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At least 1,207 records · Page 67Linked to original sources

PubMed2000

Innervation zones of the upper and lower limb muscles estimated by using multichannel surface EMG.

The distribution of innervation zones was investigated in 3 subjects for 17 muscles and 8 muscle groups in the upper and lower limb, by detecting bi-directional propagation of motor unit action potentials (MUAPs) with the multichannel surface electrode array. Clarification of the distribution of innervation zones depended on the ease in detecting the propagation of MUAPs and the actual scattering of innervation zones, which were closely related with muscle morphology with respect to the arrangements of muscle fibers. In muscles having fibers running parallel to each other, such as the biceps brachii, intrinsic hand muscles, vastus lateralis and medialis, tensor fasciae latae, peronei, soleus, tibialis anterior, and hypothenar muscles in the foot, it was relatively easy to detect the propagating MUAPs, and the innervation zones were distributed in a relatively narrow band around muscle belly. On the other hand, in muscles with a complicated structure including pinnation of muscle fibers, in-series muscle fibers and aponeurotic tissues, such as the deltoid, flexors and extensors in the forearm, rectus femoris, sartorius, hamstrings and gastrocnemius, it was more difficult to detect the propagating MUAPs and to identify the innervation zones, which were widely scattered or distributed in complex configurations. The distribution of the innervation zones clarified in the present study can be used to find the optimal location of electrodes in surface EMG recordings and of stimulus electrodes in the functional and therapeutic electrical stimulations. It may also be useful in motor point biopsy for diagnosis of neuromuscular diseases as well as in the botulinum toxin injection for the treatment of spasticity.

Action Potentials↗

PubMedDate not supplied

Arthroscopic reconstruction of the posterior cruciate ligament: a comparison of quadriceps tendon autograft and quadruple hamstring tendon graft.

PURPOSE: Considerable controversies remain on the graft choice and fixation methods in the posterior cruciate ligament (PCL) reconstruction. The purpose of this study was to compare, at minimal 2-year follow-up, the outcomes of PCL reconstruction between using quadriceps tendon autograft and using quadruple hamstring tendon autograft. TYPE OF STUDY: Case series. METHODS: All patients received only PCL reconstruction without combined severe associated posterolateral instability. From 1996 to 1998, there were 24 patients who had a quadriceps tendon autograft, and 30 patients with hamstring tendon autograft. Twenty-two of the quadriceps tendon group and 27 of the hamstring tendon autograft group with 2 more years of complete follow-up were included for final analyses. Clinical assessments consisted of Lysholm knee scores, International Knee Documentation Committee (IKDC) scores, thigh muscle girth and strength, and radiographic evaluation. RESULTS: On the Lysholm knee rating, 86% of patients showed good or excellent results in the quadriceps tendon group and so did 89% of patients in the hamstring tendon group. Fifty-nine percent of the quadriceps tendon group and 56% of the hamstring tendon group revealed a 3- to 5-mm ligament laxity. Two patients with quadriceps tendon grafts and 4 patients with hamstring tendon grafts revealed grade II laxity. The IKDC rating showed no significant difference between the 2 groups in terms of activity level, ligament laxity, and final rating. In the thigh girth side-to-side difference, 82% of the quadriceps tendon group and 78% of the hamstring tendon group had less than a 10-mm difference. CONCLUSIONS: Comparable satisfactory results between the 2 surgical groups were shown at a minimal 2 years follow-up. We suggested that both grafts could afford good ligament reconstruction likelihood and that they are reasonably acceptable graft choices for PCL reconstruction.

Adult↗

PubMed1996

Isokinetic muscle performance in healthy female handball players and players with a unilateral anterior cruciate ligament reconstruction.

