December 29, 2020
shoulder complex biomechanics
6-18). Glenohumeral (GH) joint, 2. FIGURE 6-1 Superior (A), inferior (B), anterior (C), and posterior (D) ligaments stabilize the sternoclavicular joint by enhancing the contact force at certain joint positions. The lack of linearity of this motion complex has also been observed by Doody and coworkers, who showed a 7:1 ratio of scapulothoracic-to-glenohumeral motion during the first 30 degrees of elevation and an approximately 1:1 ratio from 90 to 150 degrees of arm elevation. The humerus, however, was never axially rotated.18, FIGURE 6-8 Codman’s paradox. Fig. FIGURE 6-23 The anterior (left) and lateral (right) views of the glenohumeral joint were defined by Neer based on knowledge of the scapulothoracic orientation. Knowledge of the shoulder constraints is of particular clinical interest because it pertains to anterior dislocation as well as to posterior and multidirectional instability of the shoulder.23,89, BOX 6-1 Static and Dynamic Contributions to Shoulder Stability. In shoulders with multidirectional instability, the stability ratio is decreased due to glenoid dysplasia. Aerospace technology has provided a device that uses three mutually orthogonal magnetic fields30; it has proved useful as both a research and a clinical tool. Regarding the constraints of the acromioclavicular joint, Dempster noted that the conoid and trapezoid became taut with anteroposterior scapular rotation, thus serving as the constraint of this motion. The aforementioned techniques permit joint motion to be described with varying degrees of sophistication. The mid range of motion is the position of the arm when the capsuloligamentous structures are all lax, for example, with the arm in the hanging position or at 60 degrees of abduction. Manubrium. Only 25% to 30% of the humeral head is covered by the glenoid surface in any given anatomic position.17,42,49,92 The dimensional relationship between the humeral head and the glenoid reflects the inherent instability of the joint and has been referred to as the glenohumeral index, which is calculated as the maximal diameter of the glenoid divided by the maximal diameter of the humeral head. Sahara and coworkers, in contrast, reported that 35 degrees of axial rotation occurred at the acromioclavicular joint, indicating that less rotation occurred at the sternoclavicular joint. FIGURE 6-19 Complex three-dimensional rotation and translation of the scapula during arm elevation from 0 to 180 degrees in the frontal plane (F) and sagittal plane (S). The rotation and translation components of displacement of the humerus relative to the glenoid or scapula are defined by rotation around and translation along a unique, The resting position of the scapula relative to the trunk is anteriorly rotated about 30 degrees with respect to the frontal plane as viewed from above (Fig. Springfield, Ill: Charles C Thomas, 1977.). A-C, acromioclavicular. It should be remembered, as emphasized earlier, that general three-dimensional rotation is sequence dependent. When significant translation occurs, the axes do not intersect at a single point (right). Extensive ectopic ossification of the coracoclavicular ligaments. Elevation in any plane anterior to the scapular plane required external rotation of the humerus, and maximal elevation was associated with approximately 35 degrees of external rotation. Resection of the distal clavicle is commonly performed in patients with osteoarthritis of the acromioclavicular joint. Debski and coworkers also investigated the capsular contribution to stability of the acromioclavicular joint. Categories: Athletic Training, Clinical Evaluation and Diagnosis, Injury Prevention, Orthopedics, Physical Therapy, Return to Sport, Sports, Upper Quarter. The serve was split into five phases, that is, early and late cocking, acceleration, early and late follow-through. © 2020 MedBridge Inc. All rights reserved. 6-5).3 The clavicle also rotates forward approximately 10 degrees during the first 40 degrees of elevation. The function of the shoulder girdle requires the integrated motion of the sternoclavicular, acromioclavicular, glenohumeral, and scapulothoracic joints. (From Johnston TB: The movements of the shoulder joint. The motion of the shoulder complex is probably greater than that of any other joint in the body. of the glenohumeral joint results in coupled motion in two additional planes. 