Pathomechanics of Glenohumeral Capsule and Scapula in Idiopathic Frozen Shoulder: A Study Using a Three-Dimensional Finite Element Model

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Prince Shanavas Khan, D’Ortho, MS Orthoa,*, Yon-Sik Yoo, MD, PhDb,

Ayyappan V. Nair, D’Ortho, DNB Orthoc, Seong-Wook Jang, MSd, Aebel Raju, MRCSa, Sreehari C K, MS Orthoe

  1. JSES International – Apr 2025

LINK: https://jsesinternational.org/article/S2666-6383(25)00105-7/fulltext

The pathomechanics of primary frozen shoulder remain incompletely understood, particularly regarding the role of capsular stiffness and scapular motion. This study used three-dimensional CT-based finite element models to analyze glenohumeral capsular stress and scapular kinematics in ten patients with idiopathic frozen shoulder.

At maximal humeral abduction, the humeral head abutted the acromion in all cases, with limited abduction angles averaging 39°. Scapular compensation was evident, with significantly increased upward rotation but decreased posterior tilt, potentially predisposing to impingement. Scapular internal/external rotation patterns were inconsistent across patients, highlighting variability in scapulothoracic dynamics. Stress analysis revealed that the anteroinferior capsule consistently bore the greatest tension during abduction and internal rotation behind the back, while the anterosuperior capsule was stressed during external rotation at 0° abduction. Contrary to traditional theories, motion restriction was primarily linked to inferior rather than posterior capsule stiffness.

These findings suggest that selective release of the anteroinferior (and sometimes posteroinferior) capsule, combined with scapular mobilization, may offer more targeted treatment compared with full capsular release. Clinically, frozen shoulder demonstrates an altered scapulohumeral rhythm approaching a 1:1 ratio, reflecting heavy scapular reliance due to glenohumeral restriction.

The study acknowledges limitations, including use of normal capsular properties for modeling and discrete rather than continuous stress simulations. Nonetheless, results highlight the central role of inferior capsule contracture and compensatory scapular mechanics in frozen shoulder, supporting more selective surgical and rehabilitation strategies.

a r t i c l e i n f o Keywords: Frozen shoulder Pathomechanics Finite element model Glenohumeral motion Scapular kinematics Capsular tensionBackground: The pathomechanics of primary frozen shoulders are not yet fully understood. There is ongoing uncertainty regarding the optimal extent of surgical release, with concerns about both over- and under-release of the joint capsule. In the frozen shoulder, different ranges of motion of the shoulder joint experience varying areas of stress, contributing to stiffness and limited movement. The ultimate goal of treatment is to restore the full range of motion while carefully addressing the specific areas of pathology. The purpose of this study was to analyze the kinematics of the glenohumeral joint capsule in a frozen shoulder and to investigate scapulothoracic motion patterns. Methods: Ten patients with unilateral idiopathic frozen shoulders confirmed by a computed tomography (CT) arthrogram were enrolled in this study. All patients were scanned with additional
Level of evidence: Basic Science Study; Computer Modelinghigh-resolution CT at maximum humeral abduction position. The modelling programs were used to simulate glenohumeral and scapulothoracic motion based on reconstructed CT images. The finite element models of the glenohumeral capsule were also constructed based on the CT arthrogram at 0 abduction. We evaluated the changes in scapular position between 0 to maximal humeral abduction angles and measured the degree of scapular abduction, external rotation, and posterior tilt. The tension changes and stress patterns of the capsule during various shoulder motions were also assessed. Results: In maximal humeral abduction, abutment of the humeral head against the lateral acromion was found in all frozen shoulder models. The scapula showed an increment in scapular upward rotation and a decrement in posterior tilt but inconsistency in internal/external rotation in the humeral abduction position. The abduction and internal rotation behind the back position of the humerus caused an increase in the stress at the anteroinferior capsule, compared to other portions of the capsule. Meanwhile, the anterosuperior capsule showed a prominent stress in external rotation at 0 humeral abduction. Conclusion: Pathomechanics of the frozen shoulder characterised by glenohumeral motion limitations should be considered complicated, as confirmed by high tension in the anteroinferior glenohumeral capsule and altered scapular motion. Selective surgical release of the anteroinferior part of the glenohumeral capsule with scapular mobilization can regain glenohumeral motion in the idiopathic frozen shoulder. © 2025 The Author(s). Published by Elsevier Inc. on behalf of American Shoulder and Elbow Surgeons. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-