A total of 114 healthy female European team handball players in the elite to second division with no previous ACL injury, and the uninjured legs of 22 females with a unilaterally reconstructed ACL (the injury sustained while playing handball; mean time from reconstruction 15 months) were examined with a Biodex isokinetic testing device. Five extensions and flexions at lower speed (60 degrees/s) and 15 repetitions at higher speed (240 degrees/s) were performed. Gravity-corrected peak torque values for flexion and extension were obtained, and hamstrings-to-quadriceps ratios (H/Q) were calculated at both speeds. Compared with the control group, the uninjured legs of the injury group showed 8% weaker quadriceps muscles and 14% higher H/Q ratios at higher speed. The other between-group comparisons were not significant. These differences could have been developed by strength reduction after the injury in the noninjured limb due-to-insufficient rehabilitation, by a weaker musculature in the patient group already initially, or by both mechanisms. If the second option is true, the finding may indicate that weak quadriceps musculature is one of the risk factors for anterior cruciate ligament injuries. The study establishes additional normative data on hamstrings and quadriceps torque on high-level female handball players.

Adolescent↗

PubMed2005

Decrease of knee flexion torque in patients with ACL reconstruction: combined analysis of the architecture and function of the knee flexor muscles.

A decrease of deep knee flexion torque after anterior cruciate ligament (ACL) reconstruction, using a semitendinosus (and gracilis) tendon, has been reported. However, the cause of this weakness remains controversial. Architectural and functional differences in the knee flexor muscles influence this weakness. the fiber length of the semitendinosus, gracilis, semimembranosus, and biceps femoris were directly measured in six human cadavers. The flexion torque and EMG of the hamstrings were measured in both limbs of 16 patients (23+/-5 years) after ACL reconstruction (12-43 months post-operation), using ipsilateral semitendinosus tendon. Magnetic resonance imagings were taken, over both the thighs of those patients, to measure muscle volume and to confirm a state of semitendinosus tendon regeneration. The position of the musculotendinous junction of the semitendinosus was also analyzed. The fiber length of the semitendinosus and gracilis were three to four times longer than that of the semimembranosus and biceps femoris. The difference of flexion torque between the normal and ACL reconstructed limbs significantly increased as the knee flexion angle increased. The EMG value for the semimembranosus and biceps femoris of both limbs as well as the semitendinosus of the ACL reconstructed limbs, significantly reduced as the knee flexion angle was increased. The volume of the semitendinosus in the reconstructed limb was significantly smaller than in normal limbs. The regeneration of the semitendinosus tendon was confirmed in all subjects, and the musculotendinous junction position of the reconstructed limb in almost all subjects was found in further image from the knee joint space than that for the normal limb. The decrease of deep knee flexion torque, after ACL reconstruction, could be due to the atrophy and shortening of the semitendinosus after its tendon has been harvested, as well as the lack of compensation from the semimembranosus and biceps femoris, due to the architectural differences between the semitendinosus and the semimembranosus and biceps femoris.

Achilles Tendon↗

PubMed1987

The functional roles of the hamstrings and quadriceps during cycling: Lombard's Paradox revisited.

The purposes of this study were to describe the functional roles of the hamstrings and quadriceps at the hip and knee during cycling as determined both by the standard kinetic (SK) classification method and by the Andrews kinematic (AK) classification method (Andrews, J. biomech Engng 107, 348-353, 1985), and to examine the effect of using these two different methods on the existence of paradoxical muscle behavior (Lombard's Paradox). The results of this study indicated that the functional roles determined by the SK and AK methods differed considerably, and these differences led to the existence of paradoxical behavior in the hamstrings and quadriceps at different regions of the crank cycle. Both classification methods led to the existence of considerable paradoxical muscle behavior, with the SK method predicting somewhat more non-paradoxical activity and somewhat less paradoxical activity than the AK method at both the hip and the knee.

Bicycling↗

PubMed1987

An interneuronal relay for group I and II muscle afferents in the midlumbar segments of the cat spinal cord.