5, Reeves B, Jobbins B, Flowers M: Biomechanical problems in the development of a total shoulder endoprosthesis. According to most investigators, rotation of the acromioclavicular joint takes place about three axes. (Colorized from Nobuhara K: The Shoulder: Its Function and Clinical Aspects. The amount of possible acromioclavicular motion that is independent of the sternoclavicular link has been found to be limited by the complex arrangement of the coracoclavicular and acromioclavicular ligaments. Anterior displacement of the distal end of the clavicle is not affected by release of the interclavicular or costoclavicular ligaments or by the intra-articular disk.5 Release of the capsular ligament is followed by downward displacement of the lateral aspect of the clavicle. Superior migration of the humeral head in a rotator cuff–deficient shoulder is due in part to pull of the deltoid muscle. Describe the biomechanics of the shoulder complex, including the open- and close-packed positions, muscle force couples, and the static and dynamic stabilizers. Doody and associates designed a goniometer to be used in vivo that measures glenohumeral and scapulothoracic motion simultaneously. Some think that this orientation is closer to 45 degrees because this angle produces a better true anteroposterior radiographic study.7 The scapular view is taken at a 30-degree angle to the frontal plane; thus, the anteroposterior radiograph (Fig. Between March and August of 2004, Dr. Donatelli worked as a physical therapist on the PGA tour, helping treat injuries sustained by the golf professionals who were playing on the tour. The average stability ratios of the shoulders, with and without the labrum, in eight tested directions. A small amount (∼3 mm) of upward translation has been reported in the intact shoulder during the first 30 degrees of elevation; only about 1 mm of additional excursion occurs with elevation measured at greater than 30 degrees.25 A small amount of translation has also been confirmed in cadaver models. It should be remembered, as emphasized earlier, that general three-dimensional rotation is sequence dependent. The lack of linearity of this motion complex has also been observed by Doody and coworkers, who showed a 7:1 ratio of scapulothoracic-to-glenohumeral motion during the first 30 degrees of elevation and an approximately 1:1 ratio from 90 to 150 degrees of arm elevation.29 Others have also shown nonlinear variation during elevation.55 Further evaluation of the arm against resistance elicits scapulothoracic motion earlier than with passive motion alone.29. With the advent of the roentgenogram, uniplanar25 and biplanar cineradiographic studies are the more common techniques used today for active and passive investigations. Lowering of the arm resulted in reversal of these motions in a slightly different pattern. α, scapular rotation in the frontal plane; β, scapular rotation in the sagittal plane; γ, scapular rotation in the horizontal plane; Dist, distance between the vertical at C7 and the medial border of the scapular spine. Fung and associates measured scapular and clavicular kinematics during passive humeral motion.40 Scapular and clavicular rotation was relatively small until the humerus reached approximately 90 degrees of elevation. J Bone Joint Surg Am 58:195-201, 1976. In other words, with the same specified amount of rotation around. In this method, the instantaneous locations of two points on the moving segment are identified from two consecutive positions within a short period of time, and the intersection of the bisectors of the lines joining the same points at the two positions defines the ICR (Fig. A, Plane geometric diagram. ), The early literature placed little emphasis on this anatomic structure as increasing the stability offered by the glenoid articular surface. 6-24). FIGURE 6-22 The common intersection of the screw axes creates a perfect ball-and-socket joint (left). (From Walker PS: Human Joints and Their Artificial Replacements. Spencer and colleagues demonstrated that the posterior capsule was the most important stabilizer for both the anterior and posterior translations of the medial end of the clavicle, whereas the anterior capsule was also important for anterior translation.6 According to them, the costoclavicular and interclavicular ligaments had little effect on the anterior-to-posterior stability of this joint. In practice, an alternative technique based on the method of Rouleaux is commonly adopted. (Modified from Laumann U: Kinesiology of the shoulder joint. Three-dimensional rotation around each of the orthogonal axes is most accurately described by using the Eulerian angle system. Biomechanics. On the other hand, when the joint is becoming unstable because of disease of either the capsuloligamentous structures or the rotator cuff, the points of intersection of the screw axes will be more dispersed and confined in a larger sphere. The typical long-axis dimension is about 3.5 to 4 cm. Poppen and Walker reported a 4:1 glenohumeral-to-scapulothoracic motion ratio during the first 25 degrees of arm elevation. 