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Shoulder Anatomy & Biomechanics

Glenohumeral stability mechanisms, including static and dynamic stabilizers, and the biomechanical adaptations associated with overhead athletic activity.

Overview

The shoulder possesses the most motion of any joint in the human body, a function highly dependent on unique anatomy and biomechanical properties [4]. Clinical evaluation of altered shoulder kinematics remains complicated, requiring a thorough understanding of complex musculoskeletal interactions for both physical examination and radiologic workup [1, 4]. The biomechanical shoulder model aligns with clinical observations regarding glenoid inclination and acromion index effects on humeral head translation and glenoid articular cartilage strain [2]. Updates on the thrower's shoulder, including anatomy, mechanics, pathomechanics, and treatment, are essential for clinicians and researchers [3].

Anatomically shaped prosthetic humeral heads might lead to better shoulder function and implant survivorship compared to spherical heads [5]. An anatomical reconstruction of the glenohumeral surfaces is important for the success rate of anatomical total shoulder arthroplasty [63]. While glenoid version as traditionally defined may have limited relevance when positioning the glenoid component during total shoulder arthroplasty, glenoid and scapular body development are controlled by independent genetic and biomechanical factors [13]. Literature concerning shoulder anatomy and pathology related to stability and instability is reviewed to improve clinical diagnosis and surgical treatment [8].

Attaining full motion is a reasonable goal of all shoulder treatment, though less range of motion (ROM) is required to perform the functional tasks used in common outcome tools than full motion [24]. Both open and arthroscopic repair techniques for anterosuperior rotator cuff tears with subscapularis involvement significantly improved shoulder function and are relatively safe procedures [22]. Subpectoral biceps tenodesis is associated with a loss of glenohumeral abduction external rotation and anterior scapular tipping, yet outcome measures were equivalent when comparing post-surgical and uninvolved shoulder function and biomechanics [25]. Lateralization is achievable at both the glenoid and humeral sides in reverse total shoulder arthroplasty, where lateralization at the glenoid and humeral sides has different biomechanical effects [29]. Lateralized implant options in reverse total shoulder arthroplasty should be selected according to patients' needs [29].

Anatomy & Pathophysiology

The shoulder possesses the most motion of any joint in the human body, with function highly dependent on unique anatomy and biomechanical properties [4]. Clinical evaluation of altered shoulder kinematics remains complicated, requiring a thorough understanding of complex musculoskeletal interactions for both physical examination and radiologic workup [1, 4]. The biomechanical shoulder model aligns with clinical observations regarding glenoid inclination and acromion index effects on humeral head translation and glenoid articular cartilage strain [2]. Updates on the thrower's shoulder, including anatomy, mechanics, pathomechanics, and treatment, remain essential for clinicians and researchers [3].

Kinematics: Alterations of scapular kinematics in symptomatic subjects are multifactorial [6]. Findings suggest a plausible mechanical progression of kinematic and strength changes associated with the development of rotator cuff pathology [7]. Observed changes in scapular kinematics are associated with an increased overall range of motion following rotator cuff repair, suggesting restored function of shoulder muscles [9]. Small but significant asymmetries exist between the dominant and nondominant shoulders in terms of kinematics [17]. The rotator interval is central to normal glenohumeral kinematics, and any insult to its integrity alters shoulder motion throughout abduction [19]. Shortening of the clavicle affects the kinematics in the shoulder girdle [21].

Capsular repair significantly alters normal glenohumeral kinematics [46]. Biomechanical changes of passive glenohumeral joint motion occur in the glenohumeral joint with as little as 5% glenohumeral internal rotation deficit (GIRD) due to posterior capsular contracture [47]. The humeral head moves from an inferior position to the center of the glenoid during active arm abduction, with kinematic variability of the humeral head decreasing significantly as abduction increases [44]. The thrower's shoulder model demonstrates abnormal kinematics and path of glenohumeral motion throughout a rotational range of motion compared with an intact shoulder [45]. Superior capsular reconstruction (SCR) only partially restores native glenohumeral joint loads in a dynamic shoulder model [42].

Kinematics in arm tackle and head-in-front tackle rugby scenarios are significantly different from that in the shoulder tackle, where these differences may represent a distinct risk factor for shoulder dislocation [38]. Kinematics of reverse total shoulder arthroplasty (rTSA) shoulders are significantly altered compared to healthy subjects, utilizing more scapulothoracic motion and much less glenohumeral motion to elevate the arm [31, 35, 40]. Older asymptomatic males exhibit altered glenohumeral and scapulothoracic motion patterns compared to younger males during dynamic tasks [41]. RTSA shoulders show kinematics that are significantly different from normal shoulders [35].

Classification

Shoulder Kinematics & Function: Clinical evaluation of altered shoulder kinematics remains complicated [1], yet the biomechanical shoulder model is consistent with clinical observations [2]. The shoulder possesses the most motion of any joint in the human body [4], and its function is highly dependent on unique anatomy and biomechanical properties [4]. Physical examination and radiologic workup require a thorough understanding of complex musculoskeletal interactions [4]. Updates on the thrower's shoulder, including anatomy, mechanics, pathomechanics, and treatment, are essential for clinicians and researchers [3].

Scapular & Glenoid Morphology: Observed changes in scapular kinematics are associated with an increased overall range of motion after rotator cuff repair [9], suggesting restored function of shoulder muscles [9]. Glenoid version as traditionally defined may have limited relevance when positioning the glenoid component during total shoulder arthroplasty [13], as glenoid and scapular body development are controlled by independent genetic and biomechanical factors [13]. Scapulothoracic and glenohumeral components of shoulder motion are more specific than humerothoracic measures to diagnostic classification in children with brachial plexus birth palsy [20].

