Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Pronation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed2003

Influence of the pronator quadratus and supinator muscle load on DRUJ stability.

PURPOSE: To determine the effects of altering the load contributions of the pronator quadratus and supinator muscles on in vitro distal radioulnar joint (DRUJ) stability during pronation and supination and before and after ulnar head excision. METHODS: Multiple pronation trials were conducted with incremental loading of the pronator quadratus relative to the pronator teres muscle; supination trials were similarly conducted with incremental loading of the supinator relative to the biceps muscle. All trials were conducted using an upper-limb apparatus capable of simulating muscle/tendon loading and displacement. Stability measurements included dorsal-volar translations of the radius relative to the ulna and DRUJ diastasis and convergence. RESULTS: Increased pronator quadratus loading did not affect intact DRUJ stability but effects were noted after ulnar head excision when the forearm was positioned between neutral and full pronation. Incremental loading of the supinator muscle did not modify DRUJ stability in the intact or ulnar head excised state. CONCLUSIONS: Pronator quadratus muscle activity aggravates forearm instability after ulnar head excision. Immobilization of the forearm in mid- to full supination should minimize pronator quadratus activity and optimize soft-tissue healing. This information may be useful to develop in vitro muscle-loading scenarios and analytical forearm models.

Aged↗
PubMed2001

A mechanical study of the moment-forces of the supinators and pronators of the forearm.

We determined the torque generated by the muscles rotating the forearm at varying degrees of pronation and supination. We used 8 human cadaveric upper extremity specimens with the humerus and ulna rigidly fixed with the elbow in 90 degrees of flexion, while free rotation of the radius around the ulna was allowed. The tendons of the flexor carpi ulnaris (FCU), extensor carpi ulnaris (ECU), supinator, biceps, pronator teres (PT), and the pronator quadratus' (PQ) superficial and deep heads were isolated. After locking the forearm at intervals of 10 degrees from 90 degrees of pronation to 90 degrees of supination, we loaded each muscle/tendon with a ramp profile. We found that the biceps and supinator are both active supinators, the biceps generating four times more torque with the forearm in a pronated position. As for pronation, the PT and both heads of the PQ are active throughout the whole rotation, being most efficient around the neutral position of the forearm. The ECU and FCU contribute significantly less to pronation and supination torque. However, they do generate potential pronating torque while the forearm is positioned maximally in supination and, to a lesser extent, potential supination torque while the forearm is positioned maximally in pronation.

Adult↗
PubMedDate not supplied

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.

Electromyography↗
PubMed1994

Hallux valgus, first metatarsal pronation and collapse of the medial longitudinal arch--a radiological correlation.

In a previous study we developed a model to assess first metatarsal pronation based on the position of the inferior tuberosity of its base and showed a significant relationship between first metatarsal pronation and the intermetatarsal angle (r = 0.69, p < 0.001). The present study was undertaken to correlate first metatarsal pronation with the height of the medial longitudinal arch in an attempt to define the clinical significance of this new finding. The weight-bearing anteroposterior and lateral radiographs of the feet of 50 patients (100 feet; 36 females patients of mean age 38 years, 14 males patients of mean age 40 years) were reviewed, and in each case, the patient's age, sex, intermetatarsal angle, amount of first metatarsal pronation and medial longitudinal arch angle were recorded by independent observers. A significant relationship was demonstrated between first metatarsal pronation and the height of the medial longitudinal arch (r = 0.93, p < 0.0001). Less marked association was observed between intermetatarsal angles and first metatarsal pronation (r = 0.71, p < 0.001). Multivariate analysis of patient age, sex, intermetatarsal angle and medial longitudinal arch angle against metatarsal pronation showed that the single most dominant variable affecting metatarsal pronation was the height of the medial longitudinal arch.

Adult↗
PubMed1993

Radiographic features that enable assessment of first metatarsal rotation: the role of pronation in hallux valgus.