1. The properties of interneurones located in the 4th lumbar segment of the cat spinal cord (L4 interneurones) have been investigated by intracellular and extracellular recording from individual neurones. The study focused on interneurones projecting to hind-limb motor nuclei and/or interposed in pathways from group II muscle afferents. The projection to motor nuclei was assessed from antidromic activation of the neurones by stimuli applied in the motor nuclei of the 7th lumbar (L7) segment. 2. Interneurones which projected to gastrocnemius-soleus or hamstring motor nuclei were found in laminae VI and VII and at the border between laminae VII and VIII. The dominant peripheral input to most of them was from group II muscle afferents, but they were also influenced by group I muscle afferents and by afferents in cutaneous, joint and interosseous nerves. Both excitatory post-synaptic potentials (e.p.s.p.s) and inhibitory post-synaptic potentials (i.p.s.p.s) were evoked from all of these fibre systems. 3. The same kind of multimodal input was also found in other interneurones in laminae VI and VII. However, their axonal projections were not identified and they might have included neurones projecting to motor nuclei (though outside the areas which were stimulated) as well as neurones with more local actions. 4. Interneurones located in laminae IV and V of the dorsal horn appeared to constitute a separate functional population since both their projections and their input differed from those of the more ventrally located interneurones; none of the dorsal horn interneurones were found to project to motor nuclei and none had input from group I afferents, although they were influenced by group II muscle afferents and by afferents in cutaneous, joint and interosseous nerves. 5. Many of the excitatory actions from group I and II afferents upon L4 interneurones were found to be evoked monosynaptically. A high proportion of L4 neurones synapsing upon motoneurones would thus be interposed in disynaptic reflex pathways from these afferents. In comparison to actions evoked via interneurones of the caudal lumbar segments, any post-synaptic potentials (p.s.p.s) evoked via L4 interneurones would be delayed. These delays would amount to 0.4-0.9 ms for p.s.p.s. from group I afferents and by 0.5-2.5 ms for group II p.s.p.s. 6. In many interneurones, particularly those located ventrally, i.p.s.p.s. were evoked by group I and II muscle afferents at latencies which indicated that they were evoked disynaptically. They may therefore reflect inhibitory interactions between subpopulations of L4 interneurones.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗

PubMed2005

Motor determinants of gait in 100 ambulatory patients with multiple sclerosis.

A prospective analysis of gait and strength parameters was performed in 100 patients diagnosed with MS and pyramidal involvement admitted in a rehabilitation unit The patients were divided into two groups based on their ability to walk in daily life (nonassisted or cane-assisted gait) and into four clinical subgroups depending on associated involvements such as sensory loss or cerebellar ataxia. Twenty healthy subjects were studied as a control group. Gait parameters were evaluated with a Locometre and muscle strength with an isokinetic dynamometer. The results showed that the average velocity and strength of the hamstring and quadriceps were strongly correlated and reduced in the MS group in comparison with the control, and in the cane-assisted group compared with the nonassisted group. Gait velocity tended to be more correlated to hamstring strength in the nonassisted group with a determination coefficient (r2) reaching a value of 0.44 in the sensory subgroup. These findings provide evidence that a correlation between strength reduction and gait impairment is obvious whatever the clinical form in patients with MS. This correlation is higher with hamstrings but may change depending on the disability level and the clinical form. This could be taken into account in the individual assessment of further rehabilitation programmes.

Activities of Daily Living↗

PubMed1996

[Selective peripheral neurotomy of the hamstring branches of the sciatic nerve in the treatment of spastic flexion of the knee. Apropos of a series of 11 patients].

BACKGROUND: A series of 11 patients (9 adults and 2 children) were operated on by selective peripheral neurotomy for spastic knee in flexion. The objective of surgery was to restore bipodal stance and therefore walking for the adult patients and to improve walking for the diplegic children. METHODS: Spasticity was secondary to stroke or cranial trauma for the adult patients. The two children presented with Little disease. The delay between onset and surgery was on the average of 2 years. All the patients had a passive flexum of the knee of 20 degrees, and an excessive spasticity of the hamstrings (average Held score of 4.55). Peripheral selective neurotomies consist of a partial section of the spastic muscle's motor fascicles. The partial section concerns the afferent fibers to the spinal cord whose interruption leads to the disappearance of spasticity. The section also involves the motoneurones' axons and thus leads to partial denervation. RESULTS: The spasticity of the treated muscles disappeared in the 11 patients. Average follow-up was 16 months. The neurotomies led to improvement of walking without splint for 3 walking patients, and restored walking with a splint for 5 patients. One patient failed to walk. The two children had a dramatic improvement of their walk. CONCLUSION: Our results incite us to increasingly indicate this type of neurotomy in the treatment of the spastic lower limb.