Pathology & Risk Stratification: Evaluation of range of rotation seems to identify shoulders at risk of pathology in professional male handball players [16]. A classification system was created to divide coracoids according to their morphology and relative risk of associated subscapularis tears [39]. Twenty-six different criteria described by multiple classification systems have been identified for the magnetic resonance assessment of rotator cuff after repair [51].

Anatomical Structures & Models: The glenocapsular ligament is a constant anatomical structure consisting of one or two different parts [50], and the posterosuperior part of the joint capsule is well vascularized [50]. A two-body scapulohumeral shape model was developed that captures coupled variations in arthropathic shoulder anatomy [52], alongside a proximal-humeral statistical model constructed using a clinical dataset [52]. The anatomical structure of passive shoulder restraints has no impact on the difference in passive joint position sense values between external and internal rotation [54].

Other Considerations: The chapter provides a comprehensive review of shoulder, arm, and elbow anatomy including ossification patterns, joint mechanics, ligamentous stabilizers, musculature, neurovascular structures, and surgical approaches [49]. The article reviews and clearly defines acronyms used by shoulder specialists to identify and review acronyms related to the shoulder described in the literature [53].

Clinical Presentation

The shoulder possesses the most motion of any joint in the human body [4], and its function is highly dependent on unique anatomy and biomechanical properties [4]. Clinical evaluation of altered shoulder kinematics remains complicated [1], yet the biomechanical shoulder model is consistent with clinical observations [2]. Updates on the thrower's shoulder, including anatomy, mechanics, pathomechanics, and treatment, are essential for clinicians and researchers [3]. Physical examination and radiologic workup require a thorough understanding of complex musculoskeletal interactions [4], while a thorough understanding of shoulder physical examination and specific diagnostic tests is important for ensuring diagnostic accuracy and optimizing patient outcomes [15].

Scapular Kinematics: Alterations of scapular kinematics in symptomatic subjects are multifactorial [6]. Shortening of the clavicle affects the kinematics in the shoulder girdle [21], and altering scapula position may affect shoulder strength in asymptomatic individuals [36]. Scapulothoracic and glenohumeral components of shoulder motion are more specific than humerothoracic measures to diagnostic classification in children with brachial plexus birth palsy [20].

Pathomechanics and Diagnosis: Findings suggest a plausible mechanical progression of kinematic and strength changes associated with the development of rotator cuff pathology [7]. Evaluation of range of rotation seems to identify shoulders at risk of pathology in professional male handball players [16]. Ultrasound is a useful tool for discovering subjects in pre-symptomatic stages who may undergo shoulder symptomatic pathologies [18]. The critical shoulder angle was unaffected by demographic factors [10]. An aberrant origin of the long head of the biceps does not appear to contribute to shoulder pathology [32]. Further studies are required to understand the clinical relevance of middle glenohumeral ligament findings, notably for the treatment of shoulder stiffness [33].

Outcomes and Prosthetics: Anatomically shaped prosthetic humeral heads might lead to better shoulder function and implant survivorship [5]. The purpose of the literature review is to improve clinical diagnosis and surgical treatment of shoulder stability/instability [8]. Shoulder physical functions were mapped to outcome scores [37], and understanding the needs of patients helps physicians better comprehend the pathology and manage the weight-bearing shoulder [23].

Investigations

Plain radiography: While essential for initial workup, plain radiographs may overestimate the shoulder beta angle and inferior glenoid resection depth [66].

MRI: The shoulder possesses the most motion of any joint in the human body, with function highly dependent on unique anatomy and biomechanical properties [4], necessitating a thorough understanding of complex musculoskeletal interactions for physical examination and radiologic workup [4]. Three-dimensional MRI measurement of whole-muscle volume is required and is associated with shoulder strength [55]. Three-dimensional MRI serves as a radiation-free and reliable alternative to preoperative CT for measuring glenoid bone loss [57] and is equivalent to 3D CT in quantifying bone loss in patients with shoulder dislocation and measuring shoulder morphologic parameters [59]. Further developments in deep learning processing of MRI have the potential to allow surgeons to obtain all clinically relevant information from MRI scans and reduce the need for multiple imaging studies for patients with shoulder pathology [60]. Average cortical bone thickness measurements obtained from shoulder MRI are correlated with DXA and appear effective in differentiating patients with normal and abnormal BMD [65]. Measuring glenoid version on MRI does not appear to be significantly affected when the entirety of the medial border of the scapula is not included in the imaging field [68]. However, accuracies for shoulder MRI in a community setting were not improved by having the MRIs interpreted by selected fellowship-trained musculoskeletal radiologists [70]. Unenhanced magnetic resonance imaging of the shoulder in asymptomatic high-performance throwing athletes reveals abnormalities that may encompass a spectrum of nonclinical findings [75]. MRI abnormalities found in asymptomatic dominant shoulders of elite overhead athletes represented clinical false-positive findings that did not evolve into symptomatic conditions over 5 years [71]. Ultrasound is an useful tool for discovering subjects in pre-symptomatic stages who may undergo shoulder symptomatic pathologies [18].

