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Electromyographic (EMG) study of the elbow flexors during supination and pronation of the forearm.

Activities of the elbow flexors during supination and pronation of the forearm in a normal human volunteer were studied by an electromyography (EMG). The volunteer performed the movement slowly or quickly holding elbow flexion at various angles with or without a load. The biceps brachii showed an increase and a decrease of EMG activities during supination and pronation, respectively. The brachialis and brachioradialis showed a reduction and an increment of EMG activities accompanied by an increase and a decrease of EMG activities in the biceps brachii, respectively. These findings seem to indicate that reciprocal contractions among the elbow flexors permit the biceps brachii to work for supination without an induction of elbow flexion.

Adult↗

Pronation in runners. Implications for injuries.

In spite of some significant progress in the understanding of the biomechanics of the ankle joint complex, especially the coupling mechanism between foot and leg, various mechanisms causing overuse injuries in the lower extremities are still poorly understood. Some increased pronation of the foot is often physiological, but excessive pronation is potentially harmful. Compensatory overpronation may occur for anatomical reasons. However, not only the amount of foot eversion, but also the way this eversion is transferred into tibial rotation may be crucial to the overloading stress on the knee. In other words, the individual transfer mechanism of foot eversion into internal tibial rotation may be of some predictable value for lower extremity overloading and related injuries. Further research is necessary to improve the functional understanding of anatomical and biomechanical abnormalities and their pathological value in predicting overuse injuries.

Ankle Injuries↗

Modification of high-heeled shoes to decrease pronation during gait.

One of the reasons that high heels may contribute to the formation of halux valgus is that the wearers pronate during propulsion. This pilot study was performed to determine whether relocation of the heel under the counter of a fashion high-heeled pump could change the degree of pronation of the foot during the gait cycle. The authors report that more foot stability was experienced by the subjects when the center of the heel was offset between 2 and 4 mm medial to the center of the heel counter. This study is designed to promote further research into whether the shoe industry should change the design parameters of high-heeled fashion shoes in order to improve foot function.

Adult↗

Function of the windlass mechanism in excessively pronated feet.

The foot postures of 39 subjects were evaluated for excessive pronation by means of six static weightbearing and five nonweightbearing measurements, and two types of footprint indexes. Visual evidence of windlass function was recorded by video. Chi-square analysis revealed that excessive pronation does not affect the establishment of the windlass mechanism. The position of the forefoot relative to the rearfoot, subtalar joint axis position, and navicular drift/foot length ratio were significantly associated with dynamic windlass function. These results suggest that selected static measurements may have value in predicting some aspects of dynamic foot function during the propulsive phase of the gait cycle.

Adult↗

Effect of the low-Dye strap on pronation-sensitive mechanical attributes of the foot.

The low-Dye strap is used routinely to temporarily control pronation of the foot and, thereby, to diagnose and treat pronatory sequelae. However, the exact biomechanical effects of this strapping technique on the foot are not well documented. The main purpose of this study was to establish the specific mechanical effects of the low-Dye strap on the pronatory foot. Within this context, the specific aim was to assess the effect of the low-Dye strap on three distinct pronation-sensitive mechanical attributes of the foot in the weightbearing state: 1) calcaneal eversion, 2) first metatarsophalangeal joint range of motion, and 3) medial longitudinal arch height. Weightbearing measurements of these three attributes were made before and after application of a low-Dye strap, and statistical comparisons were made. The results of this study indicate that the low-Dye strap is effective in reducing calcaneal eversion, increasing first metatarsophalangeal joint range of motion, and increasing medial longitudinal arch height in the weightbearing state. Knowledge of the exact mechanisms of action of the low-Dye strap will provide practitioners with greater confidence in the use of this modality.

Bandages↗

[Measurement of the strength of pronation and supination forces and its significance in radius fracture displacement].

The strength of pronation and supination was measured by "Forearm-Rotate-Dynamometer" on 524 male and female students ranging in age from 16 to 32. The study showed that the strength of supination was 13% greater than that of pronation for 91.3% of all the tested subjects (1048 sides). Based on this finding, the pattern of displacement fracture of the middle lower segment of the radius was discussed. It was concluded that the proximal fragment displacement will show supination, adduction and flexion when a proximal fragment displacement occurs.

Adolescent↗

Dorsally angulated solitary metaphyseal greenstick fractures in the distal radius: results after immobilization in pronated, neutral, and supinated position.

In a prospective study, angular redisplacement has been correlated with immobilization in the pronated, neutral, or supinated position (20 children in each group). Those with greater than 20 degrees of dorsal angulation at day 1 and after 2 weeks were manipulated. Dorsal angulation after immobilization at day 1, 2 weeks, and 6 weeks was measured on accurate lateral views. Angular displacement during the first two weeks was (a) greater among reduced than unreduced cases in the pronation group (p less than 0.001), and (b) less in the supination group than in the other groups (p less than 0.05). Based on these findings, we believe that the fracture should be immobilized in the supinated position.

Child↗

[Pronator teres syndrome. Clinical and neurophysiological study of 2 cases].

