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The pronator syndrome. An evaluation of dynamic maneuvers for improving electrodiagnostic sensitivity.

The role of three test maneuvers (elbow flexion, forearm pronation and finger flexion against resistance) in improving sensitivity of conventional nerve conduction studies used in cases of suspected pronator teres syndrome were evaluated in 11 healthy control subjects and 10 patients with the clinical diagnosis of pronator teres syndrome. Stimulation of the median nerve was performed above and below the elbow before exercise and immediately after the test maneuvers; the resultant median motor and sensory responses were recorded. Before and after exercise, median motor and sensory responses (e.g., amplitude, latency, velocity) did not differ significantly between the two groups; only one patient with suspected pronator teres syndrome developed sensory amplitude changes after exercise. We concluded that these test maneuvers did not significantly improve the sensitivity of conventional nerve conduction studies in the diagnosis of pronator teres syndrome.

Adult↗

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.

Adult↗

Kinematics of the ulna during pronation and supination in a cadaver study: implications for elbow arthroplasty.

OBJECTIVE: Aim of this study was to exactly describe and quantify kinematics of the ulna during pro- and supination. DESIGN: Biomechanical study in fresh frozen cadavers. BACKGROUND: A previous MRI study revealed a varus/valgus motion of the ulna averaging 7.1 degrees during pro-/supination. Axial rotation, however, could not be quantified. METHODS: Sixteen arms were examined in a new apparatus that fixed the humerus on a template and allowed forearm rotation. Motion of a Kirschner wire placed in the ulna was recorded in steps of 30 degrees by two perpendicularly arranged charge coupled device cameras during pro- and supination. RESULTS: From supination to pronation the ulna showed a semi-lunar evasive motion in the coronal and transverse plane with an initial varus shift, then a dorsal and finally a valgus shift. Motion in the coronal plane averaged 14.14 degrees (SD 4.78). Valgus angles of the ulna in 30 degrees, 60 degrees and 90 degrees pronation were significant (P<0.05) to each other and the neutral position. Varus angles of the ulna in 30 degrees, 60 degrees and 90 degrees supination (P<0.01) were significant to each other and the neutral position.A maximum ulnar axial pronation rotation of 3.2 degrees (SD 2 degrees ) was noted. Axial rotation angles of 90 degrees and 60 degrees of pronation were significant to each other and to the neutral position (P<0.05), respectively. CONCLUSIONS: To prevent increased stress on the bone-cement interface in elbow arthroplasty, a mean axial rotation of at least 3.2 degrees should be possible.

Arthroplasty, Replacement↗

Surgery for cerebral palsy: Part 1. Classification and operative procedures for pronation deformity.

32 patients with cerebral palsy underwent operations for pronation deformity. The deformity is classified into four groups. Patients in group 1 are capable of supination beyond neutral. No surgery is necessary. Those in group 2 are able to supinate to the neutral position. A pronator quadratus release is advised and may be combined with a flexor aponeurotic release. In group 3, patients have no active supination. However a full range of passive supination is readily achieved. A pronator teres transfer is advised. Patients in group 4 have no active supination. Full passive supination may be present, but is tight. A flexor aponeurotic release and a pronator quadratus release may unmask active supinator activity. An active transfer for supination is possible as a secondary procedure.

Adolescent↗

The importance of the pronated grip x-ray view in evaluating ulnar variance.

Although dynamic increases in ulnar variance may accompany functional activity, radiographic assessment of ulnar variance traditionally has used a neutral rotation x-ray of the wrist that provides an image of the radioulnar length with the wrist unloaded. Such a view may underestimate variance in wrists in which power grip and pronation result in significant proximal migration of the radius. This study investigates the effect of a maximum grip effort in combination with forearm pronation on ulnar variance in 22 patients who presented with ulnar wrist pain. The pronated grip x-ray view resulted in statistically significant increases in ulnar variance. Preoperative ulnar variance should be measured using both neutral rotation and pronated grip x-rays before selecting treatment for causes of ulnar wrist pain that are affected by radioulnar length so that dynamic increases in ulnar variance are considered when operative treatment is necessary.

