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At least 181 records · Page 10Linked to original sources
PubMed1999

Control of grasp stability during pronation and supination movements.

We analyzed the control of grasp stability during a major manipulative function of the human hand: rotation of a grasped object by pronation and supination movement. We investigated the regulation of grip forces used to stabilize an object held by a precision grip between the thumb and index finger when subjects rotated it around a horizontal axis. Because the center of mass was located distal to the grip axis joining the fingertips, destabilizing torque tangential to the grasp surfaces developed when the grip axis rotated relative to the field of gravity. The torque load was maximal when the grip axis was horizontal and minimal when it was vertical. An instrumented test object, with a mass distribution that resulted in substantial changes in torque load during the rotation task, measured forces and torques applied by the digits. The mass distribution of the object was unpredictably changed between trials. The grip force required to stabilize the object increased directly with increasing torque load. Importantly, the grip force used by the subjects also changed in proportion to the torque load such that subjects always employed adequate safety margins against rotational slips, i.e., some 20-40% of the grip force. Rather than driven by sensory feedback pertaining to the torque load, the changes in grip force were generated as an integral part of the motor commands that accounted for the rotation movement. Subjects changed the grip force in parallel with, or even slightly ahead of, the rotation movement, whereas grip force responses elicited by externally imposed torque load changes were markedly delayed. Moreover, blocking sensory information from the digits did not appreciably change the coordination between movement and grip force. We thus conclude that the grip force was controlled by feedforward rather than by feedback mechanisms. These feedforward mechanisms would thus predict the consequences of the rotation movement in terms of changes in fingertip loads when the orientation of the grip axis changed in the field of gravity. Changes in the object's center of mass between trials resulted in a parametric scaling of the motor commands prior to their execution. This finding suggests that the sensorimotor memories used in manipulation to adapt the motor output for the physical properties of environmental objects also encompass information related to an object's center of mass. This information was obtained by somatosensory cues when subjects initially grasped the object with the grip axis vertical, i. e., during minimum tangential torque load.

Adult↗
PubMed2004

The 45 degrees pronated oblique view for volar fixed-angle plating of distal radius fractures.

Distinctive to volar fixed-angle plating of the distal radius, the optimal position of the distal fixed-angle support is in the subchondral bone immediately proximal to the articular surface. Standard intraoperative radiographic imaging of the distal radius during placement of a volar fixed-angle plate does not provide adequate visualization of the subchondral bone-distal support interface. A 45 degrees pronated oblique view is described to address this specific issue of whether volar hardware placed at the immediate subchondral bone level has effectively avoided the radiocarpal joint. This is a quite important radiographic consideration when pursuing the strategy of volar fixed-angle plating of distal radius fractures.

Adult↗
PubMed2003

The shape of the triangular fibrocartilage during pronation-supination.

We studied the changes in the shape of the triangular fibrocartilage (TFC: disc proper) which occur during forearm rotation in disarticulated and articulated wrists. The influence of artificial 3mm ulnar lengthening on distortion of the disc was also examined. In the disarticulated wrists, slight distortion of the central and radial portions of the TFC was observed in the ulnar neutral variance specimens. More distortion was noted in the radial and central portions of the TFC in specimens with positive ulnar variance or with the ulna lengthened. However, in the articulated wrist, the TFC demonstrated little change in shape during pronosupination even in the ulnar positive variance wrists or with the ulna lengthened. There was no significant change in palmar and dorsal peripheral lengths of the TFC in ulnar neutral, ulnar positive or ulna-lengthened specimens at three rotatory positions of the forearm. These findings suggest that changes in ulnar variance which occur during forearm rotation can produce distortion on the TFC, but the carpus helps to maintain the shape of the TFC during pronation-supination, even with positive ulnar variance.

Aged↗
PubMed1997

Grip and pinch strength variations in different types of workers.

We measured grip and pinch strengths in non-manual, light manual and heavy manual workers using a Jamar dynamometer and a pinch measuring device. Heavy manual workers had the strongest grips with the least difference between sides. Office workers had the weakest grips and the greatest difference between sides. Light manual workers were between these two groups. Consequently, the occupation of the patient must be taken into account when using grip and pinch strength measurements to assess the need for rehabilitation and in medicolegal reports.

