Shoulder Abduction Angle Research Articles

Position-dependent torque coupling and associated muscle activation in the hemiparetic upper extremity

Previous studies have demonstrated abnormal joint torque coupling and associated muscle coactivations of the upper extremity in individuals with unilateral stroke. We investigated the effect of upper limb configuration on the expression of the well-documented patterns of shoulder abduction/elbow flexion and shoulder adduction/elbow extension. Maximal isometric shoulder and elbow torques were measured in stroke subjects in four different arm configurations. Additionally, an isometric combined torque task was completed where subjects were required to maintain various levels of shoulder abduction/adduction torque while attempting to maximize elbow flexion or extension torque. The dominant abduction/elbow flexion pattern was insensitive to changes in limb configuration while the elbow extension component of the adduction/extension pattern changed to elbow flexion at smaller shoulder abduction angles. This effect was not present in control subjects without stroke. The reversal of the torque-coupling pattern could not be explained by mechanical factors such as muscle length changes or muscle strength imbalances across the elbow joint. Potential neural mechanisms underlying the sensitivity of the adduction/elbow extension pattern to different somatosensory input resultant from changes in limb configuration are discussed along with the implications for future research.

Influence of Shoulder Abduction and Lateral Trunk Tilt on Peak Elbow Varus Torque for College Baseball Pitchers during Simulated Pitching

Elbow varus torque is a primary factor in the risk of elbow injury during pitching. To examine the effects of shoulder abduction and lateral trunk tilt angles on elbow varus torque, we conducted simulation and regression analyses on 33 college baseball pitchers. Motion data were used for computer simulations in which two angles-shoulder abduction and lateral trunk tilt-were systematically altered. Forty-two simulated motions were generated for each pitcher, and the peak elbow varus torque for each simulated motion was calculated. A two-way analysis of variance was performed to analyze the effects of shoulder abduction and trunk tilt on elbow varus torque. Regression analyses of a simple regression model, second-order regression model, and multiple regression model were also performed. Although regression analyses did not show any significant relationship, computer simulation indicated that the peak elbow varus torque was affected by both angles, and the interaction of those angles was also significant. As trunk tilt to the contralateral side increased, the shoulder abduction angle producing the minimum peak elbow varus torque decreased. It is suggested that shoulder abduction and lateral trunk tilt may be only two of several determinants of peak elbow varus torque.

Treatment of Dogs Diagnosed with Medial Shoulder Instability Using Radiofrequency‐Induced Thermal Capsulorrhaphy

To report clinical findings and outcome in dogs diagnosed with medial shoulder instability (MSI) treated with radiofrequency-induced thermal capsulorrhaphy (RITC). Retrospective study. Dogs (n=43) with MSI. Medical records from consecutive cases with MSI based on orthopedic examination, palpation of shoulder abduction angles, and arthroscopic findings were used to determine clinical findings and long-term (> or = 1 year) outcome of RITC. Forty-three dogs met the criteria for inclusion; 2 dogs had bilateral MSI. The most common clinical findings were chronic unilateral weight-bearing lameness, large (> 45 degrees) shoulder abduction angles, and spinatus muscle atrophy in the affected limb. Mean preoperative abduction angle (50.7 degrees +/- 4.8 degrees) in affected shoulders was significantly larger than in the unaffected shoulders (32.5 degrees +/- 2.1 degrees). Mean postoperative abduction angle in affected shoulders was not significantly different from unaffected shoulders when measured immediately, 8, 16-20 weeks, and approximately 1 year after surgery. Follow-up evaluation ranged from 1 to 6.2 years. RITC treatment resulted in improved clinical function in 40 cases (93%) with 34 cases (79%) considered excellent; 3 cases (7%) were considered failures. RITC was a safe and effective method of treatment of MSI in most dogs studied. RITC can be considered as a viable option for surgical treatment of selected cases of MSI in dogs.

