Materiały źródłowe

• #1 Rotator Cuff Tears – OrthoInfo – AAOS

  https://orthoinfo.aaos.org/en/diseases–conditions/rotator-cuff-tears/

  A rotator cuff tear is a common cause of shoulder pain and disability among adults. Each year, almost 2 million people in the U.S. visit their doctors because of rotator cuff tears. […] A torn rotator cuff may weaken your shoulder. This means that many daily activities, like combing your hair or getting dressed, may become painful and difficult to do. […] When one or more of the rotator cuff tendons is torn, the tendon becomes partially or completely detached from the head of the humerus. […] Most tears occur in the supraspinatus tendon, but rotator cuff tendons may also be involved. […] In many cases, torn tendons begin by fraying. As the damage progresses, the tendon can completely tear, sometimes from lifting a heavy object. […] There are two main causes of rotator cuff tears: injury (acute) and wear (degeneration).

• #2 Rotator Cuff Injury: Pathogenesis, Biomechanics, and Repair

  https://pmc.ncbi.nlm.nih.gov/articles/PMC11580759/

  Anterior Rotator cuff tears are one of the most common surgically addressed disorders, as the tears in the tendon can affect anyone regardless of risk factors or activity level. The rotator cuff is responsible for most of the shoulder motion, hence the tendon-bone interface experiences immense stress making it incredibly prone to failure. Rotator cuff tendon tears can either occur due to trauma or natural degeneration of the rotator cuff. […] To help mitigate effects of high stress on the rotator cuff tendon-bone interface, the rotator cuff is intrinsically designed to redistribute stress through protective mechanisms, such as the rotator crescent or coronal-transverse force. But when the tear goes through the intrinsic protective mechanisms, the glenohumeral joint is left unstable and thus is no longer capable of its normal range of motion.

• #3 Rotator Cuff Injury | Cedars-Sinai

  https://www.cedars-sinai.org/health-library/diseases-and-conditions/r/rotator-cuff-disorder.html

  Injury and degeneration are the two main causes of rotator cuff tears. […] A rotator cuff tear is a common cause of pain and disability among adults. […] Rotator cuff tears can also happen due to the breakdown (degeneration) of the tissues, which may happen as part of the aging process. […] Symptoms may include pain that keeps coming back, muscle weakness, limited ability to move your arm, and grating or cracking sounds when moving your arm. […] Treatment may include rest, medicine, strengthening and stretching exercises, and surgery.

• #4 Rotator Cuff Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK547664/

  Rotator cuff injury runs the full spectrum from injury to tendinopathy to partial tears, and finally complete tears. Age plays a significant role. Injuries ranged from 9.7% in those 20 years and younger increasing to 62% in patients 80 years and older (whether or not symptoms were present). […] Increasing age and those with unilateral pain are also at risk for a tear in the rotator cuff of the opposite shoulder. In a study comparing patients with unilateral shoulder pain, the average age for a patient having no cuff tear was 48.7 years. After age 66, there is a 50% likelihood of bilateral tears. Additionally, age was linked to the presence and type of tear but did not correlate with tear size. […] Age is the most common factor for rotator cuff disease. It is a degenerative process that is progressive.

• #5 Rotator Cuff Tears – OrthoInfo – AAOS

  https://orthoinfo.aaos.org/en/diseases–conditions/rotator-cuff-tears/

  Because most rotator cuff tears are largely caused by the normal wear and tear that goes along with aging, people over 40 are at greater risk. […] People who do repetitive lifting or overhead activities are also at risk for rotator cuff tears. […] Your doctor may recommend surgery if your pain does not improve with nonsurgical methods. Continued pain is the main reason for having surgery. […] Surgery to repair a torn rotator cuff most often involves re-attaching the tendon to the head of humerus (upper arm bone).

• #6 Rotator Cuff Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK547664/

  Smoking is a known risk factor. A systematic review demonstrated increased rates and sizes of degenerative tears along with symptomatic tears seen in smokers; this has the potential to increase the number of surgeries. […] Partial tears are at risk for further propagation. These risk factors include: tear size, symptoms, location, and age. Tear size: A small tear may remain dormant, while larger tears are more likely to undergo structural deterioration. The critical size for sending a small tear towards a larger or complete tear has yet to be defined. […] Tear propagation correlates with symptom development. Actively enlarging tears have a five times higher likelihood of developing symptoms than those tears that remain the same size. […] The location of the tear also influences progression. Anterior tears are more likely to progress to cuff degeneration.

• #7

  https://www.orthobullets.com/shoulder-and-elbow/3043/rotator-cuff-tears

  Rotator cuff tears are a very common source of shoulder pain and decreased motion that can occur due to both traumatic injuries in young patients as well as degenerative disease in the elderly patient. […] mechanisms of tear includes chronic degenerative tear ( intrinsic degeneration is the primary etiology) usually seen in older patients. […] usually involves the SIT (supraspinatus, infraspinatus, teres minor) muscles but may extend anteriorly to involve the superior margin of subscapularis tendon in larger tears. […] chronic impingement typically starts on the bursal surface or within the tendon. […] acute avulsion injuries acute subscapularis tears seen in younger patients following a fall. […] acute SIT (supraspinatus, infraspinatus, teres minor) tears seen in patients 40 yrs with a shoulder dislocation.

• #8 Rotator Cuff Pathology: Practice Essentials, Anatomy, Pathophysiology

  https://emedicine.medscape.com/article/1262849-overview

  Additionally, the constant resting tension in the muscle-tendon unit, or muscle tone, pulls any detached fibers away from the bone, preventing their reattachment. Finally, joint fluid from within the shoulder may seep into the gap created by the tear and prevent the normal healing processes from occurring. […] Genetic factors may play a role in the pathogenesis of rotator cuff disease. A systematic review by Longo et al found significant associations between single-nucleotide polymorphisms and rotator cuff disease for DEFB1, FGFR1, FGFR3, ESRRB, FGF10, MMP-1, TNC, FCRL3, SASH1, SAP30BP, and rs71404070 located next to cadherin8; results reported for MMP-3 were contradictory.

• #9 Genetic basis of rotator cuff injury: a systematic review | BMC Medical Genetics | Full Text

  https://bmcmedgenet.biomedcentral.com/articles/10.1186/s12881-019-0883-y

  Even if the pathogenesis of rotator cuff disease is still largely unknown, recent studies on candidate genes and GWASs draw attention to SNPs associated with rotator cuff disease. […] Interactions between genes, encoded proteins and environment play a complex role in the development of rotator cuff disease. […] GWASs are a powerful tool to pinpoint genes that may contribute to the risk of developing rotator cuff disease. […] Studies on candidate genes and GWASs identified several genes variation associated with rotator cuff tears, such as DEFB1, FGFR1, FGFR3, ESRRB, FGF10, MMP-1, TNC, FCRL3, SASH1, SAP30BP, rs71404070 located next to cadherin8. […] Further investigations are warranted to identify complete genetic profile of rotator cuff disease and to clarify the complex interaction between genes, encoded proteins and environment.

