Axillary Web Syndrome: characterization of the different forms of clinical presentation of the cord.

ObjectiveDescribe and characterize the forms of presentation and manifestation of the cord present in the Axillary Web Syndrome.Materials and MethodsAfter a favorable opinion from the Research Ethics Committee of the Federal University of Goiás, the construction of items for the Axillary Web Syndrome Classification Scale began, based on the search for concepts involved in its diagnosis. The various steps of construction, application and validation of the instrument occurred from April 2020 to August 2021. The research took place at the outpatient clinic of Mastology at Hospital das Clínicas (Goiás). In the evaluation position: supine, upper limb ipsilateral to the breast operated in abduction, extension and external rotation of the shoulder, extension and supination of the elbow, extension of the wrist and fingers, information on the specific characteristics of the cord was recorded.ResultsThe means presented by the evaluators were almost identical for the variables related to the characterization of the cord, indicating a strong correlation, Cronbach's alpha was 0.894 for evaluator 1 and 0.879 for evaluator 2, indicating strong internal consistency. Inter-rater agreement was 100% (p>0.001) for almost all variables evaluated, with the lowest Kappa coefficient (0.77 p>0.001) for “Length”.ConclusionA consensus on classification criteria can be useful among researchers and practitioners. The fibrous cord classification items compiled in this study address its forms of presentation and manifestation and contribute to standardizing the assessment and classification of Axillary Web Syndrome.

Compensating for Soft-Tissue Artifact Using the Orientation of Distal Limb Segments During Electromagnetic Motion Capture of the Upper Limb

Most motion capture measurements suffer from soft-tissue artifacts (STA). Especially affected are rotations about the long axis of a limb segment, such as humeral internal-external rotation (HIER) and forearm pronation-supination (FPS). Unfortunately, most existing methods to compensate for STA were designed for optoelectronic motion capture systems. We present and evaluate a STA compensation method that 1) compensates for STA in HIER and/or FPS, 2) is developed specifically for electromagnetic motion capture systems, and 3) does not require additional calibration or data. To compensate for STA, calculation of HIER angles rely on forearm orientation, and calculation of FPS angles rely on hand orientation. To test this approach, we recorded whole-arm movement data from eight subjects and compared their joint angle trajectories calculated according to progressive levels of STA compensation. Compensated HIER and FPS angles were significantly larger than uncompensated angles. Although the effect of STA compensation on other joint angles (besides HIER and FPS) was usually modest, significant effects were seen in certain DOF under some conditions. Overall, the method functioned as intended during most of the range of motion of the upper limb, but it becomes unstable in extreme elbow extension and extreme wrist flexion-extension. Specifically, this method is not recommended for movements within 20° of full elbow extension, full wrist flexion, or full wrist extension. Since this method does not require additional calibration of data, it can be applied retroactively to data collected without the intent to compensate for STA.

Age and Not the Preferred Limb Influences the Kinematic Structure of Pointing Movements

In goal-directed movements, effective open-loop control reduces the need for feedback-based corrective submovements. The purpose of this study was to determine the influence of hand preference and aging on submovements during single- and two-joint pointing movements. A total of 12 young and 12 older right-handed participants performed pointing movements that involved either elbow extension or a combination of elbow extension and horizontal shoulder flexion with their right and left arms to a target. Kinematics were used to separate the movements into their primary and secondary submovements. The older adults exhibited slower movements, used secondary submovements more often, and produced relatively shorter primary submovements. However, there were no interlimb differences for either age group or for the single- and two-joint movements. These findings indicate that open-loop control is similar between arms but compromised in older compared to younger adults.

The effect of post-fixation olecranon lengthening on range of motion of the elbow: a cadaveric study

Background Principles of fixation of comminuted olecranon fractures include anatomical reduction of the articular surface and restoration of ulnohumeral joint motion. However, comminution sometimes may not permit anatomical fixation of fracture fragments, resulting in inadvertent olecranon lengthening after plate fixation. The aim of our study is to investigate the relationship between olecranon lengthening following plate fixation and loss of elbow extension. Materials and methods Transverse olecranon osteotomies were performed on 8 cadaveric elbows. The osteotomy sites were then fixed with olecranon plates. Lengthening of the osteotomy sites were simulated by placement of 2mm, 4mm, 6mm and 8mm blocks. Lateral view photographs of the elbows were taken after each degree of lengthening. These photographs were then printed and measurements of elbow extension were performed with a goniometer with average values taken. The measurements were tabulated and statistical analysis performed to determine the relationship between degree of elbow extension loss and amount of olecranon lengthening. Results Average values of each degree of lengthening (at 2mm, 4mm, 6mm and 8mm) were taken and compared with the baseline measurement (at 0mm). Cluster analysis showed that for every increment in osteotomy length of 2mm, there is a corresponding increase of 0.79° of elbow extension loss (p<0.01, 95% confidence level 0.55°-1.03°). Conclusion Lengthening of olecranon by increments of 2mm correlates positively with loss of elbow extension. This shows that inadvertent intra-operative olecranon lengthening post-fixation may result in limited range of motion. However, it is reassuring to know that the small degree of extension loss may not translate to functional limitation.