This study describes a method of detecting first metatarsal pronation on the basis of the movement of the inferior tuberosity of the base of 20 cadaveric first metatarsals at 0 degrees, 10 degrees, 20 degrees and 30 degrees pronation. On pronation, the inferior tuberosity of the base of the first metatarsal moved lateral to the mid-line axis. At 10 degrees, the tuberosity pointed to the junction of the inner third and outer two-thirds of a line between the midpoint and lateral tubercle of the base. At 20 degrees, it pointed to the junction of the inner two-thirds and outer third of that line. At 30 degrees, it pointed to the outer margin of the lateral third. Using these features, the amount of first metatarsal pronation in 100 consecutive weight-bearing views of feet was recorded and plotted against the corresponding intermetatarsal angles in those feet. Four of 43 patients with an intermetatarsal angle of less than 9 degrees had pronation greater than 10 degrees, 48 of 57 patients with an intermetatarsal angle greater than 9 degrees had pronation greater than 10 degrees (P < 0.001). As intermetatarsal angles increase, the amount of first metatarsal pronation increases (r = 0.69). Pronation and varus deviation of the first metatarsal are linked; both alter the tendon balance maintaining proximal phalanx alignment and lead to the development of hallux valgus.

Hallux Valgus↗
PubMedDate not supplied

Dorsal transfer of the brachioradialis to the flexor pollicis longus enables simultaneous powering of key pinch and forearm pronation.

PURPOSE: To show biomechanically that the brachioradialis (BR) muscle can be transferred to restore key pinch and forearm pronation simultaneously. METHODS: Nine fresh-frozen forearms were thawed and instrumented with a custom muscle-tendon excursion jig. Maximum BR muscle-tendon excursion was measured with the wrist and thumb mobile. Muscle-tendon excursion then was measured from 60 degrees of supination to 60 degrees of pronation in 15 degrees increments with the wrist and thumb fixed. Measurements were performed in 3 configurations: the native BR, the BR transferred volarly to the flexor pollicis longus (FPL) tendon, and the BR transferred dorsally (posterior to the radius) through the interosseous membrane to the FPL tendon. Muscle excursion-joint angle data were differentiated to compute pronation/supination moment arms. Two-way analyses of variance and post hoc Tukey tests were used to compare transfer conditions. RESULTS: Maximum muscle excursion was nearly identical when volar and dorsal transfer conditions were compared. When pronation/supination motions were isolated, however, the volar transfer was associated with muscle shortening and small pronation moment arms through 30 degrees +/- 9 degrees of supination. Importantly, the dorsal transfer was associated with muscle shortening and larger pronation moment arms through 28 degrees +/- 10 degrees of pronation, a significant difference of 58.0 degrees +/- 16.0 degrees compared to the traditional volar transfer. CONCLUSIONS: These data suggest that dorsal BR-to-FPL transfers can power key pinch and forearm pronation simultaneously even in the absence of other functional pronators. This transfer can be accomplished without changes to total muscle excursion compared with the traditional volar BR-to-FPL transfer. This result may enable the use of the BR-to-FPL transfer in patients who need key pinch but who lack functional pronation muscle groups (eg, ocular cutaneous 3). As result a larger patient population may benefit from the BR-to-FPL reconstructive procedure.

Aged↗
PubMed2007

Assessment of forearm pronation strength in C6 and C7 radiculopathies.

STUDY DESIGN: Consecutive case series of patients with C6 and C7 radiculopathies. OBJECTIVES: To explore the clinical utility and reliability of manual muscle testing of forearm pronation strength in C6 and C7 radiculopathies. SUMMARY OF BACKGROUND DATA: EMG evidence of denervation of the pronator teres was the most common finding in C6 radiculopathies, and frequently present in C7 radiculopathies. Clinical evaluation of the pronator teres through manual muscle testing of forearm pronation has never been explored; therefore, its clinical utility is unknown as compared with the muscle groups that are traditionally evaluated. METHODS: Fifty-five subjects with diagnostic imaging evidence of either C6 (n = 25) or C7 (n = 30) cervical root compression and clinical symptoms consistent with cervical radiculopathy were recruited for this study. These subjects underwent manual muscle testing of forearm pronation, wrist extension, elbow flexion, and elbow extension. The frequency of impaired strength was recorded and compared for C6 and C7 radiculopathies. A second examiner evaluated each subject, with his or her findings compared with the first examiner only for the determination of interrater reliability. RESULTS: In C6 radiculopathy subjects, forearm pronation weakness was present in 72%, was twice as common as wrist extension weakness, was present in all cases where elbow flexion or wrist extension weakness was noted, and was found in all but 2 subjects where elbow extension weakness was present. In C7 radiculopathy subjects, forearm pronation weakness accompanies elbow extension weakness in 23% of subjects and was the only weakness in 10% of subjects. Manual muscle testing demonstrated adequate interrater reliability. CONCLUSIONS: Forearm pronation weakness is the most frequent motor finding in C6 radiculopathies and may be noted is some cases of C7 nerve root compression.