Measurement of Angles of Abduction for Diagnosis of Shoulder Instability in Dogs Using Goniometry and Digital Image Analysis

To compare abduction angles of shoulders with medial instability and unaffected shoulders in the same dogs and in age- and breed-matched dogs. Case-control study. Dogs with medial instability of the shoulder (n=33) and 26 control dogs. Dogs were sedated and positioned in lateral recumbency with both scapulas parallel to the table. With the elbow and shoulder in extension, the non-recumbent limb was maximally abducted and the angle between the scapular spine and lateral aspect of the brachium measured with a goniometer; a digital image was taken from the cranial aspect. Both techniques were performed in triplicate by 2 examiners. Mean abduction angles for each shoulder were determined from goniometric measurements and image analysis. Data were analyzed for significant differences between affected and unaffected shoulders, measurement techniques, and examiners. Strength of correlation between measurement techniques was determined. Mean abduction angles for shoulders with instability (53.7+/-4.7 degrees goniometric, 51.2+/-4.9 degrees image) were significantly (P<.001) larger than for all unaffected shoulders (32.6+/-2.0 degrees goniometric, 30.9+/-2.3 degrees image). In dogs diagnosed with instability, affected shoulders had significantly (P<.001) larger abduction angles than the contralateral (unaffected) shoulders. No significant differences were identified between right and left shoulders for control dogs, measurement techniques, or examiners. A strong (r=0.90) significant (P<.001) positive correlation between measurement techniques was noted. Shoulder abduction angles measured under sedation provide objective data for diagnosis of shoulder instability in dogs. Shoulders with clinical and arthroscopic evidence of medial instability have significantly higher abduction angles than shoulders that are considered normal. Determination of shoulder abduction angles should be included in the diagnostic protocol for forelimb lameness assessment in dogs.

単純X線画像による上腕骨後捻角撮影法の検討

The semi-axial-view method is used to measure humeral retroversion angles by a single x-ray exposure. We examined the clinical utility of this method using a humerus model and normal volunteers. In an experiment with a humerus model, humeral retroversion angles were measured at various positioning angles by the semi-axial-view method, and compared with the angles measured by the CT method, which is considered the standard, and the best position was determined. The upper arms of three volunteers were photographed by the semi-axial-view method in the most suitable position, and humeral retroversion angles were compared with those obtained by the CT method. As a result of examination with a humerus model, the best positioning angles were 20 degrees of shoulder abduction angle, 90 degrees of shoulder flexion angle, and 90 degrees of elbow flexion angle. There were no significant differences between the humeral retroversion angles of the CT and semi-axial-view methods with the best position determined in volunteers. In conclusion, the semi-axial-view method is a useful, easy method for measuring the humeral retroversion angle. This method will be a great asset in researching large numbers of samples.

Scleredema adultorum of Buschke treated with radiation.

Scleredema adultorum of Buschke is an uncommon skin condition that may accompany diabetes mellitus. Current therapeutic options are poor, with only case reports and small series supporting their use. We describe 3 patients with severe restrictive scleredema associated with type 2 diabetes mellitus who responded to radiation therapy after other treatments had failed. Angle of shoulder abduction was used as an objective measurement of improvement, while the patients rated several subjective areas, including arm range of motion, ease of performing daily tasks, ease of breathing, and neck thickening. Objective improvement tended to plateau over time but remained well above baseline. The duration of subjective improvement was variable, lasting from a few months to the end of the observation time of 2 1/2 years. Though not consistently durable in its effect, radiation therapy appears to be a viable therapeutic option in extreme cases of this difficult-to-treat disease.

Ergonomic Analysis of Laparoscopic Knot Tying

The laparoscopic knot-tying technique of novice and expert surgeons was analyzed to determine the ergonomics of both groups. Data capture was via an established virtual reality system, which includes a human force and torque feature. Novices had on average a lower angle of shoulder abduction than experts (25.64 degrees compared with 29.57 degrees) and a wider standard deviation than experts (5.41 compared with 4.46). Average time to completion of the task (three knots) was 433 seconds for novices against 310 seconds for experts. The mean torque magnitude did not simply increase with the angle of abduction. The angle at which torque was minimal for the shoulder was 27 degrees, and for the level of the third and fourth thoracic vertebrae, it was 22 degrees.

