Differential regional pectoralis major activation indicates functional diversity in healthy females.

Pectoralis major activation enables the performance of several upper extremity movements. Its regional activation, however, is not documented in healthy females. This work used high-density surface electromyography to investigate regional pectoralis major activation in twenty-nine healthy young females across two independent experiments in several ramp and hold isometric tasks and force levels. Regional mean root mean square amplitudes (normalized to the task-specific maxima) were quantified for the clavicular, superior, and middle sternocostal regions. Two-way ANOVAs were used to determine if differences in normalized regional activation exist within each task and force level. The middle sternocostal region activated 12-108% more than the clavicular and the superior sternocostal region in extension, adduction with external rotation, and high elevation internal rotation. In high elevation adduction, the middle sternocostal region activated more (7-22%) than the superior sternocostal region. In low elevation, internal rotation (60°), the clavicular and middle sternocostal regions activated more (9-13%) than the superior sternocostal region, while in adduction 60°, the clavicular region activated 9-19% more than the superior sternocostal region. Lastly, in forward and horizontal flexion, all three regions activated similarly irrespective of the force level, except at 25% MVF in forward flexion, where the clavicular region activated 21% more than the superior sternocostal region. This work provides a first comprehensive evaluation of the normalized regional pectoralis major activation in healthy females. The present findings indicate that the performance of isometric tasks in different directions activates different pectoralis major regions in healthy females, suggesting regional specificity to functional actions.

The anatomy and variation of the coracoid attachment of the subclavius muscle in humans.

The functions of the subclavius muscle (SM) are described as stabilization of the sternoclavicular joint (SCJ) and resisting elevation of the lateral end of the clavicle. During systematic cadaveric dissections, we observed additional fibrous structures, previously described as variants of the anatomy, extending from the SM and inserting into the coracoid process (CP). Due to the high incidence of these structures in our dissections, we hypothesized that the attachment at the CP is more common than appreciated and that, as a corollary, the function of the SM was (or has been) more complex than simply depressing the clavicle and generating stability at the SCJ. For our investigation, fifty-two upper extremities of 26 human cadavers were dissected. The SM was demonstrated from costal to clavicular attachment. We documented additional fibrous structures apparently derived from the SM inserting into the CP. Measurements of the length of the SM, the length of its attachment, and the length of the clavicle were taken in situ, with the specimens supine and the upper extremity in the anatomical position. Variations in the anatomy of the SM and its coracoidal attachment were recorded, and potential correlations were investigated. For documentation purposes photographs and video sequences of passive motion of the shoulder girdle of the specimens were taken. In 49 of the 52 specimens we found additional fibrous structures passing from the SM to the CP. We differentiated three types: (1) a strong cord-like structure; (2) a small or thin cord-like structure or structures; and (3) a planar twisted sheet-like structure. The SM and its extension to the CP appears to contribute to a 'functional scapular suspension system' together with the other muscles enveloped by the clavipectoral fascia (pectoralis minor, coracobrachialis and the short head of the biceps brachii). This system assists in the control of the position of the scapula in relation to the thorax, particularly in elevated positions of the upper extremity. We speculate that the differentiation of the fibrous structure depends on the functional demands of the individual. Level of Evidence: Basic science study.

La rotación axial de la clavícula que plantea la maniobra de Mulligan ¿produce una reducción de la presión en el espacio subacromial? Un estudio ex vivo exploratorio / Does the axial rotation of the clavicle posed by the Mulligan maneuver produce a pressure reduction in the subacromial space? An exploratory ex vivo study

