Left Rectus Femoris Research Articles

Vibration-Induced Motor Responses of Infants With and Without Myelomeningocele

The severity of myelomeningocele (MMC) stems both from a loss of neurons due to neural tube defect and a loss of function in viable neurons due to reduced movement experience during the first year after birth. In young infants with MMC, the challenge is to reinforce excitability and voluntary control of all available neurons. Muscle vibration paired with voluntary movement may increase motoneuron excitability and contribute to improvements in neural organization, responsiveness, and control. This study examined whether infants with or without MMC respond to vibration by altering their step or stance behavior when supported upright on a treadmill. This was a cross-sectional study. Twenty-four 2- to 10-month-old infants, 12 with typical development (TD) and 12 with MMC (lumbar and sacral lesions), were tested. Infants were supported upright with their feet in contact with a stationary or moving treadmill during 30-second trials. Rhythmic alternating vibrations were applied to the right and left rectus femoris muscles, the lateral gastrocnemius muscle, or the sole of the foot. Two cameras and behavior coding were used to determine step count, step type, and motor response to vibration onset. Step count decreased and swing duration increased in infants with TD during vibration of the sole of the foot on a moving treadmill (FT-M trials). Across all groups the percentage of single steps increased during vibration of the lateral gastrocnemius muscle on a moving treadmill. Infants with MMC and younger infants with TD responded to onset of vibration with leg straightening during rectus femoris muscle stimulation and by stepping during FT-M trials more often than older infants with TD. Vibration seems a viable option for increasing motor responsiveness in infants with MMC. Follow-up studies are needed to identify optimal methods of administering vibration to maximize step and stance behavior in infants.

Difference of Lumbar ＆ Lower Extremity Muscle Activity when Patients are Transferred by Physical Therapists

Objective: The purpose of this study is to compare the muscle activities of lumbar and lower extremity muscles between left and right sides using EMG(Electromyogram) when patients are transferred by physical therapists. Background: Asymmetrical lift was recognized as a major cause of musculoskeletal disorder. Several studies show that physical therapists’ transferring patients needs caution as it could cause a lumbar pain to patients but there is not sufficient data to support. Method: Forty healthy rehabilitation hospital physical therapists joined for this study. The subjects were transferred from wheelchair to treatment mat(from left to right) by connecting the EMG device to the patients’ body both on erector spine and rectus fermoris. At the moment when subjects were being transferred, the EMG device collected data from both erector spine and rectus femoris and it was normalized as %MVC. Then the EMG data was statistically analyzed using paired t-tests. Results: The EMG data show that the left erector spinae and rectus femoris are more activated than right erector spinae and rectus femoris in all position(p＜.05) in a significant degree. Conclusion: The result implies that physical therapists’ asymmetrical lifting when patients are transferred by them has a potential cause of musculoskeletal disorder of patients. Further studies will be conducted to find out a same tendency in other muscles of a body and to see if there are other factors to affect to patients during asymmetrical lifting. Application: These results can be used to provide baseline information for more understanding to asymmetrical lift loading.

한센노인의 체간운동이 슬관절 굽힘·폄 동작의 최대수축 시 근피로도에 미치는 영향

This study was to investigate the change of muscle fatigue through maximum contraction during flexion and extension of knee joint before and after the isometric trunk exercise was implemented on elderly Hansen`s disease. 18 subjects exercised for 60 minutes twice a week for 12 weeks. The subjects were divided into normal sensory group, group with sensory loss in left sole, group with sensory loss in right sole, and group with sensory loss in both soles, according to the sensory condition on their soles. We obtained following results. Muscle fatigue in normal sensory group, there were significant differences in left right hamstring, left rectus femoris(p