• #10 Rotator Cuff Shoulder Tendon and Muscle Injuries | PM&R KnowledgeNow

  https://now.aapmr.org/shoulder-tendon-and-muscle-injuries/

  Rotator cuff injury occurs when any of the four muscle-tendon units that surround the shoulder become damaged. Acute tears can result from immediate increased tensile force/overload or by direct laceration. The mechanism of injury in acute RCTs are typically easy to identify by patient history with specific reported incidents followed by onset of pain. Chronic, non-traumatic tears result from gradual changes from a pre-existing injury or by diminished vascularization. The critical zone of hypovascularity is typically described as the area located between 1-2 cm from the insertion site of the supraspinatus tendon on the greater tuberosity. This region, combined with factors such as aging, generalized comorbidities, tobacco usage, as well as physiologic predispositions or aberrant shoulder mechanics, renders it more susceptible to degenerative changes. Chronic subacromial impingement syndrome is possibly the most common cause of rotator cuff tears. Though tears can be found in any of the four rotator cuff muscles, the supraspinatus is the most commonly torn muscle.

• #11 Rotator Cuff Tears – OrthoInfo – AAOS

  https://orthoinfo.aaos.org/en/diseases–conditions/rotator-cuff-tears/

  A rotator cuff tear is a common cause of shoulder pain and disability among adults. Each year, almost 2 million people in the U.S. visit their doctors because of rotator cuff tears. […] A torn rotator cuff may weaken your shoulder. This means that many daily activities, like combing your hair or getting dressed, may become painful and difficult to do. […] When one or more of the rotator cuff tendons is torn, the tendon becomes partially or completely detached from the head of the humerus. […] Most tears occur in the supraspinatus tendon, but rotator cuff tendons may also be involved. […] In many cases, torn tendons begin by fraying. As the damage progresses, the tendon can completely tear, sometimes from lifting a heavy object. […] There are two main causes of rotator cuff tears: injury (acute) and wear (degeneration).

• #12 Rotator Cuff Injuries

  https://www.sports-health.com/sports-injuries/shoulder-injuries/rotator-cuff-injuries

  An injured rotator cuff is diagnosed when muscles and tendons that support and surround the shoulder joint are torn. […] The injury reduces the rotator cuff’s ability to stabilize the shoulder’s movements, causing pain and weakness when the joint is moved or pressed. […] Shoulder problems such as shoulder impingement can lead to rotator cuff injuries over time. […] Injury to the muscle or tendon occurs in one of 2 ways: Acute injuries: Overstretching or tearing of muscles or tendons that results from a one-time traumatic event, such as holding out the arm to break a fall or an acute sports injury (eg, horseback riding, hockey, and soccer) […] Chronic degeneration: Occurs due to overuse (fatigue) or entrapment (impingement) of the rotator cuff, causing the tissue to degenerate and become weak and painful. Chronic degeneration also significantly increases the risk of an acute tear.

• #13 Rotator Cuff Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK547664/

  Finally, age is a risk factor. Patients over age 60 are more likely to develop tears that progress. Younger patients with full-thickness tears appear more capable of adapting to stress and tear propagation than those 60 years of age and older. […] Rotator cuff injury starts from trauma. Macro-trauma causes an acute tear, which is seen generally in a younger patient resulting in a complete tear. Micro-trauma causes tendon degeneration and with insufficient healing, leads to degenerative tears. Typically, acute tears happen in younger patients, and degenerative tears occur in older patients. However, a smaller amount of force is needed to cause a complete tear if there is sufficient tendon degeneration.

• #14

  https://link.springer.com/article/10.1007/s00264-021-05012-6

  A simple fall on the shoulder is often referred to as minor trauma that cannot cause a tendon tear but at best reveal a pre-existing rotator cuff pathology. […] A simple fall can cause an acute rotator cuff tear and fall-related tears are not restricted to young individuals. They can affect patients of any age. The stresses occurring within the rotator cuff during an attempt to cushion a fall may locally exceed the tensile strength of the tendon fibers and cause a partial or full-thickness tear. […] The postulated pathomechanism is a sudden stretch of the tendon-muscle unit while contracting (eccentric loading). […] The primary finding of this literature review is that a substantial number of RCTs have been associated with a traumatic event. […] The forces occurring during a fall can be so great that even a tendon of a young and healthy individual without degenerative changes can tear.

• #15 Rotator Cuff Injuries: J. Michael Bennett, MD, PA: Orthopaedic Surgeon

  https://www.orthopedicsportsdoctor.com/blog/rotator-cuff-injuries

  A Rotator Cuff Injury Can Happen When Lifting a Heavy Object. It may seem similar to a bursitis impingement type of scenario with pain, particularly with raising your arm above your head. […] What that usually means is that this rotator cuff which is in the green right here, is disrupted and you get a tear. A lot of times, it has to do with the history and how it happened, the mechanism of injury. […] That tear can be either a full thickness tear, meaning all the way through the tendon down to the bone. Or it can be a partial tear just involving a portion, a partial, a part of the tendon and not necessarily going all the way through the bone. […] If you have a full thickness tear, the problem with the full thickness rotator cuff tears is that they can get progressively get worse. They can get larger, particularly if you’re doing a lot of activities and you’re an active individual.

• #16

  https://link.springer.com/article/10.1007/s00264-021-05012-6

  Many clinical studies and biomechanical considerations confirm that a fall can cause an acute RCT and that fall-related tears are not restricted to young individuals. They can affect patients of any age. The forces and stresses occurring in the rotator cuff during an attempt to cushion a fall may locally exceed the tensile strength of the tendon fibres and cause a partial or full-thickness RCT.

• #17

  https://www.orthobullets.com/shoulder-and-elbow/3043/rotator-cuff-tears

  full thickness rotator cuff tears need to be repaired in throwing athletes. […] iatrogenic injuries due to failure of surgical repair often seen in repair failure of the subscapularis tendon following open anterior shoulder surgery. […] Impingement and rotator cuff disease are a continuum of disease including subacromial impingement, subcoracoid impingement, calcific tendonitis, rotator cuff tears (this topic), rotator cuff arthropathy. […] Mechanism is often a degenerative tear in older patients or a shoulder dislocation in patients 40 yrs. […] Mechanism is often an acute avulsion in younger patients with a hyperabduction/external rotation injury or an iatrogenic injury due to failure of repair.

