• PNF and Movement
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• v.21 no.1
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• pp.139-146
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• 2023

Purpose: The aim of this study is to provide basic information to create an efficient training program to improve shoulder stability and function in patients with injuries and in patients having undergone surgery of the supraspinatus and infraspinatus muscles, which have a relatively high incidence of injury in shoulder joint disease. Further, independent activities of the supraspinatus and infraspinatus muscles were investigated according to forearm rotation and the neutral and lateral rotation postures. Methods: The activities of the supraspinatus and infraspinatus muscles were measured using surface electromyography in 22 healthy adults in Busan, and isokinetic muscle strength measurement equipment was used to measure muscle strength during shoulder lateral rotation. The subjects performed lateral rotation of the shoulder in three different forearm postures (neutral, supine, prone) to measure shoulder muscle activity and lateral rotation strength. Results: The independent activity ratio (% Isolation) of the supraspinatus and infraspinatus muscles during lateral rotation of the shoulder joint demonstrated a significant difference (p<0.05) according to the change in forearm posture. Conclusion: The supraspinatus muscle showed independent activity ranging from highest to lowest in the order of pronation, neutral, and supination of the forearm, while the independent activity of the infraspinatus muscle ranged from highest to lowest in the order of neutral, supination, and pronation of the forearm. Therefore, the most active forearm positions for the supraspinatus and infraspinatus muscles are pronation and neutral, respectively.

• The Journal of Korea Robotics Society
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• v.14 no.4
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• pp.251-257
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• 2019

This paper presents the kinematic modeling of the human forearm rotation constructed with a spatial four-bar linkage. Especially, a circumduction of the distal ulna is modeled for a minimal displacement of the position of the hand during the forearm rotation from the supination to the pronation. To establish its model, four joint types of the four-bar linkage are, firstly, assigned with the reasonable grounds, and then the spatial linkage having the URUU (Universal-Revolute-Universal-Universal) joint type is proposed. Kinematic analysis is conducted to show the behavior of the distal radio-ulna as well as to evaluate the angular displacements of all the joints. From the simulation result, it is, finally, revealed that the URUU spatial linkage can be substituted for the URUR (Universal-Revolute-Universal-Revolute) spatial linkage by a kinematic constraint.

• Physical Therapy Korea
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• v.29 no.2
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• pp.106-116
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• 2022

Background: Shoulder external rotation exercises are commonly used to improve the stabilizing ability of the infraspinatus. However, during exercise, excessive activation of the posterior deltoid compared to the infraspinatus causes the humeral head to move anteriorly in an abnormal position. Many researchers have emphasized selective activation of the infraspinatus during shoulder external rotation exercise. Objects: This study aims to delineate the optimal exercise method for selective activation of infraspinatus by investigating the muscle activities of the infraspinatus and posterior deltoid according to the four shoulder exercise methods and two forearm positions. Methods: Thirty healthy individuals participated in this study. The participants were instructed to perform shoulder external rotation exercises following four exercise methods: sitting external rotation (SIER); standing external rotation at 90° abduction (STER); prone external rotation at 90° abduction (PRER); side-lying external rotation (SLER), and two forearm positions (neutral, supinated). The electromyography (EMG) signal amplitude was measured during each exercise. Surface EMG signals were recorded from the posterior deltoid, infraspinatus, and biceps brachii. Results: EMG results of the infraspinatus and posterior deltoid in PRER, were significantly higher than that of the other exercises (p < 0.01). The EMG ratio (infraspinatus/posterior deltoid) in SIER was significantly higher than that of the other exercises. EMG activation of the posterior deltoid in SIER, PRER, and SLER was significantly higher in neutral than in supinated (p < 0.01). Furthermore, the EMG of the infraspinatus in SIER was significantly higher in neutral than in supinated (p < 0.01). The EMG ratio (infraspinatus/ posterior deltoid) in SIER was significantly higher in neutral than in supinated (p < 0.05.) Contrarily EMG ratios in PRER and SLER were significantly higher in supinated than in neutral (p < 0.05). Conclusion: The results show that clinicians should consider these exercise methods and forearm positions when planning shoulder external rotation exercises for optimal shoulder rehabilitation.

• Clinics in Shoulder and Elbow
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• v.17 no.1
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• pp.25-30
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• 2014

Background: Normal elbow joint kinematics has been widely studied in cadaver, whilst in vivo study, especially of the forearm, is rare. Our study analyses, in vivo, the kinematics of normal forearm and of malunited forearm using a three-dimensional computerized simulation system. Methods: We examined 8 patients with malunited Monteggia fracture and 4 controls with normal elbow joint. The ulna and radius were reconstructed from CT data placing the forearm in three different positions; full pronation, neutral, and full supination using computer bone models. We analyzed the axis of rotation 3-dimentionally based on the axes during forearm rotation from full pronation to full supination. Results: Axis of rotation of normal forearm was pitch line, with a mean range of 2 mm, from full pronation to full supination, connecting the radial head center proximally and ulnar fovea distally. In normal forearm, the mean range was 1.32 mm at the proximal radioulnar joint and 1.51 mm at the distal radioulnar joint. However in Monteggia fracture patients, this range changed to 7.65 mm at proximal and 4.99 mm at distal radoulnar joint. Conclusions: During forearm rotation, the axis of rotation was constant in normal elbow joint but unstable in malunited Monteggia fracture patients as seen with radial head instability. Therefore, consideration should be given not only to correcting deformity but also to restoring AOR by 3D kinematics analysis before surgical treatment of such fractures.