RESUMEN: El pinzamiento de hombro es la principal causa del hombro doloroso. Dentro de las estrategias terapéuticas propuestas se encuentra la terapia manual. En este contexto, la maniobra de Mulligan, implica una rotación axial en sentido anterior de la clavícula, emulando la acción del músculo subclavio, lo cual hipotéticamente aumentaría el espacio subacromial. Sin embargo, no existen antecedentes que proporcionen sustento experimental a dicha hipótesis. El objetivo del presente estudio fue explorar si la rotación axial de la clavícula, producida por la maniobra de Mulligan, tiene efecto sobre la presión registrada en el espacio subacromial, con el propósito disponer de antecedentes metodológicos que puedan contribuir al diseño de futuros estudios que aborde la problemática expuesta y consideren un mayor tamaño de muestra. Mediante un estudio exploratorio ex-vivo, se evaluaron dos preparados anatómicos que comprendían la escapula, la clavícula y los dos tercios proximales del humero, ambos con indemnidad de la articulación glenohumeral y acromioclavicular. En estos se registraron la presión en el espacio subacromial y la rotación axial de la clavícula, todo durante la realización de una maniobra de rotación axial clavicular en sentido anterior. Se analizaron las diferencias de presión entre una condición basal y durante la maniobra, como también la máxima rotación axial de clavícula. Dichas variables fueron registradas mediante un sensor de presión y un sistema de análisis de movimiento. La presión en el espacio subacromial durante la maniobra, disminuyó en todas las repeticiones en un rango comprendido entre el 21-51 % de la presión basal. La máxima rotación axial registrada estuvo entre los 3.9-10°. Los resultados de este estudio exploratorio, dan pie para hipotetizar que la maniobra de rotación axial anterior de la clavícula produce una disminución de la presión subacromial, en el área comprendida inmediatamente bajo el acromion.

SUMMARY: Shoulder impingement is the main cause of shoulder pain. Manual therapy is one of the proposed therapeutic strategies. In this context, the Mulligan maneuver implies anterior axial rotation of the clavicle, emulating the action of the subclavius muscle, which hypothetically would increase the subacromial space. However, there are no antecedents that provide experimental support for this hypothesis. The objective of the present study was to explore whether the axial rotation of the clavicle, produced by the Mulligan maneuver, has an effect on the pressure registered in the subacromial space, with the purpose of having methodological antecedents that can contribute to the design of future studies that address the problem exposed and consider a larger sample size. Through an ex-vivo exploratory study, two anatomical preparations comprising the scapula, clavicle, and proximal two-thirds of the humerus, both with glenohumeral and acromioclavicular joint sparing, were evaluated. In these, the pressure in the subacromial space and the axial rotation of the clavicle were recorded, all during the performance of an anterior clavicular axial rotation maneuver. Pressure differences between a basal condition and during the maneuver were analyzed, as well as the maximum axial rotation of the clavicle. These variables were recorded using a pressure sensor and a movement analysis system. The pressure in the subacromial space during the maneuver decreased in all repetitions in a range between 21-51% of the basal pressure. The maximum axial rotation recorded was between 3.9-10°. The results of this exploratory study give rise to the hypothesis that the anterior axial rotation maneuver of the clavicle produces a decrease in subacromial pressure, in the area immediately below the acromion.

Age and sex influence the activation-dependent stiffness of the pectoralis major.

The pectoralis major fiber regions contribute uniquely to the mobility and the stability of the shoulder complex. It is unknown how age and sex influence the stiffness of these regions during volitional contractions, but this knowledge is critical to inform clinical interventions targeting the pectoralis major. The aim of the present study was to determine if the activation-dependent stiffness of the pectoralis major fiber regions differs between the sexes and if it is altered with age. Ultrasound shear wave elastography was used to acquire shear wave velocity from the clavicular and the sternocostal fiber regions of 48 healthy participants, including 24 younger (12 males, 12 females, mean ± SD age 25 ± 4.1 years) and 24 older adults (12 males, 12 females, 55 ± 3.6 years). Participants performed vertical adduction and horizontal flexion torques in neutral and 90° externally rotated shoulder positions, and one of the two shoulder abduction positions (60° and 90°) at varying torque magnitudes (passive, 15% and 30% of maximal voluntary contraction). Separate linear mixed-effects models were run for each fiber region and shoulder position to determine if the activation-dependent stiffness differed between the sexes and was altered in older adults. Age-related alterations in stiffness during volitional contractions were observed in both fiber regions and were dependent on the task. Alterations in activation-dependent stiffness due to age were more pronounced in females than males. Additionally, females had greater stiffness than males during volitional contractions in both fiber regions. The present findings provide the first line of evidence that the activation-dependent stiffness of the pectoralis major fiber regions is influenced by sex and changes with age.

Application of Image Registration to Analyze the Clavicular Rotation of Normal Upper Limb Motion in the Sagittal Plane.