Adolescent↗

PubMed1998

Overgrowth of the ischial tuberosity complicating femoral bone and muscle atrophy: implications for a delayed complication of malunited apophyseal avulsion fracture.

Delayed complications occurring several years after the fused avulsion of ischial tuberosity have rarely been reported. We present a patient with overgrowth of the ischial tuberosity who complained of knee pain associated with significant bone and muscle atrophy in the thigh, which occurred 10 years after the ischial injury. Reinforcement exercise of the hamstrings relieved the knee pain. Here, we emphasize that avulsion fractures of the ischial tuberosity can cause persistent disability and that patients with avulsion fracture of the ischial apophysis in the adolescent period should actively maintain the strength of the hamstrings, even after more than 1 decade.

Adult↗

PubMed2001

Single- versus bi-socket anterior cruciate ligament reconstruction using autogenous multiple-stranded hamstring tendons with endoButton femoral fixation: A prospective study.

PURPOSE: This prospective study was conducted to compare the single-socket and the bi-socket anterior cruciate ligament (ACL) reconstruction techniques in terms of outcome. TYPE OF STUDY: Nonrandomized control trial. METHODS: There were 160 consecutive patients with unilateral chronic ACL insufficiency who underwent endoscopic single- or bi-socket ACL reconstruction alternately using multiple-stranded medial hamstring tendon and EndoButton (Smith & Nephew, Andover, MD) femoral fixation. All patients underwent the same postoperative rehabilitation protocol. Of them, 106 patients (57 single, 49 bi) were available for 2-year follow-up. RESULTS: According to the IKDC Knee Ligament Evaluation Form, 23 patients (40%) of the single-socket group were subjectively graded as normal, 30 (53%) as nearly normal, and 4 (7%) as abnormal. Twenty-six patients (53%) of the bi-socket group were graded as normal, 21 (43%) as nearly normal, and 2 (4%) as abnormal (P =.19). The mean side-to-side anterior laxity difference (KT-1000 manual maximum force) was 0.9 +/- 1.8 mm for the single-socket group and 0.7 +/- 1.2 mm for the bi-socket group (P =.44). Fifty-three of 57 patients (93%) in the single-socket group and all patients in the bi-socket group showed anterior laxity differences of +/-3 mm or less (P =.12). There were no differences in thigh muscle strength between the groups. CONCLUSIONS: Both single- and bi-socket ACL reconstruction using autogenous multiple-stranded hamstring tendons with EndoButton fixation provided satisfactory anterior stability, and there were no statistically significant differences in subjective results or measured restored stability between the 2 groups.

Adolescent↗

PubMed1999

Patterned electromyographic activity in the sit-to-stand movement.

OBJECTIVES: Postural activity is an essential part of any voluntary movement. In movements involving all body parts such as in the sit-to-stand maneuver (STS), postural activity becomes intermingled with the activity required to perform the actual movement, and is usually difficult to recognize. METHODS: In this paper, we have analyzed the electromyographic activity of muscles of the leg, thigh, trunk and neck in 20 healthy volunteers who performed the STS maneuver. In order to identify the postural and the executional EMG activity, subjects were requested to perform the movement according to 6 predefined experimental conditions. Our hypothesis was that changing the conditions or the strategies of the movement would modify the postural activity, without significantly altering the EMG pattern required for performing the movement itself. RESULTS: Tibialis anterior (TA), abdominal (ABD) and sternocleidomastoid (SCM) were the muscles activated first in the most natural condition for the movement (reference), but their activity and that of the trapezius (TRA) was suppressed or greatly diminished in other conditions. Conversely, lumbar paraspinal (LPS), quadriceps (QUA), and hamstrings (HMS) were activated in a patterned sequence that was invariable in all conditions, and time locked to the moment of take-off from the seat. The soleus (SOL) was the last muscle activated and, together with QUA and HMS, remained active during standing. CONCLUSIONS: We conclude that TA, SOL, ABD, SCM and TRA are involved in preparatory and accompanying postural movements, while LPS, QUA, and HMS are activated in a consistent patterned sequence and can be considered the executional muscles for the STS movement. Recognition of the role of each muscle in the STS movement can contribute to a better understanding of the movement deficits of certain patients, and help to devise adaptive motor strategies in neurorehabilitation.

