Anteroinferior Bundle of The Acromioclavicular Ligament Plays a Substantial Role in The Joint Function During Shoulder Elevation and Horizontal Adduction: A Dynamic Finite Element Model.

Background: Postoperative acromioclavicular (AC) ligament deficiency has been identified as a common cause of failure after isolated coracoclavicular reconstruction. The two-bundle arrangement of the acromioclavicular ligament has recently been reported in histological and anatomical research. In addition, a clear structural advantage of the superoposterior bundle (SPB) over the less consistent anteroinferior bundle (AIB) was also found. However, the current understanding of the function of the acromioclavicular ligament in joint stability is based on uniaxial bone loading experiments and sequential ligament sectioning. Consequently, these rigid biomechanics models do not reproduce the coupled physiological kinematics, neither in the normal joint nor in the postoperative condition. Therefore, our goal was to build a dynamic finite element model to study the function of the acromioclavicular ligament based on its biomechanical performance patterns using the benefits of computational models.Methods: A three-dimensional bone model is reconstructed using images from a healthy shoulder. The ligament structures were modeled according to the architecture and dimensions of the bone. The kinematics conditions for the shoulder girdle were determined after the osseous axes aligned to simulate the shoulder elevation in the coronal plane and horizontal adduction. Three patterns evaluated ligament function. The peak von Mises stress values were recorded using a clock model that identified the stress distribution. In addition, the variation in length and displacement of the ligament during shoulder motion were compared using a two-tailed hypotheses test. P values < 0.01 were considered statistically significant.Results: The peak von Mises stress was consistently observed in the AIB at 2:30 in coronal elevation (4.058 MPa) and horizontal adduction (2.323 MPa). Except in the position 2:00, statistically significant higher deformations were identified in the two bundles during shoulder elevation. The highest ligament displacement was observed on the Y- and Z- axes. Conclusions: The AIB has the primary role in restricting the acromioclavicular joint during shoulder motion, even though the two bundles of the AC ligament have a complementary mode of action. During horizontal adduction, the SPB appears to prevent anterior and superior translation.

In Vitro Simulation of Shoulder Motion Driven by 3D Scapular and Humeral Kinematics

In vitro simulation of 3D shoulder motion using in vivo kinematics obtained from human subjects allows investigation of clinical conditions in the context of physiologically relevant biomechanics. Herein we present a framework for laboratory simulation of subject-specific kinematics that combines individual 3D scapular and humeral control in cadavers. The objectives were to: 1) robotically simulate 7 healthy subject-specific 3D scapulothoracic and glenohumeral kinematic trajectories in 6 cadavers, 2) characterize system performance using kinematic orientation accuracy and repeatability, and muscle force repeatability metrics and 3) analyze effects of input kinematics and cadaver specimen variability. Using an industrial robot to orient the scapula range of motion (ROM), errors with repeatability of ±0.1 mm and &lt;0.5° were achieved. Using a custom robot and a trajectory prediction algorithm to orient the humerus relative to the scapula, orientation accuracy for glenohumeral elevation, plane of elevation, and axial rotation of &lt;3° mean absolute error was achieved. Kinematic accuracy was not affected by varying input kinematics or cadaver specimens. Muscle forces over 5 repeated setups showed variability typically &lt;33% relative to the overall simulations. Varying cadaver specimens and subject-specific human motions showed effects on muscle forces, illustrating that the system was capable of differentiating changes in forces due to input conditions. The anterior and middle deltoid, specifically, showed notable variations in patterns across the ROM that were affected by subject-specific motion. This machine provides a platform...(truncated to fit word count, missing text in main PDF includes R2 changes).

Superior training efficacy of beginning movement load training for the baseball throwers

Background Superior shoulder motion with rotator cuff activation are essential for the performance of the throwing athletes. The present study compared the novel beginning movement load training (BMLT) and popular throwers ten program regarding the training efficacy of baseball throwers. We hypothesized that the BMLT contributed the superior training efficacy than popular throwers ten program. Methods Forty adult baseball players were randomized into study group and control group equally. In study group, the cyclic shoulder motion was repeatedly operated 3 days in a week and lasted for 6 weeks using three different BMLT training machines. As for control group, three popular cyclic training in the throwers ten program were adopted for the shoulder trainings as the same protocol in study group. The evaluations before and after training included the static range of motion (ROM), the maximal voluntary isometric contraction (MVICs) of the target muscle (pectoralis major, middle deltoid and supraspinatus) and throwing velocity. Result After 6-week course, study group had significant wider static ROM in saggital adduction (p = 0.002), coronal internal rotation (p = 0.018) and external rotation (p = 0.044) than in control group. The maximal voluntary isometric contraction (MVIC) ratio of middle deltoid/supraspinatus was significant lower in study group (Study:Control = 1.14 ± 0.76:3.56 ± 5.57, p = 0.049) which indicated the enhanced supraspinatus maximal contraction in the study group after training. In addition, the study group had significant improvement in throwing speed (117 ± 10 vs. 109 ± 10 km/h, p = 0.040). Conclusion The BMLT contributed the superiority in range of motion, recruitment of supraspinatus and throwing velocity than the popular thrower’s ten program. It could be a favourable training for the overhead activity.