OBJECTIVE: To use image registration techniques to study the clavicular rotation of the shoulders in the sagittal plane. METHODS: From 28 April 2019 to 20 May 2019, 13 healthy adults (7 males and 6 females) with no history of shoulder trauma surgery or chronic pain were recruited. Patients' ages ranged from 22 to 42 years, with a mean age of 26.5 years. Three-dimensional composite images of the sternum-clavicle-humerus were taken using CT images of upper limb movement in the sagittal plane in the 13 healthy adults. Four different postures were registered: (i) anatomical supine position; (ii) elbow joints lifted anteriorly in the supine position; (iii) posterosuperior hyperextension of the elbow joints in the prone position; and (iv) posteroinferior hyperextension of the elbow joints in the prone position. Image data from the humerus and clavicle in three of the postures were processed to calculate Euler angles for movements in the sagittal plane. SPSS 19 was used to perform statistical analyses. RESULTS: There was no significant difference in the angles of change in the clavicle and humerus between the dominant and non-dominant sides under different movement patterns. For upper limb movements in the sagittal plane, the clavicle displayed different Euler angles in different postures. The rotation angle from the anatomical to the horizontal position was the smallest angle, with an average value of 7.1°, whereas the rotation angle from horizontal to posterosuperior hyperextension was the largest, with an average value of 37.2°. When the upper limb moved from anterior protraction to a posterosuperior extension, the intrinsic rotation angle of the clavicle reached its maximum, with an average value of 27.9°; when moved from the anatomical to the horizontal position, 9.1% of the sagittal rotation was executed by the clavicle. During rotation from the horizontal position to posterosuperior hyperextension and from the anatomical to posterior extension, the clavicle showed relatively higher weights at 29.5% and 37.0%, respectively. CONCLUSION: Our results showed that dominance was not a consideration when studying clavicular rotation. Image registration is an effective method that can be used to study upper limb scapular movements. Through comparing and analyzing the data, two postures had relatively large changes in the rotation angle. This can help improve indicators of clavicular rotational function during physical examinations and postoperative functional evaluations.

Three-dimensional alignment changes of the shoulder girdle between the supine and standing positions.

BACKGROUND: Although humans spend most of their day in a standing or sitting position, it is difficult to accurately evaluate the alignment of the shoulder girdle during daily activity, and its alignment changes between positions. The purpose of this study was to evaluate the 3-dimensional alignment of the shoulder girdle in the supine and standing positions by computed tomography (CT) and to assess the alignment changes of the shoulder girdle between these two positions. METHODS: CT scans of both shoulders of 100 healthy volunteers were prospectively taken in both supine and standing positions on the same day. The local 3-dimensional coordinate systems of the thorax, clavicle, and scapula were defined from the specific bony landmarks, and 3-dimensional angular rotations and positions of the clavicle and scapula were calculated. Differences in rotations and positions of the clavicle and scapula were evaluated between the supine and standing positions. RESULTS: Compared with the supine position, the clavicle showed significantly less elevation and greater retraction, and the scapula showed significantly less upward rotation, anterior tilting, and internal rotation in the standing position. Compared with the supine position, the clavicle center was located more inferiorly, posteriorly, and laterally, and the scapula center was located more inferiorly, posteriorly, and medially in the standing position. CONCLUSIONS: The present study showed that angular rotations and positions of the clavicle and scapula change significantly with position due to the effect of gravity.

Comparative biomechanical characteristics of one-arm hang in climbing for beginners and qualified athletes.

PURPOSE: The aim of the study was to identify the basic kinematic characteristics of the one-arm hang in climbing for beginners and qualified climbers. MATERIAL AND METHODS: Technique of the one-arm hang in climbing among 20 leading climbers of the World and Ukraine and 20 beginner male amateur climbers was analyzed. A qualified athlete participated in the demonstration of various models of the one-arm hang performance. By means of Kinovea software 0.8.15, the kinematic characteristics of two models of the technique were analyzed (model 1 for beginner athletes, model 2 for qualified athletes). RESULTS: The presence of significant differences ( p < 0.001) between beginners and qualified athletes in the magnitude of the angles between the shoulder and clavicle, between the spine and the vertical axis in the phase of fixation of the one-arm hang was revealed. The dynamics of the angle between the shoulder and clavicle from the moment of capture of the climbing hold to the phase of fixation of the hang was shown. A theoretical justification for the correct climbing technique regarding to the laws of mechanics and the laws of force interaction in kinematic chain was provided. CONCLUSIONS: Beginner athletes carry out the one-arm hang mainly due to the ligamentous apparatus of the joints of the shoulder girdle with minimal inclusion of muscles, which is dangerous by trauma to the ligaments of the shoulder joint. Skilled athletes perform the one-arm hang with trunk and leg muscles included, which reduces the strain from the ligamentous apparatus and lowers the possibility of injury to the ligaments of the shoulder joint.