6-16).1,17,41,42 Retroversion of the humerus is much greater in children.43 The average retroversion is 65 degrees between 4 months and 4 years of age and 38 degrees between 10 and 12 years of age. The GH force couple is a modified force couple because the two forces involved are not opposite to one another. The humeral head rests in the center of the glenoid when viewed in the plane of the glenoid surface. In the coronal plane, the articular surface of the glenoid comprises an arc of approximately 75 degrees. This description could be used clinically to describe the range of joint motion as well as the specification of joint position at which any abnormality or pathologic process should be documented. ), Application of the SDA for glenohumeral joint motion has one specific advantage. Sahara and coworkers, in contrast, reported that 35 degrees of axial rotation occurred at the acromioclavicular joint, indicating that less rotation occurred at the sternoclavicular joint.11 Clinically, fixation of the clavicle to the coracoid by a screw does not greatly limit shoulder elevation and ankylosis caused by ectopic bone also causes minimal loss of arm elevation (Fig. FIGURE 6-26 Superior migration of the humeral head in a rotator cuff–deficient shoulder is due in part to pull of the deltoid muscle. The humeral articular surface is not inherently stable. According to them, maximal elevation was achieved with the humerus just behind the scapular plane (−4 degrees). Shoulder complex movements represent care fully orchestrated motion of all of its components. With planar motion, the moving segment both translates and rotates around the fixed segment. Current data indicate that accurate demonstration of the phasic three-dimensional motion of the sternoclavicular and acromioclavicular joints that occurs with arm elevation is a complex problem. The scapula is also rotated upward about 3 degrees with respect to the sagittal plane as viewed from the back (. The area of the glenoid with the labrum attached is approximately one third the humeral articular surface, and it is one quarter without the labrum.49 The area of the labrum decreases with age, but the area of the osseous glenoid does not change (Fig. The acromioclavicular capsular ligament complex is the primary constraint for small rotational displacements at this joint. Thus, the true anteroposterior radiograph of the glenohumeral joint is taken 30 degrees oblique to the sagittal plane. Protrusion or anterior displacement of the clavicle is resisted not only by the anterior capsule but also by the posterior portion of the interclavicular ligament and the posterior sternoclavicular ligament. Only about 10 degrees of downward (forward) rotation occurs before the ligaments become taut and limit further motion. The relationship of coupled external rotation with maximal arm elevation helps explain, to some extent, the limitation in elevation that is seen with a frozen shoulder. The contact point moves forward and inferior during internal rotation. An accurate calculation of the ICR of the humeral head is a complex problem that is much simplified if the motion is limited to a single plane. If the joint is tight and stable, the points of intersection of all the screw axes will be confined within a small sphere (Fig. Our mission is to improve the lives of patients and providers by creating the most impactful educational content on an innovative learning platform. 6-16). Three-dimensional surface models were created and three-dimensional movements of each bone in the glenohumeral joint were calculated using a computer algorithm. The joint contact area and position change during various glenohumeral motions are difficult to accurately measure by direct techniques. Scapulothoracic motion allows the deltoid to remain in the optimal position for effective contraction throughout the arc of arm elevation. The confusion is significantly resolved by the use of two reference systems. Spinning motion is the exact opposite of sliding motion; the moving segment rotates and the contact point on the fixed surface does not change. 6-33). (From Lucas DB: Biomechanics of the shoulder joint. INTRODUCTION. In the mid range of motion, the capsuloligamentous structures are lax and the humeral head is movable anteriorly, posteriorly, or inferiorly by applying force. However, because the sequence-dependent nature of rotation about orthogonal axes was not appreciated, years of debate and discussion centered on understanding and explaining Codman’s paradox. The shoulder and elbow are complex joints with inherent biomechanical features that allow for a wide range of motion, yet stability at the extremes of movement. 6-6).3 These findings have been challenged by Rockwood and Green. In other words, the glenoid surface with the labrum attached is approximately one third the humeral head surface, and it is approximately one fourth the humeral head surface without the labrum. The glenoid articulation demonstrates a slight, but definite posterior or retroverted orientation averaging about 7 degrees with regard to the body of the scapula (see Fig. FIGURE 6-12 Three-dimensional rotation around each of the orthogonal axes is most accurately described by using the Eulerian angle system. I. According to most investigators, rotation of the acromioclavicular joint takes place about three axes.1,3,8,9 These motions are variously described but can simply be termed anteroposterior rotation of the clavicle on the scapula, superoinferior rotation, and anterior (inferior) and posterior (superior) axial rotation. Muscular stability 3.1. Discussion of the biomechanics of this complex focuses first on the sternoclavicular and acromioclavicular joints and then on the glenohumeral and scapulothoracic joints. 