• Journal of Biomedical Engineering Research
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• v.18 no.4
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• pp.413-420
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• 1997

In this paper, we analyzed the contraction patterns of active elbow muscles during isometric, concentric and eccentric contraction. The analysis parameters consist of frequency domain parameters (mean frequency, median frequency, peak frequency, peak power, skewness, kurtosis) and time domain paraseters (zero crossing, positive maxima, integrated EMG). The results of this study were as follows; The BR/BB of isometric contraction appeared to be Venter as the elbow joint was more extended. The BR /BB during concentric and eccentric contraction tended to increase with more extension of the elbow joint angle, but there was no significant difference between concentric and eccentric contraction. Further, the EMG power spectrum due to the type of contraction were different betwen eccentric and concentric contraction. According to the results, it was found that the activation pattern in elbow flexor muscles was different during three different muscle contraction pattern. Therefore, elbow flexor muscles should not be considered a single functioning unit. Especially, at the time domain analysis, IEMG is a dominant parameter for analysis of activation patterns, and the skewness kurtosis can be useful parameters in functional recognition for prosthesis control purpose.

• Clinics in Shoulder and Elbow
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• v.26 no.3
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• pp.330-339
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• 2023

Rupture of the pectoralis major muscle typically occurs in the young, active male. Acute management of these injuries is recommended; however, what if the patient presents with a chronic tear of the pectoralis major? Physical exams and magnetic resonance imaging can help identify the injury and guide the physician with a plan for management. Nonoperative management is feasible, but is recommended for elderly, low-demand patients whose functional goals are minimal. Repair of chronic tears should be reserved for younger, healthier patients with high functional demands. Although operative management provides better functional outcomes, operative treatment of chronic pectoralis tears can be challenging. Tendon retraction, poor tendinous substance and quality of tissue, muscle atrophy, scar formation, and altered anatomy make direct repairs complicated, often necessitating auto- or allograft use. We review the various graft options and fixation methods that can be used when treating patients with chronic pectoralis major tears.

• The Academic Congress of Korean Shoulder and Elbow Society
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• 2009.03a
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• pp.74-74
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• 2009

The purpose of this study was to estimate force of muscles that constituted the rotator cuff during elevation motion in scapula plane, using a skeletal muscle model and quantitatively evaluate rotator cuff function in vivo. A healthy volunteer was measured with an open MR and CT system at elevation positions in scapula plane (MR: $30^{\circ}$, $60^{\circ}$, $90^{\circ}$, $120^{\circ}$, $150^{\circ}$, CT: $0^{\circ}$). After reconstruction three-dimensional MRI-based and CT-based bone surface models, matched each models with registration technique. Then supraspinatus, infraspinatus, subscapularis, teres minor, deltoid (anterior, middle, posterior portions) represented as plural lines. These lines were proportional to physiologic cross-sectional area (PCSA) and defined straight line to bind origin and insertion. Force of supraspinatus became greatest at $59^{\circ}$ of elevation. Subsequently force of deltoid middle portion became greatest at $89^{\circ}$ of elevation. Infraspinatus and subscapularis were active at the meantime. In addition, supraspinatus was active during elevation. These results resembled clinical finding and were proved force couples that contribute to mobility and stability of shoulder complex.

• Physical Therapy Korea
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• v.7 no.2
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• pp.88-95
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• 2000

Thirty normal adults were tested to measure the electrical activity of the anterior (AD), middle (MD), and posterior portion (PD) of the deltoid muscle and sternal portion of the pectoralis major muscle (PM) during the performance of four upper extremity PNF diagonal patterns with elbow flexion angle in $0^{\circ}$, $45^{\circ}$, and $90^{\circ}$. The PNF patterns in which these muscles function optimally have been theoretically advanced by Kabat and further described by Knott and Voss. They theorize that the MD should be most active with shoulder flexion, abduction, and external rotation (D2F); the PD with shoulder extension, abduction, and internal rotation (D1E); the AD with shoulder flexion, adduction, and external rotation (D1F); and the PM with shoulder extension, adduction and internal rotation (D2E). The patterns were performed through range of motion, with an isometric contraction performed in the shortened range. When the EMG activity of AD, MD, PD and PM in its optimal patterns was measured, it does not have significant difference among fixed elbow flexion angle $0^{\circ}$, $45^{\circ}$, and $90^{\circ}$ (p>.05). In addition, suggestions were made for study of patients who exhibit imbalance of muscle strength and have muscle weakness.

• Clinics in Shoulder and Elbow
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• v.14 no.1
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• pp.105-110
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• 2011

Purpose: The purpose of this article is to identify and understand the complications of RTSA and to review the current methods of preventing and treating this malady. Materials and Methods: Previous constrained prostheses (ball-and-socket or reverse ball-and-socket designs) have failed because their center of rotation remained lateral to the scapula, which has limited of the motion of the prostheses and produced excessive torque on the glenoid component, and this leads to early loosening. The Grammont reverse prosthesis imposes a new biomechanical environment for the deltoid muscle to act, thus allowing it to compensate for the deficient rotator cuff muscles. Results: The clinical experience does live up to the lofty biomechanical concept and expectations: the reverse prosthesis restores active elevation above $90^{\circ}$ in patients with a cuff-deficient shoulder. However, external rotation often remains limited and particularly in patients with an absent or fat-infiltrated teres minor. Internal rotation is also rarely restored after a reverse prosthesis. Failure to restore sufficient tension in the deltoid may result in prosthetic instability. Conclusion: Finally, surgeons must be aware that the results are less predictable and the complication/revision rates are higher in revision surgery than that in the first surgery. A standardized monitoring tool that has clear definitions and assessment instructions is surely needed to document and then prevent complications after revision surgery.