The relationship of the acromion to the distal clavicle in normal and symptomatic degenerated acromioclavicular joints.

INTRODUCTION: Although degenerative osteoarthritis of the acromioclavicular joint is a common finding on technical investigations, not every patient experiences pain or function loss. The difference between symptomatic and asymptomatic patients is currently not elucidated. Therefore, we want to investigate the acromioclavicular relationship in normal, asymptomatic, and symptomatic degenerated ACJ. MATERIALS AND METHODS: 84 normal ACJ, 39 asymptomatic degenerated ACJ, and 30 symptomatic degenerated ACJ were 3D reconstructed. The morphological dimensions and the relationship of the acromion and distal clavicle were measured using computational software. The reproducibility of this technique was evaluated using inter- and intra-observer reliability. RESULTS: The mean anteroposterior and superoinferior distance of both the clavicle and acromion was significantly larger in asymptomatic and symptomatic degenerative ACJ compared to the normal ACJ (p < 0.001). In symptomatic osteoarthritic ACJ, both the anterior and posterior borders of the acromion were significantly more anterior to the borders of the clavicle than in the normal group and asymptomatic group (p < 0.001). Subsequent ROC curve analysis resulted in a sensitivity of 86.7% and a specificity of 88.6% for anterior subluxation of the ACJ. This technique showed an excellent inter- and intra-observer reliability. CONCLUSIONS: In patients with degenerative ACJ, both the distal clavicle and acromion are enlarged. In asymptomatic patients, the AC relationship is the same as in normal patients, in contrast, in patients with symptomatic degenerative ACJ, the acromion is subluxated anteriorly compared to the clavicle.

Histovariability in human clavicular cortical bone microstructure and its mechanical implications.

The human clavicle (i.e. collarbone) is an unusual long bone due to its signature S-shaped curve and variability in macrostructure observed between individuals. Because of the complex nature of how the upper limb moves, as well as due to its complex musculoskeletal arrangement, the biomechanics, in particular the mechanical loadings, of the clavicle are not fully understood. Given that bone remodeling can be influenced by bone stress, the histologic organization of Haversian bone offers a hypothesis of responses to force distributions experienced across a bone. Furthermore, circularly polarized light microscopy can be used to determine the orientation of collagen fibers, providing additional information on how bone matrix might organize to adapt to direction of external loads. We examined Haversian density and collagen fiber orientation, along with cross-sectional geometry, to test whether the clavicle midshaft shows unique adaptation to atypical load-bearing when compared with the sternal (medial) and acromial (lateral) shaft regions. Because fractures are most common at the midshaft, we predicted that the cortical bone structure would show both disparities in Haversian remodeling and nonrandomly oriented collagen fibers in the midshaft compared with the sternal and acromial regions. Human clavicles (n = 16) were sampled via thin-sections at the sternal, middle, and acromial ends of the shaft, and paired sample t-tests were employed to evaluate within-individual differences in microstructural or geometric properties. We found that Haversian remodeling is slightly but significantly reduced in the middle of the bone. Analysis of collagen fiber orientation indicated nonrandom fiber orientations that are overbuilt for tensile loads or torsion but are poorly optimized for compressive loads throughout the clavicle. Geometric properties of percent bone area, polar second moment of area, and shape (Imax /Imin ) confirmed the conclusions drawn by existing research on clavicle macrostructure. Our results highlight that mediolateral shape changes might be accompanied by slight changes in Haversian density, but bone matrix organization is predominantly adapted to resisting tensile strains or torsion throughout and may be a major factor in the risk of fracture when experiencing atypical compression.

Forces acting on the clavicle during shoulder abduction, forward humeral flexion and activities of daily living.

BACKGROUND: The forces acting on the human clavicle in vivo are difficult if not impossible to measure. The goal of this study is to quantify the forces acting on the human clavicle during shoulder abduction, forward humeral elevation and three activities of daily living using the Delft Shoulder and Elbow Model. METHODS: The Delft Shoulder and Elbow Model and a computed tomography scan of a clavicle were used to calculate the forces and moments acting on the entire clavicle and on three planes within the middle third of the clavicle during the simulated movements. FINDINGS: The largest resultant force simulated across the clavicle was 126 N during abduction. Maximum resultant moments of 2.4 Nm were identified during both abduction and forward humeral elevation. The highest forces in the middle third of the clavicle were of a compressive nature along the longitudinal axis of the clavicle, increasing to 97 N during forward humeral elevation and 91 N during abduction. Forces in opposite direction along the y-axis were identified on either side of the conoid ligament. The three simulated activities of daily living had similar ranges of forces and moments irrespective of the sagittal plane in which these activities were performed. INTERPRETATION: Peak forces occurred at different locations on the middle third of the clavicle during different movements. The results create an understanding of the forces and their distribution across the clavicle during activities of daily living. These data may be helpful in the development of clavicular fixation devices. LEVEL OF EVIDENCE: Biomechanical study.

