Rare Variant of Vastus Medialis Detected in vivo by Ultrasound and Confirmed by High-resolution MRI

[Purpose] This report describes an unusual incidental finding during ultrasound investigation of the vastus medialis muscle. Volunteers underwent ultrasound scanning as part of an on-going investigation into the architecture of the vastus medialis muscle. [Subjects and Methods] The distal thighs of forty-one subjects were scanned using the Philips iU22 US system. An unusual muscle morphology was detected bilaterally in one subject, who then underwent a 3T Magnetic Resonance Imaging (MRI) scan in order to further investigate the muscle morphology. The subject in question was a 32 year-old female who suffers from recurrent bilateral patellar dislocations. [Results] The MRI scan confirmed the ultrasound findings, and indicated the presence of the vastus medialis in two layers, with the VML continuing deep, separate from the VMO. [Conclusion] Although this rare variant has been been reported in previous cadaveric studies, we believe this to be the first report in the literature of this morphology in vivo. The biomechanical implications of this muscle arrangement are unknown, but it may not be without significance that this individual suffers from recurrent patellar dislocations.Key words: Vastus medialis, Ultrasound, MRI     

Vastus Medialis Hoffmann Reflex Excitability Is Associated With Pain Level,Self-Reported Function,and Chronicity in Women With Patellofemoral Pain

Objective

To determine the association between the amplitude of vastus medialis (VM) Hoffmann reflex (H-reflex) and pain level, self-reported physical function, and chronicity of pain in women with patellofemoral pain (PFP).

Effects of Open and Closed Kinetic Chains of Sling Exercise Therapy on the Muscle Activity of the Vastus Medialis Oblique and Vastus Lateralis

[Purpose] The muscle strength of the quadriceps muscle is critical in patellofemoral pain syndrome. The quadriceps muscle supplies the power for dynamic patellar movement, and the vastus medialis oblique (VMO) and vastus lateralis (VL) enable the patella to stabilize during tracking. We followed the theories about open and closed kinetic chain exercises to design two exercises, sling open chain knee extension (SOCKE) exercise and sling closed chain knee extension (SCCKE) exercise. The purpose of our study was to research the changes in quadriceps muscle activity during both exercises. [Methods] Electromyographic analysis was used to explore the different effects of the two exercises. The MVC% was calculated for the VMO and VL during exercise for analysis. [Results] We found that the mean MVC% values of the VMO and VL during the SOCKE exercise were higher than those during the SCCKE exercise. The ratio of the VMO to VL was 1.0 ± 0.19 during the SOCKE exercise and 1.11 ± 0.15 during the SCCKE exercise. [Conclusions] The SOCKE exercise is targeted at quadriceps muscle training and has a recruitment effect on the VMO. The beneficial effect of the SOCKE exercise is better than that of the SCCKE exercise.Key words: Patellofemoral pain syndrome, Sling exercise therapy, Electromyography     

A comparison of the proximal and distal parts of the vastus medialis muscle

The vastus medialis muscle has two distinct parts with different fibre orientations and specific functions: the vastus medialis longus (VML) and the vastus medialis oblique/obliquus (VMO). A fascial plane dividing the two parts, and separate nerve branches supplying each muscle part have been reported. This study was designed to verify this. In 50 cadavers, the angular orientations of the VML and VMO fibres with the femoral axis were measured and found to be significantly different (t(49)=36.35; p<0.001). The VML and VMO were both shown to be innervated by femoral nerve branches. A fascial plane between the VML and VMO was demonstrated in one specimen only. In conclusion, the VML and VMO make up the vastus medialis muscle, a single muscle.     

