Forearm Angle Research Articles

Stiffness Changes in Shoulder Muscles between Pitchers and Position Players after Throwing Overhead Using Shear Wave Elastography and Throwing Motion Analysis.

Objectives: The objective is to compare stiffness changes around the shoulder muscles between pitchers and position players after throwing overhead using shear wave elastography (SWE) in relation to throwing motion analysis and muscle strength. Methods: A total of 32 male college baseball players (12 pitchers and 20 position players) were observed throwing 20 times, and SWE was performed to evaluate 13 shoulder muscle items-tendons (supraspinatus, infraspinatus, subscapularis, and teres minor), muscles (supraspinatus, infraspinatus [transverse and oblique part], teres minor, lower trapezius, latissimus dorsi, and pectoralis minor), and capsules (posterior and posteroinferior). Motion analysis was used to assess elbow torque, forearm angle, forearm rotation speed, and maximum external rotation angle of the shoulder. Muscle strength was measured using a dynamometer for abduction, internal/external rotation of the shoulder at an abduction of 0°, internal/external rotation of the shoulder at an abduction of 90°, and internal/external rotation of shoulder at a flexion of 90°. Results: In the pitcher group, SWE values for the teres minor muscle and latissimus dorsi muscle increased significantly after throwing. In the position player group, SWE values for the teres minor muscle significantly increased, and SWE values of the pectoralis minor muscle decreased after throwing. In the pitcher group, positive correlations were found between the teres minor muscle and forearm rotation speed and between the latissimus dorsi muscle and forearm angle. No significant difference was found in muscle strength after throwing in any of the groups. Conclusions: Stiffness changes occurred after throwing and were related to the motion analysis, but the regions in which stiffness occurred varied between pitchers and position players.

Participants with restricted dominant shoulder internal rotation range of motion demonstrate no side-to-side difference in humeral head translation; and no difference before and after joint mobilization: a pilot study.

[Purpose] To compare humeral head translation (HHT) during shoulder elevation between dominant and non-dominant shoulders in participants with limited dominant shoulder internal rotation range of motion (ROM). To determine if joint mobilization alters HHT, and if relationships exist between the bicipital forearm angle and HHT. [Participants and Methods] Fifteen (9 female) participants (age 25.7 ± 6.8 years) with a minimum 15-degree dominant shoulder internal rotation ROM deficit compared to the opposite shoulder participated. All participants underwent bicipital forearm angle (BFA) measurements and ultrasound imaging to measure acromiohumeral and posterior glenohumeral distances in 3 positions: Resting, 90 degrees of shoulder flexion, and 60 degrees of shoulder abduction with full external rotation. Ultrasound images were used to calculate HHT. Participants' dominant shoulders underwent posterior glide mobilization, followed immediately by repeated ultrasound images and ROM measures. [Results] There was no dominant to non-dominant shoulder, or before and after mobilization HHT differences. No correlations existed between bicipital forearm angles and HHT or ROM gains after mobilization. [Conclusion] Participants with internal rotation ROM loss demonstrated symmetrical HHT. Joint mobilization increased ROM, but HHT was unchanged. No relationships existed between BFA and HHT.

Biomechanical Basis of Interval Throwing Programs for Baseball Pitchers: A Systematic Review.

