The Impact of Glenoid Labrum Thickness and Modulus on Labrum and Glenohumeral Capsule Function

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Nicholas J. Drury ◽  
Benjamin J. Ellis ◽  
Jeffrey A. Weiss ◽  
Patrick J. McMahon ◽  
Richard E. Debski
Keyword(s):  
Finite Element ◽  
Glenohumeral Joint ◽  
External Rotation ◽  
Tensile Modulus ◽  
Activity Levels ◽  
Average Strain ◽  
Glenoid Labrum ◽  
Age Related ◽  
Glenohumeral Capsule ◽  
The Impact

The glenoid labrum is an integral component of the glenohumeral capsule’s insertion into the glenoid, and changes in labrum geometry and mechanical properties may lead to the development of glenohumeral joint pathology. The objective of this research was to determine the effect that changes in labrum thickness and modulus have on strains in the labrum and glenohumeral capsule during a simulated physical examination for anterior instability. A labrum was incorporated into a validated, subject-specific finite element model of the glenohumeral joint, and experimental kinematics were applied simulating application of an anterior load at 0 deg, 30 deg, and 60 deg of external rotation and 60 deg of glenohumeral abduction. The radial thickness of the labrum was varied to simulate thinning tissue, and the tensile modulus of the labrum was varied to simulate degenerating tissue. At 60 deg of external rotation, a thinning labrum increased the average and peak strains in the labrum, particularly in the labrum regions of the axillary pouch (increased 10.5% average strain) and anterior band (increased 7.5% average strain). These results suggest a cause-and-effect relationship between age-related decreases in labrum thickness and increases in labrum pathology. A degenerating labrum also increased the average and peak strains in the labrum, particularly in the labrum regions of the axillary pouch (increased 15.5% strain) and anterior band (increased 10.4% strain). This supports the concept that age-related labrum pathology may result from tissue degeneration. This work suggests that a shift in capsule reparative techniques may be needed in order to include the labrum, especially as activity levels in the aging population continue to increase. In the future validated, finite element models of the glenohumeral joint can be used to explore the efficacy of new repair techniques for glenoid labrum pathology.

Development of a Finite Element Model of the Inferior Glenohumeral Ligament of the Glenohumeral Joint

2003 ◽  
Author(s):  
William J. Newman ◽  
Richard E. Debski ◽  
Susan M. Moore ◽  
Jeffrey A. Weiss
Keyword(s):  
Finite Element ◽  
Glenohumeral Joint ◽  
External Rotation ◽  
Element Model ◽  
Fe Modeling ◽  
Glenohumeral Ligament ◽  
Subject Specific ◽  
Inferior Glenohumeral Ligament ◽  
Glenohumeral Capsule ◽  
Shoulder Stability

The shoulder is one of the most complex and often injured joints in the human body. The inferior glenohumeral ligament (IGHL), composed of the anterior band (AB), posterior band (PB) and the axillary pouch, has been shown to be an important contributor to anterior shoulder stability (Turkel, 1981). Injuries to the IGHL of the glenohumeral capsule are especially difficult to diagnose and treat effectively. The objective of this research was to develop a methodology for subject-specific finite element (FE) modeling of the ligamentous structures of the glenohumeral joint, specifically the IGHL, and to determine how changes in material properties affect predicted strains in the IGHL at 60° of external rotation. Using the techniques developed in this research, an improved understanding of the contribution of the IGHL to shoulder stability can be acquired.

Effects of Gender on the Mechanical Properties of the Glenohumeral Capsule: Implications for Surgical Repair Techniques

2007 ◽  
Author(s):  
Eric J. Rainis ◽  
Carrie A. Voycheck ◽  
Elizabeth A. Timcho ◽  
Patrick J. McMahon ◽  
Richard E. Debski
Keyword(s):  
Mechanical Properties ◽  
Surgical Repair ◽  
Glenohumeral Joint ◽  
External Rotation ◽  
Joint Stiffness ◽  
The Body ◽  
Males And Females ◽  
Glenohumeral Capsule ◽  
Gender Specific ◽  
Repair Techniques

The glenohumeral joint is the most dislocated major joint in the body and the axillary pouch of the glenohumeral capsule is the primary stabilizer at the extreme ranges of external rotation. [1] Procedures to repair the capsule following dislocation result in 12–25% of patients still experiencing pain and instability. [2] Studies performing clinical exams have found inconsistent data on differences between males and females. Increased laxity in the glenohumeral joint of females has been found as well as overall hypermobility when compared to males. [3,4] However, others have found no differences in overall joint stiffness between genders. [5] These findings suggest that a difference in the mechanical properties might exist between genders. Therefore, the objective of this study was to determine the effects of gender on the mechanical properties of the axillary pouch during tensile loading. A combined experimental and computational approach was used to evaluate the properties of the tissue. This data could potentially be utilized to improve surgical procedures and necessitate gender-specific repair techniques.