• #18 Rotator Cuff Relevant Anatomy and Mechanics | UW Orthopaedic Surgery and Sports Medicine

  https://orthop.washington.edu/patient-care/articles/shoulder/rotator-cuff-relevant-anatomy-and-mechanics.html

  The traumatic and the degenerative theories of cuff tendon failure can be synthesized into a unified view of pathogenesis. Through its life the cuff is subjected to various adverse factors such as traction, compression, contusion, subacromial abrasion, inflammation, injections, and, perhaps most importantly, age-related degeneration. Lesions of the cuff typically start where the loads are presumeably the greatest: at the deep surface of the anterior insertion of the supraspinatus near the long head of the biceps. Tendon fibers fail when the applied load exceeds their strength. Fibers may fail a few at a time or en masse. Because these fibers are under load even with the arm at rest, they retract after their rupture. Each instance of fiber failure has at least four adverse effects: […] it increases the load on the neighboring as yet unruptured fibers, giving rise to the zipper phenomenon,

• #19 Rotator Cuff Relevant Anatomy and Mechanics | UW Orthopaedic Surgery and Sports Medicine

  https://orthop.washington.edu/patient-care/articles/shoulder/rotator-cuff-relevant-anatomy-and-mechanics.html

  it detaches muscle fibers from bone (diminishing the force that the cuff muscles can deliver), […] it compromises the tendon fibers’ blood supply by distorting the anatomy contributing to progressive local ischemia […] and […] it exposes increasing amounts of the tendon to joint fluid containing lytic enzymes which remove any hematoma which could contribute to tendon healing. Even when the tendon heals, its scar tissue lacks the normal resilience of tendon and is, therefore, under increased risk for failure with subsequent loading. These events weaken the substance of the cuff, impair its function, and diminish its ability to effectively repair itself. In the absence of repair, the degenerative process tends to continue through the substance of the supraspinatus tendon to produce a full thickness defect in the anterior supraspinatus tendon. This full thickness defect tends to concentrate loads at its margin, facilitating additional fiber failure with smaller loads than those which produced the initial defect. With subsequent episodes of loading, this pattern repeats itself, rendering the cuff weaker, more prone to additional failure with less load, and less able to heal. Once a supraspinatus defect is established, it typically propagates posteriorly through the remainder of the supraspinatus, then into the infraspinatus.

• #20 Pathophysiology of Rotator Cuff Tears | Musculoskeletal Key

  https://musculoskeletalkey.com/pathophysiology-of-rotator-cuff-tears/

  A312334_1_En_1_Fig1b_HTML.jpg Fig. 1.1 (a) Thin and disorganized collagen fibers in the torn tendon (large tear, 10 magnification). (b) Split collagen fibers replaced with myxoid degeneration (large tear, 20). (c) Hyaline degeneration; chondrocyte-like cells are visible near hyalines areas, (large tear, 20). (d) Chondrocytes with lacunae, intracellular matrix Fig. 1.1(continued) stained with alcian blue (large tear 20). (e) Calcific deposits in tendon between spindle-shaped fibroblasts and collagen fibers (massive tear, 40). (f) Proliferation of small vessels in all tendon layers and edema (articular surface tear, 20). (g) Fatty infiltration in the proximal tendon, distributed from middle to deep tissue layer (large tear, 10). a, c, f, and g are stained with Masson trichrome; b and e are stained with hematoxylin and eosin; d is stained with alcian blue (Hashimoto et al. [37]) Longo and colleagues [38] subsequently reevaluated the histology of rotator cuff tears. In the torn rotator cuff samples, they found increased waviness and disorganization (loss of parallel architecture) of collagen fibers and an increase in vascularity.

• #21 Pathophysiology of Rotator Cuff Tears | Musculoskeletal Key

  https://musculoskeletalkey.com/pathophysiology-of-rotator-cuff-tears/

  Furthermore, rounding of tenocyte nucleinormally flat and spindle shapedto the point where they almost resembled chondrocytes was observed in the torn cuff samples. In a rat model, overuse of the rotator cuff tendon led to downregulation of TGF-1. Another study by Perry and colleagues [39] looked at rat model of repetitive microtrauma and found acute increases (peak at 3 days) in VEGF and subacute (8 weeks) increases in inducible cyclooxygenase (COX-2). The results of these studies not only support the repetitive microtrauma theory, but they imply the presence of acute inflammation as well as a central role for angiogenic mediators. […] Oxidative stress and the production of reactive oxygen species (ROS) are implicated in the degeneration and pathologic destruction of a variety of different tissue types. One of the main mechanisms by which ROS are thought to contribute to tissue degeneration is through the activation of the intrinsic apoptotic pathway. Studies by Yuan and colleagues [40] exhibited an increase in apoptotic cells at the cuff tear edge (34 %) as compared with control (13 %). In addition to induction of apoptosis, oxidative stress has been shown to induce cuff degeneration through induction of two other auxiliary factors: c-Jun N-terminal protein kinase (JNK), a mitogen-induced protein kinase (MAPK) expressed intracellularly, and matrix metalloproteinase-1 (MMP-1), an enzyme present in the extracellular environment.

• #22 Rotator Cuff Disease: Practice Essentials, Pathophysiology, The extrinsic hypothesis

  https://emedicine.medscape.com/article/328253-overview

  In 1834, Smith wrote the first description of a rupture of the rotator cuff tendon. Since then, with the work of such authors as Duplay, Von Meyer, Codman, and Neer, degenerative changes to the rotator cuff have been better characterized; however, the exact mechanisms leading to the degeneration of the rotator cuff still are debated today. […] The pathophysiology of rotator cuff degeneration is a controversial topic that still is not fully understood. Two hypotheses (ie, extrinsic, intrinsic) coexist and are supported by different authors. […] In this theory, the lesions result from progressive, age-related degeneration of the tendon. Von Meyer was probably the first to introduce the concept that degeneration of the tendon plays a major role in the production of cuff lesions. Many histologic studies show the age-related degeneration of the cuff tendon; however, it is not the purpose of this article to describe those numerous changes. Observations from various sources (eg, cadaver, surgical, MRI, ultrasonographic, arthrographic studies) show that cuff tears rarely are seen in patients before age 40 years and that the number observed after the patient has reached 50 years increases progressively.