aDepartment of Orthopaedic Surgery, Apollo Adlux Hospital, Angamali, Kochi, Kerala, India bDepartment of Orthopaedic Surgery, Hallym University, Dongtan, Republic of Korea cDepartment of Orthopaedic Surgery, Manipal Whitefield Hospital, Banglore, Karnataka, India dSchool of Computer Science and Engineering, Korea University of Technology and Education, Cheonan City, Chungnam, Republic of Korea eDepartment of Orthopaedic Surgery Aster MIMS, Kannur, Kerala, India

 The pathomechanics of the primary frozen shoulder are still not
This study was approved by IRB/EC of Dongtan Sacred Heart Hospital, IRB number: 2014-10. *Corresponding author: Prince Shanavas Khan, D’Ortho, MS Ortho, Senior Consultant, Department of Orthopaedic Surgery, Apollo Adlux Hospital, Angamaly, Ernakulam District, Kochi, Kerala, India 683576. E-mail address: drpskhan@gmail.com (P.S. Khan).clearly understood. Since 1945, when Neviaser18 first attempted to implicate shoulder capsule adhesions as the etiology of frozen shoulder, many studies have attempted to unravel the main pathology.4,10,13,17,23,29 More recently, arthrography and arthroscopy have been used to investigate the characteristics of involved

nc-nd/4.0/).

https://doi.org/10.1016/j.jseint.2025.04.003

2666-6383/© 2025 The Author(s). Published by Elsevier Inc. on behalf of American Shoulder and Elbow Surgeons. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

tissues, and have demonstrated loss of the dependent fold,17 decreased capsular volume,13,23 and capsular contractions.13 In addition, contracture of the coracohumeral ligament,19 adhesions of the subacromial bursa, rotator interval thickening and fibrosis, and capsular and intra-articular subscapularis tendon thickening have all been reported.24 The changes in these structures were thought to initiate a pathologic cascade that may compromise normal glenohumeral and scapulothoracic movements, as well as the link between the 2 movements.8,10,23,27 However, few scientific data exist to confirm the capsular mechanics that can influence entire shoulder kinematics, although fibrosis and resulting stiffness of the capsular ligaments have been widely implicated as a cause of

idiopathic frozen shoulder9

For treatment, conservative measures such as non steroidal antiinflammatory drugs, steroid injections, and structured physiotherapy are effective for most patients, focusing on pain relief and gradual restoration of range of motion (ROM). However, for cases resistant to these conservative approaches, surgical options like manipulation under anesthesia or arthroscopic capsular release may be considered, with arthroscopic capsular release emerging as the preferred method due to its controlled and precise approach.22

Improved insights into the pathomechanics of capsular stiffness can further enhance the efficacy of rehabilitation and surgical release strategies.

Therefore, we intended to explore the glenohumeral capsular kinematics in frozen shoulders using a three-dimensional (3D) finite element model. A finite element model of glenohumeral abduction is a computational representation that simulates the shoulder joint’s mechanical behavior during arm elevation. We hypothesized that the glenohumeral capsule and scapular position in patients with idiopathic frozen shoulders would have no measurable differences in kinematic patterns compared to unaffected shoulders during humeral motion.

