Pronator Muscles Research Articles

Volar Surgical Correction of Madelung's Deformity

Volar Surgical Correction of Madelung's Deformity

Chronic, recurring ligament instability in the lateral ankle.

According to the literature, chronic ankle instability occurs after acute rupture of the lateral ankle ligaments in 10-20 % of the cases. The etiology of the instability are ligamentous damage and functional neuromuscular disorder of the peroneal muscles. The standards of diagnostics are the history with the frequency of inversion trauma per period and the interval from the primary trauma, the clinical examination and radiological stress tests. Newer diagnostic methods, up to now not well established in clinical routine, include stabilometry, cybex-measurements of the pronator muscles, the evaluation of peroneal reaction time on a tilting platform and dynamic pedography. Conservative management of chronic ankle instability consists of wearing ankle braces and rehabilitation programs concerned with peroneal muscle strengthening and coordination training. The indication for surgical reconstruction of the ankle ligaments are a well-documented mechanical instability with the neuromuscular reflexes intact and a failed physiotherapeutic training program. The surgical procedure should be selected according to a priority list: 1. anatomical repair, eventually augmented with periosteum from the fibula, 2. Watson-Jones tenodesis, and 3. Chrisman-Snook tenodesis to treat a concomittant subtalar instability.

Chronic recurrent ligament instability on the lateral ankle

According to the literature, chronic ankle instability occurs after acute rupture of the lateral ankle ligaments in 10-20% of the cases. The etiology of the instability are ligamentous damage and functional neuromuscular disorder of the peroneal muscles. The standards of diagnostics are the history with the frequency of inversion trauma per period and the interval from the primary trauma, the clinical examination and radiological stress tests. Newer diagnostic methods, up to now not well established in clinical routine, include stabilometry, cybex-measurements of the pronator muscles, the evaluation of peroneal reaction time on a tilting platform and dynamic pedography. Conservative management of chronic ankle instability consists of wearing ankle braces and rehabilitation programs concerned with peroneal muscle strengthening and coordination training. The indication for surgical reconstruction of the ankle ligaments are a well-documented mechanical instability with the neuromuscular reflexes intact and a failed physiotherapeutic training program. The surgical procedure should be selected according to a priority list: 1. anatomical repair, eventually augmented with periosteum from the fibula, 2. Watson-Jones tenodesis, and 3. Chrisman-Snook tenodesis to treat a concomittant subtalar instability.

Hyperextension trauma to the elbow joint induced through the distal ulna or the distal radius: pathoanatomy and kinematics. An experimental study of the ligament injuries.

Loads applied to the forearm result in hyperextension of the elbow. The pathomechanics of hyperextension trauma with load applied to the distal radius and ulna were studied in 10 macroscopically normal cadaver elbow joint specimens to reveal patterns of injury with radial traction (n = 5) compared to ulnar traction (n = 5). The mean age of the donors was 60.8 years (range 33-74). Kinematic testing was performed in an experimental 3D-kinematic loading apparatus. The extension range of motion increased by 20.9 degrees +/- 2.9 degrees after joint loading. Hyperextension loads induced joint laxity during flexion of less than 60 degrees. In both groups, the changes were significant in joint flexion during forced valgus and external rotation, but were not significant in flexion during forced varus and internal rotation. In both groups, the same four lesions were produced: 1) Anterior capsule rupture, 2) L-formed rupture of the origin of the pronator muscle with elongation of the anterior bundle of the medial collateral ligament, 3) partial rupture of the lateral collateral ligament and 4) small cartilage damage to the posterior or anteromedial edge of the ulna. In conclusion, hyperextension trauma to the elbow joint induced through the distal ulna or the distal radius produced the same pattern of injury as reported in hyperextension of the elbow with traction to the forearm when free rotation of the radius relative to the ulna was allowed.