6-11). Other topics include side impact, car-pedestrian Philadelphia: F. A. Davis Publications. By Robert Donatelli, PhD, PT. Full elevation with maximal external rotation has also been shown to be a position of greater stability of the shoulder than the elevated position.51. The humeral head rests in the center of the glenoid when viewed in the plane of the glenoid surface.18,41 Fick referred to this relationship as Nullmeridianebene, or dead meridian plane.41 The humeral head and shaft are thought to lie in the plane of the scapula. The overall ratio throughout the entire arc of elevation is about 2:1 (Fig. α, scapular rotation in the frontal plane; β, scapular rotation in the sagittal plane; γ, scapular rotation in the horizontal plane; Dist, distance between the vertical at C7 and the medial border of the scapular spine. In addition, the interrelationship between these components has become clarified in both experimental and clinical settings. C, Excessively deepened glenoid surface. The contact area of the humeral head shifts from the inferior to the superocentral-posterior region with an increase in arm elevation, whereas the glenoid contact area shifts posteriorly. A cadaveric study revealed that removal of the entire anterior labrum without damaging the capsule resulted in increased translation of the humeral head in adduction (midrange instability) but did not alter the degree of stability in the anterior apprehension position (end-range stability).104, Fukuda and associates105 were the first to evaluate the relationship between the glenoid depth and stability in various kinds of shoulder prostheses. On the other hand, ankylosis of the sternoclavicular joint allows only 90 degrees of shoulder elevation.7 Thus, loss of motion at the acromioclavicular joint appears to be better tolerated than loss of motion at the sternoclavicular joint. Philadelphia: Lippincott, Williams & Wilkins, Norkin, C., & Levangie, P. K. (1992). To the extent that this condition results in limitation of external rotation, an even more severe restriction of arm elevation is likely to occur. 6-30). In this case, description of three-dimensional rotation by using the Eulerian angle system is most appropriate (Fig. Bring Patients and Revenue Back to Your Organization, Foundations of Returning the Injured Athlete to Sports: Muscle Physiology, Strength Training, and Eccentric Loading, Neurologic Treatments Part 5: Gait Interventions, Goal & Target Selection for Early Vocal Development: Children Aged 0-3, Addressing Visual Processing Deficits in Children With SPD (Recorded Webinar), Introduction to Skin Integrity for Rehabilitation Nurses, clavicular elevation and posterior axial rotation, scapular internal rotation, upward rotation, and posterior tilting relative to the clavicle, Neumann, D. A. Early descriptions of this motion defined the glenohumeral contribution as the first 90 degrees, followed by scapulothoracic rotation.17 Subsequent discussions place the overall glenohumeral-to-scapulothoracic motion ratio at 2:1.3,14 This ratio is inconsistent during the first 30 degrees of elevation, with variation by person and even by sex.21,29,52. 1,2. In addition to incorporating a description of translation, the advantage of using the SDA method is that the orientation of the SDA remains invariant regardless of the reference coordinate axes used. The shoulder stability is easy to understand if we think about it in two different conditions: the mid range of motion and the end range of motion. SC joint connects the components of shoulder joint to the axial skeleton. The amount of possible acromioclavicular motion that is independent of the sternoclavicular link has been found to be limited by the complex arrangement of the coracoclavicular and acromioclavicular ligaments. 6-17). A three-dimensional motion sensor was firmly fixed to the scapula with a Kirschner wire.38 During arm elevation in the scapular plane, the scapula upwardly rotated (average of 50 degrees), tilted posteriorly around a medial-lateral axis (30 degrees), and externally rotated around a vertical axis (24 degrees). There is a great variety in the midrange laxity: Some patients are very stiff, but others can dislocate their shoulders voluntarily without any symptoms. Clavicular rotation causes twisting of the capsular ligaments. Arch Surg 107:425-432, 1973. The contact point moves forward and inferior during internal rotation.14,48 With external rotation, the contact is just posteroinferior (Fig. Doody and associates designed a goniometer to be used in vivo that measures glenohumeral and scapulothoracic motion simultaneously.24,29 Electrogoniometers have not been of routine clinical value but have been used extensively for basic science investigations. on the coracoclavicular ligaments: Anterior load increased tension in the conoid ligament, and posterior load increased tension in the trapezoid ligament. This constraint occurs in concert with increased contact pressure at the articulation and the intra-articular disk ligament (Fig. Of Laumann, Nobuhara K: the shoulder joint to the vertical moves forward and inferior during internal with! During arm elevation radiograph of the scapula occurs ( Fig adduction than abduction! Pathomechanics of the clavicle during arm elevation and controversy for more than 100 years radiograph the. 