The role of pectoralis major and latissimus dorsi muscles in a biomechanical model of massive rotator cuff tear (original) (raw)
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ASME 2009 4th Frontiers in Biomedical Devices, 2009
Rotator cuff tears (RCT) commonly start at the anterior insertion of the supraspinatus and have been shown to propagate posteriorly. Early detection and repair of small or medium size tears has been shown to result in better clinical outcome and structural integrity than that of large or massive tears. However, it is unknown at which stage of rotator cuff tear propagation the biomechanical environment becomes altered. Previous biomechanical studies have not considered rotator cuff propagation based on the footprint anatomy, rotational glenohumeral joint kinematics, and the influence of anatomy-based muscle loading including pectoralis major and latissmus dorsi. Therefore, the purpose of this study was to determine the relationship between progressive rotator cuff tear and glenohumeral joint biomechanics using a rotator cuff tear progression model and anatomically based muscle loading including the influence of the pectoralis major and latissmus dorsi. Our hypotheses were 1) cuff tea...
The effect of rotator cuff tears on reaction forces at the glenohumeral joint
Journal of Orthopaedic Research, 2002
The rotator cuff muscles maintain glenohumeral stability by compressing the hunieral head into the glenoid. Disruption of the rotator cuff compromises concavity compression and can directly affect the loads on the glenohumeral joint. The purpose of this study was to quantify tlie effect of rotator cuff tears on the magnitude and direction of glenohumeral joint reaction forces during active shoulder abduction in the scapular plane using nine cadaveric upper extremities. Motion of the full upper extremity was simulated using a dynamic shoulder testing apparatus. Glenohumeral joint reaction forces were measured by a universal forcemoment sensor. Five conditions of rotator cuff tears were tested: Intcict, bicoiiiplete Suprcispiiiutus Teur, Coiiiplete SLil)rcis~)iiicitus Teur, Supru.~~~inutuslInfi.u.~piizatirs Tear, and Global Tear. Reaction forces a t the glenohumeral joint were found to steadily increase throughout abduction and peaked at maximum abduction for all conditions tested. There were no significant differences in reaction force magnitude for the intact condition (337 f 88 N) or those involving an isolated incomplete tear (296 f 83 N ) or complete tear (300 f 85 N) of the supraspinatus tendon. Extension of tears beyond the supraspinatus tendon into the anterior and posterior aspect of the rotator cuff led to a significant decrease in the magnitude of joint reaction force . Similarly, such tears resulted in a significant change in the direction of the reaction force at the glenohumeral joint. These results suggest that joint reaction forces are significantly affected by the integrity of the rotator cuff, specifically, by tlie transverse force couple formed by the anterior and posterior aspects of the cuff. The quantitative data obtained in this study on the effect of rotator cuff tears on magnitude and direction of the reaction force a t the glenohumeral joint helps clarify the relationship between joint motion, joint compression and stability.
Journal of Orthopaedic Research, 2018
Rotator cuff tears are known to affect clinical outcome of reverse total shoulder arthroplasty (RSA). This study aimed to use computational modelling to quantify the effect of rotator cuff tear severity on muscle and joint forces after RSA, as well as stresses at the glenosphere, base-plate, fixation screws, scapula, and humeral components. A multi-body musculoskeletal model of the glenohumeral joint was developed comprising the scapula, humerus and nine major upper limb muscles. Simulations of abduction and flexion after RSA were performed in the case of the intact rotator cuff and tears to (i) supraspinatus; (ii) supraspinatus and infraspinatus, and (iii) supraspinatus, infraspinatus and subscapularis. The intact and supraspinatus deficient rotator cuff resulted in the largest calculated muscle forces, glenohumeral joint contact forces and implant stresses. Peak glenohumeral joint forces during flexion were lower than those during abduction in all cases; however, substantially more posterior joint shear force was generated during flexion than abduction. A tear involving the supraspinatus and infraspinatus reduced glenohumeral joint forces by a factor of 8.7 during abduction (603.1 N) and 7.1 during flexion (520.7 N) compared to those in the supraspinatus deficient shoulder. RSA with an intact or supraspinatus deficient rotator cuff produces large glenohumeral joint forces that may increase base-plate failure risk, particularly during flexion when posterior shear forces are largest. Infraspinatus tears after RSA greatly reduce glenohumeral joint compression and may ultimately reduce joint stability. Future research ought to focus on experimental validation of subject-specific muscle recruitment strategies and joint loading after RSA.