The defence technique in Tai Chi Push Hands: A case study

Developed from traditional Chinese martial arts, Tai Chi exercise includes different forms and interactive Push Hands but biomechanical analyses have focused on the former only. To analyse the techniques of Push Hands, an experienced master was asked to defend pushing by four opponents. Movements were videotaped and digitized using a motion analysis system. Surface electrodes were used to record the electromyographic activity of ten muscle groups. Two force plates were used to measure the ground reaction force on each foot. Inexperienced individuals performed the same procedure to serve as the control group. The results indicate that the master adopted a postural adjustment to maintain balance. A clear shift of body weight from the front to the rear foot and mediolateral displacement of the centre of gravity was observed. Low electromyographic activity was observed in the upper body muscle groups, while high electromyographic activity was observed in the right rectus femoris and very high activity in the left rectus femoris during the defence. All inexperienced participants lost their balance in resisting pushing. It is concluded that the Tai Chi defensive technique includes a subtle postural adjustment that slightly changes the pushing force direction, and allows the rear leg to resist the incoming force.

Increased EMG response following electromyographic biofeedback treatment of rectus femoris muscle after spinal cord injury

Objective To study increases in electromyographic (EMG) response from the right and left rectus femoris muscles of individuals with long-term cervical spinal cord injuries after EMG biofeedback treatment. Design Repeated measure trials compared EMG responses before and after biofeedback treatment in patients with spinal cord injuries. Main outcome measures The Neuroeducator was used to analyse and provide feedback of the EMG signal and to measure EMG response. Setting Department of Traumatic Orthopaedics, School of Medicine, University of São Paulo, Brazil. Participants Twenty subjects (three men and 17 women), between 21 and 49 years of age, with incomplete spinal cord injury at level C6 or higher (range C2 to C6). Of these subjects, 10 received their spinal cord injuries from motor vehicle accidents, one from a gunshot, five from diving, three from falls and one from spinal disc herniation. Results Significant differences were found in the EMG response of the right rectus femoris muscle between pre-initial (T1), post-initial (T2) and additional (T3) biofeedback treatment with the subjects in a sitting position [mean (standard deviation) T1: 26 μV (29); T2: 67 μV (50); T3: 77 μV (62)]. The mean differences and 95% confidence intervals for these comparisons were as follows: T1 to T2, −40.7 (−53.1 to −29.4); T2 to T3, −9.6 (−26.1 to 2.3). Similar differences were found for the left leg in a sitting position and for both legs in the sit-to-stand condition. Conclusions The EMG responses obtained in this study showed that treatment involving EMG biofeedback significantly increased voluntary EMG responses from right and left rectus femoris muscles in individuals with spinal cord injuries.

Distant muscular (rectus femoris) metastasis from laryngeal squamous cell carcinoma

We report an extremely rare case of distant metastasis to the rectus femoris muscle from a laryngeal squamous cell carcinoma. We present a case report and a review of the world literature concerning distant skeletal muscle metastasis from head and neck squamous cell carcinoma. The patient showed no evidence of distant muscular recurrence at follow up after 21 months; however, two years later he died from brain and suprarenal metastases. This report describes the first case of haematogenous distant metastasis to the left rectus femoris muscle from a laryngeal squamous cell carcinoma, without evidence of cervical lymph node metastases. To the best of our knowledge, this is the second reported case of muscular distant metastasis without cervical lymph node involvement. Although the prognosis associated with skeletal muscle metastasis is considered to be poor, surgical excision may be indicated for an isolated muscular metastasis.

The effect of icepack cooling on skin and muscle temperature at rest and after exercise