Activities of the Vastus Lateralis and Vastus Medialis Oblique Muscles during Squats on Different Surfaces

[Purpose] The purpose of the present study was to examine the effects of squat exercises performed on different surfaces on the activity of the quadriceps femoris muscle in order to provide information on support surfaces for effective squat exercises. [Subjects and Method] Fourteen healthy subjects performed squat exercises for five seconds each on three different support surfaces: hard plates, foam, and rubber air discs. Their performance was measured using electromyography. As the subjects performed the squat exercises on each surface, data on the activity of the vastus medialis oblique and the vastus lateralis, and the vastus medials oblique/vastus lateralis ratio, were collected. [Results] The activity of the vastus medialis oblique and the vastus medialis oblique/vastus lateralis ratio were found to be statistically significantly higher on rubber air discs than when the squats were performed on hard plates or foam. [Conclusion] To activate the vastus medialis obilique, and to enhance the vastus medialis oblique/vastus lateralis ratio, unstable surfaces that are highly unstable should be selected.Key words: Support surfaces, Vastus medialis obilique, Vastus lateralis     

膝骨关节炎患者股内侧肌、股直肌和股外侧肌间的协调性

目的应用表面肌电图和等速肌力测定方法比较膝骨关节炎患者与正常人股内侧肌、股直肌和股外侧肌间的协调性改变。方法34例膝骨关节炎患者和34名膝关节健康者在膝关节屈曲10°、60°、100°等长伸膝和等速60°/s、180°/s伸膝运动测试模式下,进行股内侧肌(VM)、股直肌(RF)和股外侧肌(VL)的表面肌电图和股四头肌肌力的评测,包括肌肉激活启动顺序和VM/VL神经肌电比值。结果与正常人对比,膝骨关节炎患者在等速180°/s伸膝运动时VM相对于VL启动延迟（P＜0.05）;在膝屈10°等长伸膝运动时,VM/VL神经肌电比值降低（P＜0.05）。结论膝骨关节炎患者患侧股四头肌的协调性减退。     

Segmental H-reflex studies in upper and lower limbs of patients with radiculopathy

The H-reflex was recorded from the flexor carpi radialis, vastus medialis, and soleus muscles in patients with radiculopathy at C7, L4, and S1 roots. Reflex parameters were compared to normal standards and correlated with other electrophysiologic (eg, electromyography) and clinical evaluations, as well as magnetic resonance imaging scan reports. The H-reflex had significantly smaller peak-to-peak amplitude and longer latency. The stimulus threshold for eliciting the reflexes was substantially higher than normal standards, and the reflex was polyphasic in most patients. A strong correlation was recorded between the pathologic changes in reflex parameters and electrophysiologic and clinical findings of different segmental lesions. Magnetic resonance imaging reports showed moderate correlation with the H-reflex changes. A test of specificity showed that soleus and vastus medialis H-reflexes were 100% specific for lumbosacral segments; flexor carpi radialis was 90% specific for cervical spinal segments. These results indicate that flexor carpi radialis, vastus medialis, and soleus H-reflexes are useful and valid methods for testing C7, L4, and S1 radiculopathy.     

The effect of transcutaneous electrical stimulation on spinal motor neuron excitability in people without known neuromuscular diseases: the roles of stimulus intensity and location

BACKGROUND AND PURPOSE: The Hoffmann reflex (H-reflex) is widely acknowledged as an indirect indicator of spinal motor neuron excitability. The purpose of this study was to determine whether transcutaneous electrical stimulation (TES), applied over the dorsiflexors or plantar flexors of the ankle, would alter the soleus muscle's H-reflex. Attention was focused on the roles of stimulus intensity and location. SUBJECTS: Thirty-two volunteers without known neuromuscular diseases (17 women [53%]; mean years of age=27, SD=7.3, range=21-48) were studied. METHODS: Subjects were randomly assigned to 1 of 4 groups, and TES was administered for 15 minutes. Stimulation site and intensity varied according to group assignment. H-reflexes were recorded before and for 10 minutes after TES. RESULTS: H-reflex amplitudes increased following TES at sensory threshold, whereas H-reflex amplitudes did not change following TES at 1.5 times motor threshold. The site of stimulation did not influence the resulting H-reflexes. DISCUSSION AND CONCLUSION: Low-intensity TES increases H-reflex amplitudes (and presumably the excitability of spinal motor neurons to Ia afferent input) in subjects without known neuromuscular diseases. High-intensity TES had little influence on H-reflex amplitudes.     