We report two cases of pronator teres syndrome (bilateral in one case) diagnosed in our Department by electromyographic studies during the last three years. The infrequency of this syndrome (1 case/201 cases of carpal tunnel syndrome), combined with the unspecified and inconsistent symptomatology (tenderness over the pronator teres, paresthesias and weakness of flexor pollicis longus, abductor pollicis brevis and opponens pollicis) frequently induced diagnostic mistakes. The electromyographic study is very useful showing a delay in proximal motor latency of the median nerve, diminution of motor nerve conduction in the proximal forearm segment of this nerve with normality of distal motor latency and sensory latency. Corticoid infiltration is the treatment of choice keeping in reserve surgery only for resistant cases.

Adult↗

Forearm pronation and supination: reliability of absolute torques and nondominant/dominant ratios.

This study examined the reliability of pronation and supination measurements expressed in absolute units (newton-meters [Nm]) and nondominant/dominant ratios (%), and determined isometrically using the BTE (WS20) and the Cybex (340) dynamometers. Twenty-one healthy men and 22 healthy women were tested twice on each machine, within 14 days. Twelve of 16 reliability coefficients for absolute torques were considered acceptable (> 0.75) when determined as the reliability of two repetitions on one occasion, while 14 of 16 coefficients were acceptable when determined as the reliability of two repetitions on each of two occasions. However, reliability coefficients for the nondominant/dominant ratios were not acceptable on one (0 of 8 coefficients > 0.75) or two (2 of 8 coefficients > 0.75) occasions. Ratio data were also characterized by larger standard errors of measurement (SEMs) and wider 95% confidence intervals, relative to the sample mean and standard deviation. Overall, reliability coefficients, SEMs, and 95% confidence intervals were similar for men and women, pronation and supination movements, and the BTE and Cybex dynamometers. The authors suggest that absolute scores be used when possible, as these data tend to provide more reliable measurements--especially when the clinician has only limited test occasions to establish baseline scores.

Bias↗

A dynamic pronation orthosis for the C6 tetraplegic arm.

Tetraplegic arms of patients with spinal cord injury at C5 or C6 level are often held in a flexed supinated position. In supination the function of the hand is limited. This report presents a newly developed orthosis giving active pronation of the forearm for a C6 complete tetraplegic. The orthosis consists of a pretightened coiled spring that gives a torque around the longitudinal axis of the forearm. The distal part of the spring is connected to a cuff around the wrist, and the proximal part to two fitting planes on the upper arm. With the orthosis, a 27-year-old patient with a C5-C6 spinal cord injury was able to participate in activities of daily living and to perform table top activities. This new orthosis provides pronation and markedly increases the patient's degree of independence.

Adult↗

Telemetered electromyography of the supinators and pronators of the forearm in gibbons and chimpanzees: implications for the fundamental positional adaptation of hominoids.

Extant apes are similar to one another, and different from monkeys, in features granting them greater range of forearm rotation and greater size of the muscles that produce this motion. Although these traits may have been independently acquired by the various apes, the possibility arises that such features reflect adaptation to the stem behavior of the hominoid lineage. Anticipating that knowledge of forearm rotatory muscle recruitment during brachiation, vertical climbing, arm-hanging during feeding, and voluntary reaching might point to this stem behavior, we undertook telemetered electromyographic experiments on the supinator, pronator quadratus, ulnar head of pronator teres, and a variety of other upper limb muscles in two gibbons and four chimpanzees. The primary rotator muscles of the hominoid forearm were recruited at high levels in a variety of behaviors. As had been suspected by previous researchers, the supinator is usually active during the support phase of armswinging, but we observed numerous instances of this behavior during which the muscle was inactive. No other muscle took over its role. Kinetic analyses are required to determine how apes can execute body rotation of armswinging without active muscular effort. The one behavior that is common to most extant apes, is rare in monkeys, and which places a consistently great demand on the primary forearm rotatory muscles, is hang-feeding. The muscles of the supporting limb are essential to properly position the body; those of the free limb are essential for grasping food. Since the greater range of forearm rotation characterizing apes is also best explained by adaptation to this behavior, we join previous authors who assert that it lies at the very origin of the Hominoidea.

Adaptation, Physiological↗

Syndromes of compression of the median nerve in the proximal forearm (pronator teres syndrome; anterior interosseous nerve syndrome).

Entrapment of the median nerve in the proximal forearm is seen in two forms: the pronator teres syndrome, and the anterior interosseous nerve (or Kiloh-Nevin) syndrome. Both syndromes are rare, and they comprised approximately 1% of the compression syndromes of the upper limb which were treated operatively by the authors. The symptoms, signs, etiologies, and intraoperative findings are discussed. It is pointed out that certain of the clinical features may resemble those of irritation of the median nerve by a supracondylar process or Struthers' ligament. Although both proximal median entrapment syndromes have a favorable prognosis when treated non-operatively, the authors recommend operative treatment in cases in which there is no perceptible improvement following 8 weeks of non-operative treatment, since this is likely to speed and enhance recovery. Nine cases of the pronator teres syndrome (8 treated successfully by operation, 1 failure) and 2 cases of the anterior interosseous nerve syndrome (both fully recovered) are added to the cases reported previously in the literature.