Interval throwing programs are used in rehabilitation of throwing injuries, especially ulnar collateral ligament injuries. Athletes who are rehabilitating begin by throwing on flat ground progressing through increasing distances, number of throws, and intensity of throwing. If the athlete is a baseball pitcher, the flat-ground throwing phase is followed by pitching on a mound at progressively increased effort. The goal is to build back arm strength and capacity with an emphasis on proper mechanics. To determine whether interval throwing progressively builds joint kinetics (specifically, elbow varus torque) to the level required during full-effort baseball pitching. A secondary purpose was to examine the kinematics produced during interval throwing compared to those seen during baseball pitching. Systematic Review. Following PRISMA guidelines, PubMed, Embase, Web of Science, SPORTDiscus, and Google Scholar were systematically searched for biomechanical studies of flat-ground throwing and partial-effort pitching in baseball between 1987 and 2023. Studies that reported the biomechanics of either flat-ground throwing, or partial-effort pitching were included in this review. The AXIS tool was used to assess study quality. Thirteen articles met the inclusion criteria. Ten studies were determined to be of moderate quality, while three studies were deemed high quality. Elbow varus torque during partial-effort pitching was less than during full-effort pitching. Elbow varus torque for most flat-ground throws did not exceed full-effort pitching torque. While most studies showed increased elbow varus torque with increased flat-ground throwing distance, the distance at which elbow varus torque matched or exceeded full-effort pitching elbow varus torque was not consistent.As flat-ground throwing distance increased, shoulder external rotation angle and shoulder internal rotation velocity increased. Arm slot (forearm angle above horizontal) decreased as flat-ground throwing distance increased. For varied effort pitching, shoulder external rotation angle, shoulder internal rotation velocity, elbow extension velocity, and ball velocity increased as effort increased. While the front knee extended slightly from foot contact to ball release in full-effort pitching, the front knee flexed slightly during partial-effort pitching. An interval throwing program progressively builds elbow varus torque up to levels produced in full-effort baseball pitching. While differences exist between interval throwing kinematics and pitching kinematics, the patterns are similar in general. 2.

Outcomes of radialization with ulnar cuff osteotomy for radial longitudinal deficiency: a medium-term follow-up study.

Addressing the deforming stresses arising from soft tissue and continued skeletal development is crucial to obtain long-term correction of forearm carpal alignment in Radial longitudinal deficiency. The aim of the present study was to report the medium-term follow-up results of radialization with ulnar cuff osteotomy in children. A total of 17 patients (21 involved limbs) with a mean follow-up of 66 months (range 50 to 96) were reviewed. Mean correction of the hand forearm angle at the final follow-up was 51°. Mean hand forearm position preoperatively and at the final follow-up were -1.1 cm (SD 0.9) and +1.3 cm (SD 0.8), respectively. This metaphyseal osteotomy relaxed the radial structures throughout the original phase of deformity correction. The mean ulnar growth was 62% of the contralateral side at the final follow-up. Our technique may provide a feasible solution to the correction and prevent recurrence of deformity while maintaining ulnar growth in the medium to longer term.Level of evidence: III.

Quantitative Analysis of Deformity in Digital Model of Congenital Radioulnar Synostosis

The deformity of congenital radioulnar synostosis is quite complicated and difficult. This study aims to find out the related factors of the "forearm rotation angle" (FR) which relate to the severity of congenital radioulnar synostosis (CRUS), and try to quantify the internal relations of each deformity and help to understand the reconstruction method in surgery treatment of this disease. This study is case series research. We established 48 digital three-dimensional forearm bone models of 48 patients with congenital radioulnar synostosis classified as Cleary and Omer type 3. All the patients were treated at our institution from January 2010 to June 2016. In total, 10 independent deformities (the rotation angle of forearm; the internal rotation, radial, and dorsal angulation of radius and ulna; the relative length of osseous fusion at PRUJ; the relative dislocation distance of distal radioulnar joint; the relative area of proximal radial epiphysis) involved in the CRUS complex deformity were measured. Pearson correlation analysis for each deformity which was mentioned above was performed, and multivariate linear regression analysis was also performed with FR as the dependent variable and the other deformities as the influential factors. The "dorsal angle of radius" (DAR, 21.69° ± 21.55°) had the strongest correlation with the FR (79.72° ± 40.39°), the Pearson correlation coefficient was 0.601 (p < 0.01), the internal rotation angle of the radius (IRAR, 82.69° ± 54.98°) had a moderate correlation with FR, the Pearson correlation coefficient was 0.552 (p < 0.01). A forearm deformity equation was established: FR=35.896 + 0.271 DAR + 0.989 IRAR. The dorsal angulation deformity of radius may be the most important deformity that effects the severity of CRUS and should be correct in the first place during reconstruction operation.

