sonography and in four subjects also into the fat pad of the knee. The PCL was electrically stimulated during gait on a treadmill at heel strike and 100 ms after heel strike. Electromyographic signals were recorded with bipolar surface electrodes placed over the vastus medialis, rectus femoris, vastus lateralis, biceps femoris caput longum, and semitendinosus muscles. The stimuli consisted of four pulses delivered at 200 Hz; the stimulus amplitude was two to three times the sensory threshold. The electrical stimulation of the PCL inhibited the ongoing muscle activity in both the quadriceps and the hamstrings. The latency of the inhibition ranged between 78 and 148 ms in the quadriceps, between 88 and 110 ms in the hamstrings and between 189 and 258 ms in m. gastrocnemius. Stimulation of the fat pad of the knee did not influence the thigh and calf muscle motoneuron pool as evidenced by electromyography. The response elicited from the stimulation of the PCL was not limited to a specific muscle group but depended on ongoing muscle contraction, which suggests that the mechanoreceptors in the PCL are involved in the control of all muscles acting on the knee joint during gait.     

Implantation technique of tumor and crutch prostheses]

Using anatomic specimens from 58 fixed femurs, we analyzed the point of insertion and junctional variations of the gluteus medius, minimus and vastus lateralis over the greater trochanter. On six specimens the physiological muscle cross-section Q was determined for the muscles inserting at the greater trochanter. The results showed that the gluteus medius and minimus, as well as the vastus lateralis generally insert at the lateral and ventral surfaces of the greater trochanter. In 59.6% of all cases these muscles form a joint tendon junction. In 21.1% the gluteus medius inserts autonomously and with 13.5% the gluteus minimus inserts independently. In 5.8% of all specimens all three muscles insert autonomously. The average physiological muscle cross-section of the gluteus medius and minimus added up to 37.83 cm2 and that of the vastus lateralis and the fibrously connected vastus intermedius came to 36.14 cm2. Accordingly the extensor muscles of the knee, together with the counteracting gluteus medius und minimus, form a muscle sling that puts a pressure load on the greater trochanter from the lateral cranial direction. An operating technique for the implantation of tumor prostheses using this muscle sling is introduced. Hereby the greater trochanter and inserted musculature remain intact and are placed hoodlike on the implanted tumor prosthesis. Postoperatively, the procedure results in good muscle function with early exercise tolerance.     

Anatomy of the junction of the vastus lateralis tendon and the patella

Forty-one knees from adult cadavera (twenty female and twenty-one male) were dissected to study the relationship between the longitudinal axis of the patella and the angles of insertion into it of the vastus lateralis and vastus lateralis obliquus muscles. The mean and variance in the angles of insertion of the vastus lateralis obliquus tendon were found to be significantly different between men and women (p less than 0.05 and p less than 0.01, respectively). Three distinct anatomical patterns in the insertion of the vastus lateralis obliquus muscle were delineated. The vastus lateralis muscle, particularly the vastus lateralis obliquus, creates an important lateral force-vector on the patella.     

Selective thigh muscle atrophy in trans-tibial amputees: an ultrasonographic study

In trans-tibial amputees, PTB (patellar tendon bearing) prostheses provide almost physiological mobility of the knee joint in the sagittal plane. Nevertheless, there are characteristic adaptations of the knee joint muscles. Myosonography is a suitable method for depicting muscle atrophy and hypertrophy due to muscle dysfunction. The present study was intended to assess anatomical alterations of thigh muscles in trans-tibial amputees wearing a PTB prothesis. Thicknesses and cross-sectional areas of the quadriceps femoris, sartorius, gracilis, semitendinosus and biceps femoris muscles were determined ultrasonographically on both limbs in 17 amputees with a PTB prothesis. The gait was analysed using an optoelectronical system, force plates and surface electromyography of the vastus lateralis and biceps femoris muscles. Quadriceps femoris and sartorius muscles of the amputated extremity exhibited significant atrophy compared with the contralateral limb (reduction of muscle thickness ranged between 11.7% and 30.4%), whereas the gracilis and hamstring muscles were not significantly affected. Even the quadriceps femoris muscle of the non-amputated limb showed a slight atrophy compared with a reference group. Increased echointensities were found predominantly in the quadriceps muscle on the amputated leg. During gait, electromyographical activity within the amputated limb was reduced in the vastus lateralis and increased in the biceps femoris muscle. Even long-term adaptation to PTB prostheses results in characteristic deviation from normal gait. Atrophy occurs in the ventral thigh muscles, predominantly on the amputated leg, whereas the dorsal thigh muscles are hardly affected, probably due to compensatory hyperactivity. Received: 14 March 2000     

Electromyographic analysis of a modified maneuver for quadriceps femoris muscle setting with co-contraction of the hamstrings.