Adult↗
PubMed1985

The flexor function of the m. pronator teres in man: a quantitative electromyographic study.

The muscle pronator teres was studied by surface electromyography during elbow flexion in a horizontal plane. The forearm was in semi-pronation and movement was performed at various velocities. A quantitative comparison was made between pronator teres activity and two main elbow flexors, biceps brachii and brachioradialis. The mean timing of the onset of activity was constant: biceps brachii was activated first followed by pronator teres and brachioradialis, and the lower the velocity of flexion, the earlier was the onset of biceps brachii activity. There was a linear relationship between the integrated EMG from each muscle and the work done. However, this relationship was less exact for pronator teres and brachioradialis at low values of work, a finding which opens questions about the generality of this relationship and about the "muscle equivalent" concept. Pronator teres appears to participate in elbow flexion besides its role in pronation. Despite similar anatomical peculiarities, pronator teres does not behave in the same way as anconaeus or popliteus and, above all, it is not the sole muscle active in slow movement. Thus, all the stocky muscles lying close to an articulation do not behave in the same way.

Adult↗
PubMed2006

Pronator teres rerouting in children with cerebral palsy.

PURPOSE: The forearm in children with cerebral palsy often assumes uncontrolled dynamic positioning in pronation when the hand is put into use. This hypertonic positioning seems to be an expression of dystonia rather than spasticity. This article reports the effect of pronator teres rerouting (PTR) using the technique of tendon Z-lengthening and repair on active motion and on forearm positioning during use. METHODS: Thirty-one patients who had pronator teres rerouting were observed before and after surgery for active and passive forearm range of motion, changes in dynamic forearm positioning, and the performance of 5 functional tasks related to forearm rotation. The primary indication for surgery was pronation positioning of 25 degrees or greater because that positioning precludes grasping a glass or cup of water. RESULTS: The follow-up period averaged 39 months. The average active supination increased 65 degrees, and the average dynamic positioning changed from 26 degrees pronation to 7 degrees pronation. Thirty of the 31 patients gained the ability to hold a cup of water in the involved hand. Nine children positioned the hand in supination during grasp. CONCLUSIONS: Pronator teres rerouting improves both active supination and dynamic forearm positioning in children with cerebral palsy. The use of the technique described in the literature resulted in slight overcorrection of forearm positioning in the nine children. This finding is consistent with the concept that positioning disorders are at least partly dystonic rather than spastic. It is recommended that the transfer be tensioned more loosely in children who have excessive dynamic hypertonia. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic, Level IV.

Adolescent↗
PubMed2000

Normal kinematics of the interosseous membrane during forearm pronation-supination--a three-dimensional MRI study.

We studied in vivo dynamic shape changes of the interosseous membrane (IOM) during forearm rotation using three-dimensional magnetic resonance imaging (3D-MRI), and simultaneously analysed 3D-motion of the forearm rotation. Wavy deformities were seen in the IOM in the pronated position, and similar small changes were also seen at maximum supination (average 82 degrees ) and in the neutral position. These dynamic changes mainly occurred in the membranous part of the IOM, whereas the tendinous part demonstrated minimal dynamic changes during rotation in all subjects. On the dorsal aspect, deformity around the dorsal oblique cord was seen at maximum pronation. From this 3D-MRI observation, the tendinous part is considered to be taut during rotation to provide stability between the radius and ulna, because of its straightness and less dynamic changes. The more deformable membranous part is important to allow for smooth rotation, since it lies at a distance from the rotation axis. Inelasticity developing in the membranous part from trauma may pre-dispose to pronation-supination contracture. The radius rotated around the ulna from maximum supination to 45 degrees pronation. At maximum pronation (average 75 degrees ), the radius translated average 1.8 mm palmarly and rotated average 4.0 degrees ulnarward on the ulna. Incongruity of the distal radioulnar joint, contraction of the pronator quadratus and torsion between the radius and ulna at maximum pronation may produce this irregular motion of the radius and cause the dynamic changes of the IOM.

Adult↗
PubMed2001

The relationship between excessive pronation as measured by navicular drop and isokinetic strength of the ankle musculature.