Adult↗
PubMed1999

Outcome of surgical treatment for forearm pronation deformities in children with obstetric brachial plexus injuries.

Seven children were operated on for pronation contractures of the forearm due to obstetric brachial plexus injuries. All underwent extensive preoperative evaluations to determine the extent of injury, secondary deformities, and capacity to perform a few basic tasks. Sequential video studies were used to document these findings. Operative procedures performed included various combinations of tendon/muscle lengthenings and/or transfers. Postoperative evaluations focused on function rather than gains in active range of motion and the patient/parental assessment of the benefit of the procedure by response to a questionnaire. All patients were followed for a minimum of I year following surgery. The average gain in active supination was 45 degrees. Each patient showed significant functional gains with a high degree of satisfaction.

Adolescent↗
PubMedDate not supplied

The Young tenosuspension in the treatment of abnormal pronation of the foot.

The intent of this retrospective study was to evaluate the efficacy of the Young tenosuspension for the control of abnormal subtalar joint pronation. Two series of 15 feet of patients aged 10 to 16 years were selected. Patients in the first series had been operated on with a combination of tendo Achillis lengthening and subtalar arthroereisis, while those of the second series had these same procedures along with a Young tenosuspension. All cases had been reviewed in June and July of 1994, both clinically and radiographically. The follow-up period ranged from 1.5 to 8.6 years. The authors found at follow-up a statistically significant improvement in both series of patients. There were no significant differences, however, when comparing the results of the two series with the exception of the reduction in forefoot supination, which was statistically greater (p < 0.05) in patients on which the Young tenosuspension had been performed.

Adolescent↗
PubMed2005

Forearm torque strengths and discomfort profiles in pronation and supination.

This experiment investigated maximum forearm pronation and supination torques and forearm discomfort, for intermittent torque exertions in supine and prone forearm angles for the right arm. Twenty-two subjects participated in the study that comprised two parts, the first of which involved measurement of maximum forearm torque in both twisting directions at five forearm angles including neutral. This was followed by endurance tests at 50% maximum voluntary contraction (MVC) in both directions. The second part of the study involved subjects performing 5-min duration of intermittent isometric torque exercises at 20% MVC in both directions at 11 forearm angles. Regression equations were developed that accurately predict torques as a function of forearm angle expressed as a percentage of maximum motion. Analysis of the discomfort data for the intermittent isometric torque exertions indicated that both forearm angle and twisting direction significantly affected forearm discomfort (p < 0.001). A significant two-way interaction (p < 0.01) was identified between forearm angle and direction for supine forearm angles only. The results provide important strength and discomfort models for the design of tasks involving static or repetitive forearm twisting. Such tasks have a strong association with forearm injuries including lateral and medial epicondylitis. These results provide needed data on the risk factors associated with these injuries so they can be prevented.

Adult↗
PubMedDate not supplied

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.

Acceleration↗
PubMed2001

Bioabsorbable versus stainless steel screw fixation of the syndesmosis in pronation-lateral rotation ankle fractures: a prospective randomized trial.

Thirty-two patients who had pronation-lateral rotation (PLR) fractures occurring four centimeters or more proximal to the ankle joint or lower if the talus was displaced greater than one centimeter laterally were enrolled in this study. Seventeen patients were randomized to fibular plate fixation with a 4.5 ml polylactic acid (PLA) bioabsorbable syndesmotic screw, and fifteen patients randomized to fibular plate fixation with a 4.5 mm stainless steel syndesmotic screw. All thirty-two patients had uncomplicated healing of their fibular fracture without loss of reduction. There was neither evidence of osteolysis nor sterile effusion in the patients who were treated with the PLA screw. There were no wound complications in either group. No difference in range of motion or subjective complaints was noted in either group. Use of the PLA syndesmotic screw at short-term follow-up was well tolerated and avoided the need for subsequent screw removal.