A "quadriceps femoris muscle setting" is isometric quadriceps femoris exercise which can be widely used in early knee rehabilitation. However this exercise cannot obtain enough co-contraction of the hamstrings. Isolated quadriceps femoris contraction in knee extension imposes severe strain to anterior cruciate ligament. We succeeded in developing a simple training maneuver that is effective in obtaining co-contraction of the hamstrings--a modified maneuver for the quadriceps femoris muscle setting with the contralateral lower limb raised (MQS). In this study, we analyzed the effect of this maneuver by EMG quantification. Twenty-eight healthy young adult men performed sequential trials consisting of normal quadriceps femoris muscle setting (NQS) and MQS. Electromyographic activity was recorded from surface electrodes on the gluteus maximus, vastus medialis, rectus femoris, vastus lateralis, semitendinosus and biceps femoris (long head), and normalized to values derived from maximal isometric trials. The % maximal voluntary isometric contraction (%MVIC) of the vastus medialis, vastus lateralis and rectus femoris did not vary in the each maneuver. However, the %MVIC of the hamstrings varied significantly in the MQS. This study suggests that effective co-contraction of the hamstrings can be obtained in MQS by adjusting the load to the raised lower limb.     

内侧腘绳肌延长术对双侧痉挛性脑瘫下肢肌肉长度的影响

目的 观察内侧胭绳肌延长术对双测痉挛性脑瘫下肢肌肉长度的影响.方法 将双测痉挛性脑瘫患者分为两组,一组为髂腰肌组5例(10侧肢体),即内侧胭绳肌延长,股直肌远端转位加髂腰肌延长术.另一组为非髂腰肌组5例(10侧肢体),即内侧胭绳肌延长,股直肌远端转位术.利用计算机模拟骨肌肉步态模型技术,选择性计算术后下肢相关肌肉的肌肉长度,并对比分析.结果 髂腰肌组中患者的股二头肌长头肌肉长度,在步态周期中的平均值、最小值和总长度分别为0.5000±0.0080、0.4800±0.0059、50.8600±0.8084,明显长于非髂腰肌组患者(P＜0.05).股二头肌短头肌肉长度最小值在步态周期中所出现的时间(81.6700±4.3221)%GC,较非髂腰肌组患者(75.1300±1.8851)%GC明显延迟(P＜0.01),半腱肌和半膜肌肌肉长度最小值在步态周期中出现的时间分别为(72.6700±3.0768)%Gc和(73.0000±3.6332)%GC,较非髂腰肌组出现的时间(68.500±1.5119)%Gc和(68.1300±1.5526)%Gc明显延迟(P＜0.05).结论 屈髋肌挛缩组患者在施行内侧胭绳肌延长、股直肌远端转位和髂腰肌延长术后,出现胭绳肌功能不全模型的原因,是由于外侧腘肌肌肉长度较长和内侧腘绳肌肌肉长度相对较长.     

Variations in medial‐lateral hamstring force and force ratio influence tibiofemoral kinematics

A change in hamstring strength and activation is typically seen after injuries or invasive surgeries such as anterior cruciate reconstruction or total knee replacement. While many studies have investigated the influence of isometric increases in hamstring load on knee joint kinematics, few have quantified the change in kinematics due to a variation in medial to lateral hamstring force ratio. This study examined the changes in knee joint kinematics on eight cadaveric knees during an open‐chain deep knee bend for six different loading configurations: five loaded hamstring configurations that varied the ratio of a total load of 175 N between the semimembranosus and biceps femoris and one with no loads on the hamstring. The anterior–posterior translation of the medial and lateral femoral condyles’ lowest points along proximal‐distal axis of the tibia, the axial rotation of the tibia, and the quadriceps load were measured at each flexion angle. Unloading the hamstring shifted the medial and lateral lowest points posteriorly and increased tibial internal rotation. The influence of unloading hamstrings on quadriceps load was small in early flexion and increased with knee flexion. The loading configuration with the highest lateral hamstrings force resulted in the most posterior translation of the medial lowest point, most anterior translation of the lateral lowest point, and the highest tibial external rotation of the five loading configurations. As the medial hamstring force ratio increased, the medial lowest point shifted anteriorly, the lateral lowest point shifted posteriorly, and the tibia rotated more internally. The results of this study, demonstrate that variation in medial‐lateral hamstrings force and force ratio influence tibiofemoral transverse kinematics and quadriceps loads required to extend the knee. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1707–1715, 2016.     