CT: Uncorrected CT scans of the glenohumeral joint do not correct for the sagittal rotation of the glenoid, affecting axial image characteristics [80]. All glenoids showed signs of important erosion, and the 2-dimensional CT scan technique can be insufficient to evaluate this erosion due to orientation differences [73]. Manual positioning of the 3 scapula anatomical landmarks recommended by the International Society of Biomechanics can be performed in a reliable manner across measures and observers on surface bone models obtained from CT scan images [78].

Other Considerations: Clinical evaluation of altered shoulder kinematics remains complicated [1]. The biomechanical shoulder model is consistent with clinical observations regarding glenoid inclination and acromion index effects on humeral head translation and glenoid articular cartilage strain [2]. Small but significant asymmetries exist between dominant and nondominant shoulders in terms of kinematics [17]. The HDA and the VDA together distinguish between a normal shoulder and those with GHOA or CTA [77].

Treatment

Non-Operative

Non-operative management provides excellent results and return to competition for posterior-inferior instability in competitive swimmers, utilizing shoulder girdle strengthening, improved scapulothoracic coordination, and stroke technique changes [76]. Exercise therapy for supraspinatus tears does not alter glenohumeral kinematics during internal/external rotation with the arm at the side [14]. Clinician-assisted interventions for reducing posterior shoulder tightness are efficacious when using both single treatment and multimodal approaches [43]. Understanding patient needs helps physicians better comprehend pathology and manage the weight-bearing shoulder [23]. Less range of motion (ROM) is required to perform functional tasks used in common outcome tools than full motion [24].

Operative

Indications: Updates on the thrower's shoulder, including anatomy, mechanics, pathomechanics, and treatment, are essential for clinicians and researchers [3]. Literature concerning shoulder anatomy and pathology related to stability/instability is reviewed to improve clinical diagnosis and surgical treatment [8]. Treatment techniques for periscapular tendon transfers provide a novel means of addressing difficult-to-treat and complex shoulder girdle pathologies, though further follow-up is necessary before universal adoption [67].

Surgical Approach / Technique: Both open and arthroscopic repair techniques for anterosuperior rotator cuff tears with subscapularis involvement significantly improve shoulder function and are relatively safe procedures [22]. A 6-mm acromiograft significantly reduced superior translation of the humeral head in a cadaveric model of massive rotator cuff tear, while bursal acromial resurfacing improved subacromial contact mechanics compared to the massive cuff tear condition [34]. Humeral lengthening of at least 24 mm is recommended after implanting a total reverse shoulder prosthesis [64].

Implant Selection: Anatomically shaped prosthetic humeral heads may lead to better shoulder function and implant survivorship [5]. Lateralization is achievable at both the glenoid and humeral sides in reverse total shoulder arthroplasty but has different effects, meaning lateralized implant options should be selected according to patients' needs [29]. Age-induced decline in bone density led to increased micromotions in stemless shoulder arthroplasty, yet some stemless shoulder implants presented good overall performance regardless of the osseointegration threshold, suggesting that age alone may not be a contraindication to anatomic total shoulder arthroplasty [61].

Alignment / Balancing Strategy: Anterior-posterior glenohumeral kinematics was not fully restored after biceps rerouting (BR) [12]. Significant findings following subpectoral biceps tenodesis include a loss of glenohumeral abduction external rotation and anterior scapular tipping [25]. The majority of outcome measures were equivalent when comparing post-surgical and uninvolved shoulder function and biomechanics following subpectoral biceps tenodesis [25].

Other Considerations: Clinical evaluation of altered shoulder kinematics remains complicated [1]. The biomechanical shoulder model is consistent with clinical observations [2]. Physical examination and radiologic workup for the shoulder require a thorough understanding of complex musculoskeletal interactions [4]. Biomechanical properties and bone quality decrease after partial-width full-thickness supraspinatus tendon injury but are restored gradually over time, with full restoration occurring by 8 weeks post-injury; however, findings regarding restored biomechanical properties and bone quality at 8 weeks post-injury are not equivalent to the intact shoulder [11]. The effect of biceps rerouting on long-term clinical outcomes requires further investigation [12]. Data on health care resource utilization in the 2 years prior to total shoulder arthroplasty provide a baseline for understanding current trends regarding nonarthroplasty treatment of shoulder pathology [62]. There is a strong need for the development of wearable systems for shoulder kinematics assessment [69]. Nonpathologic contact beneath the coracoacromial arch may be present in normal shoulders [72]. In nonpathologic shoulders, there is no significant difference between the muscle volume of the anterior part (subscapularis) and the posterior part (teres minor/infraspinatus) of the transverse rotator cuff force couple [83]. Acromial projection allows for reproducible, non-invasive dynamic video motion capture of the scapula [82]. Quantifying kinematic patterns like scapulohumeral rhythm (SHR) using dynamic digital radiography (DDR) can be implemented as a novel, safe, and cost-effective method to diagnose shoulder pathology and monitor response to treatment [48].

Complications

Altered Kinematics: Clinical evaluation of altered shoulder kinematics remains complicated [1]. Alterations of scapular kinematics in symptomatic subjects are multifactorial [6]. Structural damage interferes with motion mechanics, causing patients with symptomatic rotator cuff tears to compensate for loss of glenohumeral motion by increasing scapulothoracic contribution when reaching at least 85° [81]. A plausible mechanical progression of kinematic and strength changes is associated with the development of rotator cuff pathology [7]. Muscle shortening negatively impacts shoulder function in the context of torn rotator cuffs [27].