Objective. To compare cooling of skin, subcutaneous fat and muscle, produced by an icepack, at rest and after short-duration exhaustive exercise. Methods. Eight male subjects were studied. With the subject supine, hypodermic needle-tip thermistors were inserted into the subcutaneous fat and the mid-portion of the left rectus femoris, to a depth of 1 cm plus the adipose thickness at the site, and a temperature probe was placed on the skin overlying the needle tips. A pack of crushed ice was applied for 15 minutes and temperatures were recorded before, during, and for 45 minutes after icepack application. Thereafter, subjects underwent a ramped, treadmill, VO2max test, an icepack was applied after temperature probes were inserted into the right leg and measurements were made as before. Results. After the treadmill run, skin (Sk), subcutaneous (SC) and muscle (Ms) temperatures (mean ± standard deviation (SD)) were 0.9 ± 1.3, 1.0 ± 0.7 and 1.3 ± 0.8°C higher than at rest. After 15 minutes of icepack cooling, temperatures fell in the exercised limb by 22.7 ± 1.5°C (Sk), 13.5 ± 4.2°C (SC) and 9.3 ± 5.5°C (Ms) and in the control limb by 20.7 ± 2.9°C (Sk), 11.4 ± 2.0°C (SC) and 8.7 ± 2.6°C (Ms). The reductions in temperature were significant in both the control and exercised limbs. Forty-five minutes after icepack cooling, muscle temperature was still approximately 5°C lower in both the rested and exercised muscle (p < 0.001). Individual variations in response to cooling were noted. Conclusions. Cooling of superficial muscle occurs after high-intensity exercise. The degree of cooling is not uniform. This may be due to differences in the sympathetic response to cooling, influencing haemodynamic and thermoregulatory changes after exercise. This needs further investigation. South African Journal of Sports Medicine Vol. 18 (3) 2006: pp. 60-66

Locomotor Training with Incremental Changes in Velocity: Muscle and Metabolic Responses

Objective: The purpose of this study was to simultaneously measure metabolic function and EMG activation of the lower legs during incremental changes in treadmill velocity during one session of locomotor training using body weight support (BWS). Method: All of the 8 participants with a spinal cord injury (SCI; 5 individuals with tetraplegia and 3 individuals with paraplegia) were 100% wheelchair reliant. The initial treadmill velocity was 1.0 mph (0.447 m/s); after every 15 strides, the treadmill velocity was increased by 0.1 mph (0.045 m/s). Results: With incremental increases in treadmill velocity, for the individuals with tetraplegia there was a significant increase in VO2 (p ⩽ .05), VE (p ⩽ .05), and left rectus femoris mean amplitude (p ⩽ .05). Conclusions: Our preliminary results suggest that incremental increases in treadmill velocity impart increases in neural activation, muscle activation, and metabolic responses for individuals with motor complete and incomplete, nonambulatory SCI. Further this ...

Age-Related Deficits in Early Response Characteristics of Obstacle Avoidance Under Time Pressure

Obstacles in the travel path are a frequent cause of falls among elderly persons. In obstacle avoidance under time pressure, elderly persons have been reported to be less successful than young persons, but possible age-related deficits at the neuromuscular control level have not been studied yet. In the present study, obstacle avoidance reactions were investigated in 15 young and 9 older adults. While the participants walked on a treadmill, an obstacle was dropped in front of the left foot either in late stance, early swing, or mid-swing. Muscle activity in response to the obstacle was measured from the left biceps femoris (BF), rectus femoris (RF), tibialis anterior (TA), and medial head of gastrocnemius (GM). Avoidance success rates, as well as initial response latencies and response amplitudes over the first 50 ms of the response, were determined. In both young and older adults, a large initial response was consistently observed in BF at very short latencies (104-111 ms in the young group), especially for mid-swing obstacle presentations (yielding the highest time pressure). Onset latencies in the elderly group were delayed by 10 ms on average. Response amplitudes were larger in young than in older adults, most prominently in BF and RF, but with a similar tendency in TA. Both onset latency and response amplitude were significantly associated with avoidance success rates. The results of the present study suggest that age-related deficits in the neuromuscular control of obstacle avoidance could play a role in the large numbers of obstacle-related falls in the elderly population.

Why Does Power Output Decrease at High Pedaling Rates during Sprint Cycling?