Optimal Shoulder Abduction Angles during Baseball Pitching from Maximal Wrist Velocity and Minimal Kinetics Viewpoints

Baseball coaches train pitchers to keep their shoulder abduction at 90º during delivery, because this angle is believed to maximize ball speed and reduce the stress on the throwing arm. In fact, however, the shoulder abduction angle for some pitchers, including professional pitchers, deviates from 90º. There likely are reasons for such deviation. The purposes of this study, therefore, were to investigate the effects of shoulder abduction angle on ball velocity and on the injury-related joint kinetic variable, and to determine why the shoulder abduction angle varies among pitchers. Eleven professional pitchers were videotaped with two high-speed cameras. The resulting kinematic data were used to simulate several pitching motions by varying the shoulder abduction angle from the actual angle. Maximum wrist velocity was used as a reasonable approximation of ball velocity. Elbow varus torque was used as a kinetic variable. The square torque for the throwing arm and torque change for the throwing arm were used to investigate the cause of the variation. It was found that the shoulder abduction angle of 90º did not always maximize wrist velocity nor minimize elbow varus torque. The actual shoulder abduction angle for each pitcher was highly consistent with the angle that minimized both square torque and torque change. The results suggested that the proficient throwers in this study moved their pitching arm so as to minimize mechanical cost while at the same time optimizing performance.

Radiologic evaluation of the ulnar styloid.

The ulnar styloid (US) architecture was examined radiologically and directly by dissection in 13 cadaver wrists to examine a potential relationship between US shape and US abutment syndrome and to determine an optimal radiographic view that could be used to detect US fractures. A higher incidence of US abutment syndrome in the radially deviated US type was observed by dissection. Radiographs taken at varying shoulder abduction angles suggested that the base of the US and ulnar head are not round. To best evaluate the fovea and the US for possible US fractures, radiographs should be taken with the glenohumeral joint abducted 45 degrees, the elbow flexed 90 degrees, the forearm in neutral rotation, and the x-ray beam directed through the wrist perpendicular to the floor.

The initial effects of an elbow mobilization with movement technique on grip strength in subjects with lateral epicondylalgia

The aim of this research was to investigate which shoulder abduction angle (30°, 90°, 150°) during shrug exercise is superior for (1) activating the scapular upward rotators and (2) improving scapular and clavicular position in subjects with scapular downward rotation impairment. Twenty subjects performed shrug exercises at three different shoulder abduction angles (30°, 90°, 150°) which were obtained and maintained actively. Surface EMG data were collected from the levator scapulae (LS), upper trapezius (UT), lower trapezius (LT), and serratus anterior (SA) during shrug exercises. Scapular downward rotation index (SDRI) and clavicular tilt angle (CTA) were measured immediately after each shrug exercise. Oneway repeated-measures analysis of variance was used to determine the significance. UT muscle activity was greater at 90° and 150° than at 30° of shoulder abduction. UT/LS muscle activity ratio was greater at 90° than at 30°. LT and LT/LS increased as shoulder abduction angle increased. SA was greater at 150° than at 30° or 90°. SA/LS was greater at 150° than at 30°. SDRI was lower at 90° and 150° than at 30°. CTA was greater at 90° and 150° than at 30°. In conclusion, shrug exercises at 90° or 150° of shoulder abduction angle may be advocated to activate scapular upward rotators, decrease SDRI, and increase CTA in patients with scapular downward rotation impairment.

Electrornyographic activity of the biceps brachii muscle in shoulders with anterior instability