Tear-Specific Biomechanics: Tears of the subscapularis have greater biomechanical consequences than tears of the infraspinatus [56]. Any insult to the integrity of the rotator interval alters shoulder motion throughout abduction [19]. The biomechanical properties and bone quality decreased after partial-width full-thickness supraspinatus tendon injury and were restored gradually over time with full restoration by 8 weeks after injury, but findings were not equivalent to the intact shoulder [11].

Surgical and Developmental Outcomes: Anterior-posterior glenohumeral kinematics was not fully restored after biceps rerouting [12]. The study reports a significant long-term decrease in shoulder abduction despite maintenance of external rotation and improvement in elbow extension following low rotation humeral osteotomy in children with Erb's obstetric brachial palsy [26]. Abnormal glenoid morphology has a significant effect on anatomical and surgical factors which can necessitate adjustments in surgical technique for reverse shoulder arthroplasty [79]. Glenoid version as traditionally defined may have limited relevance when positioning the glenoid component during total shoulder arthroplasty because the glenoid and scapular body development are controlled by independent genetic and biomechanical factors [13]. Anatomically shaped prosthetic humeral heads might lead to better shoulder function and implant survivorship [5]. More research is needed to evaluate the clinical efficacy of posterior shoulder arthroplasty, including mid- and long-term outcome and safety studies [28].

Recovery

Light activity (weeks): Evidence does not specify a discrete week range for light activity initiation. Clinical evaluation of altered shoulder kinematics remains complicated [1], and the biomechanical shoulder model is consistent with clinical observations [2]. Updates on the thrower's shoulder, including anatomy, mechanics, pathomechanics, and treatment, are essential for clinicians and researchers [3]. Anatomically shaped prosthetic humeral heads might lead to better shoulder function and implant survivorship [5]. Alterations of scapular kinematics in symptomatic subjects are multifactorial [6].

Full activity (months): Three-dimensional shoulder kinematics normalize after rotator cuff repair [9], and observed changes in scapular kinematics are associated with an increased overall range of motion and suggest restored function of shoulder muscles [9]. Exercise therapy for treatment of supraspinatus tears does not alter glenohumeral kinematics during internal/external rotation with the arm at the side [14]. Long-term results of low rotation humeral osteotomy in children with Erb's obstetric brachial palsy report a significant decrease in shoulder abduction [26], maintenance of external rotation [26], and improvement in elbow extension [26]. Muscle shortening negatively impacts shoulder function in the context of torn rotator cuff supraspinatus muscle length [27].

Complete recovery / outcome plateau (months): Biomechanical properties and bone quality decreased after partial-width full-thickness supraspinatus tendon injury in rats [11] but were restored gradually over time with full restoration by 8 weeks after injury [11]. However, restored biomechanical properties and bone quality at 8 weeks after injury were not equivalent to the intact shoulder [11]. Anterior-posterior glenohumeral kinematics was not fully restored after biceps rerouting (BR) [12], and the effect of biceps rerouting on long-term clinical outcomes requires further investigation [12]. More research is needed to evaluate the clinical efficacy of posterior shoulder arthroplasty, including mid- and long-term outcome and safety studies [28]. The critical shoulder angle was unaffected by demographic factors [10] and does not change significantly over a long-term follow-up of at least 10 years [58]. Posterior acromial height does not change significantly over a long-term follow-up of at least 10 years [58], and posterior acromial tilt does not change significantly over a long-term follow-up of at least 10 years [58]. Scapular morphologic parameters including critical shoulder angle, posterior acromial height, and posterior acromial tilt are stable anthropometric characteristics [58].

Rehabilitation protocol: Findings suggest a plausible mechanical progression of kinematic and strength changes associated with the development of rotator cuff pathology [7]. The shoulder has developed uniquely in modern man for the act of throwing, characterized by a lack of robusticity in bone and muscle architecture compared to nonhuman primates [30]. Elbow and shoulder kinetics increase with time in youth baseball pitchers, particularly after age 13 [74]. Glenoid ossification and fusion progress in a predictable and chronological manner in pediatric and adolescent shoulders [84].