The objective of this study was to partly explain, from electromyographical (EMG) activity, the decrease in power output beyond optimal pedaling rate (PRopt) during sprint cycling. Eleven cyclists performed four 8-s nonisokinetic sprints on a cycle ergometer against four randomized friction loads (0.5, twice 0.75, and 0.9 N x kg(-1) of body mass). Power output and EMG activity of both right and left gluteus maximus, rectus femoris, biceps femoris, and vastus lateralis were measured continuously. Individual crank cycles were analyzed. Crank angles corresponding to the beginning and the peak of each downstroke and EMG burst onset and offset crank angles were computed. Moreover, crank angles corresponding to the beginning and the end of muscle force response were determined assuming a 100-ms lag time between the EMG activity and the relevant force response (or electromechanical delay). Muscle coordination (EMG onset and offset) was altered at high pedaling rates. Thus, crank angles corresponding to muscle force response increased significantly with pedaling rate. Consequently, at pedaling rates higher than the optimal pedaling rate, force production of lower-limb extensor muscles was shifted later in the crank cycle. Mechanical data confirmed that downstrokes occurred later in the crank cycle when pedaling rate increased. Hence, force was produced on the pedals during less effective crank cycle sectors of the downstroke and during the beginning of the upstroke. During nonisokinetic sprint cycling, the decrease in power output when pedaling rates increased beyond PRopt may be partly explained by suboptimal muscle coordination.

Anaerobic Threshold and EMG Activity During Incremental Cycling Exercise

PURPOSE: Anaerobic threshold (AT) has been defined as the level of exercise at which a change from aerobic to partially anaerobic energy supply is supposed to occur. Even though lactate [La] accumulation is expected at the work loads above AT, accumulation rate differs between individuals. Beside the alteration of metabolic pathways, progressive recruitment of fast twitch fibers may explain the changes in [La] accumulation rate. In this study we aimed to investigate the relationship between AT and mean frequency (MF) and Root Mean Square (RMS) parameters of surface electromyogram (SEMG) during incremental cycling. METHODS: 8 male subjects aged 23.5 ± 1.4 (mean ± SE) underwent one minute incremental cycling exercise to determine peak VO2. Predetermined loads are added every minute up to voluntarily exhaustion. Anaerobic threshold was calculated according to V-slope method. The SEMG activities were recorded by bipolar surface electrodes from the left rectus femoris (RF), vastus medialis (VM), gastrocnemius lateralis (GL) and gastrocnemius medialis (GM). RMS and MF data were averaged for every work load. RMS values were normalized with VO2 at the initial, AT and maximal level of exercise for each individual. Repeated measures and paired-t test were used to analyze the SEMG data. RESULTS: Peak values obtained during the exhausting work load (281 ± 15 W) for ventilatory, metabolic and cardiovascular parameters were VE, 156.6 ± 9 l/min; VO2, 3.59 ± 0.2 l/min (50.01 ± 3.17 ml.kg−1.min−1); VCO2, 4.27 ± 0.21 l/min; HR, 187 ± 3 beats/min. Changes in MF and RMS/VO2 values for initial, AT and maximal steps of exercise are given in Figures 1 and 2.(FIGURE 1 and 2 Caption not available. pls. insert.)FigureFigureCONCLUSIONS: Presence of high and low MF may indicate the different contractile and excitation characteristics of muscle fibers together with motor unit type. Since the MF value did not increase during the incremental exercise (with the exception of VM AT value), it is possible to argue the absence of fiber recruitment with various firing characteristics. The significant elevation of RMS/VO2 in VM and RF beyond AT may indicate the addition of new motor units with similar contractile properties. This may be an important factor to discuss the possible causes of [La] accumulation.

The effect of icepack cooling on skin and muscle temperature at rest and after exercise