Primary Stability of an Acromioclavicular Joint Repair Is Affected by the Type of Additional Reconstruction of the Acromioclavicular Capsule.

BACKGROUND: The synergistic effect of the acromioclavicular (AC) capsule and coracoclavicular (CC) ligaments on AC joint stability has gained recent recognition for its importance. Biomechanical and clinical studies have shown the benefit of combined reconstruction with multiple variations of surgical techniques for AC capsule augmentation. The ideal configuration remains unknown for such capsular repair aimed at achieving optimal stability with anatomic reconstruction. HYPOTHESIS: Primary AC joint stability can be restored by AC capsule augmentation, while position of the additional suture construct is critical. It was hypothesized that techniques that reconstruct the anterior capsular structures would restore native stability against rotations and translations. STUDY DESIGN: Controlled laboratory study. METHODS: Thirty fresh-frozen human cadaveric shoulders were used. Each sample was tested in the native state and served as its own control. After complete capsulotomy, 1 of 5 AC capsular repair configurations was performed: anterior, superior, posterior, O-frame, and X-frame. After testing of the AC capsular repair configurations, the tests were repeated after dissection of the CC ligaments and after CC ligament reconstruction with a suture button system. AC joint stability was immediately tested after each step under rotation and horizontal translation. To accomplish this, the AC joints were anatomically positioned on a custom fixture linked to a servohydraulic testing system. A 3-dimensional optical measuring system was used to evaluate the 3-dimensional joint motion. Clavicle posterior translation in relation to the acromion, rotation around the long axis of the clavicle, and displacement of the lateral clavicle in relation to the center of rotation were measured. The torques and forces required to rotate and translate the clavicle were recorded. RESULTS: In terms of translational testing, after the complete capsulotomy, a significant reduction of resistance force was found across all groups, with a mean 13% to 20% remaining ( P < .05). All AC suture augmentations were able to significantly increase the average resistance force as compared with the native ( P = .01) against posterior translation. Subsequent cutting of the CC ligaments did not result in a significant change in any of the groups ( P = .23). The synergistic effect of AC capsule augmentation and CC ligament reconstruction could be demonstrated without exception. In terms of rotational testing, the complete capsulotomy resulted in a significant reduction of resistance torque in all groups ( P < .05), with a remaining torque ranging between 2% and 11% across the groups. However, all AC suture constructs significantly increased the resistance torque as compared with the capsulotomy ( P = .01). The subsequent cutting of the CC ligaments resulted in a significant change in 2 of the 5 groups (O-frame, P = .01; X-frame, P = .02) and an overall remaining torque reduction ranging from 3% and 42%. The combined reconstruction of the AC capsule and CC ligaments achieved the highest percentage of regained resistance torque but remained significantly weaker than the native specimen ( P = .01). CONCLUSION: Native translational stability could be restored by the addition of AC capsule augmentation, while partial rotational instability remained. The tested constructs revealed no significant individual differences. CLINICAL RELEVANCE: Combined stabilization of the AC capsule and CC ligaments demonstrated the greatest capacity to restore the native stability against translational and rotational loads, with the specific configuration of the AC capsule repair to be chosen according to the personal preferences of the surgeon.

Descriptive characteristics of the area of origin of the deltoid muscle on the human clavicle. Is it necessary to include new terms in the Terminologia Anatomica?