Key Evidence

  • [L2] A clinical evaluation of altered shoulder kinematics is still complicated. (10.3390/ijerph17082974)
  • [L5] The biomechanical shoulder model is consistent with clinical observations. (10.1016/j.jse.2016.05.031)
  • [L5] Updates on the thrower's shoulder, including anatomy, mechanics, pathomechanics, and treatment, are essential for clinicians and researchers treating or investigating the shoulder. (10.1016/j.arthro.2022.02.024)
  • [L5] The findings may have important clinical and economic implications given evidence that anatomically shaped heads might lead to better shoulder function and implant survivorship. (10.1016/j.jse.2018.03.002)
  • [L4] Alterations of scapular kinematics in symptomatic subjects are multifactorial. (10.1016/j.jse.2015.04.007)
  • [L3] Furthermore, these findings suggest a plausible mechanical progression of kinematic and strength changes associated with the development of rotator cuff pathology. (10.1016/j.jse.2016.11.048)
  • [L5] The purpose of this article is to review the current literature concerning shoulder anatomy/pathology related to shoulder stability/instability to improve clinical diagnosis and surgical treatment of our patients. (10.1016/j.arthro.2011.05.017)
  • [L4] The observed changes in scapular kinematics are associated with an increased overall range of motion and suggest restored function of shoulder muscles. (10.1016/j.jse.2015.10.021)
  • [L5] The critical shoulder angle was unaffected by demographic factors. (10.1016/j.jse.2014.10.021)
  • [L5] The biomechanical properties and bone quality decreased after the injury and were restored gradually over time with full restoration by 8 weeks after injury, but the findings were not equivalent to the intact shoulder. (10.1016/j.jhsa.2022.08.027)
  • [L3] However, A-P glenohumeral kinematics was not fully restored after BR, and its effect on long-term clinical outcomes requires further investigation. (10.1177/03635465241301778)
  • [L5] Glenoid version as traditionally defined may have limited relevance when positioning the glenoid component during total shoulder arthroplasty because the glenoid and scapular body development are controlled by independent genetic and biomechanical factors. (10.1016/j.jse.2008.11.012)
  • [L2] Despite satisfactory clinical outcomes following exercise therapy, glenohumeral kinematics did not change. (10.1007/s00167-017-4695-3)
  • [L5] This comprehensive review highlights the importance of a thorough understanding of shoulder physical examination and specific diagnostic tests, emphasizing history-taking and examination to ensure diagnostic accuracy and optimize patient outcomes for surgeons. (10.5435/jaaos-d-25-00024)
  • [L2] Evaluation of range of rotation seems to identify shoulders at risk of the pathology. (10.1007/s00167-017-4426-9)
  • [L5] Small but significant asymmetries exist between the dominant and nondominant shoulders in terms of kinematics. (10.1016/j.jse.2013.08.020)
  • [L3] Ultrasound is an useful tool for discovering in pre-symptomatic stages the subjects that may undergo shoulder symptomatic pathologies. (10.1186/1471-2474-11-278)
  • [L5] The rotator interval is central to normal glenohumeral kinematics, and any insult to its integrity alters shoulder motion throughout abduction. (10.1186/s12891-016-0898-x)
  • [L4] Scapulothoracic and glenohumeral components of shoulder motion are more specific than humerothoracic measures to diagnostic classification. (10.1016/j.jse.2013.06.023)
  • [L5] The findings of this study clearly indicated that shortening of the clavicle affects the kinematics in the shoulder girdle. (10.1177/0363546509355143)
  • [L3] Both techniques significantly improved shoulder function and are relatively safe procedures. (10.1016/j.jse.2019.09.035)
  • [L5] Understanding the needs of these patients helps physicians better comprehend the pathology and manage the weight-bearing shoulder. (10.5435/jaaos-d-15-00598)
  • [L5] Although attaining full motion is a reasonable goal of all shoulder treatment, our results indicate that less ROM is required to perform the functional tasks used in common outcome tools. (10.1016/j.jse.2011.07.032)
  • [L3] The majority of outcome measures were equivalent when comparing the post-surgical and uninvolved shoulder function and biomechanics, with significant findings including a loss of glenohumeral abduction external rotation and anterior scapular tipping. (10.1177/2325967117s00392)
  • [L4] The study reports a significant long-term decrease in shoulder abduction despite maintenance of external rotation and improvement in elbow extension. (10.1177/1753193409104552)
  • [L3] This suggests that muscle shortening negatively impacts shoulder function and highlights potential implications for surgical repair strategies and postoperative recovery. (10.1016/j.jse.2025.03.002)
  • [L5] More research is needed to evaluate the clinical efficacy of posterior shoulder arthroplasty, including mid- and long-term outcome and safety studies. (10.1016/j.jse.2020.10.017)
  • [L5] Lateralization is achievable at both the glenoid and humeral sides but has different effects; therefore, lateralized implant options should be selected according to patients' needs. (10.1016/j.jse.2023.03.015)
  • [L5] The shoulder has developed uniquely in modern man for the act of throwing, characterized by a lack of robusticity in bone and muscle architecture compared to nonhuman primates. (10.1016/j.jse.2023.12.010)
  • [L4] Kinematics of the rTSA shoulders are significantly altered, and more scapulothoracic motion is used to achieve shoulder elevation compared to healthy subjects. (10.1016/j.jse.2011.07.031)
  • [L4] This variant does not appear to contribute to shoulder pathology because standard treatment of concomitant diagnoses resulted in resolution of symptoms. (10.1016/j.jse.2011.05.006)
  • [L5] Further studies are required to understand the clinical relevance of these findings, notably for the treatment of shoulder stiffness. (10.1016/j.jseint.2022.10.013)
  • [L5] The 6-mm acromiograft significantly reduced superior translation of the humeral head and improved subacromial contact mechanics compared to the massive cuff tear condition, supporting its biomechanical efficacy. (10.1016/j.arthro.2024.06.019)
  • [Abstract] RTSA shoulders show kinematics that are significantly different from normal shoulders, utilizing much more scapulothoracic motion and much less glenohumeral motion to elevate the arm. (10.1016/j.jse.2014.11.012)
  • [L3] Altering scapula position may affect shoulder strength in asymptomatic individuals. (10.1111/sae.12027)
  • [L4] Shoulder physical functions were mapped to outcome scores. (10.1016/j.jse.2019.08.017)
  • [L5] The kinematics in both the arm tackle and the head-in-front tackle is significantly different from that in the shoulder tackle and may represent a distinct risk factor for shoulder dislocation. (10.1016/j.jse.2018.06.023)
  • [L3] This study was the first to create a classification system to divide coracoids according to their morphology and relative risk of associated subscapularis tears. (10.1016/j.jse.2020.01.074)
  • [L4] RTSA shoulders show kinematics that are significantly different from normal shoulders, using more scapulothoracic motion and less glenohumeral motion to elevate the arm. (10.1016/j.jse.2014.11.043)
  • [L4] This study utilized 4DCT to characterize age-related differences in shoulder kinematics, revealing that older asymptomatic males exhibit altered glenohumeral and scapulothoracic motion patterns compared to younger males during dynamic tasks. (10.1016/j.jseint.2025.10.007)
  • [L5] In this dynamic shoulder model, SCR only partially restored native glenohumeral joint loads. (10.1016/j.arthro.2023.02.019)
  • [L1] The efficacy of clinician-assisted interventions for reducing posterior shoulder tightness was identified when using both a single treatment and multimodal treatments. (10.1016/j.jse.2018.12.006)