EMG research has shown that excessive pronation affects the timing and magnitude of extrinsic muscle activity. This study was designed to investigate the relationship between excessive pronation and isokinetic strength of the ankle. The following measures were performed on 24 subjects (12 pronators, 12 normals) matched for gender and weight: 1) plantarflexion, dorsiflexion, inversion and eversion strength, both eccentrically and concentrically, determined by isokinetic peak torque at 30 degrees/sec; and 2) excessive pronation determined by navicular drop. Subjects with excessive pronation were found to have no difference in invertor strength, but decreased concentric plantarflexion strength when compared to normals. This finding agrees with biomechanical theory suggesting that a pronated foot is less rigid and generates less torque. Differences in strength ratios in excessive pronators were also observed and attributed to the decrease in plantarflexion strength.

Adult↗
PubMed1985

The pronation capacity of the foot--its consequences for axial deformity after tibial shaft fractures.

In spite of the fact that discomfort from the subtalar area is common after varus-deformed tibial shaft fractures no plausible mechanism is to be found in the literature. A mechanical analysis of the problems shows that a varus deformity is compensated as pronation of the foot. A limited pronation capacity could thus be the cause of the pain. Pronation capacity was accurately measured in ten osteoligamentous preparations. The average pronation capacity was found to be 9.5 degrees +/- 7.0 degrees. There was a marked interindividual variation. In two of the specimens the pronation capacity was less than 1 degree. Capacity decreased by 0.21 degree for every degree increase in plantar flexion of the ankle joint. Thus, a small pronation capacity may be the mechanical basis for ankle complaints after varus-deformed tibial shaft fractures. An anterior angulation, compensated as planar flexion, further decreases the pronation capacity and adds to the risk associated with varus deformities.

Aged↗
PubMed1998

A comparison of three-dimensional lower extremity kinematics during running between excessive pronators and normals.

OBJECTIVE: The purpose of this research was to compare the three-dimensional kinematics of runners exhibiting excessive rearfoot pronation with those having normal rearfoot pronation. DESIGN: The study design was a comparative investigation of two types of running patterns. BACKGROUND: Excessive rearfoot pronation is often linked with overuse injuries of the lower extremity. However, the literature is void of papers describing the rearfoot motion of runners presenting with excessive rearfoot pronation. Many knee-related injuries in runners are associated with increased rearfoot pronation; however, knee mechanics in this population of runners have yet to be studied. Finally, three-dimensional studies are needed to describe joint motion fully during running and these are also lacking. METHODS: Eighteen subjects (nine excessive pronators -- PRs; nine normals -- NLs) were studied during treadmill running at 3.35 m/s. Retroreflective markers were placed on the foot, shank and thigh segments and recorded with four 200 Hz video cameras. Three-dimensional kinematics were computed. RESULTS: A downward shift of the eversion curve was seen in the PR group resulting in an everted position of the rearfoot at both footstrike and toe-off compared with an inverted posture seen in the NL group. The amount of toe-out was not significantly different between the two groups. At the knee, the PR group demonstrated significantly less adduction and significantly greater flexion than the NL. Mean peak velocities of the PR group were greater in all angular measures except knee adduction. However, only foot dorsiflexion and eversion and knee flexion velocities were significantly different. CONCLUSIONS: Kinematic differences were noted at both the rearfoot and the knee of the runners who exhibit excessive rearfoot pronation.

Journal Article↗
PubMed1999

Cadaveric modeling of the pronator teres rerouting tendon transfer.

The purpose of this study is to report the biomechanics of the supination effect of the pronator teres rerouting procedure and to determine the optimum insertion point for the transfer using a cadaveric model. Pronator teres rerouting procedures were performed on 5 fresh-frozen above-elbow cadaver specimens mounted in a forearm rotation mounting frame. The pronator teres was detached from its native insertion and tested at 6 insertions on the radius. The amount of rotation of the forearm was measured after loading of the pronator teres muscle for each insertion site. The experiments were repeated by placing the pronator teres 1 cm proximal to the 6 experimental insertion sites for a total testing of 12 insertions. The results of this study show that placement of the pronator teres through the interosseous membrane, around the radius, with reinsertion onto the volar surface produced the greatest amount of forearm supination. Rerouting of the pronator teres tendon produces supination through a windlass effect when the tendon is rerouted through an interosseous window and reinserted onto its original insertion or onto the volar surface of the radius. Placement of the insertion 1 cm proximal on the radius did not affect the amount of forearm supination compared with 6 original insertion sites.

Biomechanical Phenomena↗
PubMed1985

Brief or new: two pronation splints.