The Collagen Fiber Kinematics in the Anteroinferior Glenohumeral Capsule Are Not Affine-Predicted

2011 ◽  
Author(s):  
Carrie A. Voycheck ◽  
Patrick J. McMahon ◽  
Richard E. Debski
Keyword(s):  
Finite Element ◽  
Structural Model ◽  
Glenohumeral Joint ◽  
Structural Models ◽  
Clinical Problem ◽  
Collagen Fibers ◽  
Material Behavior ◽  
Finite Element Models ◽  
Glenohumeral Ligament ◽  
Glenohumeral Capsule

Glenohumeral dislocation is a significant clinical problem and often results in injury to the anteroinferior (anterior band of the inferior glenohumeral ligament (AB-IGHL) and axillary pouch) glenohumeral capsule. [1] However, clinical exams to diagnose capsular injuries are not reliable [2] and poor patient outcome still exists following repair procedures. [3] Validated finite element models of the glenohumeral capsule may be able to improve diagnostic and repair techniques; however, improving the accuracy of these models requires adequate constitutive models to describe capsule behavior. The collagen fibers in the anteroinferior capsule are randomly oriented [4], thus the material behavior of the glenohumeral capsule has been described using isotropic models. [5,6] A structural model consisting of an isotropic matrix embedded with randomly aligned collagen fibers proved to better predict the complex capsule behavior than an isotropic phenomenological model [7] indicating that structural models may improve the accuracy of finite element models of the glenohumeral joint. Many structural models make the affine assumption (local fiber kinematics follow global tissue deformation) however an approach to account for non-affine fiber kinematics in structural models has been recently developed [8]. Evaluating the affine assumption for the capsule would aid in developing an adequate constitutive model. Therefore, the objective of this work was to assess the affine assumption of fiber kinematics in the anteroinferior glenohumeral capsule by comparing experimentally measured preferred fiber directions to the affine-predicted fiber directions.

The Inferior Stability Provided by the Glenohumeral Capsule Increases With External Rotation in the Abducted Glenohumeral Joint

2008 ◽  
Author(s):  
Nicholas J. Drury ◽  
Benjamin J. Ellis ◽  
Patrick J. McMahon ◽  
Jeffrey A. Weiss ◽  
Richard E. Debski
Keyword(s):  
Glenohumeral Joint ◽  
External Rotation ◽  
The Body ◽  
Multidirectional Instability ◽  
Glenohumeral Capsule ◽  
Anterior Direction

The shoulder is the most frequently dislocated major joint in the body, and the glenohumeral capsule is the primary stabilizer to the joint in positions of dislocation. Although the majority of dislocations occur in the anterior direction, multidirectional instability is common and usually occurs in the anterior and inferior directions. Clinicians have difficulty differentiating between multidirectional and unidirectional instability, and greater than 38% of post-operative recurrences may be due to misdiagnosis of the type of instability [1].

Injury to the Glenohumeral Capsule During Anterior Dislocation Leads to Higher Joint Contact Forces During Simulated Clinical Exams

2011 ◽  
Author(s):  
Carrie A. Voycheck ◽  
Daniel P. Browe ◽  
Patrick J. McMahon ◽  
Richard E. Debski
Keyword(s):  
Glenohumeral Joint ◽  
External Rotation ◽  
Permanent Deformation ◽  
Supraspinatus Tendon ◽  
Contact Forces ◽  
Anterior Dislocation ◽  
Joint Stability ◽  
Articular Surfaces ◽  
Increased Risk ◽  
Glenohumeral Capsule