Objective. To compare cooling of skin, subcutaneous fat and muscle, produced by an icepack, at rest and after short-duration exhaustive exercise. Methods. Eight male subjects were studied. With the subject supine, hypodermic needle-tip thermistors were inserted into the subcutaneous fat and the mid-portion of the left rectus femoris, to a depth of 1 cm plus the adipose thickness at the site, and a temperature probe was placed on the skin overlying the needle tips. A pack of crushed ice was applied for 15 minutes and temperatures were recorded before, during, and for 45 minutes after icepack application. Thereafter, subjects underwent a ramped, treadmill, VO2max test, an icepack was applied after temperature probes were inserted into the right leg and measurements were made as before. Results. After the treadmill run, skin (Sk), subcutaneous (SC) and muscle (Ms) temperatures (mean ± standard deviation (SD)) were 0.9 ± 1.3, 1.0 ± 0.7 and 1.3 ± 0.8°C higher than at rest. After 15 minutes of icepack cooling, temperatures fell in the exercised limb by 22.7 ± 1.5°C (Sk), 13.5 ± 4.2°C (SC) and 9.3 ± 5.5°C (Ms) and in the control limb by 20.7 ± 2.9°C (Sk), 11.4 ± 2.0°C (SC) and 8.7 ± 2.6°C (Ms). The reductions in temperature were significant in both the control and exercised limbs. Forty-five minutes after icepack cooling, muscle temperature was still approximately 5°C lower in both the rested and exercised muscle (p < 0.001). Individual variations in response to cooling were noted. Conclusions. Cooling of superficial muscle occurs after high-intensity exercise. The degree of cooling is not uniform. This may be due to differences in the sympathetic response to cooling, influencing haemodynamic and thermoregulatory changes after exercise. This needs further investigation. South African Journal of Sports Medicine Vol. 18 (3) 2006: pp. 60-66

Femoral neuropathy induced by a low–grade myofibroblastic sarcoma of the groin

Sirs: Femoral neuropathy is an uncommon disorder [4] and has sometimes been found to be associated with a pelvic hematoma due to anticoagulation therapy [10], the lithotomy position [1], pelvic surgery [7], renal transplantation [8] and radiation injury [6]. Here we report a case of femoral neuropathy induced by a low-grade myofibroblastic sarcoma (LGMS) of the groin, which is a recently established pathological entity [3], and which explains the characteristic radiological findings. A 64-year-old woman noticed numbness of the inner surface of the left leg, which was gradually spreading. An orthopedist made a diagnosis of lumbar spinal disk disease and prescribed a muscle relaxant. In spite of this, the patient’s left leg became gradually weaker and the sensory disturbance worsened. She then began to drag her left leg while walking and was referred to our department 2 months later. A neurological examination revealed weakness and muscle atrophy in her left quadriceps muscle. The left knee jerk reflex was decreased and numbness in the saphenous nerve distribution was found. There was no evidence of central nervous system involvement. On the basis of these clinical findings, the function of the left femoral nerve was considered to be impaired. The motor conduction velocity between above and below the inguinal ligament was estimated to be 64m/s for the right femoral nerve, and 33m/s for the left femoral nerve. Electric stimulation proximal to the inguinal ligament demonstrated that the amplitude of the motor action potential in the rectus femoris muscles was markedly reduced on the left side (8.9 mV on the right and 1.5 mV on the left). When the left saphenous nerve was stimulated antidromically, the sensory action potential decreased to 3.9 μV (7.3 μV in the right saphenous nerve), though nerve conduction was not impaired. This implied the presence of axonal damage in the distal part of the femoral nerve. Other nerve conduction studies showed no evidence of generalized peripheral neuropathy or lumbosacral plexopathy. Needle electromyographic (EMG) evaluation could only be performed for the left rectus femoris muscle, which indicated positive sharp waves and fibrillation potentials at rest. The patient declined further EMG investigation owing to the pain. CT revealed an ill-defined mass lesion in the left groin (Fig. 1a). This was a tumor that appeared to be infiltrating into the retroperitoneal area and surrounding muscles. It also showed heterogeneous enhancement and involved the left femoral nerve (Figs. 1a and b). Compared with the right femoral nerve, the left femoral nerve appeared to be enlarged and probable gadolinium enhancement was observed close to the tumor (Fig. 2). Short-tau inversion recovery (STIR) MRI of the lower leg revealed homogeneous high-intensity signal changes in the left denervated quadriceps muscle and sartorius muscle supplied by the femoral nerve (Fig. 3) [9]. In order to make a precise diagnosis, LETTER TO THE EDITORS