Elbow stress in youth softball windmill pitchers: predictors of increased torque

Purpose: To assess torque at the elbow in the underhand throwing motion utilizing wearable sensor technology and discover the predictors of medial elbow toque in young female softball pitchers. Methods: Female softball players 12 to 18 years old whose primary position was pitcher and actively participating in sport were studied. Players experiencing throwing arm pain, lower extremity injury hindering pitching motion, or prior surgery were excluded. Age, handedness, height, weight, and throwing arm dimensions were measured and recorded. Pitchers threw 15 pitches, max effort from 43 feet and were given 30 to 60 second rest between pitches. A wearable sensor was placed inside an athletic compression sleeve which recorded data. Measurements included medial elbow torque (Newton-meters; NM), arm speed (peak rotational velocity of the forearm; in rotations per minute; RPM), arm slot (forearm angle in relation to the ground at release; in degrees), and shoulder rotation (maximum forearm angle during the 12 o’clock phase; in degrees). Peak ball velocity in miles per hour (MPH) was measured by a radar gun. Results: Twenty females mean age 15.2 years (range, 12.6-16.9 years) achieved an average elbow stress of 35.5 NM (14-78 NM). Average arm speed measured 583.8 RPM (3502.8 deg/sec) and ball speed ranged from 33-56 mph with an average of 44.1 mph. Multivariate analysis demonstrated arm stress significantly associated with increasing age (P-value 0.00003), and arm length (P-value 0.000006); however, increased forearm length measured a decreased arm stress (P-value 0.00007). Conclusions: There was significant stress measured across the medial elbow in young softball pitchers. Elbow torque was associated with increasing age and total arm length; however, increased forearm length was associated with decreased elbow torque.

Elbow stress in youth softball windmill pitchers: predictors of increased torque

Purpose: To assess torque at the elbow in the underhand throwing motion utilizing wearable sensor technology and discover the predictors of medial elbow toque in young female softball pitchers. Methods: Female softball players 12 to 18 years old whose primary position was pitcher and actively participating in sport were studied. Players experiencing throwing arm pain, lower extremity injury hindering pitching motion, or prior surgery were excluded. Age, handedness, height, weight, and throwing arm dimensions were measured and recorded. Pitchers threw 15 pitches, max effort from 43 feet and were given 30 to 60 second rest between pitches. A wearable sensor was placed inside an athletic compression sleeve which recorded data. Measurements included medial elbow torque (Newton-meters; NM), arm speed (peak rotational velocity of the forearm; in rotations per minute; RPM), arm slot (forearm angle in relation to the ground at release; in degrees), and shoulder rotation (maximum forearm angle during the 12 o’clock phase; in degrees). Peak ball velocity in miles per hour (MPH) was measured by a radar gun. Results: Twenty females mean age 15.2 years (range, 12.6-16.9 years) achieved an average elbow stress of 35.5 NM (14-78 NM). Average arm speed measured 583.8 RPM (3502.8 deg/sec) and ball speed ranged from 33-56 mph with an average of 44.1 mph. Multivariate analysis demonstrated arm stress significantly associated with increasing age (P-value 0.00003), arm length (P-value 0.000006); however, increased forearm length measured a decreased arm stress (P-value 0.00007). Conclusions: There was significant stress measured across the medial elbow in young softball pitchers. Elbow torque was associated with increasing age and total arm length; however, increased forearm length was associated with decreased elbow torque.

The LET Procedure for Gesture Recognition With Multiple Forearm Angles

A-mode ultrasound, like other biological signals, has a certain deviation in the signals obtained by performing the same gesture at different arm positions. This problem hinders the clinical application of gesture recognition based on A-mode ultrasound. To tackle this problem, we propose the linearly enhanced training (LET) procedure to compensate for the deviation of gesture signals after forearm position changes. The training set does not contain the gesture data of the new position, so no additional training is required. Instead, we determine the scale parameters to construct enhanced features for the new positions by the original position gesture features. We tested the method on 10 gestures after the forearm angle is changed. Results show that the classification accuracy can be improved by 7.8% and 9.4% after the forearm bent and stretched 40° respectively. Since the LET procedure is a step between feature extraction and model construction, it is suitable for various features and algorithms, offering a multi-scene solution based on wearable A-mode ultrasound.