Lycra garments designed for patients with upper limb spasticity: Mechanical effects in normal subjects

Objective: To assess the stretch of pronator muscles produced by a specifically designed upper-limb Lycra garment that could have a better acceptability than rigid splints in treating upper-limb spasticity. Design: Double-blind comparison among three garments. They were designed to produce a supinating, a pronating, and no torsional force, and were individually manufactured and tested in 10 healthy volunteers. Main Outcome Measure: Angular position and passive rotational stiffness of the forearm were measured with and without each of the garments immediately after the garment was fitted and every hour for 6 hours. Results: When put on by a trained person, the supinator garment supinated the forearm in all subjects (mean, 17°; p < .01; range, 5° to 44°) while the pronator garment pronated the forearm in 8 of 10 subjects (mean, 5°; p < .01). These effects gradually decayed over 6 hours, as garment position was not readjusted. Passive rotational stiffness of the forearm increased by about 30% with each type of garment. The garments designed to produce no torsional force exerted no intrinsic rotational effect. Conclusion: Individually made Lycra garments can produce continuous stretch of muscles for several hours and may be useful in the treatment of spasticity. The garments, however, must be put on by a trained person and their position adjusted when necessary.

Ligamentomuscular protective reflex in the elbow

A reflex are from the medial elbow ligaments to the forearm pronator muscles was shown to exist in the feline model. A single articular branch emerging from the median nerve and converging on the medial collateral ligament was identified and stimulated with supramaximal pulses of 100 microseconds duration at a rate of 10 pulses/s. Stimulation of the articular nerve elicited myoelectric activity in the flexor digitorum superficialis, flexor digitorum profundus, flexor carpi radialis, flexor carpi ulnaris, and pronator teres. Transection of the articular nerve between the electrodes and the median nerve resulted in the disappearance of any myoelectric activity in the muscles, thus confirming the afferent nature of the articular nerve. The mean time delay from the application of the stimulus to the corresponding myoelectric discharge ranged from 3.2 to 5.8 ms for the 5 muscles. The existence of a fast-acting reflex arc from the medial elbow ligaments to the forearm muscles both confirms the concept of ligamentomuscular protective synergy (shown to exist in the knee, shoulder, and ankle joints) and extends it to the elbow. This reflex arc has significant implications for both the planning of elbow surgery while preserving the neural supply of the ligaments and for the planning of postsurgical or conservative therapeutic rehabilitation modalities.

The functional importance of the ulnocarpal ligaments and triangular fibrocartilage on the transmission of the pronator and supinator muscles torque towards the hand

The functional importance of the ulnocarpal ligaments and triangular fibrocartilage on the transmission of the pronator and supinator muscles torque towards the hand

Functional anatomy of the flexor pronator muscle group in relation to the medial collateral ligament of the elbow.

To describe the relationship of the pronator teres, flexor carpi radialis, flexor digitorum superficialis, and flexor carpi ulnaris muscles to the medial collateral ligament at 30 degrees, 90 degrees, and 120 degrees of elbow flexion, we dissected 11 cadaveric specimens. The flexor carpi ulnaris muscle is the predominant musculotendinous unit overlying the medial collateral ligament in the majority of cases and is the only one at 120 degrees of elbow flexion. The flexor digitorum superficialis muscle is the only other significant contributor. The medial collateral ligament is the primary stabilizer of the medial elbow with elbow flexion greater than 30 degrees, as in throwing. The flexor carpi ulnaris muscle, because of its position directly over the medial collateral ligament, and the flexor digitorum superficialis muscle, with its near proximity and relatively large bulk, are the specific muscles best suited to provide medial elbow support. This is especially relevant to overhand throwing athletes who encounter extreme valgus force across the elbow during the cocking and acceleration phases of the throwing motion. Exercise and conditioning of the medial elbow musculature, specifically the flexor digitorum superficialis muscle and the flexor carpi ulnaris muscle, may prevent injury or assist in rehabilitation of medial elbow instability, especially in overhand throwing athletes.

Clarification of the pronator reflex.

The pronator reflex has been used in evaluating the 6th and 7th cervical roots. It has been described as a muscle stretch reflex of the pronator muscles; however, a review of the literature did not elucidate which muscles are active in this reflex. We examined 10 healthy subjects with surface electromyograms recorded over the pronator quadratus and pronator teres and used a Teca reflex hammer to produce a muscle stretch and trigger the electromyogram sweep. A reproducible response was found in all patients when recordings were made over the pronator teres (mean latency, 9.7 +/- 1.8 ms). No response was found in any of the subjects when recordings were made over the pronator quadratus. We conclude that the pronator reflex represents a muscle stretch reflex of the pronator teres (and not the pronator quadratus), which would make it helpful in evaluating C6 and C7 root lesions.