Adult↗

Symptoms and sickleave among forestry machine operators working with pronated hands.

Nineteen forestry machines operators worked with two types of hand controls. Harvesting operators, who worked with their hands in pronated position, were more often on sickleave compared with operators working with their hands semi-pronated. This is one of several important factors related to musculoskeletal symptoms. The experience from laboratory studies as well as epidemiological studies should be carefully considered when designing hand controls for machine operators.

Journal Article↗

Median nerve compression within the humeral head of pronator teres.

We describe a case of the pronator syndrome caused by compression of the median nerve by a fibrous band as the nerve passed through the humeral head of origin of pronator teres. This rare anatomical arrangement resulted in displacement of the median nerve to the anterior aspect of the medial humeral epicondyle and, as far as we are aware, has not previously been described as a site of compression neuropathy.

Elbow Joint↗

Reference values for median nerve conduction to the pronator quadratus.

OBJECTIVE: To derive a normative database for nerve conduction values of the median nerve to the pronator quadratus using a large and varied subject population. DESIGN: Descriptive study. SETTING: Private office or university-based clinic. PARTICIPANTS: Volunteers (N=207), recruited, without risk factors for neuropathy. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Onset latency, duration, amplitude, and area were recorded for all subjects. Side-to-side variability was calculated and the normative ranges were derived (97th percentile of observed values). RESULTS: Because the latencies increased with longer distances (longer forearms), the data were divided into 3 categories. The mean latency for those subjects whose distance from stimulator to recording electrode was 23 cm or less was 3.8+/-0.4 ms; the comparable values for those subjects with distances of 23.5 to 24.5 cm was 4.0+/-0.4 ms; and for those with distances of 25 cm and more, 4.5+/-0.4 ms. The amplitude and area varied with age. The mean amplitude for those subjects under 60 years of age was 4.4+/-1.8 mV, while those 60 years and over had an amplitude of 3.7+/-1.7 mV. The upper limit of normative side-to-side variability for latency was 0.6 ms, and the upper limit decrease in amplitude from 1 side to the other was 37%. CONCLUSIONS: This study establishes normative values for the median motor nerve conduction to the pronator quadratus.

Adult↗

Treatment of painful neuromas of the hand and wrist by relocation into the pronator quadratus muscle.

Thirteen painful end-neuromas of nerves of the palm and the dorsum of the hand were treated by resection of the neuroma and relocation of the nerve ends into the pronator quadratus muscle proximal to the wrist in ten patients. The effectiveness of this treatment was assessed by measurement of changes in level of spontaneous pain, pain on pressure, pain on movement and hyperaesthesia at the original site and at the site to which the nerve was relocated. Subjective comments on changes of hand function and ability to return to work were also recorded. All ten patients reported total relief or marked improvement in each of the four modalities of pain assessed. In the five patients in whom the neuromas were the only significant cause of hand dysfunction, there was sufficient improvement in hand function to allow the patients to return to work. In this series, the pronator quardratus muscle has proved a suitable site for relocation of sensory nerve ends after resection of painful neuromas in the proximal part of the hand and wrist.

Adult↗

Vascular anatomy of the pronator quadratus muscle-bone flap: a justification for its use with a distally based blood supply.

The vascular anatomy of the pronator quadratus muscle and distal radius was studied in 24 cadaveric forearms by dissection under magnification and india ink and latex injection studies. The anterior interosseous artery divides into a muscular branch and a dorsal branch 1 cm to 3.5 cm from the proximal margin of the pronator quadratus muscle, and on its deep surface. Injection studies showed a rich periosteal plexus contributed by the anterior interosseous artery. Retrograde injection through the dorsal branch also showed good perfusion of the distal radius that was confirmed microscopically on bone sections. A muscle-bone graft from the anteromedial cortex of distal radius with an intact anterior interosseous artery has mobility of less than 2 cm. After ligating and dividing the anterior interosseous artery, blood supply to the distal radius bone flap relies on a retrograde flow and the bone flap could then be mobilized distally up to 4 to 6 cm.

Forearm↗

The pronator quadratus in motions and in stabilization of the radius and ulna at the distal radioulnar joint.

Based upon the findings of dissections of 15 forearms and clinical observations in patients with disturbed architecture of the distal radioulnar joint, the pronator quadratus was found to be composed of two heads. A superficial head originated from the ulna and passed transversely to its insertion into the radius. It averaged 5.1 cm. in length, 4.5 cm. in width, 0.2 cm. in thickness, with a cross-sectional area of 0.95 cm.2 and a contractile volume of 2.6 cm.3. The deep head ran obliquely from a more proximal origin on the ulna to a distal insertion on the radius, with an average length of 4.0 cm., average width of 3.2 cm., and a thickness of 0.4 cm. Its average cross-sectional area was 1.64 cm.2 and its contractile volume 2.5 cm.3. A group of fibers occasionally was noted deep to both heads, running at right angles to them and paralleling the direction of the fibers of the interosseous membrane. The superficial head initiates pronation while the deep head coapts the joint surfaces and stabilizes the joint.

Adult↗