• #23 Rotator Cuff Disease | Calgary Guide

  https://calgaryguide.ucalgary.ca/rotator-cuff-disease-pathogenesis-and-clinical-findings/rotator-cuff-disease/

  Rotator Cuff Disease: Pathogenesis and clinical findings […] Aging Collagen fiber disorientation and myxoid degeneration Tendons, ligaments, and connective tissue are replaced by gelatinous and/or mucoid substance […] Repeated eccentric tension from overhead activities Trauma, sports, and occupation Torque, compression, and translational stresses […] Reactive oxygen species interact with glucose forming advanced glycation end-products (AGEs) which accumulate in soft tissues […] Macro-trauma causing an acute, complete tear in the rotator cuff muscle(s) […] Rotator Cuff Syndrome (Inflammation, impingement, or tearing of one or more of the four muscles/tendons of the rotator cuff: supraspinatus, subscapularis, infraspinatus, teres minor) […] Repetitive loading and micro-tearing of tendon/muscle fibers Oxidative stressors and inflammatory cascades

• #24 Rotator Cuff Relevant Anatomy and Mechanics | UW Orthopaedic Surgery and Sports Medicine

  https://orthop.washington.edu/patient-care/articles/shoulder/rotator-cuff-relevant-anatomy-and-mechanics.html

  The traumatic and the degenerative theories of cuff tendon failure can be synthesized into a unified view of pathogenesis. Through its life the cuff is subjected to various adverse factors such as traction, compression, contusion, subacromial abrasion, inflammation, injections, and, perhaps most importantly, age-related degeneration. Lesions of the cuff typically start where the loads are presumeably the greatest: at the deep surface of the anterior insertion of the supraspinatus near the long head of the biceps. Tendon fibers fail when the applied load exceeds their strength. Fibers may fail a few at a time or en masse. Because these fibers are under load even with the arm at rest, they retract after their rupture. Each instance of fiber failure has at least four adverse effects: […] it increases the load on the neighboring as yet unruptured fibers, giving rise to the zipper phenomenon,

• #25 Rotator Cuff Tears – OrthoInfo – AAOS

  https://orthoinfo.aaos.org/en/diseases–conditions/rotator-cuff-tears/

  A rotator cuff tear is a common cause of shoulder pain and disability among adults. Each year, almost 2 million people in the U.S. visit their doctors because of rotator cuff tears. […] A torn rotator cuff may weaken your shoulder. This means that many daily activities, like combing your hair or getting dressed, may become painful and difficult to do. […] When one or more of the rotator cuff tendons is torn, the tendon becomes partially or completely detached from the head of the humerus. […] Most tears occur in the supraspinatus tendon, but rotator cuff tendons may also be involved. […] In many cases, torn tendons begin by fraying. As the damage progresses, the tendon can completely tear, sometimes from lifting a heavy object. […] There are two main causes of rotator cuff tears: injury (acute) and wear (degeneration).

• #26 Rotator Cuff Disease: Practice Essentials, Pathophysiology, The extrinsic hypothesis

  https://emedicine.medscape.com/article/328253-overview

  In 1834, Smith wrote the first description of a rupture of the rotator cuff tendon. Since then, with the work of such authors as Duplay, Von Meyer, Codman, and Neer, degenerative changes to the rotator cuff have been better characterized; however, the exact mechanisms leading to the degeneration of the rotator cuff still are debated today. […] The pathophysiology of rotator cuff degeneration is a controversial topic that still is not fully understood. Two hypotheses (ie, extrinsic, intrinsic) coexist and are supported by different authors. […] In this theory, the lesions result from progressive, age-related degeneration of the tendon. Von Meyer was probably the first to introduce the concept that degeneration of the tendon plays a major role in the production of cuff lesions. Many histologic studies show the age-related degeneration of the cuff tendon; however, it is not the purpose of this article to describe those numerous changes. Observations from various sources (eg, cadaver, surgical, MRI, ultrasonographic, arthrographic studies) show that cuff tears rarely are seen in patients before age 40 years and that the number observed after the patient has reached 50 years increases progressively.

• #27

  https://journals.lww.com/sportsmedarthro/abstract/2011/09000/biological_factors_in_the_pathogenesis_of_rotator.3.aspx

  Rotator cuff tears are common, and lead to shoulder pain and functional impairment. Despite their frequency and related disability, etiology and pathogenesis are still debated. Multiple factors contribute to tears of the rotator cuff. Extrinsic factors are anatomic variables, such as acromial morphologic characteristics, os acromiale, and acromial spurs that compress the rotator cuff by bony impingement or direct pressure from the surrounding soft tissue. Intrinsic factors arise from the tendon itself, because of tensile overload, aging, microvascular supply, traumatisms, or degeneration. […] Understanding the mechanism of rotator cuff pathology would facilitate the rationale for therapeutic interventions, by guiding the design, selection, and implementation of treatment strategies such as biologic modulation and preventive measures.

• #28 Rotator Cuff Shoulder Tendon and Muscle Injuries | PM&R KnowledgeNow

  https://now.aapmr.org/shoulder-tendon-and-muscle-injuries/

  The rotator cuff is composed of 4 separate muscle tendon units (supraspinatus, infraspinatus, subscapularis, and teres minor) originating from various portions of the scapula and inserting into the humerus. Of note, in considering mechanisms of injury, the supraspinatus tendon travels through a confined space above the humeral head, referred to as the subacromial space. Subacromial impingement syndrome (SAIS) is the most common shoulder disorder, accounting for 44-65% of all shoulder pain complaints. This occurs as result of inflammation and degeneration of the structures within the subacromial space (supraspinatus tendon and subacromial bursa) by either an intrinsic or extrinsic mechanism. Extrinsic explanations for SAIS in the literature suggest that narrowing of the acromiohumeral distance (AHD) is a key factor. In healthy shoulders, this measures approximately 7-14 mm. Variations in the shape of the acromion have been shown to increase the risk of RCTs by decreasing AHD contributing to impingement of the rotator cuff tendons.

• #29 Rotator Cuff Pathology: Practice Essentials, Anatomy, Pathophysiology

  https://emedicine.medscape.com/article/1262849-overview

  Rupture of the rotator cuff tendon was first described by Smith in 1834. Subsequently, degenerative changes of the rotator cuff have been better characterized by Duplay (1872), Von Meyer (1924), Codman (1934), and Neer (1972). The exact mechanisms leading to the degeneration of the rotator cuff, however, are still being debated. […] Rotator cuff pathology can result from extrinsic or intrinsic factors. Extrinsic examples include a traumatic tear in tendons from a fall or accident. Overuse injuries from repetitive lifting, pushing, pulling, or throwing are also extrinsic in nature. Intrinsic factors include poor blood supply, normal attrition or degeneration with aging, and calcific invasion of tendons. […] Rotator cuff dysfunction is typically a continuum of pathology ranging from tendinitis and bursitis to partial tearing to complete tearing in one or more of the tendons. Although the earlier stages may resolve with conservative care, actual tearing of the tendon can be more problematic. These tears most commonly occur at the tenoperiosteal (tendon-to-bone) junction. Because this area has a relatively poor blood supply, injury to the tendon at this location is very unlikely to heal well.

