Elbow Flexion Angle Research Articles

3. The Relationship Between Functional Reach and the Angle of Elbow Flexion (as Part of Associated Reaction) in the Hemiplegic Person Elia Panturm, RPT, MEd, and Orit Elion, RPT (Jerusalem, Israe

3. The Relationship Between Functional Reach and the Angle of Elbow Flexion (as Part of Associated Reaction) in the Hemiplegic Person Elia Panturm, RPT, MEd, and Orit Elion, RPT (Jerusalem, Israe

The effects of work load and operation position on the spine during manual activity

The objective of this research is to provide designers with efficient work posture guidance for the design of workplaces. Analysis of data produced through the use of electromyography (EMG) facilitated the achievement of this objective. In the experimental study, essential anthropometric data such as body link length, elbow flexion angles, body weight, and load weights were collected on the basis of a static 2-dimensional model. Three different load weights and carrying positions were considered, and the muscle activity of the back musculature was recorded with EMG. The relationships among normalized EMG levels, muscle forces, compression forces, and moments were analyzed. Finally, a linear regression equation of muscle forces at normalized EMG levels, as well as a quadratic regression equation of normalized EMG levels on load weights and carrying positions, was developed. © 1999 John Wiley & Sons, Inc

The Effect of Elbow Position on the Radial Pulse Measured by Doppler Ultrasonography After Surgical Treatment of Supracondylar Elbow Fractures in Children

We performed a prospective study of 20 patients with displaced extension supracondylar humerus fractures and evaluated the effect of elbow flexion, forearm supination, and forearm pronation on blood flow to the injured arm after closed reduction and Kirschner wire fixation. Ten patients had a Gartland type II fracture and 10 patients had a Gartland type III fracture. After closed reduction and percutaneous pinning, the radial pulse was examined with Doppler ultrasonography starting with the elbow in extension. The elbow was slowly flexed, and the angle of elbow flexion at which the radial pulse disappeared was determined. This angle of elbow flexion was measured with the forearm in both supination and pronation. Gartland type III fractures demonstrated less elbow flexion prior to radial pulse ablation compared to Gartland type II fractures when the forearm was placed in supination (p = 0.001) and in pronation (p = 0.005). Supination allowed > or = 5 degrees of elbow flexion prior to radial pulse ablation in six Gartland type II and four Gartland type III fractures. We concluded that after closed reduction and percutaneous Kirschner wire fixation of displaced extension supracondylar fractures, vascular safety is enhanced by extending the elbow and supinating the forearm. The ideal position of elbow immobilization depends on the amount of swelling and the presence of a radial pulse.

Radioulnar load-sharing in the forearm. A study in cadavera.

Custom-designed miniature load-cells were inserted into the distal end of the ulna and the proximal end of the radius in ten fresh-frozen forearms from cadavera. The forces transmitted through the bones at these sites were measured under 134 newtons of constant axial load that was applied through the metacarpals as the forearm was rotated from 60 degrees of supination to 60 degrees of pronation. The simultaneous measurements of these forces allowed the calculation of radioulnar load-sharing at the wrist and the elbow as well as the calculation of the amount of force that was transferred from the radius to the ulna through the interosseous membrane. With the elbow in valgus alignment (that is, with contact between the radial head and the capitellum), the main pathway for load transmission through the forearm was direct axial loading of the radius; measurements from both load-cells were unaffected by the angle of elbow flexion. When the forearm was in neutral rotation, the mean force in the distal end of the ulna averaged 2.8 per cent of the load applied to the wrist and the mean force in the proximal end of the ulna averaged 11.8 per cent; this indicated that only a small amount of tension developed in the interosseous membrane. With the elbow in varus alignment (that is, with no contact between the radial head and the capitellum), load was transmitted through the forearm by a transfer of force from the radius to the ulna through the interosseous membrane. When the forearm was in neutral rotation, the force in the distal end of the ulna averaged 7.0 per cent of the load applied to the wrist and the force in the proximal end of the ulna averaged 93.0 per cent; the force through the interosseous membrane decreased with supination of the forearm. Testing with the elbow in valgus alignment and shortening of the distal end of the radius in two-millimeter increments produced corresponding increases in force in the distal end of the ulna and decreases in force in the radial head. The forces through the interosseous membrane remained low after each amount of radial shortening.

Kinesthetic perceptions of intrinsic anterior-posterior axes.