Purpose: The purpose of this study was to evaluate the activity of the biceps muscle in the vulnerable abduction and external rotation position of the shoulder in patients with anterior instability. Type of Study: This experimental study included a prospective analysis of the electromyographic (EMG) data on a group of patients with traumatic unilateral anterior instability of the shoulder. The EMG data of the unstable shoulders was compared with those of the opposite shoulders as control. The optimal sample size for the case-control study was calculated using an nQuery Advisor program (nQuery Advisor 3.0, Statistical Solutions, Cork, Ireland). Methods: The EMG analyses were conducted in 76 shoulders in 38 patients who had a traumatic anterior instability in 1 shoulder. The EMG records were obtained at different positions of the shoulder, which included 0°, 45°, 90°, and 120° of shoulder abduction. In each angle of shoulder abduction, the arms were placed in an external rotation as tolerated by the anterior apprehension. The paired-sample t test was used to compare the difference of the root mean square (RMS) voltages between the stable and unstable shoulders in each degree of arm position. Results: The RMS voltage of the biceps muscle was significantly greater in the unstable shoulder than the opposite stable shoulder in all positions of the arm (P = .00). The RMS voltage of the biceps was maximal at 90° and 120° of external rotation in the unstable shoulder (P < .05). The RMS voltage of the supraspinatus muscle revealed no differences in any of the test conditions (P = .904, .506, .119, and .781 in 0°, 45°, 90°, and 120°, respectively). Conclusions: In the vulnerable abduction and externally rotated position, the biceps muscle plays an active compensatory role in the unstable shoulder but not in the stable shoulder.

Electromyographic activity of the biceps brachii muscle in shoulders with anterior instability

Purpose : The purpose of this study was to evaluate the activity of the biceps brachii muscle in the vulnerable abduction and external rotation position of the shoulder in patients with anterior instability. Materials and Methods: This experimental study include a prospective analysis of the electromyographic(EMG) data on a group of patients with traumatic unilateral anterior instability of the shoulder. The EMG data of unstable shoulders was compared with those of opposite shoulders as control. The optimal sample size for the case-control study was calculated using an nQuery Advisor program(nQuery Adviser 3.0, Statisticl solutions Ltd., Ireland). The EMG analyses were conducted in 76 shoulders in 38 patients who had a traumatic anterior instability in one shoulder. The EMG records were obtained at different position of shoulder, which included 0° , 45° , 90° and 120° of shoulder abduction. In each angle of shoulder abduction, the arms were placed in an external rotation as tolerated by the anterior apprehension. The paired-sample T test was used to compare the difference of the root mean square(RMS) voltages between the stable and unstable shoulders in each degree of arm position. Results : The RMS voltage of the biceps muscle was significantly greater in the unstable shoulder than opposite stable shoulder in all position of the arm(p

Radiographic assessment of scapular rotational tilt in chronic shoulder impingement syndrome

This study presents an objective evaluation of both scapular upward and axial rotational tilts in shoulder impingement syndrome, using a scapular spine line defined on antero-posterior (AP) radiographs of the shoulder as the referential line. Twenty-seven patients with unilateral shoulder motion pain, who were diagnosed as having chronic shoulder impingement syndrome, were enrolled in the study. Scapular upward and axial rotational tilts were compared between the affected and contralateral shoulders. AP radiographs were obtained at shoulder abduction angles of 0°, 45°, and 90°, and the X-ray films were digitized by computer. The upward and axial rotational tilts of the scapula were then evaluated on the digital images. In shoulder impingement syndrome, both upward and axial external rotations of the scapula were impaired at the painful arc angle of abduction. This tended to be more apparent for the axial rotation of the scapula than for the upward rotation. These reductions in scapular rotations reduce available clearance for the rotator cuff and humeral greater tuberosity as the shoulder is abducted.

Dependence of deltoid muscle activity upon initial angles of shoulder abduction prior to flexion.

The present study was undertaken to investigate the hypothesis that the direction and selectivity of an appropriately modified version of shoulder flexion is dependent upon initial angles of shoulder abduction. Analysis indicated that initial small angles of shoulder abduction were associated with longer electromyographic (EMG) durations of the agonist (anterior deltoid) muscle. Moreover, as initial angles became smaller, EMG onsets of the antagonist (posterior deltoid muscle) occurred nearer to those of the agonist. Modulations of duration of the agonist EMG activity can be explained by changes in amplitude of movement. Two possible interpretations of the changes of EMG onset of the antagonist in accordance with different initial angles of shoulder abduction are considered. One concerns the effect of the change on the load of the upper limb, dependent on different angles of shoulder abduction. The second concerns the changing role of the antagonist to a synergist, dependent upon decreased initial angles of shoulder abduction prior to the shoulder flexion. Based on the present findings, it is suggested that angles of shoulder abduction are an important determinant of agonist-antagonist muscle activity of the deltoid during flexion of the shoulder.