• #30 Clinical outcomes of rotator cuff repair in athletes – Seiter – Annals of Joint

  https://aoj.amegroups.org/article/view/5847/html

  The etiology of RC injury varies based on age and sport type. Overhead athletes are susceptible to chronic repetitive microtrauma, often leading to partial thickness tears. In a study of asymptomatic Major League Baseball (MLB) pitchers, a significant correlation between innings pitched and the presence of RC tears (RCTs) was observed, suggesting that tears in these athletes are likely a consequence of chronic strain on the RC tendons. Contact athletes are also at risk of suffering RC injury, usually of traumatic rather than attritional nature. In reports of RCTs in American football players; tears present as mild contusions to partial and full thickness tears, and usually occur after a direct blow to the shoulder or a fall. […] The pathophysiology of atraumatic, degenerative RCTs is perceived to be a combination of wear and tear and inherent degenerative processes. In athletes, atraumatic RCTs are common in overhead sports such as baseball, attributable to repetitive overuse and supraphysiological tendon strain during the throwing motion. RCTs in overhead athletes are thought to be attributable to tensile overload of the cuff, internal impingement, or subacromial impingement. Internal impingement was first described as a pattern of cuff injury associated with the late cocking and early acceleration phases of throwing, when the undersurface of the supraspinatus tendon impinges between the greater tuberosity and the posterosuperior glenoid rim. Microtrauma from repetitive internal impingement is associated with partial-thickness RCTs, generally on the articular surface of the cuff. This is in contrast to subacromial impingement, which usually results in bursal-sided RCTs.

• #31 Rotator Cuff Injury: Pathogenesis, Biomechanics, and Repair

  http://www.fortunejournals.com/articles/rotator-cuff-injury-pathogenesis-biomechanics-and-repair.html

  Tendinopathy, usually the first stage of progressive rotator cuff injury, is clinically defined as acute or chronic pain associated with inflammation. […] However, histological studies of patients with rotator cuff disease have found minimal inflammatory cells on rotator cuff tendons, thus implying that tendinopathy and progressive tendon degeneration must occur due to reasons other than inflammation. […] It has been proposed that these degenerative changes must either be from intrinsic, extrinsic factors, or both. […] The repetitive overloading of the tendon results in inflammation of the paratenon, degeneration of the tendon body, or both. […] Overall, tendon healing can occur intrinsically or extrinsically. […] Intrinsic versus extrinsic healing determines how a tendon will heal and its resultant biomechanics, as tenocytes and fibroblasts have differing mechanisms of repair.

• #32 Rotator Cuff Mechanics | ShoulderDoc

  https://www.shoulderdoc.co.uk/article/384

  The aim of this presentation is to discuss the current literature and opinions on the biomechanics of the rotator cuff and relate this to the clinical relevance in rotator cuff tears. I intend to cover: […] Pathomechanics of cuff tears […] The rotator cuff stabilises the glenohumeral joint through force couples in both the coronal and transverse planes. […] The progression of a rotator cuff tear or dysfunction leads to superiorsubluxation of the humeral head. This leads to dysfunction of the shoulder. […] The pathogenesis of rotator cuff tears has been considered to be influenced by the microvascular supply of the rotator cuff tendons. […] It has been suggested that this area of hypovascularity has a significant role in the attritional degeneration of the aging tendon. […] More recent studies of the microvascular supply to the supraspinatus tendon in symptomatic patients with impingement syndrome suggest that in the area of greatest impingement, i.e., the critical zone (8mm proximal to the insertion of the supraspinatus tendon), there is actually hypervascularity. […] The rotator cuff appears to degenerate with age. […] The aetiological and pathomechanical factors in the development of rotator cuff tears appear to have multifactorial roots.

• #33 Pathophysiology of Rotator Cuff Tears | Musculoskeletal Key

  https://musculoskeletalkey.com/pathophysiology-of-rotator-cuff-tears/

  There exists some controversy with regard to the role that vascular changes play in the degeneration of the rotator cuff tendon. The traditional line of belief is that a critical zone of hypovascular tissue exists 1015 mm from the insertion of the supraspinatus tendon, which makes this area more prone to tears [19, 57, 58]. […] However, more recent data published by Millar and colleagues [50] showed that hypoxia, in addition to inducing apoptotic mediators, will induce a change in collagen synthesisdecreasing collagen I synthesis and increasing collagen III synthesis, as well as increasing key inflammatory mediators: monocyte chemotactic protein (MCP)-1, interleukin (IL)-6, and IL-8. […] Various studies have indicated that genetics may be involved in the pathogenesis of rotator cuff tears [6568]. Although no specific gene mutations or abnormalities have been correlated with rotator cuff tear incidence, there is an epidemiologic data indicating a genetic component to rotator cuff disease.

• #34 Rotator Cuff Relevant Anatomy and Mechanics | UW Orthopaedic Surgery and Sports Medicine

  https://orthop.washington.edu/patient-care/articles/shoulder/rotator-cuff-relevant-anatomy-and-mechanics.html

  The traumatic and the degenerative theories of cuff tendon failure can be synthesized into a unified view of pathogenesis. Through its life the cuff is subjected to various adverse factors such as traction, compression, contusion, subacromial abrasion, inflammation, injections, and, perhaps most importantly, age-related degeneration. Lesions of the cuff typically start where the loads are presumeably the greatest: at the deep surface of the anterior insertion of the supraspinatus near the long head of the biceps. Tendon fibers fail when the applied load exceeds their strength. Fibers may fail a few at a time or en masse. Because these fibers are under load even with the arm at rest, they retract after their rupture. Each instance of fiber failure has at least four adverse effects: […] it increases the load on the neighboring as yet unruptured fibers, giving rise to the zipper phenomenon,

• #35 Rotator Cuff Relevant Anatomy and Mechanics | UW Orthopaedic Surgery and Sports Medicine

  https://orthop.washington.edu/patient-care/articles/shoulder/rotator-cuff-relevant-anatomy-and-mechanics.html

  it detaches muscle fibers from bone (diminishing the force that the cuff muscles can deliver), […] it compromises the tendon fibers’ blood supply by distorting the anatomy contributing to progressive local ischemia […] and […] it exposes increasing amounts of the tendon to joint fluid containing lytic enzymes which remove any hematoma which could contribute to tendon healing. Even when the tendon heals, its scar tissue lacks the normal resilience of tendon and is, therefore, under increased risk for failure with subsequent loading. These events weaken the substance of the cuff, impair its function, and diminish its ability to effectively repair itself. In the absence of repair, the degenerative process tends to continue through the substance of the supraspinatus tendon to produce a full thickness defect in the anterior supraspinatus tendon. This full thickness defect tends to concentrate loads at its margin, facilitating additional fiber failure with smaller loads than those which produced the initial defect. With subsequent episodes of loading, this pattern repeats itself, rendering the cuff weaker, more prone to additional failure with less load, and less able to heal. Once a supraspinatus defect is established, it typically propagates posteriorly through the remainder of the supraspinatus, then into the infraspinatus.