Rectus femoris muscle flap donor-site morbidity

Donor-site morbidity in four patients after reconstruction with free neurovascular rectus femoris muscle was examined through a series of strength tests in which the leg with rectus femoris muscle harvested was compared with the contralateral leg with an intact rectus femoris muscle. The tests were conducted with three testing devices: (1) the 'Con-Trex Leg-press' in which the force and power of right and left leg extensions at 0.2 and 0.4 m/s in a knee angle from 50 to 90 degrees were tested separately; (2) the isometric power tester, which enabled the unilateral evaluation of the isometric leg extension at three knee angles: 50, 70 and 90 degrees ; and (3) at the 'SP-Force Platforms' in which the patients performed a counter-movement jump where the amplitude of the ground reaction force, the parameters maximum force, and the jump height were calculated in order to compare the right and left leg during a single dynamic movement. Our results showed that the patients (with one exception) demonstrated a balanced relationship between the donor leg and the intact contralateral leg. The patient that primarily demonstrated a large strength deficit was retested 3 months later and showed, after an extensive rehabilitation and training program, an impressive increase in strength. The authors concluded that there is no significant limitation in the strength of the donor leg after removal of the rectus femoris muscle and consequently no significant functional donor-site morbidity. We believe that for the realisation of such results that the intraoperative linking of the vastus lateralis muscle with the vastus medialis muscle, especially in their lower third, and an extensive postoperative rehabilitation and training program are essential.

Femoral head of the rectus femoris muscle

Variability of the muscles of the anterior thigh is minimal. After review of the extant medical literature, we believe this to be the first reported case of a femoral head of the left and right rectus femoris muscles. In addition to this anomaly, our anatomic specimen demonstrated an accessory head of the right brachialis muscle and the quadratus plantae muscles inserted into the tendons of both the flexor hallucis longus and flexor digitorum longus. In clinical practice, knowledge of the possibility of an anomalous accessory femoral head of the rectus femoris muscle in clinical practice would be useful for those who might palpate this unusual muscle or encounter it surgically.