Materials and methods

Subjects

Ten patients with unilateral frozen shoulders were enrolled in this study. The frozen shoulder was defined as more than 50% loss of passive ROM of the shoulder joint relative to the nonaffected side in 3 movement directions. The 3 movements consist of maximal possible scapular plane abduction, external rotation at 0 abduction, and possible internal rotation behind the back position up to L5. Diagnosis of frozen shoulder was finally confirmed with reduced capsular volume (<10 mL) and no evidence of rotator cuff tear on computed tomography (CT) arthrogram.32

Once diagnosed with a frozen shoulder, all patients underwent additional CT in maximum humeral abduction position in neutral rotation for the affected shoulder, and behind the back internal rotation position to L5 for the contralateral side in the prone position in neutral rotation. They were enrolled in a prospective study approved by our institutional review board. As part of the diagnosis and research protocol, all patients provided permission for their CT arthrogram study and additional positioned CT to be used for research purposes.

Creation of three-dimensional bone and capsule models

We created 3D models of the humerus, scapula, glenoid labrum, and capsule using CT arthrogram data, with the help of Amira software (v 4.1.1; Mercury Computer Systems, Inc., Chelmsford, MA, USA). We manually refined the capsule’s front, back, top, and bottom areas to improve the model and fix any artefacts between the humeral head and scapular neck.

Next, we used CT data from the arm in the abduction position to create clear 3D models of the humerus and scapula, which would serve as the main bone models. The images from the arthrogram, where the capsule was filled with a hyperopaque fluid, were not clear enough to model joint movement accurately, so we replaced those with the abduction position data. Finally, we combined the 3D models of the humerus and scapula in the abduction position with the capsule and labrum models from the arthrogram to create a complete shoulder model at rest.

Simulation of glenohumeral motion

We measured the glenohumeral angle at 2 humeral positions: 0 and maximal abduction, relative to the scapula, and used these to identify the screw axis within the humeral head to simulate continuous abduction motion.

The limit for internal rotation behind the back was 50, corresponding to the L5 level. The motion axis was mirrored from the opposite shoulder.

For external rotation from the 0 position to 50, we used the reference vector along the long shaft of the humerus. The glenohumeral joint was modelled as a ball-and-socket joint, with the rotation centre determined by fitting a sphere to the articulating surface of the humeral head Figure 1.

Measurement of scapular motions

Two scapular positions were used to measure 3 types of motion: upward/downward rotation, internal/external rotation, and anterior/posterior tilt, relative to the rib-spine complex.

The scapular coordinate system, the scapular reference frame, and the Euler angle sequence of rotations (X-Y-Z order) were defined in accordance with the International Society of Biomechanics recommendations.26 The coordinate system (X-Y-Z) had its origin coincident with the posterolateral acromion.

The rotation about the X-axis is defined as upward/downward rotation, the rotation about the Z-axis is described as anterior/ posterior tilt, and the rotation around the Y-axis is referred to as internal/external rotation Figure 2.

Angular displacements in the scapula’s abduction position were measured starting from the reference position, which is the scapula’s position when the arm is at rest.

Finite element model development

The surface models for the humerus, scapula, labrum, and capsular regions were then imported into a finite element preprocessor. Triangular surfaces representing the scapula, humerus, and glenoid labrum were converted directly to quadrilateral elements of a rigid body (humerus: 4028.0 ± 237.7, scapula: 10036.7 ± 1017.1, and labrum: 4809.7 ± 619.5). The inner sides of the capsular regions were meshed with quadrilateral shell elements (2549 ± 112.4). A 0.01 mm uniform thickness was prescribed for all capsular regions. The nodes along the edges of 2 adjacent meshes were then merged. Each node of the edge of the capsule had a constraint condition of 3 degrees of freedom for translation, except for rotation.

The constructed capsule was considered a nonlinear hyperelastic material with its own elastic modulus, which was the mathematical description of an object’s or substance’s tendency to be deformed elastically. Baseline material properties of the components in a 3D model of the glenohumeral joint are described in Table I. The contact condition between the capsular regions and bony structure was prescribed via a frictionless sliding surface, and contact was enforced.