• #36 Rotator Cuff Disease: Practice Essentials, Pathophysiology, The extrinsic hypothesis

  https://emedicine.medscape.com/article/328253-overview

  In all probability, the intrinsic and the extrinsic theories coexist and explain the pathophysiology of rotator cuff degeneration. Nevertheless, this degeneration is the result of a continuum that is beautifully described by Matsen, Arntz, and Lippitt. […] The lesion starts where the load is presumably the greatest (eg, on the articular side of the anterior insertion of the supraspinatus tendon, near the tendon of the long head of the biceps muscle). Tendon fibers fail when the load exceeds their strength. The fibers tend to retract because they are under tension, causing rupture. Fiber failure causes at least the following 4 complications: […] The scar tissue of the healing tendon lacks the normal resilience of tendon and, therefore, is under increased risk for failure. In the absence of repair, the degenerative process tends to continue through the substance of the supraspinatus tendon to produce a full thickness defect in the anterior supraspinatus tendon.

• #37 Rotator Cuff Relevant Anatomy and Mechanics | UW Orthopaedic Surgery and Sports Medicine

  https://orthop.washington.edu/patient-care/articles/shoulder/rotator-cuff-relevant-anatomy-and-mechanics.html

  With progressive dissolution of the cuff tendon, the spacer effect of the cuff tendon is lost, allowing the humeral head to displace superiorly, placing increased load on the biceps tendon. As a result, the breadth of the long head tendon of the biceps is often greater in patients with cuff tears in comparison to uninjured shoulders. In chronic cuff deficiency, the long head tendon of the biceps is frequently ruptured. Further propagation of the cuff defect crosses the bicipital groove to involve the subscapularis, starting at the top of the lesser tuberosity and extending inferiorly. As the defect extends across the bicipital groove, it may be associated with rupture of the transverse humeral ligament and destabilization of the long head tendon of the biceps allowing its medial displacement. The concavity compression mechanism of glenohumeral stability is compromised by cuff disease. Beginning with the early stages of cuff fiber failure, the compression of the humeral head becomes less effective in resisting the upward pull of the deltoid. Partial thickness cuff tears cause pain on muscle contraction similar to that seen with other partial tendon injuries (such as those of the Achilles tendon or extensor carpi radialis brevis). This pain produces reflex inhibition of the muscle action. In turn, this reflex inhibition along with the absolute loss of strength from fiber detachment makes the muscle less effective in balance and stability. However, as long as the glenoid concavity is intact, the compressive action of the residual cuff muscles may stabilize the humeral head. When the weakened cuff cannot prevent the humeral head from rising under the pull of the deltoid, the residual cuff becomes squeezed between the head and the coracoacromial arch. Under these circumstances, abrasion occurs with humeroscapular motion, further contributing to cuff degeneration. Degenerative traction spurs develop in the coracoacromial ligament which is loaded by pressure from the humeral head. Upward displacement of the head also wears on the upper glenoid lip and labrum, reducing the effectiveness of the upper glenoid concavity. Further deterioration of the cuff allows the tendons to slide down below the center of the humeral head, producing a „boutonniere” deformity. The cuff tendons become head elevators rather than head compressors. Just as in the boutonniere of the finger, the shoulder with a buttonholed cuff is victimized by the conversion of balancing forces into unbalancing forces. Erosion of the superior glenoid lip may thwart attempts to keep the humeral head centered after cuff repair. Once the full thickness of the cuff has failed, abrasion of the humeral articular cartilage against the coracoacromial arch may lead to a secondary degenerative joint disease known as cuff tear arthropathy. The cuff muscle deterioration which inevitably accompanies chronic cuff tears is one of the most important limiting factors in cuff repair surgery. Atrophy, fatty degeneration, retraction, loss of excursion are all commonly associated with chronic cuff tendon defects. To a large extent, these factors are irreversible. These changes increase with the duration of the tear and do not rapidly reverse after cuff repair.

• #38

  https://www.orthobullets.com/shoulder-and-elbow/3044/rotator-cuff-arthropathy

  Rotator cuff arthropathy is a specific pattern of shoulder degenerative joint disease that results from a rotator cuff tear leading to abnormal glenohumeral wear and subsequent superior migration of the humeral head. […] Pathophysiology […] cuff tear arthropathy […] mechanical factors […] loss of the concavity due to compression effect […] decreased range of motion and shoulder function […] humeral head migration […] instability with possible recurrent dislocations. […] Rotator cuff arthropathy is characterized by the combination of […] rotator cuff insufficiency […] glenohumeral cartilage destruction […] superior migration of the humeral head […] subchondral osteoporosis […] humeral head collapse. […] crystalline-induced arthropathy […] degradation proteins in the synovium destroy the rotator cuff and cartilage […] end-stage disease leads to calcium phosphate crystal deposits.

• #39 Rotator Cuff Mechanics | ShoulderDoc

  https://www.shoulderdoc.co.uk/article/384

  The aim of this presentation is to discuss the current literature and opinions on the biomechanics of the rotator cuff and relate this to the clinical relevance in rotator cuff tears. I intend to cover: […] Pathomechanics of cuff tears […] The rotator cuff stabilises the glenohumeral joint through force couples in both the coronal and transverse planes. […] The progression of a rotator cuff tear or dysfunction leads to superiorsubluxation of the humeral head. This leads to dysfunction of the shoulder. […] The pathogenesis of rotator cuff tears has been considered to be influenced by the microvascular supply of the rotator cuff tendons. […] It has been suggested that this area of hypovascularity has a significant role in the attritional degeneration of the aging tendon. […] More recent studies of the microvascular supply to the supraspinatus tendon in symptomatic patients with impingement syndrome suggest that in the area of greatest impingement, i.e., the critical zone (8mm proximal to the insertion of the supraspinatus tendon), there is actually hypervascularity. […] The rotator cuff appears to degenerate with age. […] The aetiological and pathomechanical factors in the development of rotator cuff tears appear to have multifactorial roots.