The Direct Anterior Approach for Hip Revision: Accessing the Entire Femoral Diaphysis Without Endangering the Nerve Supply

Background

The direct anterior approach (DAA) to the hip has been criticized as an approach that is limited to primary arthroplasty only. Our study objective was to demonstrate, in a cadaveric setting, that an alternate extension of the DAA can be used to reach the femur at the posterior border of the lateral vastus muscle without endangering the nerve supply.

Chondropathia patellae and knee muscle control

The activity of knee-related muscles was registered via exercising on a bicycle ergometer by 17 patients with clinically diagnosed chondropathia patellae. M. quadriceps activity was shorter and the hamstring activity longer in the chondropathy group compared with a matched healthy control group. The changes in m. quadriceps occurred to an almost equal extent in lateral and medial sections. In five patients with unilateral complaints, the electromyographic changes were nevertheless noted on both sides. The study shows that chondropathia patellae involves a change in muscle control affecting not only the knee extensors but also the hamstrings. Through the changed innervation pattern the coactivation phase, i.e. the phase of simultaneous activation of knee flexors and extensors at the end of the extension phase, takes place at a higher angle of flexion. Physiotherapy should involve all knee-related muscles and should include not only isometric but also dynamic exercises.     

The Effects of Knee Joint Effusion on Quadriceps Electromyography During Jogging

To investigate and describe the influence of intra-articular effusion on knee joint kinematics and electromyographic (EMG) profiles during jogging. Thirteen individuals underwent a 20 cc 0.9% saline insufflation of the knee joint capsule and completed 8 jogging trials. Stance phase, sagittal plane knee joint kinematics and thigh muscular EMG profiles were compared pre- and post-insufflation utilizing a paired t-test ( = 0.05). Mild knee effusion caused a reduction in vastus medialis (p = 0.005) and lateralis (p = 0.006) EMG activity. The rectus femoris, biceps femoris and medial hamstring muscles did not exhibit changes due to this protocol. There were no changes in the sagittal plane knee joint kinematic pattern. Twenty cc effusion can cause quadriceps inhibition in the vastus medialis and the vastus lateralis in otherwise healthy individuals during jogging. This study provides baseline data for the effects of mild knee joint effusion on thigh musculature during jogging.

Key Points

• 20 cc of knee effusion can cause vastus medialis and lateralis inhibition as noted by decreases in EMG amplitude.
• This effusion does not appear to alter sagittal plane knee joint kinematics during jogging.
• This finding if different from previous work investigating knee joint kinematic changes during a less dynamic activity (gait) with 20 cc of effusion.

Key words: Electromyography (EMG), kinematics, jogging, muscle inhibition, knee     

A study of factors influencing muscle activity about the knee joint

Several factors influencing the myoelectric activity of muscles surrounding the knee joint were studied using fine-wire monopolar electrodes. The muscles studied included the vastus lateralis, vastus intermedius, rectus femoris, vastus medialis, gracilis, sartorius, biceps femoris, semimembranosus, semitendinosus, tensor fasciae latae, medial head of the gastrocnemius, and lateral head of the gastrocnemius. Muscle activity was measured in response to unidirectional loads tending to flex and extend the knee, and to combined loads of flexion-adduction, flexion-abduction, extension-adduction, and extension-abduction. Results indicate that the individual muscle responses are dependent upon the direction, magnitude, and combination of external moments, as well as on the flexion angle of the knee joint. Muscle response appeared to be influenced by certain intrinsic mechanical characteristics of the knee joint that tend to change the moment arms of the muscles as the knee moves. For example, the substantial changes in quadriceps myoelectric activity with knee flexion, with constant load applied, can be related to the movement of the tibial-femoral contact changing the lever arm of the quadriceps mechanism. This study indicates that the mechanics of the knee joint must be taken into consideration while attempting to interpret or predict the load response of muscles crossing the knee joint.     

A study of factors influencing muscle activity about the knee joint

Several factors influencing the myoelectric activity of muscles surrounding the knee joint were studied using fine-wire monopolar electrodes. The muscles studied included the vastus lateralis, vastus intermedius, rectus femoris, vastus medialis, gracilis, sartorius, biceps femoris, semimembranosus, semitendinosus, tensor fasciae latae, medial head of the gastrocnemius, and lateral head of the gastrocnemius. Muscle activity was measured in response to unidirectional loads tending to flex and extend the knee, and to combined loads of flexion-adduction, flexion-abduction, extension-adduction, and extension-abduction. Results indicate that the individual muscle responses are dependent upon the direction, magnitude, and combination of external moments, as well as on the flexion angle of the knee joint. Muscle response appeared to be influenced by certain intrinsic mechanical characteristics of the knee joint that tend to change the moment arms of the muscles as the knee moves. For example, the substantial changes in quadriceps myoelectric activity with knee flexion, with constant load applied, can be related to the movement of the tibial-femoral contact changing the lever arm of the quadriceps mechanism. This study indicates that the mechanics of the knee joint must be taken into consideration while attempting to interpret or predict the load response of muscles crossing the knee joint.     