Adolescent↗

Flexor digitorum superficialis nerve transfer to restore pronation: two case reports and anatomic study.

Loss of pronation affects most activities of daily living. We report 2 cases of traumatic loss of pronator teres function and successful reconstruction by transfer of a redundant motor branch to the flexor digitorum superficialis to the pronator teres branch(es). Follow-up period was 2 years and pronation strength was restored to +4/5 and 5/5 in the 2 patients. The anatomy of the median nerve in the proximal forearm was examined by dissecting 31 cadaver specimens. A branching scheme was formulated. The histomorphometric properties of the individual muscular branches were studied in 15 fresh specimens to evaluate their suitability and size match for nerve transfer.

Accidents, Traffic↗

Transfer of flexor carpi ulnaris branch of the ulnar nerve to the pronator teres nerve: histomorphometric analysis.

Partial median-nerve injury high in the upper extremity, resulting from brachial plexus neuritis or trauma, can affect the pronator teres muscle and result in the inability to pronate the forearm. A nerve transfer from an ulnar nerve-innervated branch to the flexor carpi ulnaris (FCU) muscle to the branch to the pronator teres (PT) is an attractive option in this clinical scenario. This study, a histomorphometric analysis of nine cadaver specimens harvested at the proposed FCU branch to PT branch transfer site, demonstrates sufficient similarities between the two branches in total number of nerve fibers (371.6 with SEM 35.1, and 361.9 with SEM 47.1; p = 0.87) and nerve cross-sectional area (122,181 microm2 with SEM 14,546 microm2, and 142,492 microm2 with SEM 19,633 microm2; p = 0.42), to predict a functional transfer result. In addition, clinical application of this transfer resulted in functional pronation strength of M4+.

Aged↗

Pronator teres reflex: reliability and normal value.

The pronator reflex has been used clinically and electrophysiologically to evaluate the sixth and seventh cervical roots (C-6, C-7). This has been proven to be the result of stretching the pronator teres muscle. We examined 25 healthy individuals with surface electromyogram to establish electrophysiologically the reproducibility and reliability of this reflex, in addition to finding the 95% confidence interval (C.I.) for the latency for both males and females and to correlate it with the arm length. Standard procedure was used for all people. To elicit the pronator teres reflex, the volar report of the distal radius was struck by the hammer with the forearm in neutral position and the elbow flexed at 90 degrees. The response was pronation of the forearm. A reproducible diphasic response was found in all individuals. The mean latency was 15.9 (+/-1.3) ms with the 95% C.I. 16.8 for females and 17.4 (+/- 1.4) ms with the 95% C.I. 18.7 for males. The data were collected to be used for further evaluation of C-6, C-7 radiculopathy.

Adult↗

Comparison of foot pronation and lower extremity rotation in persons with and without patellofemoral pain.

Abnormal foot pronation and subsequent rotation of the lower extremity has been hypothesized as being contributory to patellofemoral pain (PFP). The purpose of this study was to test the hypothesis that subjects with PFP would exhibit larger degrees of foot pronation, tibia internal rotation, and femoral internal rotation compared to individuals without PFP. Twenty-four female subjects with a diagnosis of PFP and 17 female subjects without PFP participated. Three-dimensional kinematics of the foot, tibia, and femur segments were recorded during self-selected free-walking trials using a six-camera motion analysis system (VICON). No group differences were found with respect to the magnitude and timing of peak foot pronation and tibia rotation. However, the PFP group demonstrated significantly less femur internal rotation compared the comparison group. These results do not support the hypothesis that individuals with PFP demonstrate excessive foot pronation or tibial internal rotation compared to nonpainful individuals. The finding of decreased internal rotation in the PFP group suggests that this motion may be a compensatory strategy to reduce the quadriceps angle.

Adolescent↗

Effects of rearfoot-controlling orthotic treatment on dorsiflexion of the hallux in feet with abnormal subtalar pronation: a preliminary report.