KNEE INJURY - JAZZ/THEATRICAL DANCE

HISTORY 17 y/o female theatrical/jazz dancer presented to a sports medicine clinic two months after sustaining her fifth left patellar dislocation in a two-year span. She was doing well five months prior, when she had this most recent dislocation that occurred while she was standing still doing an upper body dance routine. Her patella was reduced in the ER with normal post reduction films. She left the ER with a patellar cut-out brace w/o lateral buttress and no instructions on proper use/weaning. She was started on a very basic strengthening program that included only quad extension sets, isometric quad sets and lunges. She felt that the knee was unstable and had significant retro-patellar pain that precluded almost all activity. Other significant medical problems included HTN and recently diagnosed sponge kidney disease. PHYSICAL EXAMINATION Significant atrophy noted w/in entire left quadriceps group. There was a five-centimeter difference in thigh circumference when compared to the right. The calf on the left was 1.5 cm smaller as compared to the right. ROM of the left knee revealed 30–35 degrees of hyperextension & 70–75 degrees of flexion. There was a smaller degree of genu recurvatum noticed on the right. There was tightness at her end limit of left knee flexion along the anterior inferior patella. Increased laxity in the left patella as compared to the right. Slight medial joint line tenderness. No notable effusion or erythema of the knee. No laxity of the ACL, PCL, MCL, or LCL was noted. MMT was significant for left hip flexors 4+-5/5, left knee extensors 3–3+/5, left ankle dorsiflexors 4+/5, and left hamstrings 4/5. The left EHL, EDL, & all muscle groups tested in the right lower extremity were 5/5 strength. Pinprick in L1 to S2 dermatomes and in all peripheral nerve distributions was intact and symmetrical bilaterally. Reflexes were a brisk 3+ at the left patella, ankle, and internal hamstrings. DIFFERENTIAL DIAGNOSIS Status post Left patellar dislocation & persistent patellofemoral pain. Disuse atrophy. Left femoral nerve injury. Left lumbrosacral plexopathy. Left L4 radiculopathy R/O meniscal tear. R/O ACL tear R/O osteochondritis Dissecans. TEST AND RESULTS MRI Left thigh (9 days post injury): Large knee joint effusion. Medial patellar & lateral femoral bone contusions. Complete tear of medial retinaculum. Abnormal placement of lateral meniscus with a tear at lateral joint line & possible meniscal cyst inferior to lateral meniscus displacement. MRI Left thigh, STIR sequencing (4 months post injury): Abnormal signal within vastus medialis, lateralis and intermedius musculature w/o evidence of fatty atrophy. No abnormality within neurovascular bundle. Septate uterus. EMG/NCS left lower extremity (2 months post injury): Normal saphenous sensory response. Needle EMG - Abnormal spontaneous activity in vastus medialis (fibs and PSWs) & vastus lateralis (PSWs) with normal motor units. Normal exam of iliopsoas, tibialis anterior, adductor longus, & medial gastrocnemius muscles. EMG left lower extremity (6 months post injury): Needle EMG — Few polyphasics & reduced recruitment pattern seen in left vastus lateralis & rectus femoris. FINAL WORKING DIAGNOSIS Left patellar dislocation. Acute femoral neuropathy distal to inguinal ligament & saphenous sensory branch d/t patellar dislocation. Sponge kidney disease (no apparent impact on patellofemoral pathology). TREATMENT AND OUTCOMES Patellar buttress brace. McConnell taping. Quadriceps strengthening exercises: VMO >VL strengthening. Adductor, hip flexor, & TFL strengthening. Slow quadriceps & TFL stretching to increases knee flexion. Gait mechanics training to reduce genu recurvatum (focus on reverse origin-activation of gastrocnemius & eccentric activation of hamstrings). Proprioceptive & balance training Complete abstinence from the use of e-stim & U/S. Patient referred to orthopedic surgeons to evaluate for possible realignment if no femoral recovery and/or recurrent dislocations. Continued persistent atrophy, but slowly advancing ADLs & social activities. Await progress after activity increases.

Mobile and fixed bearing total knee prosthesis functional comparison during stair climbing

Objective. The purpose of this investigation is to determine the functional performance of the mobile bearing total knee replacement prosthesis as compared to the fixed bearing type total knee replacement prosthesis. Design. Kinematics, kinetics, and electromyography data were gained from 10 patients with mobile bearing and 10 patients with a fixed bearing posterior stabilized Insall Burstein II total knee replacement during ascending and descending stairs. A control group of 10 normal subjects, matched by sex and age, was also analysed. Background. No significant biomechanical differences in patients with different total knee replacement designs have been reported from level-walking studies. Slightly better performance of posterior retaining with respect to cruciate sacrificing total knee replacement designs have been claimed from stair climbing studies. Only one study has been conducted regarding mobile versus fixed bearing total knee replacement assessed by gait analysis. This study did not show any biomechanical differences between the two groups. Methods. Motion analysis was used to quantify the knee kinematics, kinetics, and electromyography (right and left longissimus dorsi, gluteus medius, rectus femoris, biceps femoris, semitendinosus, gastrocnemius and tibialis anterior muscles) during stair ascent and descent. Results. The mobile bearing group demonstrated a reduced knee extensor moment during stair climbing and descending, and a reduced knee adductor moment during stair climbing. When ascending stairs, most of the mobile bearing patients show a peak knee flexion and a peak knee flexion moment at the late stance phase during the double support period. This kinematic and kinetic pattern is absent in normal subject. Both mobile bearing and fixed bearing groups showed abnormal electromyography patterns in both descending and ascending. Conclusions. During stair climbing, the mobile bearing design demonstrates a different kinematic pattern to the fixed bearing total knee replacement. Lower limb compensatory mechanisms seemed to be adopted particularly by the mobile bearing patients during ascending stairs. Relevance Total knee replacement patient with mobile bearing design can feel excessive femoro-tibial motion during daily living activities such as stair climbing and descending. Proprioceptive control of this tibio-femoral translation is needed as demonstrated by the lower limb compensatory mechanism. This data suggest that antero-posterior constraint structures (ligamentous or mechanical) are important to obtain reproducible knee kinematics.