DEPENDENCE OF DELTOID MUSCLE ACTIVITY UPON INITIAL ANGLES OF SHOULDER ABDUCTION PRIOR TO FLEXION

The present study was undertaken to investigate the hypothesis that the direction and selectivity of an appropriately modified version of shoulder flexion is dependent upon initial angles of shoulder abduction. Analysis indicated that initial small angles of shoulder abduction were associated with longer electromyographic (EMG) durations of the agonist (anterior deltoid) muscle. Moreover, as initial angles became smaller, EMG onsets of the antagonist (posterior deltoid muscle) occurred nearer to those of the agonist. Modulations of duration of the agonist EMG activity can be explained by changes in amplitude of movement. Two possible interpretations of the changes of EMG onset of the antagonist in accordance with different initial angles of shoulder abduction are considered. One concerns the effect of the change on the load of the upper limb, dependent on different angles of shoulder abduction. The second concerns the changing role of the antagonist to a synergist, dependent upon decreased initial angles of shoulder abduction prior to the shoulder flexion. Based on the present findings, it is suggested that angles of shoulder abduction are an important determinant of agonist-antagonist muscle activity of the deltoid during flexion of the shoulder.

先天性肩甲骨形成異常の治療経験

This study reports the outcomes of surgical treatments for congenital elevation and hypoplasia of the scapula.6 shoulders of 5 patients with congenital elevation (1 Sprengel's deformity, 1 Noonan syndrome bilateral, 3 Klippel-Feil syndrome) and 1 patient with congenital hypoplasia of the scapula were treated surgically. They were followed-up for 2 months to 17 years 3 months (average: 7 years 4 months). There were 2 males and 4 females and their ages ranged from 3 to 15 years (average: 6 years 5 months).For the congenital elevation of the scapula, the König method was carried on 3 shoulders (in 1 case, Z-plasty was added for the webbed neck), and the Woodward method on 1 shoulder. The patient with the Noonan syndrome was operated on by osteotomy with release in 2 shoulders. In this bilateral case, for the weakness of the shoulder abductor, pectoralis major muscle transfer was added during reoperation. The congenital hypoplasia was treated with pectoralis major muscle transfer only.The range of motion of the shoulder and downward displacement of the inferior angle of the scapula were investigated in these patients.The average shoulder abduction angle improved from 99.2° to 140° at the final follow-up. The average downward displacement of the scapula was 6.2mm (-11mm to 26mm). Patients with Sprengel's deformity showed better results functionally and cosmetically compared to those with underlying diseases such as Klippel-Feil and Noonan syndrome. Patients with muscle hypoplasia around the shoulder girdle were treated with pectoralis major muscle transfer, and satisfactory functional improvement was observed, From these results, good results may be obtained for shoulder girdle muscle hypoplasia by pectoralis major muscle transfer to improve scapular abduction.

Intramuscular Pressure and Electromyography in the Supraspinatus Muscle at Shoulder Abduction

In ergonomic and biomechanic research, estimations of shoulder muscle load and evaluation of different measuring techniques are important. Intramuscular pressure (IMP), using the microcapillary infusion technique and bipolar intramuscular electromyography (EMG), was recorded from the same part of the supraspinatus muscle. In 12 subjects, IMP and EMG were recorded at shoulder abduction angles of 0 degrees, 30 degrees, 60 degrees, 90 degrees, and 135 degrees with no or a 1- or 2-kg hand load in each position. The shoulder torque was calculated for each test position. A correlation was found for both mean IMP and mean EMG versus shoulder torque if the position with extreme muscle shortening (135 degrees abduction) was excluded. IMP was high (greater than 50 mmHg) in almost all test situations. In seven other subjects, isometric force in abduction was correlated with IMP and EMG. Both methods showed an equally good correlation with external shoulder force, IMP gives as good an estimation of relative muscle force as EMG, but any comparison between EMG and IMP must be done at the same muscle length.