Glenohumeral joint stability is maintained by a combination of active and passive soft tissue structures and osteoarticular contact. Anatomical structures that contribute to each of these categories include the rotator cuff muscles, the glenohumeral capsule, and the contact between the articular surfaces of the humeral head and glenoid of the scapula, respectively. Dislocation may result in injury to one or more of these stabilizing components requiring the other structures to account for the deficit. For example, previous research has shown that a torn supraspinatus tendon results in increased bony contact forces during glenohumeral abduction. [1] Another common injury resulting from dislocation is permanent deformation of the glenohumeral capsule as the capsule is the primary static restraint to anterior translation in positions of external rotation. [2] Increased joint translations and rotations usually occur following permanent deformation [3] indicating a loss in joint stability provided by the capsule. These changes in joint kinematics following dislocation imply that differences in the contact forces between the humerus and scapula may exist as well. Irregular contact between two articular surfaces can lead to abnormal wear and an increased risk of osteoarthritis when left untreated. Therefore, the objective of this work was to assess the affect of anterior dislocation on glenohumeral joint stability by determining the in situ force in the glenohumeral capsule and the bony contact forces between the humerus and scapula during a simulated clinical exam at three joint positions in the intact and injured joint.

scholarly journals Direction of Capsular Strain Implies Surgical Repair Following Recurrent Anterior Shoulder Dislocation

2018 ◽  
Vol 6 (7_suppl4) ◽  
pp. 2325967118S0011
Author(s):  
Tetsuya Takenaga ◽  
Masahito Yoshida ◽  
Calvin Chan ◽  
Volker Musahl ◽  
Albert Lin ◽  
...  
Keyword(s):  
Glenohumeral Joint ◽  
External Rotation ◽  
Reference State ◽  
Circular Statistics ◽  
Recoverable Strain ◽  
Glenohumeral Ligament ◽  
The Maximum Principle ◽  
Capsular Plication ◽  
Glenohumeral Capsule ◽  
Williams Test

Objectives: Capsular plication is often performed in addition to arthroscopic Bankart repair. However, little is known regarding the direction of capsular injury making the direction of plication fairly arbitrary. This study aimed to determine the optimal direction for capsular plication within four sub-regions of the inferior glenohumeral capsule following multiple dislocations. Methods: Seven fresh-frozen cadaveric shoulders (age range 48-66 yrs) were dissected free of all soft tissue except the glenohumeral capsule. A grid of strain markers was affixed to the anterior and posterior band (A/PB) of the inferior glenohumeral ligament (IGHL), and the axillary pouch. The position of the markers while the capsule was inflated with minimal pressure served as the reference state. The humerus and scapula were then mounted in a 6 degree-of-freedom robotic testing system. At 60 degrees of abduction and 60 degrees of external rotation of the glenohumeral joint, an anterior load was applied to reach an anterior translation of one half the maximum AP width of the glenoid plus 10 mm. This definition of dislocation resulted in non-recoverable strain and a reproducible Bankart lesion. Following 1, 2, 3, 4, 5 and 10 dislocations, the positions of the strain markers were again recorded with the capsule inflated. The difference in these positions compared to the reference state defined the non-recoverable strain. The strain map was split into four sub-regions, the anterior band of IGHL (AB), anterior axillary pouch (AA), posterior axillary pouch (PA), and the posterior band of IGHL (PB) (Fig. 1). The angle of deviation between each of the maximum principle strain vectors and the AB-IGHL or PB-IGHL for the anterior and posterior regions of the capsule were determined using ImageJ. Circular statistics were employed to calculate mean direction of each sub-region and a Watson-Williams test was performed to compare mean direction among each dislocation with significance set at p < 0.05. The mean direction of all strain vectors in each sub-region was categorized as parallel or perpendicular to the AB-IGHL or PB-IGHL serving as the clinical reference. Direction ranging from 0 to 45 or 135 to 180 degrees was categorized as parallel. Direction ranging between 45 and 135 degrees was categorized as perpendicular. Results: The direction of 81.8% of the AB sub-regions was categorized as parallel and 18.2% categorized as perpendicular to the AB-IGHL. Direction of 61.3% of the AA sub-region was categorized as parallel (Table 1) and 38.7% categorized as perpendicular to AB-IGHL. The direction of 33.3% of the PA sub-region was categorized as parallel and 66.7% categorized as perpendicular to the PB-IGHL. The direction of 21.4% of PB sub-region was categorized as parallel and 78.6% categorized as perpendicular to PB-IGHL. A Watson-Williams test demonstrated that the direction of 81.3% of the sub-regions were not significantly different (p > 0.05) among dislocations for each specimen (Table 1). Conclusion: The non-recoverable strain in most of the AB and AP sub-regions were categorized as parallel to the AB-IGHL while for the PA and PB sub-regions mostly perpendicular to the PB-IGHL. These findings imply that it may be more optimal to plicate the anteroinferior capsule parallel to the AB-IGHL while posteroinferior capsular plication, which is often not classically considered for plication in the setting of anterior instability, may also be necessary and best performed perpendicular to the PB-IGHL. [Figure: see text][Table: see text]