Figure 1 Flow chart showing the development of three-dimensional bone and capsule models and simulation of glenohumeral motion. CT, computed tomography. Figure 2 Scapular coordinate system, the scapular reference frame, and the Euler angle sequence of rotations (X-Y-Z order) in accordance with the International Society of Biomechanics recommendation. The coordinate system (X-Y-Z) had its origin coincident with the posterolateral acromion. Table I Baseline material properties of the glenohumeral joint in a 3D model. Anatomy Material type Parameter Reference Bony structure (humerus, scapula) Labrum Capsular ligament Rigid body Rigid body Nonlinear hyperelasticity E ¼ 15,000 MPa, m ¼ 0.3 E ¼ 33 MPa, m ¼ 0.475 m ¼ 0.475 16 17 18,19

Data analysis

Finite element analysis from the reference position to the maximal abduction position of the glenohumeral model was performed with the explicit solver of Abaqus software (Simulia) for dynamic analysis of the area of stress and degree of stress on the glenohumeral capsule. The distributions of the von Mises stress on the capsule were calculated according to various humeral motions consisting of abduction, internal rotation behind the back, and external rotation at 0 abduction. External rotation at 0 abduction and internal rotation behind the back were simulated up to the same degree of abduction angle, based on the rotation center of the humerus and the instantaneous center between 2 fixed humeri, respectively.

The most prominent areas of stress were identified at the end of each motion on the capsule and classified as anterosuperior, anteroinferior, posteroinferior, and posterosuperior areas of the capsule.

Statistical method

Statistical analysis was performed using SPSS for Windows (version 16.0; SPSS Inc., Chicago, IL, USA). Descriptive statistics including means and frequencies were used to evaluate scapular movement. One-way analysis of variance and Repeated measures analysis of variance were used to investigate the stress differences among 4 districts of the capsule according to various shoulder motions. Results were statistically significant at P < .05.

Results

In maximal humeral abduction, abutment of the humeral head against the lateral acromion was found in all frozen shoulder models, with a low abduction angle averaging 39, and ranging from 24 to 64 (Fig. 3, A). The scapula demonstrated a discernible pattern of rotation with elevation of the humerus (Fig. 3, B).

The maximal scapular plane abduction with an average of 39 demonstrated high stresses on the anteroinferior capsule followed by the posteroinferior capsule (1.42 ± 0.79Mph and

0.78 ± 0.48Mph, respectively) but stresses on the anterior superior and posterosuperior capsule showed consistently lower at this angle (0.05 ± 0.04 Mph and 0.03 ± 0.02 Mph, respectively). The value of peak stress on anteroinferior capsule showed a statistical significance compared to those of anterior superior and posterosuperior capsules on abduction (P < .001 and P < .001, respectively).

The internal rotation behind the back position of the humerus showed a similar stress pattern observed in abduction. At 50 degrees of internal rotation showed a high stress at the anteroinferior capsule (1.20 ± 0.49 Mph), followed by the posteroinferior capsule (0.82 ± 0.41 Mph), but lower stresses on the posterosuperior (0.22 ± 0.17 Mph) and anterosuperior (0.16 ± 0.22 Mph) capsule. Statistical difference was found between the stress value of the inferior parts of the capsule and that of the superior parts of the capsule (P < .01).

The 50-degree external rotation at 0 humeral abduction induced prominent stress on the anterosuperior capsule with

1.31 ± 1.16Mph followed by the anteroinferior capsule with 0.65 ± 0.54Mph. A statistical difference was found between the stress value on the anterosuperior capsule and the posterior capsule of both the superior and inferior parts (P < .001 and P < .001, respectively) (Figs. 4 and 5).

The average scapular upward rotation angle with respect to the rib cage during maximal humeral abduction was 39 ± 26. The posterior tipping and external rotation of the affected shoulder were 26.3 ± 5.7 and 4.2 ± 12.9, respectively (Fig. 6).