The aim of this study was to determine whether the treatment of abnormal subtalar pronation restores functional (as opposed to structural) limited dorsiflexion of the first metatarsophalangeal joint (functional hallux limitus). We studied 16 feet of eight individuals with abnormal subtalar pronation. Orthoses were made for all of the feet, and hallux dorsiflexion was measured during weightbearing. Each patient was unshod without the orthosis, unshod with the orthosis fitted on the same day, and unshod with the orthosis fitted approximately 5 months later. The results suggest that in functional hallux limitus caused by abnormal subtalar pronation, hallux dorsiflexion will gradually be restored by the use of foot orthoses to control the abnormal subtalar pronation.

Adult↗

Pronation. The orthotist's view.

Pronation of the foot is one of the commonest reasons for prescribing orthotics for the lower extremity. Many different bracing systems are available for the management of this complex problem. To select the most efficient method for a given case, the healthcare professional and the orthotist must have a firm understanding of the pathophysiology of pronation and the special requirements of each patient. Additionally, the medical condition resulting in pronation and necessitating bracing may alter after the selection of the orthoses. Selection of cases for treatment depends on the type, because pronatory deformities can be grouped according to markers that are cause specific. The use of orthotic therapy as a modifier of the natural history in simple pronation remains controversial.

Biomechanical Phenomena↗

The pronator compression test revisited. A forgotten physical sign.

Pronator compression testing is a valuable clinical feature of median nerve entrapment diagnosis. Of 10 patients with this disorder, all developed paresthesias preoperatively in the hand after 30 seconds or less of manual compression of the median nerve at or near the pronator muscle. Eight patients had a positive Tinel's sign at the impingement site, but only one patient had a positive electromyographic result. More than 50% of the patients had undergone previous carpal tunnel release or were diagnosed at presentation with double crush syndrome. All patients had a good or excellent result from surgical decompression of the median nerve in the forearm, except for one workers' compensation case who had excellent postoperative strength testing but multiple residual complaints. Pronator compression testing is a helpful and dependable physical sign in the diagnosis of pronator syndrome.

Carpal Tunnel Syndrome↗

Anterior interosseous nerve syndrome presenting with pronator teres weakness: a case report.

Anterior interosseous nerve syndrome (AINS) has been well described. A key muscle to examine clinically and on electromyography is the pronator teres, as this can differentiate between forearm and more proximal entrapment sites. We present a case of AINS with marked weakness and denervation of pronator teres. At operation the anterior interosseous nerve gave rise to the nerve to pronator teres and was entrapped by a fibrous band from the deep head of pronator teres.

Adult↗

Median nerve entrapment. Pronator teres syndrome. Surgical anatomy and correlation with symptom patterns.

The surgical anatomy of interest in the pronator teres syndrome was studied to shed light on the ramifying pattern of the median nerve, the number of its muscular branches and their branching levels and to pinpoint the location of the fibrous bands which may cause median nerve entrapment. The fibrous arch of the pronator teres muscle (pronator arch) was found to lie 3 cm to 7.5 cm below Hueter's line, that of the flexor digitorum superficialis muscle (superficialis arch), which is distal to the pronator arch, was found to lie 6.5 cm below Hueter's line in its most proximal position. Symptom patterns in terms of muscle weakness caused by median nerve entrapment at different levels were also evaluated.

Arm↗

Distal radio-ulnar ligament motion during supination and pronation.

The dorsal and palmar distal radio-ulnar ligaments (DRUL) play an important role in the stability of the distal radio-ulnar joint (DRUJ). Various authorities, however, hold opposite opinions regarding DRUL motion during DRUJ pronation and supination, thus implying opposite techniques for reconstruction of the unstable DRUJ. With the hypothesis that relative displacement would increase in the dorsal DRUL during pronation and would increase in the palmar DRUL during supination, measurements were made of the relative DRUL displacement with a Hall-effect displacement transducer during DRUJ pronation and supination in six fresh cadaver wrists. The hypothesis was confirmed that the dorsal radio-ulnar ligament undergoes relative displacement during pronation, while the palmar radio-ulnar ligament undergoes relative displacement during supination.