Glenohumeral stability in simulated rotator cuff tears
Journal of Biomechanics, 2009
Rotator cuff tears disrupt the force balance in the shoulder and the glenohumeral joint in particular, resulting in compromised arm elevation torques. The trade-off between glenohumeral torque and glenohumeral stability is not yet understood. We hypothesize that compensation of lost abduction torque will lead to a superior redirection of the reaction force vector onto the glenoid surface, which will require additional muscle forces to maintain glenohumeral stability. Muscle forces in a single arm position for five combinations of simulated cuff tears were estimated by inverse dynamic simulation (Delft Shoulder and Elbow Model) and compared with muscle forces in the non-injured condition. Each cuff tear condition was simulated both without and with an active modeling constraint for glenohumeral stability, which was defined as the condition in which the glenohumeral reaction force intersects the glenoid surface. For the simulated position an isolated tear of the supraspinatus only increased the effort of the other muscles with 8%, and did not introduce instability. For massive cuff tears beyond the supraspinatus, instability became a prominent factor: the deltoids were not able to fully compensate lost net abduction torque without introducing destabilizing forces; unfavorable abductor muscles (i.e. in the simulated position the subscapularis and the biceps longum) remain to compensate the necessary abduction torque; the teres minor appeared to be of vital importance to maintain glenohumeral stability. Adverse adductor muscle co-contraction is essential to preserve glenohumeral stability.
Assessment of the shoulder in rotator cuff tears
1996
The rotator cuff consists of four muscles; the subscapularis, supraspinatus, infraspinatus, and teres minor. The long head of the biceps tendon is another important component of the complex. The subscapularis is a head depressor, and in certain positions an internal rotator. The infraspinatus and teres minor are external rotators. The conjoint tendon of these muscles, attached to the tuberosities, anatomically and functionally, works as a unit, to maintain dynamic glenohumeral stability centering the humeral head onto the glenoid articulation. The long head of the biceps attaches to the supraglenoid tubercle of the glenoid and has a stabilising and depressing action on the humeral head. The rotator cuff gives 50% of the abductor power and 80% of the external rotator power to the gleno-h umeral joint.
Journal of Shoulder and Elbow Surgery, 2020
Background: The concept of stabilizing the humerus has taken on an important role in the treatment of irreparable cuff tears, and the biceps rerouting (BR) method is considered one of the most effective treatments in this field. The study aimed to evaluate the biomechanical effects of BR for large irreparable rotator cuff tears (LICTs). Methods: A total of 8 cadaveric shoulders were used for testing under 5 conditions: intact shoulder, LICT, partial repair (PR), BR, and biceps rerouting with side-to-side repair (BRSS). Total rotational range of motion was measured at 40 , then 20 , and finally 0 of glenohumeral (GH) abduction. Superior humeral translation and subacromial contact pressure were measured at 0 , 30 , 60 , and 90 of external rotation at each abduction angle. Repeated-measures analyses of variance with Tukey post hoc tests were used for statistical comparisons. Results: Superior humeral translation was significantly decreased in the BR and BRSS conditions compared with the LICT and PR conditions at 0 and 20 of GH abduction (P < .001). BR and BRSS significantly reduced subacromial contact pressure compared with LICT and PR at 0 of GH abduction (P < .001). There was no significant decrease in total rotational range of motion after BR at any abduction angle. Conclusion: BR biomechanically restored shoulder stability without overconstraining range of motion in an LICT model.
The biomechanics of the rotator cuff in health and disease – A narrative review
Journal of Clinical Orthopaedics and Trauma, 2021
The rotator cuff has an important role in the stability and function of the glenohumeral joint. It is a complex anatomic structure commonly affected by injury such as tendinopathy and cuff tears. The rotator cuff helps to provide a stabilising effect to the shoulder joint by compressing the humeral head against the glenoid cavity via the concavity compression mechanism. To appreciate the function of the cuff it is imperative to understand the normal biomechanics of the cuff as well as the mechanisms involved in the pathogenesis of cuff disease. The shoulder joint offers a wide range of motion due to the variety of rotational moments the cuff muscles are able to provide. In order for the joint to remain stable, the cuff creates a force couple around the glenohumeral joint with coordinated activation of adjacent muscles, which work together to contain the otherwise intrinsically unstable glenohumeral joint and prevent proximal migration of the humerus. Once this muscular balance is lost, increased translations or subluxation of the humeral head may result, leading to changes in the magnitude and direction of the joint reaction forces at the glenohumeral joint. These mechanical changes may then result in a number of clinical presentations of shoulder dysfunction, disease and pain. This narrative review aims to highlight the importance of functional rotator cuff biomechanics whilst assessing the kinetics and kinematics of the shoulder joint, as well as exploring the various factors involved in cuff disease.