The Effect of Self-Myofascial Release on the Pennation Angle of the Vastus Medialis Oblique and the Vastus Lateralis in Athletic Male Individuals: An Ultrasound Investigation

BackgroundMaintenance of patellar stability requires a balance between the vastus medialis oblique (VMO) and the vastus lateralis (VL). The imbalance between these muscles is thought to be implicated in the etiology of patellofemoral pain (PFP). Where there is hypertrophy of the VL in PFP patients, self-myofascial release (SMR) may be utilized for its management. However, there is no current evidence regarding SMR and its effects on VMO and VL architecture. The aim of this study, therefore, was to use ultrasound to gain further understanding of the effects of a program of SMR on the fiber angles of the VMO and VL.HypothesisThere will be a significant decrease in the pennation angles of the VMO and VL after seven weeks of SMR using a foam roller.Study DesignCohort StudyMethodsTwenty-five young, athletic, male participants were recruited to use a foam roller, along the full length of both anterior thighs, three times weekly, on three separate days, for seven weeks. Ultrasound was used to determine the initial and final VMO and VL pennation angles on both limbs. One eligible participant was chosen as an intra-rater control and did not partake in the SMR regimen.ResultsThere was a statistically significant (p < 0.001) decrease in the pennation angles of the VMO and VL after the SMR regime. Mean combined right and left VL angle change was -6.65° (-18% mean change) and the mean combined right and left VMO angle change was -7.65° (-11.5% mean change). A weak negative correlation was found between initial VMO fiber angle and the angle change (Rsquared = -0.21), as well as moderate negative correlation for the VL (Rsquared = -0.51).ConclusionA program of SMR on the anterior thighs of young, asymptomatic males resulted in changes to the fiber angles of both the VMO and VL. There was a significant decrease in pennation angle after seven weeks of SMR using a foam roller.     

Electromyographic activity of the quadriceps components during the final degrees of knee extension

An imbalance in the recruitment patterns of the quadriceps muscle has been implicated in patellofemoral knee pain; however ambiguity remains in the normal recruitment patterns of this muscle. We investigated the activity of the quadriceps muscle during the final degrees of knee extension, specifically in the medial and lateral components. Sixteen healthy subjects (age; 22.5 (± 3.4) years, body mass; 67.5 (± 12.1) kg and height; 173.9 (± 10.4) cm) participated.Torque and electromyographic (EMG) activity of the quadriceps muscle were measured during isokinetic and isometric knee extensions. Torque and EMG activity reduced in all component muscles during the final degrees of isokinetic extension, but this did not occur during isometric contractions at similar angles. Normalised activity of rectus femoris (RF) was greater than that of vastus lateralis (VL) and vastus medialis obliquus (VMO) during the final degrees of isokinetic knee extension at 30°/sec; there were no differences between any component muscles at the higher velocities. VMO:VL and vastus medialis longus (VML):VL ratios were unchanged during knee extensions, except that VML:VL ratio increased significantly during the final degrees of extension at 30°/sec. Future work should compare these results with people with anterior knee pain, and explore this further during activities of daily living.     

Effect of air-splint application on soleus muscle motoneuron reflex excitability in nondisabled subjects and subjects with cerebrovascular accidents.