Effect of endurance running on cardiac and skeletal muscle in rats.

We studied the effect of resistance running on left cardiac ventricle size and rectus femoris muscle fiber composition. Ten male Wistar rats were trained on a treadmill 6 days per week for 12 weeks. Ten rats remained sedentary and served as controls. A higher endurance time (40%) and cardiac hypertrophy in the trained animals were indicators of training efficiency. Morphometric analysis of the left ventricle cross-sectional area, left ventricular wall, and left ventricular cavity were evaluated. The endurance-running group demonstrated a hypertrophy of the ventricular wall (22%) and an increase in the ventricular cavity (25%); (p<0.0001). Semi-quantitative analysis of rectus femoris fiber-type composition and of the oxidative and glycolytic capacity was histochemically performed. Endurance running demonstrated a significant (p<0.01) increase in the relative frequency of Type I (24%), Type IIA (8%) and Type IIX (16%) oxidative fibers, and a decrease in Type IIB (20%) glycolytic fibers. There was a hypertrophy of both oxidative and glycolytic fiber types. The relative cross-sectional area analysis demonstrated an increase in oxidative fibers and a decrease in glycolytic fibers (p<0.0001). Changes were especially evident for Type IIX oxidative-glycolytic fibers. The results of this study indicate that the left ventricle adapts to endurance running by increasing wall thickness and enlargement of the ventricular cavity. Skeletal muscle adapts to training by increasing oxidative fiber Type. This increase may be related to fiber transformation from Type IIB glycolytic to Type IIX oxidative fibers. These results open the possibility for the use of this type of exercise to prevent muscular atrophy associated with age or post-immobilization.

Effect of applied pressure in the determination of vibration sensitivity using the Neurothesiometer

Vibration perception threshold (VPT) measurements are becoming widely accepted as a determinant for neurological dysfunction in a clinical setting. In this study, VPT measurements were taken from 10 normal subjects using a Neurothesiometer. Three sites on the body – the left 1st metacarpo-phalangeal joint; left rectus femoris muscle; and left proximal phalanx of the hallux – were studied as these are most commonly used for clinical examination. Varying masses (0–100 g) were applied to the head of the neurothesiometer and the VPT was determined for each mass applied. A trend existed between the mass applied and the VPT; the greater the mass, the lower the VPT. This study indicates the importance of the correct use of the hand-held Neurothesiometer in a busy clinical environment.Only when the vibrating head is placed perpendicular to the site for VPT determination, and no extraneous mass (or pressure) is applied to the vibrating head, can truly reproducible VPTs be determined for potential conditions such as diabetic neuropathy or leprosy. An inexpensive in-house device, which was designed and implemented in this study, is described which allows the adaptation of the Neurothesiometer for improved accuracy.

Pressure on the Tibial Plateau when Standing from a Seated Position.

The object of this study was to estimate changes in pressure on the tibial plateau as a person stands up from being seated in a chair. Eight young men and eight young women performed this task while being photographed by a video camera from the left side in such a way that movements of individual segments of the body in the sagittal plane could easily be determined. All subjects used the same chair, which had a seat height of 40 cm. Myoelectric activity was recorded from the left rectus femoris during the task as well. Pressure on the tibial plateau was calculated on the basis of a rigid-body link model and of published data on area of contact between the femur and the tibia at different angles of knee flexion. Pressure estimated in this manner was highest at the onset of the task and decreased in a fairly uniform fashion over angular displacement of the knee into full extension. Because the peak pressure was at the very beginning of the task, adjusting height of the chair to height of the subject became a more critical variable than we had originally anticipated. Also, because we used the same values for area of joint contact for all subjects, we found that adjusting the magnitude of the area of contact to the size the subject was another consideration worthy of further investigation.