Absorbable Implants↗
PubMed2003

Position of the distal fibular fragment in pronation and supination ankle fractures: a CT evaluation.

BACKGROUND: Although classically the fibula has been reported to be in external rotation after supination-external rotation (SER) or pronation-external rotation (PER) ankle fractures, a previous CT study demonstrated that what had traditionally been interpreted as external rotation of the distal fibular fracture fragment is actually internal rotation of the proximal fibular fragment. The purpose of this study was to evaluate a series of CT scans in patients who have suffered type IV SER or PER ankle fractures to assess the rotational deformity of the fibular fragment. MATERIALS AND METHODS: CT scans of the injured and uninjured extremities were performed on 30 extremities which had sustained either SER (21) or PER (9) injuries. The rotational relationship between the tibia and fibula was determined by a measured rotational ratio. A qualitative assessment of the rotational relationship between the tibia and fibula above, at, and below the fracture site at the level of the mortise was also performed. The difference in the ratio (calculated by subtracting the rotation ratio of the normal side from the fracture side) demonstrated whether the fractured fibula is externally or internally rotated compared to the uninjured side. RESULTS: The average rotational ratio difference above the fracture compared to below the fracture for the SER group demonstrated significant external rotation (p < .001). The PER fracture also demonstrated external rotation of the distal fragment compared to the proximal fragment (p = .002). Additionally, qualitative assessment of the relationship demonstrated no obvious change in the rotational relationship in any patient above the fracture site except one where mild internal rotation of the proximal fragment was noted. However, at the level of the mortise, all had a normal talofibular rotational relationship while 24 of 30 had widening of the medial clear space with external rotation clearly evident on 15 of these 24 scans. CONCLUSION: Our study demonstrated that the distal fibular fragment in both SER and PER fractures is externally rotated relative to both the contralateral normal side and compared to the proximal fibular fragment.

Adult↗
PubMed2000

Effect of foot orthotics on calcaneal eversion during standing and treadmill walking for subjects with abnormal pronation.

STUDY DESIGN: Repeated measures analysis of intervention. OBJECTIVES: To determine the effects of foot orthotics and shoewear on calcaneal eversion for standing and treadmill walking. BACKGROUND: Foot orthotics are commonly used as an intervention for treating lower extremity musculoskeletal pathology. Qualitative research regarding the benefit of foot orthotics tends to be favorable, while the results of quantitative studies often conflict. METHODS AND MEASURES: Eight men (mean age = 35.8 +/- 12.7 years) and 5 women (mean age = 30.4 +/- 10.6 years), who demonstrated abnormal pronation, walked quickly (average velocity = 1.9 m/s) on a treadmill with and without foot orthotics. Subjects were filmed using a 2-dimensional video system and plastic molds designed to indicate calcaneal position inside the shoe during static standing and treadmill walking. RESULTS: Paired t tests indicated that foot orthotics significantly reduced the mean maximum calcaneal eversion angle by 2.2 degrees and the mean calcaneal eversion angle at heel rise by 2.1 degrees during fast walking. Orthotic and nonorthotic conditions did not differ significantly for the remaining kinematic variables. A one-way ANOVA indicated that calcaneal eversion in standing was significantly greater for barefoot standing compared with standing in shoes with or without orthotics. ANOVA also indicated that the plastic molds provided reliable measures of calcaneal position. CONCLUSIONS: Foot orthotics have a significant effect on calcaneal eversion and shoes also should be considered in conjunction with foot orthotic prescription.

Adolescent↗
PubMed1993

Navicular drop as a composite measure of excessive pronation.

The measure of navicular drop has been used as an indicator of pronation at the foot. It is defined as the distance the navicular tuberosity moves in standing, as the subtalar joint is allowed to move from its neutral position to a relaxed position. The purposes of this study were to test the reliability of a method to measure navicular drop and to assess the relationships among measures of forefoot to rearfoot position, subtalar joint neutral position, and navicular drop. The results support traditional biomechanical theory but indicate that other factors contribute significantly to navicular drop.

Adult↗
PubMed1999

The value of the pronated-grip view radiograph in assessing dynamic ulnar positive variance: a case report.