The Relationship of Some Kinematic Variables to the Performance of Forehand Clear Stroke with Accuracy in Badminton Players

The study aimed to: Recognizing the values of a number of kinematical variables for the performance of the forehand clear stroke for badminton players. Recognizing the values of the accuracy test for the performance for the forehand clear stroke of badminton players. Recognizing the relationship between a number of kinematical variables and the accuracy values of the forehand clear stroke for badminton players. In order to verify the objectives of the study, the researcher had assumed the following: - There is a significant relationship between the values of a number of bio kinematical variables and the accuracy values of the forehand clear stroke for badminton players. The researchers used the descriptive approach with the correlational style, for its suitability to the study nature, The research sample was selected from the players of the elite clubs registered with the Iraqi Badminton Federation, and the research sample consisted of (7) players. The researcher used the resources, scientific references, interviews, questionnaires, testing, measurement and scientific observation as means of data collecting, the study included biokinematical variables, and the accuracy of the forehand clear stroke skill. The main experiment was conducted in two different locations due to the presence of the research sample (4) of them representing the Iraqi national badminton team in Baghdad and (3) players representing the Akad Sports Club in Erbil province, and in order to achieve the first scientific and technical observation, two digital cameras were used. At a speed (240 f /s), the first camera was placed on the side of the player's hitting arm at a distance of (4 m) and with a lens height (1.25 m) , and the second was placed in front of the player at a distance of (3.35 m) With a lens height (1.25 m). In order to achieve the second scientific and technical observation, two digital cameras were used. The first camera was placed on the side of the player's hitting arm at a distance (5.35 m) and a lens height (1.29 m), it was set at speed (300f /s), and the second camera was placed in front of the player at a distance (3.70 m) and with a lens height (1.29 m), and it was set at speed (210 f/s). The data were statistically handled using the (SPSS) program to obtain (the arithmetic mean, standard deviation, coefficient of variation, simple correlation coefficient, and T-test for independent samples. The researchers concluded: - The variables (horizontal displacement, horizontal velocity and velocity resultant) for BMC in the final phase of the forehand clear stroke skill had a positive significant relationship with accuracy. - The shuttlecock starting velocity in the forehand clear stroke skill had a direct relationship with accuracy. - Accuracy has a direct relationship with variable of the striking arm wrist joint angle and inversely with the forearm angle with the racket variable at the moment of maximum return of the racket in the forehand clear stroke skill. - The relationship was direct between (shoulder angle, forearm angle with the racket) variables (each separately) with the accuracy at the moment of shuttlecock impact in the forehand clear stroke skill. - The increase in the angular deference of the forearm with racket was significantly correlated with accuracy in the main phase of the forehand clear stroke skill. - There is a direct relationship between the angular velocity of the forearm with the racket variable with the accuracy in the main phase of the forehand clear stroke skill. Through the conclusions, the researchers recommend: - The necessity to direct the players to pay attention to the ideal angles of technical performance of badminton skills. - Directing the coaches to use a kinematic analysis programs or seeking the help of an expert and specialist in kinetic analysis to correct some of the players' performance errors that are not seen with the naked eye. - Paying attention to the results of the current study for use by workers in the field of badminton training and education.