• #40 Rotator Cuff Injury: Pathogenesis, Biomechanics, and Repair

  https://pmc.ncbi.nlm.nih.gov/articles/PMC11580759/

  Anterior Rotator cuff tears are one of the most common surgically addressed disorders, as the tears in the tendon can affect anyone regardless of risk factors or activity level. The rotator cuff is responsible for most of the shoulder motion, hence the tendon-bone interface experiences immense stress making it incredibly prone to failure. Rotator cuff tendon tears can either occur due to trauma or natural degeneration of the rotator cuff. […] To help mitigate effects of high stress on the rotator cuff tendon-bone interface, the rotator cuff is intrinsically designed to redistribute stress through protective mechanisms, such as the rotator crescent or coronal-transverse force. But when the tear goes through the intrinsic protective mechanisms, the glenohumeral joint is left unstable and thus is no longer capable of its normal range of motion.

• #41 Rotator Cuff Injury and Joint Damage | Soslowsky Laboratory | McKay Orthopaedic Research Laboratory | Perelman School of Medicine at the University of Pennsylvania

  https://www.med.upenn.edu/orl/soslowskylab/rotator-cuff.html

  Rotator cuff tears are common, affecting millions of individuals each year in the United States. Tendon tears can dramatically alter shoulder function in a complex, multifactorial manner resulting in significant, permanent damage to the shoulder joint. This damage can manifest as articular cartilage degeneration, injury to adjacent (intact) tendons, and abnormal joint motion. […] Our earlier work demonstrated that rotator cuff force balance disruption is the mechanical mechanism that causes overload on intact tendons and results in tissue damage and loss of function. […] The subscapularis is the largest and most powerful of the rotator cuff muscles and serves as the anterior aspect of the rotator cuff force balance. […] Thus, previously unidentified and untreated subscapularis tears could contribute to continued shoulder dysfunction, chronic pain, and rotator cuff tendon re-tear and/or tear progression.

• #42 The Radiology Assistant : Shoulder Rotator cuff injury

  https://radiologyassistant.nl/musculoskeletal/shoulder/rotator-cuff-injury

  The rotator cuff plays an important role in the stabilization of the glenohumeral joint during movements of the arm. Rotator cuff tears are the most common cause of shoulder pain and result in loss of strength and loss of stability of the shoulder. […] The etiology of rotator cuff tears can be traumatic, like in a direct trauma to the subscapular muscle and tendon or a more chronic tear of the supraspinatous tendon due to repetitive trauma in overhead sports-activity. This is usually seen in younger people. In older people the cause of rotator cuff tears is degenerative as seen in subacromial impingement or due to hypovascularity in specific parts of the tendons. […] Full thickness tears (FTT) extend from the bursal surface all the way to the articular surface. […] Rotator cuff arthropathy is a pattern of joint degeneration due to loss of stabilizing function by the rotator cuff. The rotator cuff provides a net inferiorly directed force, balanced by a superiorly directed force by the deltoid muscle. In rotator cuff arthropathy the following findings can be seen: massive rotator cuff tear, glenoid erosion, cartilage loss, cysts and osteophyte formation, collapse of humeral head, superior migration of humeral head with femoralization of humeral head and acetabularization of the coraco-acromial arch. […] Signs of irreparability and indication for reverse total shoulder arthroplasty are: static superior migration, narrowed or absent acromiohumeral interval, fatty infiltration 50% of RC muscles.

• #43 Pathophysiology of Rotator Cuff Tears | Musculoskeletal Key

  https://musculoskeletalkey.com/pathophysiology-of-rotator-cuff-tears/

  The development of symptoms related to rotator cuff pathology is poorly understood. Having an asymptomatic rotator cuff tear increases the risk of future symptomatic progression [74]. […] Definitive histologic evidence of inflammation within a degenerating rotator cuff is elusive, but many proinflammatory cytokines and inflammatory mediators such as COX-2, leukotriene B4, and PGE2 are overexpressed in rotator cuff injuries. It is hypothesized the painful symptoms of rotator cuff disease could be mediated by COX-2 and PGE2 [35, 76].

• #44 Rotator Cuff Related Shoulder Pain | Diagnosis & Treatment

  https://www.physiotutors.com/conditions/rotator-cuff-related-shoulder-pain/

  Tendinopathy is a persistent pain and loss of function in tendons due to mechanical loading. […] The pathogenesis of rotator cuff tendinopathies is still mostly unknown and based on animal studies and surgically removed tendons. Tendinopathy is caused by collagen disruption, inflammation, or tendon cell response and the imbalance of synthesis and degradation may lead to disorganization. […] The pain mechanisms in tendinopathy are not clear but are thought to involve local nociception mediated by changes within the tenocytes. […] The etiology of chronic tendinopathy is complex and multifactorial. The current understanding is the imbalance between the load demands placed on the tendon and its capacity to remodel.

• #45 Rotator Cuff Injury: Pathogenesis, Biomechanics, and Repair

  https://pmc.ncbi.nlm.nih.gov/articles/PMC11580759/

  This is due to extrinsically healing of rotator cuff tendons, instead of the more intrinsic healing, which causes rotator cuff tendons to not undergo the necessary biomechanical remodeling to prevent reinjury leading to a mechanically and functionally inferior healed tendon. […] In this article, we thoroughly discussed the underlying pathophysiology of rotator cuff tears from onset to repair to healing, demonstrating that rotator cuff tendon healing is an intrinsically flawed process, irrespective of the risk factors, occurrence of rotator cuff tears, or surgical treatment. […] Rotator cuff healing can only be successful if rotator cuff tendon repair surgery is augmented with biologics to promote a successful intrinsic healing environment.

• #46 Rotator Cuff Injury: Pathogenesis, Biomechanics, and Repair

  http://www.fortunejournals.com/articles/rotator-cuff-injury-pathogenesis-biomechanics-and-repair.html

  Tendinopathy, usually the first stage of progressive rotator cuff injury, is clinically defined as acute or chronic pain associated with inflammation. […] However, histological studies of patients with rotator cuff disease have found minimal inflammatory cells on rotator cuff tendons, thus implying that tendinopathy and progressive tendon degeneration must occur due to reasons other than inflammation. […] It has been proposed that these degenerative changes must either be from intrinsic, extrinsic factors, or both. […] The repetitive overloading of the tendon results in inflammation of the paratenon, degeneration of the tendon body, or both. […] Overall, tendon healing can occur intrinsically or extrinsically. […] Intrinsic versus extrinsic healing determines how a tendon will heal and its resultant biomechanics, as tenocytes and fibroblasts have differing mechanisms of repair.