We investigated the effect of air-splint pressure on soleus muscle motoneuron reflex excitability in 18 nondisabled subjects with no history of neurological disease and 8 subjects with cerebrovascular accidents (CVAs). Motoneuron reflex excitability was assessed by measuring the percentage of amplitude (peak-to-peak measurement) change in the Hoffman reflex (H-reflex). Pressure was applied for 5 minutes, after which the air-splint was deflated. Ten H-reflexes were recorded and averaged for each subject before pressure application to obtain a baseline value. H-reflexes were also recorded at set intervals during and after pressure application. Two-way analyses of variance for repeated measures were used to compare each group's pressure and postpressure measurements with the baseline value. Significant F tests were followed by post hoc t tests. Analyses of variance were used to compare the nondisabled subjects' H-reflex recordings with those obtained for the subjects with CVAs. The nondisabled subjects demonstrated reductions of 55% at 1 minute, 52% at 3 minutes, and 40% at the fifth minute of pressure application. The postpressure measurements showed increases in the reflex amplitude at 1 and 3 minutes postpressure; however, by the fifth minute, the amplitude was not different from the baseline value. The subjects with CVAs demonstrated reductions of 41% at 1 minute, 48% at 3 minutes, and 52% at 5 minutes of pressure application. None of the postpressure measurements, however, were statistically different from the baseline value. A statistically significant difference was demonstrated between the nondisabled subjects and the subjects with CVAs at the first minute of pressure release.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of massage on alpha motoneuron excitability.

The purpose of this study was to investigate the specificity of the effects of massage (petrissage) on spinal motoneuron excitability as measured by changes in the peak-to-peak amplitude of H-reflex recordings. H-reflexes (and M-responses) were recorded from the distal aspects of the right triceps surae muscle of 8 men and 8 women, aged 20 to 37 years, with no neuromuscular impairments of the lower extremities. The H-reflexes were recorded during five control and four experimental conditions (20 trials at each condition). The control conditions (C1-C5) preceded and followed each experimental condition, providing a measure of the stability of the H-reflex. Each experimental condition consisted of a 4-minute period of massage of the ipsilateral and contralateral triceps surae and hamstring muscle groups (ITS, CTS, IHS, and CHS, respectively). The mean peak-to-peak amplitude of the H-reflex was found to be stable (range = 1.91-1.95 mV) across the five control conditions. H-reflex amplitudes recorded during the experimental conditions indicate that massage of the ITS resulted in a reduction of the H-reflex (0.83 mV) in comparison with the pretest control condition (C1) and the remaining experimental conditions (range = 1.77-2.23 mV). This difference was significant, and subsequent Newman-Keuls tests indicated a specificity of the effects of massage on the muscle group being massaged. [Sullivan SJ, Williams LRT, Seaborne DE, Morelli M. Effects of massage on alpha motoneuron excitability.     

Methodological considerations contributing to variability of the quadriceps H-reflex

The clinical usefulness of the quadriceps H-reflex is limited because of the difficulty of elicitation and its inherent variability in amplitude. In the present study we attempted to identify the influence of methodological variables (head position and remote muscle contractions) on the amplitude of the H-reflex evoked in vastus medialis, vastus lateralis and rectus femoris from the right leg of 13 healthy adult subjects. Square wave stimuli (1-ms duration) were delivered percutaneously to the femoral nerve. The 50% maximal amplitude H-reflexes were evoked while the subject reclined with head facing to the right, left, up and down or while the subject performed Jendrassik's maneuver. The results show a significant increase in the reflex amplitude when the subject's head was turned to the right; there was either a mild increase or no change in amplitude of the response when the subjects faced to the left, up and down. The evoked potential tended to decrease when the subjects closed their eyes; however, the tendency to increase with neck position was not changed. Remote muscle contractions enhanced the amplitude of the response. These results present further evidence of the characteristics of the quadriceps H-reflex and identify postural influences as one controllable source of variability in the L3-L4 root electrodiagnostic test.     