Development of AI Algorithm for Weight Training Using Inertial Measurement Units

Thanks to the rapid development of Wearable Fitness Trackers (WFTs) and Smartphone Pedometer Apps (SPAs), people are keeping an eye on their health through fitness and heart rate tracking; therefore, home weight training exercises have received a lot of attention lately. A multi-procedure intelligent algorithm for weight training using two inertial measurement units (IMUs) is proposed in this paper. The first procedure is for motion tracking that estimates the arm orientation and calculates the positions of the wrist and elbow. The second procedure is for posture recognition based on deep learning, which identifies the type of exercise posture. The final procedure is for exercise prescription variables, which first infers the user’s exercise state based on the results of the previous two procedures, triggers the corresponding event, and calculates the key indicators of the weight training exercise (exercise prescription variables), including exercise items, repetitions, sets, training capacity, workout capacity, training period, explosive power, etc.). This study integrates the hardware and software as a complete system. The developed smartphone App is able to receive heart rate data, to analyze the user’s exercise state, and to calculate the exercise prescription variables automatically in real-time. The dashboard in the user interface of the smartphone App can display exercise information through Unity’s Animation System (avatar) and graphics, and records are stored by the SQLite database. The designed system was proven by two types of experimental verification tests. The first type is to control a stepper motor to rotate the designed IMU and to compare the rotation angle obtained from the IMU with the rotation angle of the controlled stepper motor. The average mean absolute error of estimation for 31 repeated experiments is 1.485 degrees. The second type is to use Mediapipe Pose to calculate the position of the wrist and the angles of upper arm and forearm between the Z-axis, and these calculated data are compared with the designed system. The root-mean-square (RMS) error of positions of the wrist is 2.43 cm, and the RMS errors of two angles are 5.654 and 4.385 degrees for upper arm and forearm, respectively. For posture recognition, 12 participants were divided into training group and test group. Eighty percent and 20% of 24,963 samples of 10 participants were used for the training and validation of the LSTM model, respectively. Three-thousand-three-hundred-and-fifty-nine samples of two participants were used to evaluate the performance of the trained LSTM model. The accuracy reached 99%, and F1 score was 0.99. When compared with the other LSTM-based variants, the accuracy of one-layer LSTM presented in this paper is still promising. The exercise prescription variables provided by the presented system are helpful for weight trainers/trainees to closely keep an eye on their fitness progress and for improving their health.

The Reliability and Validity of a Clinical Measurement Proposed to Quantify Humeral Torsion.

BackgroundRange of motion (ROM) impairments of the overhead athletes’ shoulder are commonly addressed through mobility-based treatments, however, adaptations from humeral torsion (HT) are not amenable to such interventions. A clinical measurement to quantify HT has been proposed, however, the validity is not conclusive.PurposeThe primary aim of this study is to determine the intrarater reliability and standard error of measurement (SEM) of the biceps forearm angle (BFA) measurement. The secondary aim of this study is to investigate the convergent validity of the BFA compared to diagnostic ultrasound.Study DesignCross Sectional Reliability and Validity StudyMethodsHT measurements, utilizing diagnostic ultrasound, were compared to BFA in 74 shoulders (37 subjects) over two sessions. Each measurement was performed three times and a third investigator recorded measures to ensure blinding. Reliability was investigated using utilizing an intraclass correlation coefficient (ICC 3,k)ResultsIntrarater reliability values were 0.923 and 0.849 for diagnostic ultrasound and BFA methods respectively. Convergent validity was r = 0.566. The standard error of measurement for diagnostic ultrasound and BFA was 3° and 5°, respectively. The 95% limits of agreement between the two measurement methods were -24.80° and 19.80° with a mean difference of -2.50° indicating that on average the diagnostic ultrasound measurement was lower than that of the BFA method.ConclusionThe BFA is a reliable clinical method for quantifying HT, however, demonstrates moderate to poor convergent validity when compared to diagnostic ultrasound.Level of Evidence2b

Elements Influencing sEMG-Based Gesture Decoding: Muscle Fatigue, Forearm Angle and Acquisition Time.

The surface Electromyography (sEMG) signal contains information about movement intention generated by the human brain, and it is the most intuitive and common solution to control robots, orthotics, prosthetics and rehabilitation equipment. In recent years, gesture decoding based on sEMG signals has received a lot of research attention. In this paper, the effects of muscle fatigue, forearm angle and acquisition time on the accuracy of gesture decoding were researched. Taking 11 static gestures as samples, four specific muscles (i.e., superficial flexor digitorum (SFD), flexor carpi ulnaris (FCU), extensor carpi radialis longus (ECRL) and finger extensor (FE)) were selected to sample sEMG signals. Root Mean Square (RMS), Waveform Length (WL), Zero Crossing (ZC) and Slope Sign Change (SSC) were chosen as signal eigenvalues; Linear Discriminant Analysis (LDA) and Probabilistic Neural Network (PNN) were used to construct classification models, and finally, the decoding accuracies of the classification models were obtained under different influencing elements. The experimental results showed that the decoding accuracy of the classification model decreased by an average of 7%, 10%, and 13% considering muscle fatigue, forearm angle and acquisition time, respectively. Furthermore, the acquisition time had the biggest impact on decoding accuracy, with a maximum reduction of nearly 20%.