The purpose of this research was to investigate whether kinesthetic and proprioceptive perceptions of "straight ahead" were defined by a head- or trunk-fixed axis. Subjects were instructed to align the forearm with the head or trunk anterior-posterior (a/p) axis by elbow flexion or extension in the horizontal plane in five different conditions. In each condition the experimenter varied initial elbow and shoulder horizontal flexion or extension angles and head and/or trunk orientation (by rotation about a vertical axis) on each trial before the subject moved the forearm to align it with the head or trunk axis. The upper limb motion was voluntarily constrained to the horizontal plane through the shoulder. Variable errors were significantly lower when subjects aligned the forearm to the trunk-fixed a/p axis. Furthermore, the perceptual errors showed a greater dependence on body segment orientations when the forearm was aligned to the head axis than to the trunk axis. We conclude that the trunk a/p axis is preferred to the head a/p axis for specifying upper limb segment orientations in the horizontal plane at the kinesthetic perceptual level.

Evaluation of the Arthroscopic Valgus Instability Test of the Elbow

Seven fresh-frozen cadaveric elbows were used to evaluate the extent to which the medial collateral ligament must be injured before arthroscopic evidence of valgus instability is seen, the amount of ulnohumeral joint opening that does occur after such an injury, and the elbow position that maximizes visualization of this opening. While visualizing the most medial aspect of the ulnohumeral joint arthroscopically through the anterolateral portal, we sequentially sectioned the medial collateral ligament complex until all of the medial ligamentous restraints were cut. A valgus load was applied after each incision, and the extent to which the ulnohumeral joint opened was measured. Ulnohumeral joint opening was not visualized in any specimen until complete sectioning of the anterior bundle was performed. After the anterior bundle was released, 1 or 2 mm of joint opening was present in all specimens. Complete release of the medial collateral ligament led to dramatic increases in medial joint opening in all seven specimens (4 to 10 mm). Varying the angle of elbow flexion from 15 degrees to 120 degrees revealed that visualization of the medial joint opening was best at 60 degrees to 75 degrees. Finally, forearm pronation increased ulnohumeral joint opening and supination decreased joint opening in all specimens. We found that the entire anterior bundle must be sectioned before measurable and reproducible medial joint opening can occur.

Variation of muscle moment arms with elbow and forearm position

We hypothesized that the moment arms of muscles crossing the elbow vary substantially with forearm and elbow position and that these variations could be represented using a three-dimensional computer model. Flexion/extension and pronation/supination moment arms of the brachioradialis, biceps, brachialis, pronator teres, and triceps were calculated from measurements of tendon displacement and joint angle in two anatomic specimens and were estimated using a computer model of the elbow joint. The anatomical measurements revealed that the flexion/extension moment arms varied by at least 30% over a 95° range of motion. The changes in flexion/extension moment arm magnitudes with elbow flexion angle were represented well by the computer model. The anatomical studies and the computer model demonstrate that the biceps flexion moment arm peaks in a more extended elbow position and has a larger peak when the forearm is supinated. Also, the peak biceps supination moment arm decreases as the elbow is extended. These results emphasize the need to account for the variation of muscle moment arms with elbow flexion and forearm position.

Changes induced by eccentric training on force-velocity relationships of the elbow flexor muscles

The aim of this study was to examine the effects of a short term eccentric training period on force-velocity relationships of the elbow flexor muscles. From a muscle model, the maximal shortening velocity Vo(x) and the af parameter which varies according to the curvature of the force-velocity relationship of the muscle were determined. Sixteen volunteer subjects divided into 2 groups participated in this study (Group Eccentric GE, n = 8; Group Control GC, n = 8). The subjects performed, on an isokinetic ergometer, 2 maximal concentric elbow flexions at different angular velocities (60, 120, 180, 240, 300, 360 degrees s-1) and held maximal and submaximal isometric actions at an elbow flexion angle of 90 degrees. Under isometric conditions, myoelectrical activity (EMG) of the biceps was recorded and quantified as a RMS value. All tests were performed before and after training sessions. Training was conducted 3 times a week for 4 weeks by the GE, and included 6 x 5 eccentric actions with a load of 100% of 1 RM. After training and for the GE, the af parameter and Vo(x) increased significantly (p < 0.05). These changes were accompanied by a significant increase (p < 0.05) of the RMS value of the maximal isometric action. This evolution towards faster characteristics for the elbow flexor muscles after training could be partly due to nervous adaptation.