Overuse syndrome in ballet: study of the effect of a tape bandage of the upper ankle joint with motion analysis

In six ballet dancers with overuse syndromes of the foot a study on the effect of taping on stabilisation, proprioception and muscular activity was performed. By using synchronous surface electromyography and 3-dimensional motion analysis three standard ballet positions without and with applied tape were performed. Muscular activities of pronator muscles (peroneus longus) and supinator muscles (tibialis posterior) were recorded. EMG measurements showed significant differences between patients with stable or unstable ankles and painful or pain-free feet. Applying tape led to significant changes of muscle activities in height and antagonist reflex patterns. These changes were highest in dancers with unstable ankle joints and metatarsalgia.

Skeletal muscle capillarization and fiber types in urban and homing pigeons ( Columba livia)

1. 1. Fiber types, capillary supply and other morphometrical parameters were analysed in pectoral, gastrocnemius and pronator muscles of homing and urban pigeons. 2. 2. The two kinds of birds were analysed before and after a restrainment period of at least 5 months. 3. 3. Only slight differences in fiber type frequencies were noted between urban and horning pigeons in control conditions. 4. 4. The effect of restrainment on the different parameters studied was unclear in gastrocnemius and pronator muscles and negligible in M. pectoralis. 5. 5. Mean diffusion distances for oxygen from capillaries were smaller in oxidative fibers; also, vascularization indexes were higher for these fiber types. 6. 6. The contribution of each fiber type to total sectional area of muscle remains stable in spite of fiber type frequencies heterogeneity.

Electromyography of pronators and supinators in great apes.

We obtained electromyographic recordings from the supinator, biceps brachii, pronator quadratus, and pronator teres muscles of a chimpanzee and a gorilla and from the supinator, pronator quadratus, and biceps brachii muscles of an orangutan as they stood and walked quadrupedally on horizontal and inclined surfaces, engaged in suspensory behavior, reached overhead, and manipulated a variety of foods and artifacts. In Pan troglodytes and Pan gorilla, as in Homo sapiens, the supinator muscle is the prime supinator, with the biceps brachii muscle serving to augment speed or force of supination. Primary of the pronator quadratus muscle over the pronator teres muscle during pronation is less clear in the African apes than in humans. Possibly, pongid radial curvature or forelimb elongation or both factors are related to the somewhat different patterns of activity that we observed in the pronator muscles of Pan versus those reported for Homo sapiens. In Pongo pygmaeus, as in P. troglodytes and P. gorilla, the pronator quadratus muscle acts as a pronator and the supinator muscle acts to supinate the hand at the radioulnar joints. The biceps brachii muscle is active at low levels as the orangutan supinates its hand with the elbow flexed.

Komplexe Bewegungsanalyse: dynamische Untersuchung zum Effekt des Tapeverbandes auf die Pronation beim Hochsprung mit dreidimensionaler Bewegungsanalyse und Elektromyographie

Overuse syndromes in the lower extremity are a frequent problem in athletics, especially in jumping events. Athletes notice a comfortable support by using ankle taping without restriction of their performance. Up to now no objective data is available about efficiency of taping against overpronation which is frequent in high jumping. In high jumping without boots little difference of pronation between taped and untaped take off leg was found. In contrast in jumping with spikes boots a marked pronation during take off was found, which was reduced by ankle taping with a reduction of maximum medial malleolar medialisation by 77%, reduction of pronation time by 33% and time of maximum pronation by 8.2% in the take off leg. Surface electromyography showed an increased activity of M. peroneus longus by 30.7% as a plantarflector and pronator muscle with ankle taping. Activity of other jump supporting muscles of the lower extremity was little influenced.

A fixation technique for the Steindler flexorplasty

A curved longitudinal incision is made over the medial side of the elbow beginning 8 cm proximal to the medial epicondyle and extending distally posterior to the medial epicondyle, and then along the anterior surface of the forearm in line with the course of the pronator teres muscle. The medial antebrachial cutaneous nerve in the distal portion of the incision is identified and protected. The ulnar nerve is isolated and retracted posteriorly. The median nerve and its branches to pronator teres and flexor digitorum superficialis are identified. The median nerve and brachial artery are retracted laterally. Common origins are defined of the pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis, and flexor carpi ulnaris at the medial epicondyle. The cortex of the medial epicondyle is drilled with a 2.0 mm drill bit. The epicondyle is then osteotomized, fashioning a 1.2 cm diameter, 1 cm deep, bone “plug” that is to be fixed subsequently to the anterior surface of the humerus. The flexor pronator muscles are freed distally for 5 to 6 cm taking care to preserve the median nerve branches to the pronator teres and flexor digitorum superficialis muscles and the ulnar nerve branches to flexor carpi ulnaris (Fig. 1, A). The brachialis muscle is split and the anterior surface of the humerus is exposed 5 to 7 cm proximal to the medial epicondyle. The mobility of the flexor pronator group is checked with the elbow in flexion to assure their proximal transfer without un-