Optimization of the forearm angle for arm wrestling using multi-camera stereo digital image correlation: A preliminary study

This study analyzes the function of different muscles during arm wrestling and proposes a method to analyze the optimal forearm angle for professional arm wrestlers. We built a professional arm-wrestling platform to measure the shape and deformation of the skin at the biceps brachii of a volunteer in vivo during arm wrestling. We observed the banding phenomenon of arm skin strain during muscle contraction and developed a model to evaluate the moment provided by the biceps brachii. According to this model, the strain field of the area of interest on the skin was measured, and the forearm angles most favorable and unfavorable to the work of the biceps brachii were analyzed. This study demonstrates the considerable potential of applying DIC and its extension method to the in vivo measurement of human skin and facilitates the use of the in vivo measurement of skin deformation in various sports in the future.

Exerted force estimation using a wearable sensor during manual material handling

AbstractWhile evaluating the physical workload on workers, the force exerted needs to be estimated in a convenient way because biomechanical analysis for physical workload evaluation requires data on both posture and exerted force. The aim of this study was to investigate the effectiveness of exerted force estimation using a wearable device that can be easily utilized even by ordinary workers. We measured eight electromyograms (EMGs) on the forearm and the forearm posture with an armband type wearable sensor during manual material handling with varying holding weights and heights. The measurement results showed that the EMGs monotonically increased with an increase in weight. In addition, the EMGs varied with the holding height even when the same weight was held. We constructed an estimation function of the weight using multiple regression analysis. Two sets of explanatory variables were used to investigate the effectiveness of the forearm posture data: the eight EMGs (i.e., SET 1) and the eight EMGs and the two forearm angles (i.e., SET 2). Multiple regression analysis showed that the accuracy of SET 2 was better than that of SET 1. In addition, the average absolute error of the estimation function with SET 2 was 1.49 kg; thus, we concluded that the accuracy of this estimation function has sufficient accuracy for the evaluation of physical workload.

Children\u2019s coordination of the \u201csweet spot\u201d when striking a forehand is shaped by the equipment used

Children’s movement coordination is significantly influenced by the equipment used when performing multi-articular actions. Previously we reported that scaled equipment (smaller racket and a softer ball), but not full-sized equipment, promoted a functional coupling between upper arm and forearm angles in children performing a forehand. However, it remains unclear whether the shoulder-racket distance—which is controlled by this coupling—is a performance variable. This study therefore advanced previous research by examining whether the shoulder-racket distance is associated with performance. We also improved our understanding of how the shoulder-racket distance is controlled by including the hand-racket segment in our biomechanical model. Twenty-one children performed 40 forehands in a hitting for accuracy task. Participants were randomly divided into two groups—a scaled equipment group and a full-sized equipment group. Results revealed that the shoulder-racket distance was a performance variable, as evidenced by: (a) its variance reduced closer to ball impact, (b) its distance at ball impact, but not at the start of the forward swing, differentiated good from poor performance, and (c) its distance was similar for both groups, implying that there was a “sweet spot” for striking a ball, regardless of racket size. We also showed that it is the shoulder-racket vector in state-space (i.e., distance and angle) that differentiates good from poor performance. Finally, the manner in which the shoulder-racket distance was controlled differed between the groups, with scaled equipment promoting a more distal control than full-sized equipment. Implications for skill acquisition are discussed.