Discussion

Our findings reveal several critical points that challenge conventional understandings and suggest refined therapeutic considerations for managing a frozen shoulder. Contrary to Cyriax’s classical theorydwhich suggests external rotation is most limited followed by abduction and internal rotation. Our findings demonstrate that abduction is the most restricted shoulder motion. This limitation results from increased stress in the anteroinferior capsule, rather than the traditionally implicated anterosuperior capsule or rotator interval.21,25 Our findings align with fluoroscopic and electromagnetic tracking studies by Eto and Rundquist7,28 Internal rotation behind the back was predominantly restricted by the inferior capsule rather than the posterior capsule, contrasting findings from prior studies that have highlighted the posterior capsule as the primary limiting factor.20,30,33 These observations align with recent cadaveric16 and finite element modelling studies,6 reinforcing the concept that pathologic stiffness is more pronounced in the inferior capsule.

The strain becomes highest in the anterior band of the inferior glenohumeral ligament when the joint is abducted and externally rotated. Our findings align with prior studies, indicating anterior glenohumeral ligament tightness contributes more to pathological stiffness than posterior capsule regions during abduction and

external rotation.1,2,6,15,16

Normally, during initial shoulder abduction (0-30), movement occurs primarily at the glenohumeral joint with minimal scapular involvement. Beyond 30, the scapula significantly rotates upward and tilts posteriorly, bringing its inferior angle anteriorly and superior border posteriorly. This posterior tipping elevates the acromion, creating additional subacromial space to prevent impingement. Our investigation into scapular biomechanics demonstrated notable deviations in scapular movement patterns among individuals with adhesive capsulitis. Notably, a significant increase in scapular upward rotation was recorded (mean of 39), considerably higher compared to reported values in normal populations (9-23). This exaggerated scapular upward rotation likely represents compensatory adaptation aimed at overcoming glenohumeral restriction. Conversely, we observed decreased posterior tipping of the scapula during abduction. Reduced posterior tipping potentially narrows the subacromial space, increasing the risk of impingement due to earlier contact between the humeral head and the anterior acromion. The measured values for posterior tipping of the scapula in frozen shoulder abduction were lower than those for a normal population.3,5,11 Inconsistent patterns of scapular external rotation or decrease in posterior tipping indicated a high probability of local stiffness between the scapula and corresponding outer thorax.

An unexpected finding was the substantial variability observed in scapular internal and external rotation ranging from 14 to 22 highlighting the complexity of scapulothoracic dynamics in adhesive capsulitis. In the meantime, the pattern of internal/external rotation of the scapula on shoulder abduction was quite variable between subjects, with standard deviations. This finding suggests that scapular motion in adhesive capsulitis (frozen shoulder) is not consistent across individuals. Unlike scapular upward rotation or posterior tipping, which follow relatively predictable trends, scapular internal and external rotation varied greatly, indicating differences in how the scapula interacts with the thoracic wall and surrounding musculature. The high variability underlines the importance of tailored rehabilitation approaches rather than a “one-size-fits-all” approach.

Normal scapulohumeral abduction relationship is nonlinear (1:2). The altered scapulohumeral rhythm observed in this study underscores the increased reliance on scapular rotation during humeral elevation, approximating a nearly equal contribution (1:1 ratio) in frozen shoulder. This causes the early abutment of the humerus against the acromion in the frozen shoulder abduction. This shift in scapulohumeral rhythm may stem from muscular imbalances, particularly involving weakness or dysfunction of the serratus anterior and lower trapezius muscles, or from localized stiffness resulting from adhesions between the scapula and thoracic wall. Determining the exact cause warrants further electromyographic investigations of periscapular muscle activity alongside kinematic assessments.24 It may be more appropriate to observe and interpret scapulohumeral rhythm in increments or isolated arcs of motion for better clarity in future studies.

Figure3 Humeral and scapular movements on abduction. (A) Abutment of the humerus against acromion with a low abduction angle in a representative frozen shoulder model. (B) Depicts of overlapped scapulars with respect to the chest wall, indicating hyperabduction, posterior tilt and external rotation of scapula on maximal humeral abduction. Figure 4 Stress patterns in anterior (Left) and posterior glenohumeral capsule (Right) during various humeral motions in representative case. ER, external rotation; IR, internal rotation.