Ligamentous Restraints to External Rotation of the Humerus in the Late-Cocking Phase of Throwing

2000 ◽  
Vol 28 (2) ◽  
pp. 200-205 ◽  
Author(s):  
John E. Kuhn ◽  
Michael J. Bey ◽  
Laura J. Huston ◽  
Ralph B. Blasier ◽  
Louis J. Soslowsky
Keyword(s):  
Rotator Cuff ◽  
Glenohumeral Joint ◽  
External Rotation ◽  
Coracoacromial Ligament ◽  
Glenohumeral Ligament ◽  
Coracohumeral Ligament ◽  
Potential Source ◽  
Glenohumeral Ligaments ◽  
Inferior Glenohumeral Ligament ◽  
Glenohumeral Capsule

The late-cocking phase of throwing is characterized by extreme external rotation of the abducted arm; repeated stress in this position is a potential source of glenohumeral joint laxity. To determine the ligamentous restraints for external rotation in this position, 20 cadaver shoulders (mean age, 65 16 years) were dissected, leaving the rotator cuff tendons, coracoacromial ligament, glenohumeral capsule and ligaments, and coracohumeral ligament intact. The combined superior and middle glenohumeral ligaments, anterior band of the inferior glenohumeral ligament, and the entire inferior glenohumeral ligament were marked with sutures during arthroscopy. Specimens were mounted in a testing apparatus to simulate the late-cocking position. Forces of 22 N were applied to each of the rotator cuff tendons. An external rotation torque (0.06 N m/sec to a peak of 3.4 N m) was applied to the humerus of each specimen with the capsule intact and again after a single randomly chosen ligament was cut (N 5 in each group). Cutting the entire inferior glenohumeral ligament resulted in the greatest increase in external rotation (10.2° 4.9°). This was not significantly different from sectioning the coracohumeral ligament (8.6° 7.3°). The anterior band of the inferior glenohumeral ligament (2.7° 1.5°) and the superior and middle glenohumeral ligaments (0.7° 0.3°) were significantly less important in limiting external rotation.

scholarly journals Effect of age-related alterations on the biomechanics of teeth affected by non-carious cervical lesions

2019 ◽  
Vol 22 (2) ◽  
pp. 171-177
Author(s):  
Marina Gullo Augusto ◽  
Tabata Do Prado Sato ◽  
Maria José Domingues De Castro ◽  
Marcia Carneiro Valera ◽  
Alexandre Luis Souto Borges ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Stress Distribution ◽  
Cervical Lesions ◽  
Element Analysis ◽  
Compact Structure ◽  
Age Related ◽  
Occlusal Surfaces ◽  
The Impact

Objective: The prevalence of non-carious cervical lesions (NCCLs) has increased in the recent years, especially in the elderly population. The successful prevention and treatment of those lesions requires an understanding of the biomechanics of aged teeth. Considering the importance of such aspect, the impact of the age-related dentin deposition on the stress distribution of NCCLs was evaluated by means of finite element analysis. Material and Methods: A 2-dimensional model of a sound maxillary first premolar was created using CAD software. Two tooth geometries (sound, aged) and two lesion shapes (wedge, saucer) were simulated to the model. The mesh was built with 35,000 triangle and square elements of 0.1 mm in length. All tissues were considered isotropic, homogeneous and linear. Occlusal surfaces were loaded with 300 N for simulating normal chewing forces. The stress distribution was analyzed by a color scale and by the maximum principal stress at the cavosurface line angle. Results: The aged models presented lower stress concentration in the overall system in comparison to sound models. The sharp angle of wedge shaped lesions promoted higher stress concentration at the center of cavosurface angle, favoring the lesions progression. Conclusion: Considering the limitations of the current methodology, it is possible to conclude that aged tooth is a more compact structure that can better respond to stress loadings. This protective intrinsic mechanism should be considered when adopting preventive and restorative measures for NCCLs for the elderly.KeywordsAging; Finite element analysis; Non-carious; Cervical lesions.