Strength recovery and muscle activation of the knee extensor and flexor muscles after arthroscopic meniscectomy. A pilot study

Maximal isokinetic strength and electromyographic activity of the operated leg were measured preoperatively and one, two, three, and eight weeks postoperatively after a partial medial meniscectomy by arthroscopy in a group of ten patients. Strength deficits, measured with a Kin-Com dynamometer using a static preloading protocol, were found in comparison with a group of matched healthy subjects preoperatively and three and eight weeks postoperatively in the knee extensors. These deficits were related to previously unreported modifications in the shape of the moment-angle curves and a tendency to lower activation levels of the vastus medialis (VM) but not the vastus lateralis or rectus femoris muscles. No deficits were found in the knee flexors preoperatively or three and eight weeks postoperatively, but the medial hamstrings activation level was lower for movements at 30 degrees per second. During flexion movements, the percentage of coactivation of the antagonist VM was significantly greater than healthy values at 30 degrees and 180 degrees per second. These results clearly indicate that neuromuscular recovery is not complete when return to work is advocated three to four weeks postoperatively. Such findings suggest the need for a rehabilitation program to promote recovery of the knee muscles in workers with a physically demanding occupation.     

Reflex hamstring contraction latency in anterior cruciate ligament deficiency

Decreased dynamic stability of the knee joint associated with functional disability is a feature of anterior cruciate ligament deficiency (ACLD). The purposes of this study were to examine the between-limbs difference in reflex contraction latency of the hamstring muscles in patients with unilateral ACLD and to investigate its relationship with instability and function. Fifty patients with arthroscopically diagnosed unilateral ACLD were measured bilaterally for reflex hamstring contraction latency (RHCL), and 20 normal volunteers were similarly tested. The subjects were measured in a position of single-limb full weight-bearing with the knee flexed 30°. An anteriorly directed shear force was applied to the tibia, and surface electromyographs (EMGs) recorded the activity of the hamstrings in response to the applied force. The latency of contraction was defined as the time from initial tibial movement, identified by accelerometry, to the onset of increased hamstring EMG activity. Both legs were tested and a between-limbs difference was computed. A significant difference in RHCL wasfound between the limb with ACLD and the control limb. The mean RHCL of the limb with ACLD was nearly double that of the unaffected limb, for a significant mean between-limbs difference (p < 0.05). The mean between-limbs difference for the control subjects was not statistically significant. The conclusion is that patients with ACLD have an increased RHCL of the injured leg. As the RHCL is dependent on proprioceptive activity around the joint, it can be used as a measure of proprioceptive ability. The loss of the neurophysiological protective reflex involving the anterior cruciate ligament and hamstrings in patients with ACLD is likely to be a contributory factor in the decreased joint stability experienced by these patients.     

中药联合选择性股内侧肌电刺激治疗髌骨软化症的疗效观察

[目的]观察中药联合选择性股内侧肌电刺激治疗髌骨软化症(CMP)的疗效。[方法]选择90例CMP患者,随机分成三个治疗组进行治疗,每组各30例,分别为单纯中药治疗组(A组)、单纯选择性股内侧肌电刺激治疗组(B组)、中药联合选择性股内侧肌电刺激治疗组(C组)。随访9~12个月,测量膝关节轴位片适应角(CA)、外侧髌股角(LPA),对治疗后的疗效进行评价,并进行统计分析。[结果]三个治疗组治疗前后CA、LPA均有明显差异性(P0.05),且中药联合选择性股内侧肌电刺激治疗组(C组)治疗后的CA、LPA更优于单纯中药治疗组(A组)及单纯选择性股内侧肌电刺激治疗组(B组)治疗后的CA、LPA(P0.05),中药联合选择性股内侧肌电刺激治疗组(C组)治疗后的疗效优良率明显高于A组及B组的优良率(P0.05),而单纯中药治疗组(A组)与单纯选择性电刺激治疗组(B组)治疗后的CA、LPA、优良率无明显差异性(P0.05)。[结论]中药联合选择性股内侧肌电刺激治疗CMP的疗效优于单纯中药治疗及单纯选择性股内侧肌电刺激治疗CMP的疗效,它是一种更好的治疗CMP的方法。