According to our results and speculation based on 3D kinematics, early abutment of the humeral head against the acromion due to the checkrein function of inferior capsular contracture, which in turn causes failure of obligatory external rotation, can be an initiator of a pathologic cascade in pathogenic mechanics of the frozen shoulder. The change in position of the humeral head causes another change in the axis of rotation of both the humerus and scapula, resulting in unpredictable periscapular muscular action Table II.

Selective surgical interventions aimed at releasing the anteroinferior capsule, and to a lesser extent the posteroinferior capsule, combined with targeted scapular mobilization exercises, could potentially yield improved clinical outcomes by addressing the primary mechanical impediments identified in our analysis. The Ala-Carte capsular release over the pancapsular release offers significant clinical advantages by specifically targeting pathological areas of the shoulder capsule while preserving healthy tissues. This selective intra-articular approach notably reduces operative time, minimizes the risk of axillary nerve injury by avoiding bursal-side dissection of glenohumeral joint with selective release of anteroinferior part of the capsule. It is precise in targeting the patient’s specific range of motion deficits, facilitating quicker functional recovery and enhanced patient outcomes. Furthermore, the role of the scapula in shoulder injuries has been widely studied for shoulder impingement and rotator cuff disease, but there are few studies on the role of the scapula in adhesive capsulitis of glenohumeral joint stiffness.12,14,31

However, certain limitations of our study merit discussion. Primarily, stress patterns were analyzed using biomechanical modelling based on normal capsular tissues rather than explicitly representing the pathological tissues characteristic of a frozen shoulder. This approach limits the generalizability of absolute stress magnitudes but remains valuable in elucidating relative stress distribution patterns. Moreover, the evaluation of capsular

Figure 5 Angle eStress curves during (A) maximum humeral abduction (ABD), (B) external rotation (EXT) at 0 degrees of abduction, and (C) internal rotation behind the back position (INT) of the humerus. (D) Peak stresses in 4 anatomical regions on the capsule according to 3 types of motion. y indicates all other regions except the one with the next higher value. z indicates against listed regions. Error bars: standard deviation. SA, superior anterior; SP, superior posterior; IA, inferior anterior; IP, inferior posterior. Figure 6 Scapular kinematic patterns and associated stress at maximal humeral abduction in patients with frozen shoulder. (A) Peak principal stress (in MPa) in the scapula under three humeral movement conditions: abduction (ABD, red), external rotation (ER, green), and internal rotation (IR, blue). (B) Angular measurements (in degrees) of three distinct scapular movement patterns during maximal humeral abduction: abduction (ABD, red), external/internal rotation (EXT/INT, green), and posterior tilt (PT, blue). ABD, abduction; EXT/

INT, external/internal rotation; PT, posterior tilt.

stresses was limited to discrete angles rather than continuous movement sequences, which may omit insights into dynamic variations throughout a complete ROM. Recruiting healthy volunteers for invasive CT arthrograms raises ethical concerns, as the procedure offers no direct benefit to them. Moreover, using patients’ contralateral shoulders may introduce biases due to subclinical effects or compensatory changes. Future studies incorporating multimodal imaging (magnetic resonance imaging and CT) could further improve labral segmentation accuracy.

In conclusion, our study highlights significant biomechanical differences in capsular and scapular motion patterns in adhesive capsulitis, particularly emphasizing the pivotal role of inferior

Table II

Shoulder capsule biomechanics and motion restrictions.

FindingsObservations
Stress distributionIncreased stress in the anteroinferior capsule during abduction & external rotation.
Rotator interval stressMinimal stress except in early internal rotation behind the back & external rotation at 0 abduction.
Internal rotation restrictionLimited by the anteroinferior ligament, not the posterior capsule.
Posterior capsule roleNot significantly related to internal rotation restriction.
Motion limitation factorsInfluenced by capsular shape, scapular stiffness, and scapulohumeral mechanics.

capsular stiffness and altered scapulothoracic mechanics. Therapeutically, these findings support strategies involving selective capsular release combined with interventions targeting scapular mobility and periscapular muscle function. Future research should incorporate pathological tissue modelling, dynamic stress distribution analyses, and electromyographic assessments to clarify the precise interplay between muscular, capsular, and scapular contributions to frozen shoulder pathomechanics.