Morphological Change in the Biceps Brachii Muscles during Shoulder Rotation: A Cadaver Study

In the literature, the passive movement of the biceps brachii during shoulder motion is unclear. This study investigated the passive movement of the long head (LHBB) and short head (SHBB) of the biceps brachii during shoulder rotation. We included 18 shoulders from 15 cadavers. At three shoulder positions (internal rotation [IR]20°, 0°, external rotation [ER]20°), the three sides of the triangle consisting of the confluence of the SHBB and LHBB, coracoid processes, and lesser tubercles were measured. The confluence angle of the LHBB and SHBB (Angle A) was calculated using the cosine theorem. The mean values for Angle A and standardized three sides of the triangle were statistically compared among the three shoulder positions. Angle A values were 13.5° ± 7.6° at IR20°, 15.2° ± 5.8° at 0°, and 15.7° ± 4.3° at ER20° with no significant difference (p = 0.096). The lengths of all three sides and Angle A were the smallest at IR20° and highest at ER20°. All the three sides revealed significant differences among the three shoulder positions (p < 0.0001). These results imply that morphological changes of the biceps brachii occur during shoulder rotation. These morphological changes in biceps brachii may contribute to shoulder joint stabilization by adjusting the forces the act on the tendons of both heads.

Prevalence of Physical Activity with Mobility Disabilities among Senior Citizens in a Selected Old Home

The purpose of the study was to identify the mobility problem of aged people in selected old homes. The ages of the respondents are 60 plus age, which is clustered into 3 age groups 60-69 years, 70-79 years, and 80 plus age. This study established among 100% respondents 89.3% have self-bathing capacity, 89.3% have self-dressing capacity, 89.8% have self-toileting capacity, 93.3% have self-teeth washing capacity, 93.7% have self-eating capacity. For finding other problems of aged people set up among 206 participants of the old home area, 35.0% are disability problem. Besides, in old homes 19.9% have suffered diabetic mellitus for a long time, 51.0% suffered from hypertension, 11.7% suffered from low blood pressure, 14.6% have heart problems, 64.6% have urine catching difficulty, 6.8% have kidney disease. Among 206 respondents of the old home, area was 44.2% abnormal posture and they have 36.9% kyphosis, 4.4% scoliosis 0.5% lordosis, and 2.4% another abnormal posture. For the finding of aged people, we have asked some questions to identify pain severity and several labels found that among 206 participants of the old home area were 52.4% have pain during straight walking, 36.9% have neck pain, 56.3% have hip pain or lower back pain, 28.6% have thoraco-lumber pain and 34.0% have pain during sleeping time. Besides On this area respondents there was pain severity 21.4% have mild pain, 22.3% have moderate pain and 24.8% have severe pain. In this paper among 206 respondents of the old home area was 10.7% having a stroke history. Here 3.4% right side, 4.4 left sides, both sides 2.9% paralyzes. In this study Right shoulder motion 56.8% of participants ROM under 150 degrees and Left shoulder motion 61.2% of participants ROM under 150 degrees. Conversely, Right hip motion was 27.7% of participant's ROM under 60 degrees and Left hip motion 30.6% of participant's ROM under 60 degrees. Besides, Right knee motion 56.8% of participants ROM under 120 degrees and Left knee motion 57.3% participants ROM under 120 degrees. After completing the current study we think that everyone should take responsibility to survive the aged people for a long time.

Robotic Tensegrity Structure with a Mechanism Mimicking Human Shoulder Motion

This paper proposes a three degrees-of-freedom tensegrity structure with a mechanism inspired by the ligamentous structure of the shoulder. The proposed mechanism simulates the wide motion ranges of the human shoulder joint and is composed of three rigid bodies and sixteen steel wires with three mutually perpendicular rotating axes. Since it belongs to the class 1 tensegrity structure that the rigid bodies do not make any contact with each other, the joint has a certain amount of flexibility, which not only can help protect its mechanism from external impacts but also can prevent human injury that might happen when the mechanism and humans interact each other. Moreover, the proposed mechanism can be manufactured by using fewer materials than a fully rigid mechanism, and thus, it can be made in a lightweight fashion and reduce the inertial effects as well. Finally, to actuate the robotic shoulder, the cables connected to each motor are able to drive the rotating shafts of the joint mechanism.

High-dose short-course oral corticosteroid protocol for treatment of primary frozen shoulder: a retrospective cohort study

Objective To evaluate the effect of high-dose prednisolone on the functional outcome of patients with early-stage primary frozen shoulder. Methods Eighteen patients treated with oral prednisolone at an initial dose of 1 mg/kg/day for primary frozen shoulder were retrospectively evaluated. The patients’ range of motion, Disabilities of the Arm, Shoulder, and Hand (DASH) score, Constant–Murley score, American Shoulder and Elbow Surgeons (ASES) score, and visual analog scale score were recorded at baseline and at 4 weeks and 6 months after treatment. Results Rapid recovery of shoulder motion was noted at 4 weeks with the exception of abduction, which was maintained at 6 months. Significant improvement in pain perception and the Constant–Murley score was evident at 4 weeks and extended to 6 months. The DASH and ASES scores did not show significant improvement in the first 4 weeks but were significantly improved at 6 months. Conclusion High-dose oral prednisolone treatment provides rapid symptom resolution that persists long after drug discontinuation. The early treatment period is characterized by marked reduction in pain and rapid recovery of shoulder motion. Improvements in functional outcomes and disability indices tend to be more subtle in the early period but significantly improve during late treatment.