Adult↗

PubMed1996

A comparison of isokinetics and muscle strength ratios following intra-articular and extra-articular reconstructions of the anterior cruciate ligament.

A prospective, randomized clinical trial was conducted to compare an intra-articular with an extra-articular reconstruction of the anterior cruciate ligament. Isokinetic muscle testing was carried out 6 months to 2 years following operation using the Biodex isokinetic dynamometer. The extra-articular procedure resulted in a lower deficit for the peak quadriceps and hamstring torques and the range of motion.

Adult↗

PubMed2006

Randomized prospective study of ACL reconstruction with interference screw fixation in patellar tendon autografts versus femoral metal plate suspension and tibial post fixation in hamstring tendon autografts: 5-year clinical and radiological follow-up results.

Patellar tendon graft has been the most frequently used material in anterior cruciate ligament (ACL) reconstruction, but the hamstring tendons have been increasingly used as well; however, which graft is to be preferred is not adequately supported by existing clinical studies. In this prospective randomized clinical trial, the study hypothesis was that the hamstring tendons are equally good graft material as the patellar tendon in ACL reconstruction. Ninety-nine patients with laxity due to a torn ACL underwent arthroscopically assisted reconstruction with graft randomization according to their birth year to either patellar tendon with metal interference screw fixation or double looped semitendinosus and gracilis tendons with fixation similar to the Endobutton technique using a titanium metal plate suspension proximally and screw-washer postdistally. Excluding preoperative Lysholm knee score, there were no significant differences between the two groups in the preoperative and operative data. A standard rehabilitation regimen was used for all the patients, including immediate postoperative mobilization without a knee brace, protected weight bearing for 2 weeks, and return to full activity at 6-12 months postoperatively. Forty patients in the patellar tendon group and 39 patients in the hamstring tendon group were available for clinical evaluation at median 5 years after surgery (ranges 3 years 11 months-6 years 7 months). The results revealed no statistically significant differences with respect to clinical and instrumented laxity testing, isokinetic muscle torque measurements, International Knee Documentation Committee ratings, Lysholm (knee score), Tegner (activity level) and Kujala patellofemoral knee scores. There was an enlargement of the drill tunnels, statistically more in the hamstring tendon group, but no increase from 2 to 5 years in either group. Narrowing of the joint spaces (IKDC measurement method) from 2 to 5 years postoperatively was seen in both the groups, however, without difference between the two groups.

Anterior Cruciate Ligament↗

PubMed1998

Isokinetic muscle strength after anterior cruciate ligament reconstruction.

The purpose of the present study was to investigate the isokinetic muscle strength 6 months after reconstruction of the anterior cruciate ligament (ACL). In order to recommend full-load come-back in sport, sufficient muscle strength may be important. Ninety female elite team handball players (mean 24.1 years) were postoperatively tested with Biodex. The operated limb was compared with the contralateral limb: 82.2% had a hamstring strength of a minimum of 49.6 Nm, corresponding to at least 90% of the non-operated limb, while only 12.2% fulfilled the recommended strength of 117.7 Nm for quadriceps femoris. Patients over 26 years showed significantly lower muscle strength in the operated limb than their younger counterparts. Increased focus on quadriceps femoris muscle strength during rehabilitation may improve the knee function faster after ACL reconstruction.

Acceleration↗

PubMed1995

Cycle-to-cycle control of swing phase of paraplegic gait induced by surface electrical stimulation.

Parameterised swing phase of gait in paraplegics was obtained using surface electrical stimulation of the hip flexors, hamstrings and quadriceps; the hip flexors were stimulated to obtain a desired hip angle range, the hamstrings to provide foot clearance in the forward swing, and the quadriceps to acquire knee extension at the end of the swing phase. We report on two main aspects; optimisation of the initial stimulation parameters, and parameter adaptation (control). The initial stimulation patterns were experimentally optimised in two paraplegic subjects using a controlled stand device, resulting in an initial satisfactory swinging motion in both subjects. Intersubject differences appeared in the mechanical output (torque joint) per muscle group. During a prolonged open-loop controlled trial with the optimised but unregulated stimulation onsets and burst duration for the three muscle groups, the hip angle range per cycle initially increased above the desired value and subsequently decreased below it. The mechanical performance of the hamstrings and quadriceps remained relatively unaffected. A cycle-to-cycle controller was then designed, operating on the basis of the hip angle ranges obtained in previous swings. This controller successfully adapted the burst duration of the hip flexors to maintain the desired hip angle range.