The clavicular portion of the deltoid muscle (CPDM) in the human clavicle does not have a nomenclature in the Terminologia Anatomica (TA). This area is relevant in anatomy since the muscle participates in motions of glenohumeral articulation. The aim of this study was to describe the origin of the CPDM and to propose a name for the structure. Dry clavicles of 176 adults were studied, without distinction by sex. An osteometric board was used to measure the maximum length of the clavicles and a digital caliper to measure length of the CPDM's origin, distance from the origin to the sternal end, distance from the origin to the acromial end, distance of the lateral third and middle vertical diameter. The mean of maximum of the distances and CPDM's origin of left/right clavicle do not present significant differences. The CPDM s origin showed a high prevalence of structures as groove and roughened area (over 96% of cases). In conclusion, our definition of the CPDM shows the importance of clearly describing the observed groove and roughened area. Due to the high prevalence of the structures, the authors suggest that the terms "sulcus musculi deltoidei" and "tuberositas musculi deltoidei" be included in the TA to denominate the CPDM's origin on the human clavicle.

Forensic age estimation using computed tomography of the medial clavicular epiphysis: a systematic review.

Medicolegal physicians are increasingly called upon to aid in determining the administrative age group affiliation of refugees with questionable unaccompanied minor claims. According to guidelines for forensic age assessment, age differentiation along the 18-year-old cut-off relies on clavicular ossification. The thin-slice computed tomography scan (TSCTs) of the medial clavicular epiphysis (MCE) is one of the methods contributing to this assessment, though it is not yet universally accepted. The aim of this systematic review was to identify scientific papers where age was assessed using TSCTs of the MCE and to observe whether this examination was reproducible and reliable in estimating a person's age relative to the 18-year-old threshold. A search algorithm was applied to several databases to identify articles in accordance with the PRISMA (Preferred Reporting Items for Systematic-Reviews and Meta-Analyses) statement. One boxplot per article was constructed, separating by stage of maturation and sex. The 13 articles selected represented a sample of 5605 individuals (3396 males, 2209 females) aged 10 to 35 years. All individuals classified as stages 4 and 5 were aged 18 years or older. The same result was obtained concerning stage 3c, except in one article. The results thus appear reliable and reproducible, in particular, with respect to the 18-year-old threshold; medicolegal physicians should be able to estimate that all individuals in stages 4 and 5 are at least 18 years old. Additional studies applied to several other populations in the world should complement the selected studies.

Investigations of cortical and cancellous clavicle bone patterns reveal an explanation for the load transmission and the higher incidence of lateral clavicle fractures in the elderly: a CT-based cadaveric study.

Clavicle fracture is known to be one of the injuries frequently occurring in the elderly. The purpose of this study was to characterise the internal structures that might correlate with the higher incidence of lateral clavicle fracture in the elderly. Twenty clavicles were collected from ten Japanese cadavers ranging from 70 to 99 years (83.6 ± 7.6), scanned, and three-dimensional computed tomography (3D CT) images reconstructed. The clavicle lengths were divided into five equal segments. The four demarcation lines from the acromial end of the clavicle were defined as the observation points A, B, C, and D. The clavicles were then measured and analysed. It was shown that along the clavicles observation point A was the widest and points B and C the narrowest. Regarding the thickness, point D was the thickest among all four points, and there was no significant difference among the points A, B, and C. No male-female difference was found in either the cortical or cancellous bone ratio at all four points. Interestingly, the highest cortical bone ratio was observed at point B and the ratio was significantly decreased toward either end. The cancellous bone ratio was highest at point C and decreased toward both ends. Further observations showed that there were rays of trabeculae around point A, spreading from the superior-posterior edge or anterior edge toward each other and toward the lateral end and point B. Characteristics in the cortical and cancellous bone ratios and cancellous bone patterns might shed light on understanding the fractures in the lateral portion of the clavicle in the elderly.

A New Interpretation of the Crocodile Forelimb Morphological Features as Adaptation to Parasagittal Quadrupedal Locomotion on the Ground.

We describe the crocodile forelimb features that distinguish them from other reptiles. Reduction of the clavicle and a change in the coracoid shape seem to be another way of maintaining the efficient step length, while the antebrachium and manus transformations create peculiar oblique manus position on the ground to promote the forelimb parasagittalization.

Concurrent validity of inclinometer measures of scapular and clavicular positions in arm elevation.