Differences of quadriceps activity during inline lunge by using FMS assessment

[Purpose] This study assessed the exercise capacity of healthy adults while performing the inline lunge exercise by using Functional Movement Screen (FMS). Compared the difference in muscle activity of the quadriceps according to the exercise capacity. [Participants and Methods] Thirty two healthy participants (12 males, 20 females) participated in this study. The surface electromyography (sEMG) was used to measure the electrical activities for the vastus medialis (VM), rectus femoris (RF), vastus lateralis (VL) of quadriceps. [Results] Both groups had significant difference when sitting up and getting up during the inline lunge. In scores 3 group, vastus medialis showed higher muscle activity than vastus lateralis. On contrary, in scores 2 group, vastus lateralis had higher muscle activity than vastus medialis. [Conclusion] Therefore, this study suggests that inline lunge can help to strengthen the quadriceps effectively by showing the difference of quadriceps activity according to exercise capacity.Key words: Inline lunge, Muscle activity, Functional movement screen     

Effects of tendon pressure on alpha motoneuron excitability in patients with stroke

The purpose of this study was to evaluate the effects of two intensities (5 and 10 kg) of continuous and intermittent Achilles tendon pressure on the H-reflex in eight hemiparetic subjects. A decrease in the H-reflex was interpreted as a depression in motoneuron excitability, a condition conducive for reducing muscle tone. The H-reflex measurements were obtained before, during, immediately after, and 2.5 minutes after tendon pressure application. Piecewise linear regression equations were used to evaluate the effects of four pressure conditions. The mean of the midpoints of the lines for each pressure condition was compared with prepressure baseline values by t tests and with the other pressure conditions by an analysis of variance. All four pressure conditions demonstrated H-reflexes less than prepressure baseline values, with three of the four conditions (5 and 10 kg of intermittent pressure and 5 kg of continuous pressure) being significantly less than prepressure baseline values (p less than .05). The analysis of variance revealed a significant difference among pressure conditions. Scheffé post hoc contrast comparisons revealed significant differences between intermittent and continuous pressure but not between 5 and 10 kg of pressure. The results of this study indicate that in these hemiparetic subjects, the H-reflex was depressed during both continuous and intermittent tendon pressure. Intermittent pressure was more effective then continuous, but 10 kg of pressure had no greater effect than 5 kg of pressure. The effects of pressure lasted only as long as the stimulus was present.(ABSTRACT TRUNCATED AT 250 WORDS)     

Vastus medialis obliquus and vastus lateralis activity in open and closed kinetic chain exercises in patients with patellofemoral pain syndrome: an electromyographic study

OBJECTIVES: To evaluate the electromyographic activities of vastus medialis obliquus (VMO) and vastus lateralis (VL) muscles in open and closed kinetic chain exercises in subjects with patellofemoral pain syndrome (PFPS). DESIGN: Case-controlled study. SETTING: Rehabilitation science center in a tertiary medical center. PARTICIPANTS: Ten patients with bilateral knee pain diagnosed with PFPS and 10 healthy volunteers. INTERVENTIONS: Subjects performed open kinetic chain exercise on an isokinetic dynamometer and closed kinetic chain exercise by squat-to-stand and stand-to-squat tasks. Surface electromyography was done for the VMO and VL muscles. MAIN OUTCOME MEASURES: VMO/VL ratios were calculated after normalization of muscle activities. RESULTS: The VMO/VL ratios of PFPS subjects were significantly lower than were those of unimpaired subjects during knee isokinetic closed kinetic chain exercises (p = .047). However, there was no statistical difference in VMO/VL ratio between subjects with and without PFPS during closed kinetic chain exercises (p = .623). Maximum VMO/VL ratio was obtained at 60 degrees knee flexion in closed kinetic chain exercise. CONCLUSION: In closed kinetic chain exercises, more selective VMO activation can be obtained at 60 degrees knee flexion. Maximal VMO/VL ratio was observed at this knee flexion angle, and muscle contraction intensity was also greatest.     