The influence of task and angle on torque production and muscle activity at the elbow

This study investigated the effect of changing internal mechanical variables and task demands on muscle activity and torque production during high effort isometric contractions of the elbow flexors. The effect of adding a 50% maximal voluntary contraction (MVC) of supination to an MVC of elbow flexion was studied over a range of angles from 30° to 110° of elbow flexion. Surface EMGs were recorded from the biceps brachii (BIC), brachioradialis (BRAD) and triceps brachii (TRI) of 10 healthy subjects. BIC was the only muscle to show a consistent trend of increasing root mean square (rms) EMG with increasing elbow flexion angle. BIC activity also remained constant or increased with the addition of the supination task at all angles. In contrast, BRAD showed decreased activity when supination was added at several angular positions. Maximal flexion torque was reduced when the second task of submaximal supination was added. This torque reduction was statistically significant at all angles except 70° and appeared related to the decreased contribution from BRAD. In a small subset of subjects, however, BRAD activity did not decrease when the second degrees of freedom ( df) task was added. These subjects exhibited higher flexion torques averaged over task than the majority, at all angles except 30°. These data support the view that internal mechanical considerations influence the manner in which the central nervous system (CNS) distributes activity to muscular synergists in response to altered task demands. Further, subject-specific patterns exist which must be recognized if these findings are to be incorporated in training or rehabilitation programmes.

Body Roll and Handpath in Freestyle Swimming: A Computer Simulation Study

The purpose of this study was to determine the effect that body roll has on the path followed by the hand during the pull phase in freestyle swimming. The trunk and right arm were modeled as two rigid segments joined at the shoulder by a simple hinge joint. The arm segment was assigned an elbow flexion angle, and the hand was made to move in a plane through the shoulder parallel to the sagittal plane of the rotating trunk. Shoulder extension and trunk roll occurred simultaneously at selected rates. Medial deviations of the hand to the midline of the trunk can be obtained with body roll alone and require less roll than is usually observed among competitive swimmers. When body roll exceeds the amount necessary to produce the desired medial deviation of the hand, the swimmer must move the arm away from, rather than toward, the trunk's midline.

Effect of pronation and supination tasks on elbow flexor muscles

The aim of this study was to verify the presence of modulatory effects of pronation (P) and supination (S) on biceps brachii (BB) and brachioradialis (BR) electromyographic (EMG) signals while performing isometric elbow flexions at different angles (50, 90, and 130°). The EMG activity of BB and BR was recorded for normal subjects ( N = 6) with surface electrodes during an isometric ramp contraction of elbow flexion (F) that was combined with 20% of maximal voluntary contraction (MVC) in pronation or in supination. The results indicate that (a) the BB muscle presents an increased EMG activity in the combined task of S-F and a decreased EMG activity in the combined task of P-F (Friedman ANOVA, p < 0.01); (b) the EMG activity of the BR is not significantly influenced by the different tasks (Friedman's ANOVA, p > 0.05); and (c) the modulation of the BB occurs only at a midrange angle of flexion. This study partly supports results that were previously reported by other authors, suggesting that a combined task can modulate the EMG activity of elbow flexor muscles. However, this modulation, observed especially for the BB, appears to be limited to elbow flexion angles that are close to 90°.

Single camera photogrammetric technique for restricted 3D motion analysis

The purpose of this study was to use a single camera to determine the true elbow flexion angle with the arm plane oriented arbitrarily with respect to the camera. A mathematical theory was developed and a mechanical arm model was constructed to validate the theory. A static weightlifting skill was analysed to investigate the viability of the technique on the human subject. The validation of the theory showed the error associated with the elbow flexion angle was reduced from as high as 108° when uncorrected to within 3° when corrected by the technique. The elbow flexion angle of the human arm can be calculated to within 6° of error for static weightlifting skill analysis.

Elbow moment and forces at the hands during swing-through axillary crutch gait.

We investigated swing-through axillary crutch gait (nonweight bearing on the left lower extremity) to determine the effects of gait speed, crutch length, and handle position on the forces exerted at the hands and on the moments exerted about the elbow joints. Ten healthy subjects, skilled in swing-through crutch gait, walked at three speeds using fitted crutches, at a fixed speed with four different crutch lengths, and at a fixed speed with four different handle positions. We collected ground reaction forces that exerted simultaneously on the right crutch and motion data with a force plate and three high-speed movie cameras. A biomechanical model was developed to calculate the forces exerted at the right hand and the moments exerted about the right elbow joint. Changing gait speed from slow to the normal gait of the subject showed statistically significant effects (p less than .05) on the forces at the hand. When we changed crutch heights for the subjects, we found no significant effects on the forces at the subjects' hands. Changing handle position significantly affected the moment at the elbow. Increasing the elbow-flexion angle above 30 degrees by raising the crutch handle 1 to 2 in resulted in a 100 percent increase in elbow-extension moment. We found a correlation of .82 between actual average elbow-flexion angle and elbow-extension moment. Changing gait speed or crutch length did not affect elbow moment.

A Discrete Step Goniometer for the Human Elbow

A discrete step goniometer has been developed which measures the total integrated angle of elbow flexion and extension movements. It is compact, comfortable and convenient to wear and use. Preliminary results have shown that it is sufficiently accurate for most clinical applications if calibration is carried out prior to the experiments and it should prove to be a useful device in diagnosis, evaluation of treatment and normal data collection.