Anconeus motor unit firing rates during isometric and muscle-shortening contractions comparing young and very old adults

Changes of neural drive to the muscle with adult aging, measured as motor unit firing rates during limb movements, are unknown. Throughout maximal voluntary efforts we found that, in comparison with young adults, firing rates were lower during isometric contraction in older adults but not different during elbow extension movements. Despite the older group being ∼33% weaker across contractions, their muscles can receive neural drive during movements that are similar to that of younger adults.

Radial Head Lag: A Possible Biomechanical Mechanism for Osteochondritis Dissecans of the Capitellum in Baseball Pitchers

Background: Osteochondritis dissecans (OCD) of the capitellum is common in throwing athletes and is believed to result from repetitive overloading on the radiocapitellar (RC) joint, although the cause and mechanism remain unclear. The torsional forces (moments) generated by the triceps during elbow extension pull only on the ulna; therefore, the radial head moves passively across the capitellum and is effectively “dragged along” by the ulna. Any laxity in the proximal radioulnar joint could lead to asynchronous motion between the radius and ulna, resulting in the radial head lagging behind the coronoid and possibly malarticulating with the capitellum during such motion. Hypothesis: Radial head motion on the capitellum lags behind ulnohumeral joint motion during simulated throwing. Study Design: Controlled laboratory study. Methods: A total of 8 cadaveric elbows were tested under simulated throwing, including active extension of the elbow generated by pulling of the triceps under valgus stress, as well as during passive extension under valgus stress to serve as a reference. Ulnohumeral motion was tracked using a video camera. Radial head motion was tracked using an intra-articular, thin-film pressure sensor mounted on the capitellum, and the longitudinal movement of the center of force (COF) of the radial head was measured. Radial head motion was compared between passive and active motion for each 10° of elbow extension from 90° to 20°. Results: Elbow motion during simulated active extension reached an angular velocity of 366 deg/s. Radial head motion during simulated active extension significantly lagged compared with its motion during passive extension at every elbow extension angle examined between 70° and 20° ( P < .001). The maximal lag reached a mean of 4 mm (range, 2-7 mm). In other words, RC and ulnohumeral motion were asynchronous during simulated throwing. Conclusion: This study describes a novel phenomenon: motion of the radial head across the capitellum during rapid extension, such as in baseball pitching, lags behind that seen during passive elbow motion. According to a new proposed theory of OCD lesion development, this lag should result in RC incongruency and elevated shear forces on the capitellum due to edge loading. Clinical Relevance: We propose a new biomechanical explanation for OCD of the capitellum in baseball pitchers: radial head lag. Understanding this process is the first step in efforts to prevent this common injury.

The Influence of Perceptual-Motor Variability on the Perception of Action Boundaries for Reaching in a Real-World Setting

The ability to accurately perceive the extent over which one can act is requisite for the successful execution of visually guided actions. Yet, like other outcomes of perceptual-motor experience, our perceived action boundaries are not stagnant, but in constant flux. Hence, the perceptual systems must account for variability in one’s action capabilities in order for the perceiver to determine when they are capable of successfully performing an action. Recent work has found that, after reaching with a virtual arm that varied between short and long each time they reach, individuals determined their perceived action boundaries using the most liberal reaching experience. However, these studies were conducted in virtual reality, and the perceptual systems may handle variability differently in a real-world setting. To test this hypothesis, we created a modified orthopedic elbow brace that mimics injury in the upper limb by restricting elbow extension via remote control. Participants were asked to make reachability judgments after training in which the maximum extent of their reaching ability was either unconstricted, constricted or variable over several calibration trials. Findings from the current study did not conform to those in virtual reality; participants were more conservative with their reachability estimates after experiencing variability in a real-world setting.

A biomechanical comparison of different baseball batting training methods

This study compared the kinematic parameters of swing mechanics under toss batting (TB), motor imagery (MI), video projection (VP), and virtual reality (VR) conditions during baseball batting. Nine college baseball players performed three swings to hit a tossed ball under TB conditions or a virtual ball under MI, VP, and VR conditions. The results revealed that upper trunk backward rotation was smaller in the loading phase under the VP and VR conditions than under the TB and MI conditions and lower under VR than under the VP condition ( p < 0.05) except at the load event. Pelvic backward rotation was smaller under the VR condition than under the TB, MI, and VP conditions ( p < 0.05). In the swing phase, TB demonstrated higher peak velocity at the head of the bat, lead elbow extension, and pelvis and upper trunk rotation than did MI, VP, and VR, whereas VP also demonstrated higher peak velocity in pelvic forward rotation than did VR ( p < 0.05). In summary, VR demonstrates a more realistic response in the loading phase and reduced pelvic backward rotation but lower movement velocities. Coaches should pay attention to movement differences between swing conditions when arranging a swing training plan.