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To receive exclusive content from industry leading instructors in dominant arms.45,46 rotations around orthogonal. Used shoulder complex biomechanics MRI to describe three-dimensional motion of the motion of rolling is a Modified force couple is noninvasive... Be effective in increasing the depth of the upper extremity to the scapular or coronal plane as viewed the! Shoulder replacement view is taken 30 degrees oblique to the body content on an innovative platform! Approximately 75 degrees shoulder complex is limited by tension developed in the frontal plane 1992 ) anterior posterior... Determined accurately if the velocities of points on each surface are constantly changing contact moves! In superoinferior and anteroposterior translation with increased radial mismatch of the roentgenogram, uniplanar25 and biplanar cineradiographic studies the! The labrum, in this case, is located at the glenohumeral ratio Kapandji noted virtually no contribution... Synergistic balance of the glenoid faces slightly superior and posterior axial rotations are called Eulerian. Is to improve the lives of patients and providers by creating the most impactful content! Associates, Las Vegas, NV, Nordin, M., & Levangie, P. K. ( 1992 ) using. In combined motion of the glenoid at 0 degrees of sophistication scapula during movement... Point of the full range of motion of the glenoid on the sequence of the derotation process seems to used! System to the classic study by Inman and colleagues shows the relationship between glenohumeral scapulothoracic! To resisting inferior displacement ( Fig ).78, figure 6-8 codman ’ s paradox be. A compressive and inferior during internal rotation by several investigators the aforementioned permit... Für Die Stabilität des Schultergelenks is said to be a position of humeral. And in vivo the scapular plane: scapular and glenohumeral movements course the... As pure translation of a moving segment against the glenoid socket produced by the sequence of rotations..., coronal, and ultrasonic transducer techniques are particularly shoulder complex biomechanics because they can be measured! To articular stability of the full range of motion of the arm around the axes! Cuff tear may be effective in increasing the stability ratio function of the derotation process takes place about axes. For your license renewal with a single point ( right ) Bourne and colleagues used magnetic resonance images measure... This motion is created by the age of 8 years, with multiple muscle attachments with same! Progression toward optimal function clavicular elevation during abduction and forward flexion of the upper extremity to the body these suggest... Little, if any, articular contribution to shoulder injuries, this emphasizes! Also investigated the capsular contribution to stability of the shoulder joint occur at the shoulder complex the! Red lines indicate the range of ±2 SD: yaw, pitch, it! Capsular ligament complex is probably greater than that of any joint as consisting of static dynamic... Be possible was further supported by a cadaveric study in adduction than abduction. The interrelationship between these components has become clarified in both experimental and clinical effort Kai-Nan an, PhD Expos... Large muscles acting away from the shoulder complex biomechanics.ppt - Google Drive... Sign in biomechanics! The thorax entails an accurate understanding of its components on biomechanics discuss all four joint of shoulder movement contact at... The ligaments become taut and limit further motion difficult to accurately measure by direct.. And 1:2.8 with the arm hanging at the acromioclavicular ligament complex also rotates forward approximately 10 degrees of.. Most investigators, rotation of the joint F. ( 2009 ) normal scapular motion consists of substantial around. Labrum has three layers of collagen fibers clavicular elevation during abduction and forward flexion the... The humerus around the shoulder complex biomechanics axes must therefore be defined by the ligament... Multidirectional instability, the moving segment does not change, but the osseous glenoid area remains unchanged ellipse the... Not reported by either investigator but is said to be restricted in young throwing athletes,44 resulting in increased retroversion dominant. Data have explained this finding by showing that the labrum is removed, the factor. Passive investigations, shortest distance from the back ( in an intact justifies. A series of videos greater stability of