  • [L4] The humeral head moves from an inferior position to the center of the glenoid during active arm abduction, with kinematic variability decreasing significantly as abduction increases. (10.1016/j.jse.2007.05.018)
  • [L5] The study demonstrates abnormal kinematics and path of glenohumeral motion throughout a rotational range of motion in the thrower's model compared with an intact shoulder. (10.1177/0363546506287740)
  • [L5] Capsular repair also significantly alters normal glenohumeral kinematics. (10.1007/s00167-015-3915-y)
  • [L5] Biomechanical changes of passive glenohumeral joint motion occur in the glenohumeral joint with as little as 5% GIRD. (10.1177/0363546512462012)
  • [L4] Quantifying kinematic patterns like SHR using DDR can be implemented as a novel, safe, and cost-effective method to diagnose shoulder pathology and to monitor response to treatment. (10.1016/j.jse.2022.12.023)
  • [L5] The glenocapsular ligament is a constant anatomical structure that consists of one or two different parts. (10.1007/s00167-017-4603-x)
  • [L4] Twenty-six different criteria described by multiple classification systems have been identified for the magnetic resonance assessment of rotator cuff after repair. (10.1007/s00167-014-3486-3)
  • [L5] This study developed the first two-body scapulohumeral shape model that captures coupled variations in arthropathic shoulder anatomy and the first proximal-humeral statistical model constructed using a clinical dataset. (10.1186/s13018-025-05855-4)
  • [L4] The purpose of this article is to review and clearly define acronyms used by shoulder specialists to identify and review the acronyms related to the shoulder that have been described in the literature to date. (10.1016/j.arthro.2010.09.006)
  • [L3] The anatomical structure of passive shoulder restraints has no impact on the difference in passive joint position sense values between external and internal rotation. (10.1186/s12891-016-0971-5)
  • [L5] Three-dimensional MRI measurement of whole-muscle volume is required and is associated with shoulder strength. (10.1016/j.arthro.2015.11.008)
  • [L5] Tears of the subscapularis have greater biomechanical consequences than do tears of the infraspinatus. (10.1016/j.arthro.2009.09.007)
  • [L3] This study shows that a 3D MRI could be a radiation-free and reliable alternative to a preoperative CT shoulder scan. (10.1016/j.arthro.2018.06.050)
  • [L3] The critical shoulder angle, posterior acromial height, and posterior acromial tilt do not change significantly over a long-term follow-up of at least 10 years, supporting the hypothesis that these scapular morphologic parameters are stable anthropometric characteristics. (10.1016/j.jse.2020.09.042)
  • [L2] Three-dimensional MRI (FRACTURE) is equivalent to 3D CT in quantifying bone loss in patients with shoulder dislocation and measuring shoulder morphologic parameters. (10.1016/j.arthro.2023.12.016)
  • [L3] Further developments of this technology have the potential to allow for surgeons to obtain all clinically relevant information from MRI scans and reduce the need for multiple imaging studies for patients with shoulder pathology. (10.1016/j.jseint.2023.05.008)
  • [L5] Age-induced decline in bone density led to increased micromotions, but some stemless shoulder implants presented good overall performance regardless of the osseointegration threshold, suggesting that age alone may not be a contraindication to anatomic total shoulder arthroplasty. (10.1016/j.jse.2024.04.013)
  • [L3] These data provide a baseline for understanding current trends regarding nonarthroplasty treatment of shoulder pathology before shoulder replacement. (10.1016/j.jse.2024.11.033)
  • [L5] This numerical study highlights the importance of an anatomical reconstruction of the glenohumeral surfaces for the success rate of anatomical total shoulder arthroplasty. (10.1016/j.jse.2010.06.006)
  • [L4] We recommend humeral lengthening of at least 24 mm after implanting a total reverse shoulder prosthesis. (10.1016/j.jse.2018.05.027)
  • [L3] Average cortical bone thickness measurements obtained from shoulder MRI are correlated with DXA and appear effective in differentiating patients with normal and abnormal BMD, potentially guiding further diagnostic assessments. (10.1177/17585732241279090)
  • [L3] Plain radiographs may overestimate shoulder beta angle and inferior glenoid resection depth. (10.1177/23259671251405414)
  • [L5] Although many treatment techniques remain in their infancy and further follow-up is necessary before universal adoption, they provide a novel means of addressing difficult-to-treat and complex shoulder girdle pathologies. (10.1016/j.jhsa.2015.06.123)
  • [L3] Measuring glenoid version on MRI does not appear to be significantly affected when the entirety of the medial border of the scapula is not included in the imaging field. (10.1016/j.arthro.2019.07.030)
  • [L4] There is a strong need for development of this novel technologies which undeniably serves in shoulder evaluation and therapy. (10.1186/s12891-019-2930-4)
  • [L1] The accuracies for shoulder MRI in this community setting were not improved by having the MRIs interpreted by selected fellowship trained musculoskeletal radiologists. (10.1016/j.jse.2011.01.003)
  • [L3] MRI abnormalities found in asymptomatic dominant shoulders of elite overhead athletes represented clinical false-positive findings that did not evolve into symptomatic conditions over 5 years. (10.1177/03635465030310051501)
  • [L5] Nonpathologic contact beneath the coracoacromial arch may be present in normal shoulders. (10.1016/j.jse.2009.12.006)
  • [L4] All glenoids showed signs of important erosion, and the 2-dimensional CT scan technique can be insufficient to evaluate this erosion due to orientation differences. (10.1016/j.jse.2013.04.009)
  • [L3] Elbow and shoulder kinetics increase with time, particularly after age 13. (10.1177/0363546517732034)
  • [L4] Unenhanced magnetic resonance imaging of the shoulder in asymptomatic high performance throwing athletes reveals abnormalities that may encompass a spectrum of nonclinical findings. (10.1177/03635465020300012501)
  • [Abstract] Non-operative management provides excellent results and return to competition with shoulder girdle strengthening, improving scapulothoracic coordination, and stroke technique changes. (10.1016/j.jse.2007.02.079)
  • [L4] Together, the HDA and the VDA distinguish between a normal shoulder and those with GHOA or CTA. (10.1016/j.jse.2023.08.025)
  • [L4] Manual positioning of the 3 scapula anatomical landmarks recommended by the International Society of Biomechanics can be performed in a reliable manner across measures and observers on surface bone models obtained from CT scan images. (10.1016/j.jseint.2024.09.027)
  • [L4] Abnormal glenoid morphology was shown to have a significant effect on anatomical and surgical factors which can necessitate adjustments in surgical technique for reverse shoulder arthroplasty. (10.1016/j.jse.2009.02.013)
  • [L4] Uncorrected CT scans of the glenohumeral joint do not correct for the sagittal rotation of the glenoid, affecting axial image characteristics. (10.1016/j.jse.2015.06.017)
  • [L4] Patients who reached at least 85° compensated for the loss of glenohumeral motion by increased scapulothoracic contribution, suggesting that structural damage interferes with motion mechanics. (10.1016/j.jse.2016.02.031)
  • [L4] Acromial projection allows for reproducible, non-invasive dynamic video motion capture of the scapula. (10.1111/sae.12008)
  • [L4] In nonpathologic shoulders, there is no significant difference between the muscle volume of the anterior (subscapularis) and posterior part (teres minor/infraspinatus) of the TFC. (10.1016/j.jse.2013.09.027)
  • [L4] Glenoid ossification and fusion progress in a predictable and chronological manner. (10.1016/j.arthro.2019.08.011)