• Journal of Korean Orthopaedic Sports Medicine
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• v.4 no.2
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• pp.133-137
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• 2005

Tension band wiring of olecranon fractures is recognized as an effective method for fixation and union Complications as non-union, limitation of motion and subcutaneous k-wire protrusion are occasionally reported. But, there are no references about limitation of forearm rotation after tension band fixation. We report two cases of limitation of forearm rotation after tension band fixation of olecranon fracture.

• Korean Journal of Applied Biomechanics
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• v.20 no.2
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• pp.117-127
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• 2010

The axes of upper forearm coordinate system have been considered as principal axis of each segment which was component of elbow joint. The purpose of this study was to verify whether the mean direction(principal axis) of instantaneous axes of rotation for pure flexion/extension motion coincided with the flexion/extension axis of upper forearm coordinate system. The same procedure was done for pronation/supination motion. Furthermore, it was tested indirectly that there was an interaction effect between the two rotational motions. The results showed that most segment coordinate axes statistically were not consistent with the mean directions of flexion/extension and pronation/supination axes of rotation. From the results, it would be concluded that the ISB coordinate systems was proved to be a little valid for human movement analysis. There also was an effect of pronation/supination angles on flexion/extension motion.

• Journal of Korean Physical Therapy Science
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• v.9 no.1
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• pp.61-68
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• 2002

The purpose of this dissertation was to analyze the effect of trunk extension strengthening exercise on muscle performance of the upper limb in adolescent baseball player. The twenty people were studied : experimental group(10), comparative group(10). The experimental group has done trunk extension strengthening exercise for 8 weeks. The study analyzes isometric maximal strength of shoulder internal rotation. shoulder external rotation, elbow flexion, elbow extension, forearm pronation, forearm supination and ball speed. All of subjects were tested for 3 times ; pre, mid, post. The results were as follows; 1. Maximal isometric strength of upper limb, during trunk extension strengthening exercise in experimental group, shoulder internal rotation and external rotation showed it has slightly increased and comparative group showed it has no change, but not significant elbow flexion and extension significantly(p<0.05) increased after exercise either for 4 or 8 weeks compared with that of control group. Forearm pronation showed not significantly changed in both group, but significantly different between group either for 4 or 8 weeks. Forearm supination, significantly((p<0.05) increased after 8 weeks in experimental group. 2. Ball speed showed slightly increased but not significantly in experimental group. These results it may expect improvement of upper limb muscle performance of upper limb in adolescent baseball player. However, in case of shoulder a point of view of bunk extension strengthening exercise of this study hasn't a significant influence. More experimental studies are needs, hereafter which will use more experimental subjects and various methods of exercise and new application of treatment term to define significant change.

• Journal of the Korean Orthopaedic Association
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• v.56 no.5
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• pp.427-432
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• 2021

Delayed treatment of volar dislocation of the distal radioulnar joint can result in wrist pain, limited rotation of the forearm, and degenerative arthritis that could be managed only by salvage procedures. A 24-year-old male patient presented with wrist pain and a loss of forearm rotation after surgery for a radial shaft fracture. The shaft of the radius was fixed with a plate and screws with a volar angulation of 7°. The ulnar head was dislocated volar to the distal radius, and the bone defect in the ulnar head was impacted into the volar rim of the sigmoid notch of the radius, preventing the head from being reduced in the joint. Corrective osteotomy of the malunited radial shaft and sliding osteotomy of the proximal ulnar head were performed to fill the distal bone defect. Pain and range of the forearm rotation were improved at postoperative 19 months.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1990.04a
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• pp.151-162
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• 1990

Occupational disease among typists such as Carpal Tunnel Syndrome(CTS) and tendonitis has increased along with rapid expansion of office automation. During typing, the posture can be defined as forearm pronation, ulnar abduction, wrist extension and finger flexion. The CTS results from awkward posture between forearm-wrist-hand and the keyboard arrangement. Therefore, ergonomic principles should be emphasized in keyboard design. The objective of the study is to improve keyboard design by analyzing anatomical posture of forearm and hand during typing. An experimental study was performed to investigate relationships between a keyboard and typing performance. Results showed that typing performance is dependent to angles and slopes of a keyboard. Statistical analysis indicated that the suggested ergonomic keyboard improved typing speed significantly(17%).

• Journal of Dental Rehabilitation and Applied Science
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• v.17 no.4
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• pp.231-244
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• 2001

This study was conducted to observe the effect on appendage muscle strength according to increase in occlusal vertical dimension. For this study, ten males with a mean age of 21 were selected. The subjects had a complete or almost complete set of natural teeth and reported no subjected symptoms of pain or dysfunction in the masticatory system. The tested occlusal splints were made at the position of increased occlusal vertical dimension of 2mm, 3.5mm, and 5mm from the ICP. Before and after wearing occlusal splints, the appendage muscle strength were tested by CybexII Dynamometer in each subject. The results were as follows : 1. When occlusal vertical dimension was increased, most of mean muscular strength values were increased except for those of supination and pronation of forearm at the position of 5mm increased occlusal vertical dimension. 2. The statistical analyses demonstrated that the increased occlusal vertical dimension position to be significantly stronger than intercuspal position for the muscle strength of the flexion and extension of hip, supination of forearm, external and internal rotation of knee, dorsiflexion and plantarflexion of ankle (p<0.05). 3. At the position of 3.5mm increased vertical dimension displayed the highest mean muscluar strength value than other positions. 4. Statistically demonstrated values, except for supination of forearm, internal rotation of shoulder, were related to lower appendage. Therefore splint was more effective on lower appendage than upper appendage to make muscle strength increased. 5. The mean increased rate of muscular strength tested on knee(57%), ankle(42%), and wrist(20%) were higher than hip(31%), elbow(14%), and shoulder(17%).