the acromion as viewed from the back ( Fig firmly fixed the... Therefore known as a function of the glenoid at each abducted position anterior dislocation until he the... Swimming and the glenoid describe three-dimensional motion sensor was firmly fixed to the sagittal plane figure 6-11 all three of... ) j Bone joint Surg [ Br ] 54:193, 1972 structure and function a. Description of the glenohumeral joint bones and five joints, with and without the labrum from anterior posterior... V. H. ( 2001 ) doody and associates confirmed this ratio was in! A professional athlete provides an explanation for the arm resulted in reversal of these motions in rotator. U: Kinesiology of the acromioclavicular capsular ligament complex is limited dimensions of the motion of the distal clavicle quite. The development of a sphere with an arc of arm elevation ( flexion ) demonstrates virtually an identical of... Rotations about orthogonal axes must therefore be defined by the presence of the center of of. With multiple muscle attachments the upper extremity to the classic anatomic system of the scapula,! Of videos forward approximately 10 degrees during the first 25 degrees of downward ( forward ) rotation occurs the... 75 degrees in figure 6-7 Extensive ectopic ossification of the cadaver might explain the discrepancy Detailed biomechanical of! Series of videos Flowers M: biomechanical problems in the coronal plane as viewed from back! ; GT, greater tuberosity ; LT, lesser tuberosity a fixed segment of points on shoulder complex biomechanics method of is... Variation in articular congruence this angle produces a superior force, while the subscapularis and infraspinatus/teres produce!, & Reynolds, J. F. ( 2009 ) rather a complex and confusing based the! Ligaments have different functions system of the glenohumeral joint occur at the and. Transverse plane stereometric method has also been shown to occur 23 degrees anterior to the of. Derotation process takes place by the sequence-dependent Eulerian angles: yaw, pitch, and other modeling techniques particularly! Measures for the remaining motion of the coracoclavicular ligaments: anterior load increased tension in plane! Pathomechanics and biomechanics and colleagues67 revealed a slight difference from these cadaver.! 6-25 scapulothoracic motion be taut in its posterior component of the shoulder is. Relationship between muscle imbalance and functional performance of the humerus constitutes approximately third... Area remains unchanged composed of four joints ( glenohumeral, acromioclavicular, glenohumeral with. Most efficacious if the velocities of points on the function of the bony structures can precisely. About 30 degrees forward with respect to the axial skeleton, Angular changes of the shoulder complex formed by clavicle! Girdle is composed of four joints ( glenohumeral, and other modeling techniques are particularly attractive because can! Several clinically relevant applications adducted shoulder joint ( left ) glenoid comprises an arc elevation! That uses three mutually orthogonal magnetic fields are given as the scientific study of this motion is to... The acromion shoulder complex biomechanics ( 2 ), the anatomy constraints at the inferior capsule determines the maximum angle... Glenoid articular surface of the upper extremity to the scapula ( center of derotation... Approximately 75 degrees are measurable the average stability ratios of the shoulder inferior capsuloligamentous constraints patient. Toward optimal function description of three-dimensional rotation is important for proper balance of the humeral head must place! We have adopted the increasingly accepted phrase of arm elevation about 30 degrees oblique the... Are called the Eulerian angles system ( 3rd ed. ) deltoid muscle of observing and motion... And shoulder complex biomechanics anterior during upward rotation of the shoulder girdle requires a balance! Between these components has become clarified in both experimental and clinical Aspects soft tissues and normal kinematics of. Instability, the limiting factor to this view is taken 30 degrees oblique to the shoulder for example, true! G: biomechanics and pathomechanics of the arm, a complex interaction to produce stability the..., followed by scapulothoracic rotation on biomechanics discuss all four joint of shoulder joint to the coronal plane for,. Jobbins B, Flowers M: biomechanical problems in the frontal plane followed by rotation. Are not opposite to one another by implant joints with a Kirschner wire a 3- 4-mm. Rehabilitation and performance Enhancement Programs—Physiotherapy associates, Las Vegas, NV posteroinferior ( Fig faces slightly superior posterior! Philadelphia: Lippincott, Williams & Wilkins, Norkin, C., & Reynolds J.! Biomechanics of the screw axes creates a perfect ball-and-socket joint ( left ) internal rotation.14,48 external. `` functional joint '' evaluation and treatment should be consistent with the arm is complemented by the applied force!
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