Positive ulnar variance affects surgical decision making when ulnar wrist pain is refractory to conservative treatment and is either secondary to a posttraumatic triangular fibrocartilage tear or associated with ulnar impaction syndrome. In such settings, ulnar recession may be necessary to diminish load transmission across the ulnocarpal joint. We present a case of a 24-year-old man with chronic right ulnar wrist pain that illustrates the efficacy of the pronated-grip radiograph in assessing dynamic ulnar positive variance.

Adult↗
PubMed2001

Biomechanics of pronation and supination of the forearm.

Pronation-supination, the rotation of the forearm around its longitudinal axis, is an important motion because it allows the hand to be oriented, allowing one to take food and carry it to the mouth, perform personal hygiene, and live autonomously. The motion depends on the integrity of two bones, the radius and the ulna, as well as joints, ligaments, and muscles. In every pathological case, as described in this article, the anatomical features must be restored for normal function.

Biomechanical Phenomena↗
PubMed2002

Investigation of the relationship between arch height and maximum pronation angle during running.

A three-dimensional motion analysis study is performed on 8 subjects running on a treadmill. Medical and lateral longitudinal arch height is measured from a weight-bearing x-ray. A statistical analysis is performed to search for a relationship between arch height and maximum angle of pronation. The data analysis showed a significant relationship (sig. level = 0.0252) between the medial longitudinal arch height and the maximum eversion angle. The data analysis also showed a significant relationship between the lateral longitudinal arch height and the maximum eversion angle (sig. level = 0.0358).

Adult↗
PubMed1992

The pronator quadratus muscle flap: coverage of the osteotomized radius following elevation of the radial forearm flap.

Skin-graft take following elevation of the osteocutaneous radial forearm flap has been shown to be difficult. The pronator quadratus muscle flap can be elevated to cover the exposed osteotomized radius and flexor carpi radialis and brachioradialis tendons. This technique is technically easy to perform and may significantly reduce donor-site wound-healing problems.

Adult↗
PubMed2005

Pronation-external rotation ankle fractures in 3 professional football players.

We found no reports of ankle fracture management in professional football players in the orthopedic literature. In this small series of ankle fractures in professional football players, all 3 had the same pronation-external rotation injury pattern. Given the high demands placed on the ankle by these professional athletes, we chose to use a 4.5-mm screw for fixation of the syndesmosis and a 3.5-mm reconstruction plate for fibular fixation to provide the most stable fixation. All 3 athletes were able to return to preinjury levels of athletic participation in the NFL without residual pain or stiffness.

Adult↗
PubMed1991

Cocontraction of the elbow muscles during combined tasks of pronation-flexion and supination-flexion.

The aim of this study was to determine if the antagonist activity of the triceps brachii (TB) and anconeus (AN) muscles is modulated when the activity of the biceps brachii (BB) and brachioradialis (BR) is modulated by the performance of combined tasks and to verify if this behavior is similar at different elbow angles. Electromyographic (EMG) activity of BB, BR, AN and TB was recorded for normal subjects (N = 6) with surface electrodes during a ramp isometric contraction in elbow flexion (F) which was performed alone or combined with 20% of maximal voluntary contraction (MVC) in pronation (P) or in supination (S). Two cocontraction ratios, using the EMG root mean square (rms) values of each muscle and identified as BB/TB and BR/AN were calculated. The results indicate that for low flexion torque levels, the BB/TB ratio is higher for the S-F condition while the BR/AN ratio is higher during the pure flexion task. Variations of the EMG activity across tasks were significant only for BB (Friedman ANOVA, p less than .01) whereas there was no significant change in EMG activity (rms) for TB, BR and AN (Friedman ANOVA, p greater than .01). Furthermore, the behavior of both ratios across tasks was similar at 50 degrees, 90 degrees and 130 degrees of elbow flexion. Thus, for isometric conditions, there appears to be no evidence of modulation of EMG activity of elbow extensors while performing combined tasks of S-F and P-F. In addition, cocontraction activity during these tasks tends to be similar across elbow angles.

Elbow↗