Electric Stimulation↗

PubMed1993

Effects of a quantitative progressive rehabilitation program applied unilaterally to the osteoarthritic knee.

Decreases in muscular strength, endurance, and angular velocity have previously been demonstrated in the elderly. Osteoarthritis (OA), especially of the knee, may cause further reductions in these parameters and lead to functional limitations. This study measured the effects of a quantitative progressive exercise muscle rehabilitation program (QPE) that was added to a physical therapy (PT) program. Forty subjects (20 men and 20 women) with OA of the knees were randomly selected from a group of volunteers (N = 437) for the 3-month program. Measurements of strength, endurance, angular velocity, and the Jette Functional Status Index were determined before and after 1, 2, and 3 months of the program. The QPE program was composed of isometric, isotonic, isotonic with resistance, endurance, and speed contractions prescribed in a progressive sequence. Muscle strength (14% and 29%) and endurance (38% and 43%) increased significantly (p < 0.05, ANOVA for repeated measures) for both the quadriceps and hamstrings, respectively, after rehabilitation. There were marked decreases in walking time and the difficulty and pain experienced during functional activities.

Activities of Daily Living↗

PubMed2005

Gender differences in leg stiffness and stiffness recruitment strategy during two-legged hopping.

The authors compared leg stiffness (K(VERT)), muscle activation, and joint movement patterns between 11 men and 10 women during hopping. Physically active and healthy men and women performed continuous 2-legged hopping at their preferred rate and at 3.0 Hz. Compared with men, women demonstrated decreased K(VERT); however, after the authors normalized for body mass, gender differences in K(VERT) were eliminated. In comparison with men, women also demonstrated increased quadriceps and soleus activity, as well as greater quadriceps-to-hamstrings coactivation ratios. There were no significant gender differences for joint movement patterns (p>.05). The relationship between the observed gender differences in muscle recruitment and the increased risk of anterior cruciate ligament injury in women requires further study.

Adult↗

PubMed2005

Knee stabilization in patients with medial compartment knee osteoarthritis.

OBJECTIVE: Individuals with medial knee osteoarthritis (OA) experience knee laxity and instability. Strategies aimed at muscle stabilization may influence the long-term integrity of the joint. This study sought to determine how individuals with medial knee OA respond to a rapid valgus knee movement, to investigate the relationship between muscle-stabilization strategies and knee instability. METHODS: Twenty-one subjects with medial knee OA and genu varum and 19 control subjects were tested. Subjects stood with the test limb on a movable platform, comprising a plate that translated laterally to rapidly stress the knee's medial periarticular structures and create a potentially destabilizing sensation at the knee joint. Knee motion and muscle responses were recorded. Subjects rated the condition of their knee with a self-report questionnaire about knee instability during daily activities. RESULTS: Prior to plate movement, the OA subjects demonstrated more medial muscle co-contraction than did controls (P = 0.014). Following plate movement, the OA subjects shifted less weight off the test limb (P = 0.013) and had greater medial co-contraction (P = 0.037). OA subjects without knee instability had higher co-contraction of the vastus medialis medial hamstrings than did those who reported having instability that affected their daily activities (P = 0.038). More knee stability correlated positively with higher co-contraction of the vastus medialis medial hamstrings prior to plate movement (r = 0.459, P = 0.042). CONCLUSION: Individuals with medial knee OA attempt to stabilize the knee with greater co-contraction of the medial muscle in response to laxity that appears on the medial side of the joint only. This strategy presumably contributes to higher joint compression and could exacerbate joint destruction, and therefore needs to be altered to slow or stop the progression of the OA disease process.

Compartment Syndromes↗