For two years we have made pronation splints to assist quadriplegic patients who lack adequate forearm pronation but who have enough upper extremity strength to feed themselves and perform other self-care or functional activities. We have found the splints to be an appropriate alternative to the MAS. The first pronation splint fits underneath the arm, is simple in design and fabrication, and is hidden. However, occasionally the lever of the splint hangs up in the shirt, catches on the post of the wheelchair, or slips out from underneath the arm when the patient reaches away from the body. To eliminate these problems, we designed a second splint. But, this splint requires more time to make and adjust, has two parts to put on instead of one, and is more noticeable because it is worn on top of the arm rather than underneath it. When a patient uses either splint, the degree of pronation may be adjusted according to the activity by slightly rotating the splint either way when strapping it on. For example, full pronation may be required for feeding, but only half the range is necessary to operate the keyboard of a computer or typewriter. Once the Velcro straps are applied, the splints do not slip. The splints are not interchangeable from left to right and assistance is always needed to put them on. For patients with "weak" or "absent" wrist extensors, a wrist support and cuff splint may be used along with the pronation splint or a universal cuff, if wrist extension is adequate. The pronation splints are appropriate for those patients whose forearms supinate when they reach their hand to or near their mouth.

Equipment Design↗
PubMed1987

Atypical electromyographic findings in pronator teres syndrome.

The electrodiagnostic differentiation between pronator teres syndrome and entrapment of the median nerve at the ligament of Struthers is generally thought to be aided by the absence of electromyographic (EMG) findings in the pronator teres muscle in pronator syndrome. This report describes a patient with surgically documented pronator teres syndrome who had EMG changes in the m. pronator teres, which was apparently innervated as or after the median nerve passed through. It is concluded that EMG abnormalities in the m. pronator teres should not alone be used to distinguish pronator teres syndrome from entrapment of the median nerve at the ligament of Struthers.

Diagnosis, Differential↗
PubMed1991

The free moment of ground reaction in distance running and its changes with pronation.

Many running injuries are successfully treated with footwear modifications designed to reduce pronation, but the underlying mechanism of treatment is not well understood. Previous attempts to correlate reduction in pronation with changes in ground reaction parameters have been unsuccessful. In this study, the free moment of ground reaction (Mz') was measured for 10 rearfoot strikers running at 4.5 m s-1 in each of three different pairs of running shoes designed to vary the extent of pronation during ground contact. Mz' patterns were highly variable between feet, but were repeatable within a given foot/footwear combination. Mz' was greatest in magnitude during the first half of support, when it acted in a direction resisting foot abduction, a component of pronation. It was opposite in sign and smaller in magnitude during the last 30% of support. The peak magnitude and the net angular impulse of Mz' were both increased significantly with increases in pronation. A net ground reaction moment was also calculated about a vertical axis fixed in the shoe, and was used in a first approximation model of the shoe/ground interface to predict when the foot is most likely to ab/adduct during running. In conclusion, this study characterized the Mz' pattern for a well-defined group of runners, and found that Mz' is sensitive to relatively large within-subject changes in pronation.

Adult↗
PubMedDate not supplied

Anatomy of the anterior interosseous innervation of the pronator quadratus: evaluation of structures at risk in the single dorsal incision wrist denervation technique.

PURPOSE: Patients with chronic wrist pain often are treated with wrist denervation, which typically involves transecting both the anterior interosseous nerve (AIN) and the posterior interosseous nerve. A single dorsal incision approach is an improvement over the more traditional multiple-incision technique. The purpose of our study was to describe the branches of the AIN to the pronator quadratus and evaluate the risk of denervation with the single dorsal incision technique. METHODS: Twelve fresh-frozen cadaver forearms were dissected. The branches of the AIN to the pronator quadratus were identified and the individual branch points were measured from the articular edge of the distal radius. Wrist denervation was then performed on each specimen through the single dorsal incision (as suggested by Berger). RESULTS: There were an average of 3 branches from the AIN to the pronator quadratus. All forearms had at least 1 branch to the pronator quadratus more proximal to the distal end of the dorsal skin incision; however, in only 2 of the forearms was the most proximal branch more than 2 cm proximal to the distal end of the dorsal skin incision. CONCLUSIONS: Wrist denervation through the recommended single dorsal incision poses a serious risk for completely denervating the pronator quadratus. Therefore the resection of the AIN must be performed close to the distal margin of the pronator quadratus.

Denervation↗