Aged↗

Co-contraction of the pronator teres and extensor carpi radialis during wrist extension movements in humans.

In order to elucidate the functional significance of excitatory spinal reflex arcs (facilitation) between musculus (M.) pronator teres (PT) and M. extensor carpi radialis (ECR, longus: ECRL, brevis: ECRB) in humans, activities of the muscles were studied with electromyography (EMG) and electrical neuromuscular stimulation (ENS). In EMG study, activities of PT, ECRL, ECRB, and M. flexor carpi radialis during repetitive static (isometric) wrist extension and a series of a dynamic motion of wrist flexion/extension in the prone, semiprone, and supine positions of the forearm were recorded in 12 healthy human subjects. In the prone, semiprone, and supine positions, PT and ECR showed parallel activities during the static extension in all, eight, and eight subjects, respectively, and at the extension phase during the dynamic motion in all, eight and five subjects, respectively. These findings suggest that co-contraction of PT and ECR occurs during wrist extension movements at least with the prone forearm. The facilitation must be active during the co-contraction. In ENS study, ENS to PT was examined in 11 out of the 12 and that to ECRL was in the 12 subjects. Before ENS, the forearm was in the prone, semiprone, and supine positions. In all the subjects, ENS to PT induced a motion of forearm pronation to the maximum pronation. ENS to ECRL induced motions of wrist extension to the maximum extension and abduction (radial flexion) to 5-20 degrees of abduction regardless of the positions of the forearm. Moreover, it induced 30-80 degrees supination of the forearm from the prone position. Consequently, combined ENS to PT and ECRL resulted in motions of the extension and abduction while keeping the maximum pronation. These findings suggest that the co-contraction of PT and ECR during wrist extension movements occurs to prevent supinating the forearm. Forearm supination from the prone position should be added to one of the actions of ECRL.

Adult↗

Three-dimensional video analysis of forearm rotation before and after combined pronator teres rerouting and flexor carpi ulnaris tendon transfer surgery in patients with cerebral palsy.

The effect of combined pronator teres rerouting and flexor carpi ulnaris transfer on forearm rotation was prospectively studied by comparison of pre- and postoperative three-dimensional analysis of forearm range of motion in ten patients with cerebral palsy. One year postoperatively, surgery had improved maximal supination of the forearm in all patients by an average of 63 degrees, but there was also a mean loss of 40 degrees pronation. Forearm range of motion increased by a mean of 23 degrees. The centre of the range of motion on average shifted 52 degrees in the direction of supination. Based on these results of objective forearm range of motion analysis, we conclude that the common combination of pronator teres rerouting and flexor carpi ulnaris transfer in patients with cerebral palsy effectively facilitates active supination but impairs active pronation.

Adolescent↗

The stabilizing mechanism of the distal radioulnar joint during pronation and supination.

A biomechanical cadaver study was performed to determine the roles of the stabilizing structures of the distal radioulnar joint during pronation and supination. Subluxation and dislocation of the radius with respect to the ulna were evaluated in seven cadaver forearms placed in supination, pronation, and neutral forearm rotation. The amount of subluxation was measured with all structures intact, and after sectioning in various sequences the dorsal and palmar radioulnar ligaments, the distal portion of the interosseous membrane including the pronator quadratus, and the entire interosseous membrane. After sectioning two of any four structures, the distal radioulnar joint remained stable. When the interosseous membrane was disrupted first, the dorsal radioulnar ligament was found to be more important than the palmar radioulnar ligament in stabilizing the distal radioulnar joint in pronation, and conversely the palmar radioulnar ligament was more important than the dorsal radioulnar ligament in supination. Dislocation, and frequently diastasis, occurred only with sectioning of all four structures. This suggests that all four structures contribute to stability of the distal radioulnar joint.

Biomechanical Phenomena↗