A controlled study on the effects of transcutaneous electrical nerve stimulation and interferential therapy upon the RIII nociceptive and H-reflexes in humans

OBJECTIVE: To study the effect of transcutaneous electrical nerve stimulation (TENS) and interferential therapy (IFT) upon the RIII nociceptive reflex and H-reflex. DESIGN: Double-blind conditions. PARTICIPANTS: Seventy healthy subjects were randomly allocated to one of seven groups (n = 10 per group): Control, TENS 1 (5 Hz), TENS 2 (100 Hz), TENS 3 (200 Hz), IFT 1 (5 Hz), IFT 2 (100 Hz), IFT 3 (200 Hz). INTERVENTION: In the treatment groups, stimulation was applied over the right sural nerve for 15 minutes. MAIN OUTCOME MEASURES: Ipsilateral RIII and H-reflexes were recorded before treatment, immediately after treatment, and subsequently at 25, 35, and 45 minutes. Subjects rated the pain associated with the RIII reflex using a computerized visual analogue scale (VAS). RESULTS: Statistical analysis using ANOVA showed no significant differences between baseline and posttreatment measurement for RIII reflex, H-reflex, or VAS data. CONCLUSION: These results suggest that neither type of electrical stimulation (TENS or IFT) affects the RIII or H-reflexes, at least using the parameters and application time in this study.     

Topical anesthetics: effects on the Achilles tendon and H-reflexes. I. Able-bodied subjects

Achilles tendon reflexes (ATR) and H-reflexes were monitored to determine changes in motor responses after the application of a benzocaine spray or an air spray to normal individuals. There was no change in ATR after application of the spray or the benzocaine, even when the sequence of reflex elicitation was reversed. The only significant change (p less than 0.05) in the H-reflex was an increase in its amplitude from baseline at all posttest times following (1) the placebo application when the H-reflex preceded the ATR (0.264 +/- 0.054V, ten minutes; 0.290 +/- 0.054V, 20 minutes; and 0.322 +/- 0.058V, 30 minutes), and (2) the benzocaine spray when the ATR preceded the H-reflex (0.277 +/- 0.084V, ten minutes; 0.309 +/- 0.152V, 20 minutes; and 0.329 +/- 0.131V, 30 minutes). Within-group comparisons revealed that a significantly greater H-reflex (p less than 0.05) was obtained at 20 and 30 minutes after air spray when H-reflex/ATR test sequence was used, whereas at 30 minutes after application of the benzocaine spray a significantly greater H-reflex was seen using the ATR/H-reflex test sequence. Changes in H-reflex amplitude appear to be as much a function of the reflex testing sequence as whether an air or benzocaine spray is used.     

Segmental H-reflex studies in upper and lower limbs of healthy subjects

The H-reflex has been recorded from the flexor carpi radialis muscle in the upper limb and vastus medialis (quadriceps) muscle in the lower limb in relaxed healthy subjects. The characteristics of these reflexes have been compared with those of the soleus H-reflexes, recorded with the same technique, and similar behavior has been reported. The techniques and pitfalls of recording these segmental reflexes and their clinical and neurophysiologic significance are discussed in light of the relevant literature. These segmental reflexes will be useful in studying conduction and integrity of C7, L4, and S1 spinal segments.     

Arthrogenic muscle inhibition is not present in the limb contralateral to a simulated knee joint effusion

OBJECTIVE: The purpose of this investigation was to estimate bilateral neuromuscular activity in the vastus medialis on induction of a unilateral knee joint effusion. DESIGN: Eight subjects each were assigned to effusion or control groups. The effusion group had 60 ml of sterile saline injected into their superolateral knee joint capsules. The control group rested for 8 mins. Bilateral recruitment curves for the Hoffmann reflex (H-reflex) and muscle response (M-wave) were obtained before and 10, 20, and 30 mins after the effusion or rest. The maximum H-reflex (Hmax), maximum M-wave (Mmax), and the Hmax/Mmax ratio were utilized for data analysis. RESULTS: Both Hmax and Hmax/Mmax ratios decreased from the baseline measure in the effused vastus medialis, whereas no changes were detected on the contralateral side. Effused subjects demonstrated decreased motoneuron pool excitability in the effused limb, whereas control subjects did not differ from baseline. CONCLUSIONS: Knee joint effusion results in ipsilateral but not contralateral impairment of quadriceps function. Rehabilitation protocols after knee joint injury should focus on ipsilateral neuromuscular and mechanical alterations that occur as the result of joint damage.