See Also

References

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[2] Effects of glenoid inclination and acromion index on humeral head translation and glenoid articular cartilage strain. Journal of Shoulder and Elbow Surgery. 2017. DOI: 10.1016/j.jse.2016.05.031

[3] Understanding the Disabled Throwing Shoulder Requires Updated Review of Anatomy, Mechanics, Pathomechanics, and Treatment. Arthroscopy: The Journal of Arthroscopic & Related Surgery. 2022. DOI: 10.1016/j.arthro.2022.02.024

[4] Chapter 23 Shoulder Anatomy and Biomechanics, Clinical Evaluation, Imaging. 2020.

[5] Spherical versus elliptical prosthetic humeral heads: a comparison of anatomic fit. Journal of Shoulder and Elbow Surgery. 2018. DOI: 10.1016/j.jse.2018.03.002

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[10] The influence of radiographic viewing perspective and demographics on the critical shoulder angle. Journal of Shoulder and Elbow Surgery. 2015. DOI: 10.1016/j.jse.2014.10.021

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[20] Scapulothoracic and glenohumeral contributions to motion in children with brachial plexus birth palsy. Journal of Shoulder and Elbow Surgery. 2014. DOI: 10.1016/j.jse.2013.06.023

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[29] Biomechanical consequences of glenoid and humeral lateralization in reverse total shoulder arthroplasty. Journal of Shoulder and Elbow Surgery. 2023. DOI: 10.1016/j.jse.2023.03.015

[30] Evolution of the throwing shoulder: why apes don’t throw well and how that applies to throwing athletes. Journal of Shoulder and Elbow Surgery. 2024. DOI: 10.1016/j.jse.2023.12.010

[31] Kinematic analysis of dynamic shoulder motion in patients with reverse total shoulder arthroplasty. Journal of Shoulder and Elbow Surgery. 2012. DOI: 10.1016/j.jse.2011.07.031

[32] Aberrant origin of the long head of the biceps: a case series. Journal of Shoulder and Elbow Surgery. 2012. DOI: 10.1016/j.jse.2011.05.006

[33] Role of middle glenohumeral ligament in external shoulder rotation. JSES International. 2023. DOI: 10.1016/j.jseint.2022.10.013

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[35] Scapulohumeral Rhythm in Shoulders with Reverse Shoulder Arthroplasty. Journal of Shoulder and Elbow Surgery. 2015. DOI: 10.1016/j.jse.2014.11.012

[36] Altering Scapular Position Reduces Isometric Shoulder Strength. Shoulder & Elbow. 2013. DOI: 10.1111/sae.12027

[37] Mapping physical functions of the shoulder to American Shoulder and Elbow Surgeons and Patient-Reported Outcomes Measurement Information System scores. Journal of Shoulder and Elbow Surgery. 2020. DOI: 10.1016/j.jse.2019.08.017