Diurnal Profiles of Physical Activity and Postures Derived From Wrist-Worn Accelerometry in UK Adults

Background: Wrist-worn accelerometry is the commonest objective method for measuring physical activity in large-scale epidemiological studies. Research-grade devices capture raw triaxial acceleration which, in addition to quantifying movement, facilitates assessment of orientation relative to gravity. No population-based study has yet described the interrelationship and variation of these features by time and personal characteristics. Methods: 2,043 United Kingdom adults (35–65 years) wore an accelerometer on the non-dominant wrist and a chest-mounted combined heart-rate-and-movement sensor for 7 days free-living. From raw (60 Hz) wrist acceleration, we derived movement (non-gravity acceleration) and pitch and roll (forearm) angles relative to gravity. We inferred physical activity energy expenditure (PAEE) from combined sensing and sedentary time from approximate horizontal arm angle coupled with low movement. Results: Movement differences by time-of-day and day-of-week were associated with forearm angles; more movement in downward forearm positions. Mean (SD) movement was similar between sexes ∼31 (42) mg, despite higher PAEE in men. Women spent longer with the forearm pitched &gt;0°, above horizontal (53% vs 36%), and less time at &lt;0° (37% vs 53%). Diurnal pitch was 2.5–5° above and 0–7.5°below horizontal during night and daytime, respectively; corresponding roll angles were ∼0° (hand flat) and ∼20° (thumb-up). Differences were more pronounced in younger participants. All diurnal profiles indicated later wake-times on weekends. Daytime pitch was closer to horizontal on weekdays; roll was similar. Sedentary time was higher (17 vs 15 hours/day) in obese vs normal-weight individuals. Conclusions: More movement occurred in forearm positions below horizontal, commensurate with activities including walking. Findings suggest time-specific population differences in behaviors by age, sex, and BMI.

Torsion Sensing on a Cylinder Using a Flexible Piezoelectric Wrist Band

A wrist band undergoes torsional loads during twisting motions of the human forearm. In this article, we investigate sensing torsional loads on a silicone cylinder using a wrist band hosting a sensor. We utilize a flexible sensor based on polyvinylidene fluoride, which is a flexible piezoelectric material. The flexible piezoelectric sensor is inserted into a pocket of the wrist band and outputs an electrical response to the torsional loads on the cylinder. We model the sensing response from the wrist band during the torsional loads on the silicone cylinder through an electromechanical model for a piezoelectric beam. To validate the model, we compare theoretical predictions with experimental data at systematically varied torsional loading conditions. The experimental results demonstrate that the sensor outputs are linearly proportional to the rotation angle of the cylinder. Moreover, we conduct human tests using the flexible piezoelectric wrist band sensor, and its result shows the same linearity about twisting motion angles of the human forearm. This article shows the feasibility of sensing from the twisting motion of a human forearm using a wrist band with a piezoelectric sensor.

Lambeau circonférentiel en rotation pour la stabilisation longitudinale du radius

Surgical management of radial longitudinal deficiency (RLD) aimed to correct the wrist radial deviation by centralizing the carpus upon the ulnar distal end, conjointly with soft tissue structures balancing around the wrist, whilst preserving the distal ulnar physis growth potential. Although, several skin incisions were used for centralization procedure, but few of them dealt with the issue of substantial skin tension radially with available redundant skin ulnarly, and the difficulty for full access of the radio-volar aspect for fully release the tethering structures. Nineteen wrists in 13 patients with RLD of Bayne and Klug type IV, were operated on by centralization using circumferential rotational flap between 2008 and 2017. The average age at the time of centralization was 18.5 months. Follow-up evaluation was done at 3 months intervals, average follow-up was 42 months. Patients were evaluated at postoperative follow-up according to the clinical appearance of scar, wrist stability, and radiological parameters on preoperative and postoperative radiographs. Encouraging primary wound healing, and on the latest follow-up; a smooth satisfactory wrist contour was restored, significant improvement of the hand forearm angle (HFA) and hand forearm position (HFP) compared with the preoperative measures, and a significant ulna growth continued postoperatively signifying no distal ulnar physis injury occurred. Parents were satisfied with the resulted esthetics and function of the hand, which would be attributed to the improved stability of the carpo-ulnar pseudo-articulation. This flap allowed excellent access to the radio-volar aspect of the wrist, and facilitates rotation of the ulnar redundant skin in a radio-volar direction, whilst rotating the distal hand and carpus into ulnar-sided direction, provided additional skin to the radial aspect. It was safely used for centralization procedure in this study preserving the growth potential of the distal ulna without memorable complications attributed to the flap, leaving a smooth satisfactory contoured wrist. A circumferential rotational flap was safely used for centralization procedure in this study, provided additional skin on the radial aspect and take up the slack on the ulnar aspect and gave excellent access to the wrist and surrounding soft tissue structures without recorded complications attributed to the flap.