OBJECTIVE: To assess concurrent validity, between and within-day reliability of scapular and clavicular digital inclinometer measures. DESIGN: Test-retest and concurrent validity. SETTING: Laboratory. PARTICIPANTS: Twenty-three participants with and without shoulder symptoms. MAIN OUTCOME MEASURES: Static positions of scapular upward rotation, anterior/posterior tilting and clavicular elevation were measured between days with an inclinometer and compared to a 3-dimensional electromagnetic tracking system in different positions of sagittal plane humeral elevation (neutral, 30°, 60°, 90°, 120°). The two methods were compared using a two-way Analysis of Variance. Linear regressions at each arm position were also performed to further assess concurrent validity. RESULTS: Between-day reliability demonstrated Intraclass Correlation Coefficients ≥ 0.50 for all comparisons. There were statistically significant differences between methods or interactions of method and arm position for clavicle elevation (p = 0.004, maximum offset between methods 7.7º in the neutral position), and scapular upward rotation (p = 0.001). For scapular upward rotation, the maximum difference between methods was less than 2° across all humeral positions. Clavicle elevation (r = 0.67-0.82) and scapular upward rotation (r = 0.57-0.81) demonstrated higher correlations between measurement methods than scapular anterior/posterior tilt (r = 0.10-0.67). CONCLUSIONS: Concurrent validity in assessing scapular upward rotation and clavicle elevation with an inclinometer was shown when compared with electromagnetic tracking. However, the inclinometer method may not have adequate concurrent validity to clinically measure scapular anterior/posterior tilting.

Changes in clavicle length in acute fractures within 3 weeks: a prospective ultrasonographic study of 59 patients.

BACKGROUND: Within traumatology a common indication for acute surgery of fractured clavicles is bone shortening over 2 cm. This indication is among but a few indications; which are recommended to be treated operatively within the very first weeks after a fracture. Theoretically clavicle fractures could become less shortened over time due to decreasing muscle pull. If this reduced shortening does indeed happen, some patients with initial bone shortening over 2 cm could perhaps be treated conservatively? However, it is unknown what happens to the length of the clavicle within the first weeks after a fracture. The aim of this study was to investigate if the length of the fresh fractured clavicles changes within the first three weeks. METHODS: Rested length measurements using navigation ultrasound were done on 59 patients with a fractured clavicle. Measurements were performed within the first three weeks after a lateral or mid-clavicular fracture. The inclusion period was from March 2014 to February 2016. Median age was 40 years and age range was 18-81 years. The data was analyzed using mixed linear models. RESULTS: The clavicle length showed no change within the first three weeks after fracture (p = 0.24). CONCLUSION: Fractured clavicles retain their length for the first three weeks.

Reliability and Validity of an Acromion Marker Cluster for Recording Scapula Posture at End Range Clavicle Protraction, Retraction, Elevation, and Depression.

Acromion marker cluster (AMC) methods have been shown to accurately track scapula motion during humeral elevation below 90°, however, their accuracy has not been assessed in shoulder girdle motion such as clavicle protraction, retraction, elevation, and depression independent of humeral movement. The aim of this study was to examine the reliability and validity of the AMC method to record scapula orientation at end range clavicle protraction, retraction, elevation, and depression. The right scapulae of 22 female and 20 male asymptomatic volunteers were assessed with an AMC and scapula locator (SL) method during end range clavicle protraction, retraction, elevation, and depression (without humeral elevation) using an 8-camera 3D movement registration system. Measurements recorded from the AMC and SL measures showed fair to excellent agreement (ICC 0.4-0.92). While the AMC method overestimated and underestimated scapular motion in some planes compared to the SL, root mean square error between methods were low for scapular internal/external rotation (2.3-3.7°), upward/downward rotation (4.5-6.6°), and anterior/posterior tilt (3.2-5.1°), across all conditions. The AMC method was shown to be a reliable and valid measurement of scapula orientation at end range clavicle movements independent of humeral movement.

Procedure to describe clavicular motion.

BACKGROUND: For many years, researchers have attempted to describe shoulder motions by using different mathematical methods. The aim of this study was to describe a procedure to quantify clavicular motion. METHODS: The procedure proposed for the kinematic analysis consists of 4 main processes: 3 transcortical pins in the clavicle, motion capture, obtaining 3-dimensional bone models, and data processing. RESULTS: Clavicular motion by abduction (30° to 150°) and flexion (55° to 165°) were characterized by an increment of retraction of 27° to 33°, elevation of 25° to 28°, and posterior rotation of 14° to 15°, respectively. In circumduction, clavicular movement described an ellipse, which was reflected by retraction and elevation. Kinematic analysis shows that the articular surfaces move by simultaneously rolling and sliding on the convex surface of the sternum for the 3 movements of abduction, flexion, and circumduction. CONCLUSION: The use of 3 body landmarks in the clavicle and the direct measurement of bone allowed description of the osteokinematic and arthrokinematic movement of the clavicle.