[38] The kinematics of 1-on-1 rugby tackling: a study using 3-dimensional motion analysis. Journal of Shoulder and Elbow Surgery. 2019. DOI: 10.1016/j.jse.2018.06.023

[39] Coracoid morphology and humeral version as risk factors for subscapularis tears. Journal of Shoulder and Elbow Surgery. 2020. DOI: 10.1016/j.jse.2020.01.074

[40] Scapulohumeral rhythm in shoulders with reverse shoulder arthroplasty. Journal of Shoulder and Elbow Surgery. 2015. DOI: 10.1016/j.jse.2014.11.043

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[42] Superior Capsular Reconstruction Partially Restores Native Glenohumeral Joint Loads in a Dynamic Biomechanical Shoulder Model. Arthroscopy. 2023. DOI: 10.1016/j.arthro.2023.02.019

[43] The efficacy and fidelity of clinical interventions used to reduce posterior shoulder tightness: a systematic review with meta-analysis. Journal of Shoulder and Elbow Surgery. 2019. DOI: 10.1016/j.jse.2018.12.006

[44] Determination of in vivo glenohumeral translation using fluoroscopy and shape-matching techniques. Journal of Shoulder and Elbow Surgery. 2008. DOI: 10.1016/j.jse.2007.05.018

[45] Path of Glenohumeral Articulation Throughout the Rotational Range of Motion in a Thrower's Shoulder Model. The American Journal of Sports Medicine. 2006. DOI: 10.1177/0363546506287740

[46] Biomechanical comparison of the modified Bristow procedure with and without capsular repair. Knee Surgery, Sports Traumatology, Arthroscopy. 2015. DOI: 10.1007/s00167-015-3915-y

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[61] Influence of age-related bone density changes on primary stability in stemless shoulder arthroplasty: a multi-implant finite element study. Journal of Shoulder and Elbow Surgery. 2025. DOI: 10.1016/j.jse.2024.04.013

[62] Health care resource utilization in the 2 years prior to total shoulder arthroplasty. Journal of Shoulder and Elbow Surgery. 2025. DOI: 10.1016/j.jse.2024.11.033

[63] Biomechanical consequences of humeral component malpositioning after anatomical total shoulder arthroplasty. Journal of Shoulder and Elbow Surgery. 2010. DOI: 10.1016/j.jse.2010.06.006

[64] Geometric modification of the humeral position after total reverse shoulder arthroplasty: what is the optimal lowering of the humerus?. Journal of Shoulder and Elbow Surgery. 2018. DOI: 10.1016/j.jse.2018.05.027

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c. The disclaimer of warranties and limitation of liability provided above shall be interpreted in a manner that, to the extent possible, most closely approximates an absolute disclaimer and waiver of all liability.

Section 6 -- Term and Termination.

a. This Public License applies for the term of the Copyright and Similar Rights licensed here. However, if You fail to comply with this Public License, then Your rights under this Public License terminate automatically.

b. Where Your right to use the Licensed Material has terminated under Section 6(a), it reinstates:

1. automatically as of the date the violation is cured, provided it is cured within 30 days of Your discovery of the violation; or

2. upon express reinstatement by the Licensor.

For the avoidance of doubt, this Section 6(b) does not affect any right the Licensor may have to seek remedies for Your violations of this Public License.

c. For the avoidance of doubt, the Licensor may also offer the Licensed Material under separate terms or conditions or stop distributing the Licensed Material at any time; however, doing so will not terminate this Public License.

d. Sections 1, 5, 6, 7, and 8 survive termination of this Public License.

Section 7 -- Other Terms and Conditions.

a. The Licensor shall not be bound by any additional or different terms or conditions communicated by You unless expressly agreed.

b. Any arrangements, understandings, or agreements regarding the Licensed Material not stated herein are separate from and independent of the terms and conditions of this Public License.

Section 8 -- Interpretation.

a. For the avoidance of doubt, this Public License does not, and shall not be interpreted to, reduce, limit, restrict, or impose conditions on any use of the Licensed Material that could lawfully be made without permission under this Public License.

b. To the extent possible, if any provision of this Public License is deemed unenforceable, it shall be automatically reformed to the minimum extent necessary to make it enforceable. If the provision cannot be reformed, it shall be severed from this Public License without affecting the enforceability of the remaining terms and conditions.

c. No term or condition of this Public License will be waived and no failure to comply consented to unless expressly agreed to by the Licensor.

d. Nothing in this Public License constitutes or may be interpreted as a limitation upon, or waiver of, any privileges and immunities that apply to the Licensor or You, including from the legal processes of any jurisdiction or authority.

Creative Commons is not a party to its public licenses. Notwithstanding, Creative Commons may elect to apply one of its public licenses to material it publishes and in those instances will be considered the “Licensor.” The text of the Creative Commons public licenses is dedicated to the public domain under the CC0 Public Domain Dedication. Except for the limited purpose of indicating that material is shared under a Creative Commons public license or as otherwise permitted by the Creative Commons policies published at creativecommons.org/policies, Creative Commons does not authorize the use of the trademark "Creative Commons" or any other trademark or logo of Creative Commons without its prior written consent including, without limitation, in connection with any unauthorized modifications to any of its public licenses or any other arrangements, understandings, or agreements concerning use of licensed material. For the avoidance of doubt, this paragraph does not form part of the public licenses.

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