The effect of tendon rotation on distal biceps repair

BackgroundThe distal biceps tendon externally rotates from proximal to distal before inserting onto the radius. Our hypothesis is that an externally rotated (anatomic) repair would re-create native supination moment arm and flexion force, whereas an internally rotated (nonanatomic) repair would result in reduced force transmission.MethodsThe mechanical tests performed in this study measured isometric moment arms and elbow flexion force using a validated elbow simulator as previously published. Mechanical testing was performed on 8 native cadaveric elbows (61 ± 15 years). The distal biceps tendons in all specimens were then incised from their footprint and repaired with anatomic and nonanatomic tendon rotations. After each repair, the specimens were retested. The repair sequence was randomly assigned.ResultsGross observation showed repair site bunching with the nonanatomic repairs. There was no statistical difference in the moment arms between the native, anatomic, and nonanatomic rotations for the 3 forearm angles (P ≥ .352). Analysis showed no statistical difference in flexion force ratio for the elbow at 90° (P ≥ .283).DiscussionThe study showed that biceps tendon rotation does not play a role in supination moment arm or flexion force. Twisting the distal biceps tendon around the tendon axis does not change the direction of its applied force on the tuberosity. Tendon bunching in nonanatomic reattachments increases repair site width, which may lead to tendon-ulnar impingement during forearm rotation.

Headless double-threaded compression screws plus microplate for capitellar fracture of Ring typeII

Objective To investigate the clinical effects of headless double-threaded compression screws plus microplate for treatment of capitellar fracture of Ring type Ⅱ. Methods In the period from March 2015 to February 2018, 12 capitellar fractures of Ring type Ⅱ were treated at Department of Upper limb Orthopedics, Zhengzhou Orthopaedics Hospital. There were 8 men and 4 women, aged from 25 to 57 years (average, 35.4 years). There were 5 left and 7 right fractures. The fractures were exposed and reduced through the posterolateral elbow approach in 6 patients and through the lateral elbow approach in the other 6 ones. Fixation of all the fractures was conducted with headless double-threaded compression screws plus microplate. At the final follow-up, the elbow function was evaluated by the Mayo elbow performance score and the severity of traumatic arthritis by the Broberg & Morrey imaging criteria. Results All the patients were followed up for 9 to 36 months (average, 23 months). The fracture healing time ranged from 9 to 12 weeks (average, 10.6 weeks). The final follow-ups revealed fine stability of the affected elbow joint in all the patients, and no loss of reduction, loosening or breakage of internal fixators or ischemic necrosis in any case. At the final follow-ups, the elbow inflection angles ranged from 90° to 130° (average, 114.3°), the elbow extension angles from 0° to 20° (average, 12.4°), the forearm pronation angles from 50° to 85° (average, 70.5°) and the forearm supination angles from 45° to 80° (average, 64.3°). The Mayo elbow performance scores at the final follow-up averaged 93.2 points (from 85 to 100 points), yielding 8 excellent and 4 good cases. According to the Broberg & Morrey imaging criteria, 10 patients showed no regressive change and 2 patients change by one grade. Conclusions A proper surgical approach should be chosen according to the preoperative imaging findings. The fracture of articular surface can be firmly fixated by head-less double-threaded compression screws and the integrity of the distal lateral column of the humerus can be restored with a microplate to achieve a strong biomechanical fixation. Fine clinical outcomes can be obtained by early functional exercise. Key words: Elbow joint; Bone fixation, internal; Capitellar fracture; Headless double-threaded screws; Microplate