scholarly journals Effects of region and sex on the mechanical properties of the glenohumeral capsule during uniaxial extension

2010 ◽  
Vol 108 (6) ◽  
pp. 1711-1718 ◽  
Author(s):  
Carrie A. Voycheck ◽  
Eric J. Rainis ◽  
Patrick J. McMahon ◽  
Jeffrey A. Weiss ◽  
Richard E. Debski
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Material Properties ◽  
Surgical Repair ◽  
Glenohumeral Joint ◽  
Uniaxial Extension ◽  
Posterior Capsule ◽  
Finite Element Models ◽  
Men And Women ◽  
Glenohumeral Capsule

Surgical repair of the glenohumeral capsule after dislocation ignores regional boundaries of the capsule and is not sex specific. However, each region of the capsule functions to stabilize the joint in different positions, and differences in joint laxity between men and women have been found. The objectives of this research were to determine the effects of region (axillary pouch and posterior capsule) and sex on the material properties of the glenohumeral capsule. Boundary conditions derived from experiments were used to create finite-element models that applied tensile deformations to tissue samples from the capsule. The material coefficients of a hyperelastic constitutive model were determined via inverse finite-element optimization, which minimized the difference between the experimental and finite-element model-predicted load-elongation curve. These coefficients were then used to create stress-stretch curves representing the material properties of the capsule regions for each sex in response to uniaxial extension. For the axillary pouch, the C1(men: 0.28 ± 0.39 MPa and women: 0.23 ± 0.12 MPa) and C2(men: 8.2 ± 4.1 and women: 7.7 ± 3.0) material coefficients differed between men and women by only 0.05 MPa and 0.5, respectively. Similarly, the posterior capsule coefficients differed by 0.15 MPa (male: 0.49 ± 0.26 MPa and female: 0.34 ± 0.20 MPa) and 0.6 (male: 7.8 ± 2.9 and female: 7.2 ± 3.0), respectively. No differences could be detected in the material coefficients between regions or sexes. As a result, surgeons may not need to consider region- and sex-specific surgical repair techniques. Furthermore, finite-element models of the glenohumeral joint may not need region- or sex-specific material coefficients when using this constitutive model.

scholarly journals Simulator Based Experimental Motion Analysis of 3D Printed Artificial Shoulder Joint Geometries

10.29007/4vgs ◽  
2018 ◽  
Author(s):  
Nad Siroros ◽  
Mark Verjans ◽  
Klaus Radermacher ◽  
Jörg Eschweiler
Keyword(s):  
Motion Analysis ◽  
Humeral Head ◽  
Shoulder Joint ◽  
Glenohumeral Joint ◽  
External Rotation ◽  
Initial Study ◽  
Biomechanical Behavior ◽  
Pneumatic Muscles ◽  
Main Component ◽  
The Impact

The glenohumeral joint is an important joint with large mobility of the human upperextremity. In shoulder arthroplasty patients often has an unsatisfactory outcome. In order to understand the biomechanical complexity of the shoulder, a novel computer controlled experimental shoulder simulator with an innovative muscle control were constructed. The main component of the simulator includes the active pneumaticmuscles to replicatethe deltoid and the rotator-cuff function and two springs as passive muscle. The aim of this study is to evaluate the impact of a variation of shoulder joint geometries on shoulder biomechanics in the basis of motion analysis. The radius of the glenoid cavity varied from 28-33mm with 2.5mm increment while the radius the humeral head are varied from 20.1-25.1 with 2.5mm increment. The “teach-in” function of the simulator allows an operator to assign the movement to the simulator where the lengths of the pneumatic muscles are recorded. Then the simulator repeats the assigned movement according to the recorded muscles length. The daily living activities includes abduction/adduction, internal/external rotation with adducted arm, and circumduction. The results show promising repeatability of the simulator with minor deviation. However, damage on the surface of the humeral head has been found which should be further studied for both shoulder behavior investigation and the shoulder simulator optimization. Therefore, this study is a decent initial study toward the verification of the simulator and lead to a better understanding of shoulder biomechanical behavior to cope with the clinical problems in the future.

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