Conclusion

The scapula in the idiopathic frozen shoulder showed an increment in scapular upward rotation and a decrement in posterior tilt, but inconsistency in internal/external rotation in the humeral abduction position. Pathomechanics of the frozen shoulder characterized by glenohumeral motion limitations should be considered complicated, as confirmed by high tension in the anteroinferior glenohumeral capsule and unregulated motion in the scapula.

Disclaimers:

Funding: This research paper was funded by National Research Foundation (NRF) of Korea, Ministry of Education. Grant number2013R1A1A2011589.

Conflicts of interest: The authors, their immediate families, and any research foundation with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.

References

  1. Bankart ASB. Recurrent or habitual dislocation of the shoulder-joint. Br Med J 1923;2:1132.
  2. Bankart ASB. The pathology and treatment of recurrent dislocation of the shoulder-joint. Br J Surg 1938;26:23-9.
  3. Borsa PA, Timmons MK, Sauers EL. Scapular-positioning patterns during humeral elevation in unimpaired shoulders. J Athl Train 2003;38:12-7.
  4. Bunker TD. Frozen shoulder: unravelling the enigma. Ann R Coll Surg Engl 1997;79:210-3.
  5. Doody SG, Freedman L, Waterland JC. Shoulder movements during abduction in the scapular plane. Arch Phys Med Rehabil 1970;51:595-604.
  6. Ellis BJ, Drury NJ, Moore SM, Weiss JA, Debski RE. Maximum principal strains inthe glenohumeral capsule during a clinical exam: a validated finite element model. Comput Methods Biomech Biomed Engin 2010;13:413-8. https:// doi.org/10.1115/SBC2007-175358.
  7. Eto M. Analysis of the scapulo-humeral rhythm for periarthritis scapulohumeralis. Nihon Seikeigeka Gakkai Zasshi 1991;65:693-707.
  8. Fayad F, Roby-Brami A, Yazbeck C, Hanneton S, Lefevre-Colau MM, Gautheron V, et al. Three-dimensional scapular kinematics and scapulohumeral rhythm in patients with glenohumeral osteoarthritis or frozen shoulder. J Biomech 2008;41:326-32. https://doi.org/10.1016/j.jbiomech. 2007.09.004.
  9. Hand GC, Athanasou NA, Matthews T, Carr AJ. The pathology of frozen shoulder. J Bone Joint Surg Br 2007;89:928-32. https://doi.org/10.1302/0301620X.89B7.19097.
  10. Hsu JE, Anakwenze OA, Warrender WJ, Abboud JA. Current review of adhesivecapsulitis. J Shoulder Elbow Surg 2011;20:502-14. https://doi.org/10.1016/ j.jse.2010.08.023.
  11. Johnson GR, Stuart PR, Mitchell S. A method for the measurement of threedimensional scapular movement. Clin Biomech (Bristol) 1993;8:269-73.
  12. Kibler WB, Ludewig PM, McClure PW, Michener LA, Bak K, Sciascia AD. Clinicalimplications of scapular dyskinesis in shoulder injury: the 2013 consensus statement from the ‘Scapular Summit’. Br J Sports Med 2013;47:877-85. https://doi.org/10.1136/bjsports-2013-092425.
  13. Loyd JA, Loyd HM. Adhesive capsulitis of the shoulder: arthrographic diagnosis and treatment. South Med J 1983;76:879-83.
  14. Ludewig PM, Reynolds JF. The association of scapular kinematics and glenohumeral joint pathologies. J Orthop Sports Phys Ther 2009;39:90-104. https:// doi.org/10.2519/jospt.2009.2808.
  15. Malicky DM, Soslowsky LJ, Kuhn JE, Bey MJ, Mouro CM, Raz JA, et al. Total strain fields of the antero-inferior shoulder capsule under subluxation: a stereoradiogrammetric study. J Biomech Eng 2001;123:425-31.