Influence of rotator cuff tears on glenohumeral stability during abduction tasks
Journal of Orthopaedic Research, 2016
One of the main goals in reconstructing rotator cuff tears is the restoration of glenohumeral joint stability, which is subsequently of utmost importance in order to prevent degenerative damage such as superior labral anterior posterior (SLAP) lesion, arthrosis, and malfunction. The goal of the current study was to facilitate musculoskeletal models in order to estimate glenohumeral instability introduced by muscle weakness due to cuff lesions. Inverse dynamics simulations were used to compute joint reaction forces for several static abduction tasks with different muscle weakness. Results were compared with the existing literature in order to ensure the model validity. Further arm positions taken from activities of daily living, requiring the rotator cuff muscles were modeled and their contribution to joint kinetics computed. Weakness of the superior rotator cuff muscles (supraspinatus; infraspinatus) leads to a deviation of the joint reaction force to the cranial dorsal rim of the glenoid. Massive rotator cuff defects showed higher potential for glenohumeral instability in contrast to single muscle ruptures. The teres minor muscle seems to substitute lost joint torque during several simulated muscle tears to maintain joint stability. Joint instability increases with cuff tear size. Weakness of the upper part of the rotator cuff leads to a joint reaction force closer to the upper glenoid rim. This indicates the comorbidity of cuff tears with SLAP lesions. The teres minor is crucial for maintaining joint stability in case of massive cuff defects and should be uprated in clinical decision-making.
The influence of rotator cuff tears on glenohumeral stability during abduction tasks
Journal of Orthopaedic Research, 2016
One of the main goals in reconstructing rotator cuff tears is the restoration of glenohumeral joint stability, which is subsequently of utmost importance in order to prevent degenerative damage such as superior labral anterior posterior (SLAP) lesion, arthrosis, and malfunction. The goal of the current study was to facilitate musculoskeletal models in order to estimate glenohumeral instability introduced by muscle weakness due to cuff lesions. Inverse dynamics simulations were used to compute joint reaction forces for several static abduction tasks with different muscle weakness. Results were compared with the existing literature in order to ensure the model validity. Further arm positions taken from activities of daily living, requiring the rotator cuff muscles were modeled and their contribution to joint kinetics computed. Weakness of the superior rotator cuff muscles (supraspinatus; infraspinatus) leads to a deviation of the joint reaction force to the cranial dorsal rim of the glenoid. Massive rotator cuff defects showed higher potential for glenohumeral instability in contrast to single muscle ruptures. The teres minor muscle seems to substitute lost joint torque during several simulated muscle tears to maintain joint stability. Joint instability increases with cuff tear size. Weakness of the upper part of the rotator cuff leads to a joint reaction force closer to the upper glenoid rim. This indicates the comorbidity of cuff tears with SLAP lesions. The teres minor is crucial for maintaining joint stability in case of massive cuff defects and should be uprated in clinical decision-making.
Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.], 2015
It was the purpose of this paper to analyze structural, functional, and electrophysiologic variables that may determine preserved overhead function for patients with massive rotator cuff tears. Nineteen patients (20 shoulders) were prospectively included in either the pseudoparalytic (n = 9) or the non-pseudoparalytic group (n = 11). Fatty infiltration was graded according to Goutallier, and anterior (subscapularis) and posterior (infraspinatus and teres minor) tear extension was graded 0 (no involvement) to 4 (full tear) on magnetic resonance imaging. Glenohumeral and scapulothoracic rhythm was assessed by fluoroscopic motion analysis, and electromyographic evaluation of the deltoid muscle was performed. We found no significant difference of fatty infiltration of the supraspinatus (3.9 vs 3.6), infraspinatus (3.9 vs 3.8), and teres minor (1.7 vs 0.6) or of the posterior tear extension (2.6 vs 2.0) between pseudoparalytic and non-pseudoparalytic shoulders. Global tear extension in t...