Effects of ankle disc training on muscular strength and postural control

Ankle disc training gave good objective results in patients with functional instability of the ankle joint, that is a feeling of giving way or recurrent sprains. The training programme improved both postural control, as demonstrated by stabilometry, and isokinetic pronator muscle strength. A 10-week training period was apparently sufficient, and further training could not be shown to be beneficial.

Neandertal radial tuberosity orientation.

Examination of adult and immature Neandertal radii demonstrates that the medial versus anterior orientations of their radial tuberosities fall within recent human ranges of variation, but on the average their radial tuberosities are significantly more medially, as opposed to anteromedially, oriented. This more posterior positioning of their radial tuberosities implies a maintenance of an effective moment arm for M. biceps brachii through the full range of supination, an interpretation which fits with the hypertrophy of and increased moment arms for their forearm pronator muscles. It is an additional indication of the muscular hypertrophy evident elsewhere in Neandertal upper limbs.

Pronator muscle weakness in functional instability of the ankle joint.

Functional instability, i.e., recurrent sprains or a feeling of "giving way" of the ankle, is common after ankle sprains. These patients have been supposed to have peroneal muscle weakness based on manual methods for measuring muscle strength. We have confirmed this theory by an isokinetic method for testing pronator muscle strength. Pronator muscle weakness on the affected side was found among patients with unilateral functional instability of the ankle joint. Impaired postural control was demonstrated by stabilometry with the patient standing on either foot.

Clinical and Neurophysiologic Characteristics of the Pronator Syndrome

Nine patients were clinically diagnosed as having a pronator syndrome, i.e., high median nerve compression. The main symptom was pain at the proximal volar aspect of the forearm increasing for several hours after exercise. All patients showed local tenderness over the median nerve 4-5 cm distal to the elbow and pain on active forearm pronation against resistance. Two patients had been previously operated upon for carpal tunnel syndrome. Preoperative routine neurographic-electromyographic studies were normal. In the differential diagnosis, the exclusion of carpal tunnel syndrome and anterior interosseous nerve entrapment is most important. On active isometric forearm pronation, interference with median nerve motor conduction occurred in three patients preoperation. This phenomenon had disappeared following median nerve decompression at the level of the pronator muscle. Fibrous bands from the pronator muscle, encircling the nerve, seemed to be an etiological factor. Eight of nine patients were either improved or recovered completely by surgical treatment.

Contribution of the biceps brachii and pronator teres muscles to the efforts of pronation or supination. II. dynamic work (author's transl)

The electrical activity of the biceps brachii and pronator teres muscles is studied through the prono-supination of the forearm in some anisometrical conditions (dynamic work) when the inertia of the mobile system and the elbow position are being varied. The subjects are required to perform pronation, supination and flexion movements, either isolated or combined. From the findings obtained when the integrated electrical activity (Q) is related to the mechanical work (W), one can conclude that a. the Q-W linear relationship seems to characterize the chief function of a muscle, b. the slope of the Q-W relationship depends on the elbow position, c. the pronator muscles do not inhibit in a selective manner the biceps supinating function. So a bifunctional muscle seems to act as a whole.

Radiology of athletic injuries: baseball.

The radiographs and medical records of 29 professional basebell players from several teams were reviewed. Each player had been selected because of radiographic abnormalities. Abduction views of the shoulder were employed in pitchers and outfielders who complained of shoulder pain. Upper extremity abnormalities predominated and accounted for 22 injuries including avulsion injuries of the origin of the long head of the triceps at the infraglenoid tubercle of the scapula and traction injuries at the origin of the pronator muscles at the medial epicondyle of the humerus. Trauma to the lower extremities was caused by collision with a fixed barrier in one man and by running and sliding in 13 others.