  16. Moore SM, Stehle JH, Rainis EJ, McMahon PJ, Debski RE. The current anatomicaldescription of the inferior glenohumeral ligament does not correlate with its functional role in positions of external rotation. J Orthop Res 2008;26:1598604. https://doi.org/10.1002/jor.20685.
  17. Neviaser TJ. Adhesive capsulitis. Orthop Clin North Am 1987;18:439-43.
  18. Neviaser AS, Neviaser RJ. Adhesive capsulitis of the shoulder. J Am AcadOrthop Surg 2011;19:536-42. https://doi.org/10.5435/00124635-2011090 00-00004.
  19. Nobuhara K, Sugiyama D, Ikeda H, Makiura M. Contracture of the shoulder. Clin Orthop Relat Res 1990:105-10.
  20. O’Brien SJ, Neves MC, Arnoczky SP, Rozbruck SR, Dicarlo EF, Warren RF, et al. The anatomy and histology of the inferior glenohumeral ligament complex of the shoulder. Am J Sports Med 1990;18:449-56.
  21. Ozaki J, Nakagawa Y, Sakurai G, Tamai S. Recalcitrant chronic adhesive capsulitis of the shoulder. Role of contracture of the coracohumeral ligament and rotator interval in pathogenesis and treatment. J Bone Joint Surg Am 1989;71: 1511-5.
  22. Pandey V, Madi S. Clinical guidelines in the management of frozen shoulder: anupdate! Indian J Orthop 2021;55:299-309. https://doi.org/10.1007/s43465021-00351-3.
  23. Parker RD, Froimson AI, Winsberg DD, Arsham NZ. Frozen shoulder. Part I: chronology, pathogenesis, clinical picture, and treatment. Orthopedics 1989;12:869-73.
  24. Pearsall AW 4th, Osbahr DC, Speer KP. An arthroscopic technique for treating patients with frozen shoulder. Arthroscopy 1999;15:2-11.
  25. Petchprapa CN, Beltran LS, Jazrawi LM, Kwon YW, Babb JS, Recht MP. The rotator interval: a review of anatomy, function, and normal and abnormal MRI appearance. AJR Am J Roentgenol 2010;195:567-76. https://doi.org/10.2214/ AJR.10.4406.
  26. Roy JS, Moffet H, Hebert LJ, St-Vincent G, McFadyen BJ. The reliability of three- dimensional scapular attitudes in healthy people and people with shoulder impingement syndrome. BMC Musculoskelet Disord 2007;8:49. https:// doi.org/10.1186/1471-2474-8-49.
  27. Rundquist PJ. Alterations in scapular kinematics in subjects with idiopathic lossof shoulder range of motion. J Orthop Sports Phys Ther 2007;37:19-25. https:// doi.org/10.2519/jospt.2007.2121.
  28. Rundquist PJ, Anderson DD, Guanche CA, Ludewig PM. Shoulder kinematics insubjects with frozen shoulder. Arch Phys Med Rehabil 2003;84:1473-9. https:// doi.org/10.1016/s0003-9993(03)00359-9.
  29. Shaffer B, Tibone JE, Kerlan RK. Frozen shoulder. A long-term follow-up. J Bone Joint Surg Am 1992;74:738-46.
  30. Terry GC, Hammon D, France P, Norwood LA. The stabilizing function of passive shoulder restraints. Am J Sports Med 1991;19:26-34.
  31. Vermeulen HM, Stokdijk M, Eilers PH, Meskers CG, Rozing PM, Vliet Vlieland TP. Measurement of three dimensional shoulder movement patterns with an electromagnetic tracking device in patients with a frozen shoulder. Ann Rheum Dis 2002;61:115-20. https://doi.org/10.1136/ard.61.2.115.
  32. Wirth MA, Rockwood CA, Matsen FA, Lippitt SB, editors. The shoulder. 4th ed. Philadelphia, PA: Elsevier; 2009.
  33. Zuckerman JD, Rokito A. Frozen shoulder: a consensus definition. J Shoulder Elbow Surg 2011;20:322-5. https://doi.org/10.1016/j.jse.2010.07.008.
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