• #47 Rotator Cuff Tears – Dr. Franklin – Orthopedic Specialists of Seattle

  https://orthopedicspecialistsofseattle.com/healthcare/injuries/rotator-cuff-tears-dr-franklin/

  Rotator cuff tears can occur after an acute injury such as a fall or catching a heavy falling object, or they can occur over time as a gradual wearing of a hole in the rotator cuff from ongoing rubbing on the acromion such as overuse with overhead or throwing sports. […] In younger, more active patients, surgery is almost always recommended when a full thickness rotator cuff tear has occurred, since the rotator cuff has poor blood supply, therefore poor healing potential. […] Because there is poor blood supply at the attachment site to the bone, one usually creates a small groove in the bone and pulls sutures through drill holes or uses anchors in the bone for fixation.

• #48 Abstract | Rotator Cuff Injury: Pathogenesis, Biomechanics, and Repair

  http://www.fortunejournals.com/abstract/rotator-cuff-injury-pathogenesis-biomechanics-and-repair-5402.html

  Location, size, and type of rotator cuff tendon tears are the strongest indicators for interventional therapy. […] Surgical therapies demonstrate low success rates, as seen by the significantly high recurrence rate of rotator cuff reinjury following initial repair. […] This is due to extrinsically healing of rotator cuff tendons, instead of the more intrinsic healing, which causes rotator cuff tendons to not undergo the necessary biomechanical remodeling to prevent reinjury leading to a mechanically and functionally inferior healed tendon. […] In this article, we thoroughly discussed the underlying pathophysiology of rotator cuff tears from onset to repair to healing, demonstrating that rotator cuff tendon healing is an intrinsically flawed process, irrespective of the risk factors, occurrence of rotator cuff tears, or surgical treatment. […] Rotator cuff healing can only be successful if rotator cuff tendon repair surgery is augmented with biologics to promote a successful intrinsic healing environment.

• #49 Rotator Cuff Relevant Anatomy and Mechanics | UW Orthopaedic Surgery and Sports Medicine

  https://orthop.washington.edu/patient-care/articles/shoulder/rotator-cuff-relevant-anatomy-and-mechanics.html

  With progressive dissolution of the cuff tendon, the spacer effect of the cuff tendon is lost, allowing the humeral head to displace superiorly, placing increased load on the biceps tendon. As a result, the breadth of the long head tendon of the biceps is often greater in patients with cuff tears in comparison to uninjured shoulders. In chronic cuff deficiency, the long head tendon of the biceps is frequently ruptured. Further propagation of the cuff defect crosses the bicipital groove to involve the subscapularis, starting at the top of the lesser tuberosity and extending inferiorly. As the defect extends across the bicipital groove, it may be associated with rupture of the transverse humeral ligament and destabilization of the long head tendon of the biceps allowing its medial displacement. The concavity compression mechanism of glenohumeral stability is compromised by cuff disease. Beginning with the early stages of cuff fiber failure, the compression of the humeral head becomes less effective in resisting the upward pull of the deltoid. Partial thickness cuff tears cause pain on muscle contraction similar to that seen with other partial tendon injuries (such as those of the Achilles tendon or extensor carpi radialis brevis). This pain produces reflex inhibition of the muscle action. In turn, this reflex inhibition along with the absolute loss of strength from fiber detachment makes the muscle less effective in balance and stability. However, as long as the glenoid concavity is intact, the compressive action of the residual cuff muscles may stabilize the humeral head. When the weakened cuff cannot prevent the humeral head from rising under the pull of the deltoid, the residual cuff becomes squeezed between the head and the coracoacromial arch. Under these circumstances, abrasion occurs with humeroscapular motion, further contributing to cuff degeneration. Degenerative traction spurs develop in the coracoacromial ligament which is loaded by pressure from the humeral head. Upward displacement of the head also wears on the upper glenoid lip and labrum, reducing the effectiveness of the upper glenoid concavity. Further deterioration of the cuff allows the tendons to slide down below the center of the humeral head, producing a „boutonniere” deformity. The cuff tendons become head elevators rather than head compressors. Just as in the boutonniere of the finger, the shoulder with a buttonholed cuff is victimized by the conversion of balancing forces into unbalancing forces. Erosion of the superior glenoid lip may thwart attempts to keep the humeral head centered after cuff repair. Once the full thickness of the cuff has failed, abrasion of the humeral articular cartilage against the coracoacromial arch may lead to a secondary degenerative joint disease known as cuff tear arthropathy. The cuff muscle deterioration which inevitably accompanies chronic cuff tears is one of the most important limiting factors in cuff repair surgery. Atrophy, fatty degeneration, retraction, loss of excursion are all commonly associated with chronic cuff tendon defects. To a large extent, these factors are irreversible. These changes increase with the duration of the tear and do not rapidly reverse after cuff repair.

• #50 Rotator Cuff Pathology: Practice Essentials, Anatomy, Pathophysiology

  https://emedicine.medscape.com/article/1262849-overview

  Rupture of the rotator cuff tendon was first described by Smith in 1834. Subsequently, degenerative changes of the rotator cuff have been better characterized by Duplay (1872), Von Meyer (1924), Codman (1934), and Neer (1972). The exact mechanisms leading to the degeneration of the rotator cuff, however, are still being debated. […] Rotator cuff pathology can result from extrinsic or intrinsic factors. Extrinsic examples include a traumatic tear in tendons from a fall or accident. Overuse injuries from repetitive lifting, pushing, pulling, or throwing are also extrinsic in nature. Intrinsic factors include poor blood supply, normal attrition or degeneration with aging, and calcific invasion of tendons. […] Rotator cuff dysfunction is typically a continuum of pathology ranging from tendinitis and bursitis to partial tearing to complete tearing in one or more of the tendons. Although the earlier stages may resolve with conservative care, actual tearing of the tendon can be more problematic. These tears most commonly occur at the tenoperiosteal (tendon-to-bone) junction. Because this area has a relatively poor blood supply, injury to the tendon at this location is very unlikely to heal well.

• #51 Answers to Your Questions About Rotator Cuff Tears: J. Michael Bennett, MD, PA: Orthopaedic Surgeon

  https://www.orthopedicsportsdoctor.com/blog/answers-to-your-questions-about-rotator-cuff-tears

  So now, its important that you understand that rotator cuff tears can propagate and they can get worse especially if youre an active individual. […] When you have a massive tear, thats when all the tendons are gone and you no longer have coverage of this ball. […] But when you lose a tendon, the shoulder becomes imbalanced. […] And then this tendon over here is now turning atrophic. You get whats called fat atrophy in that muscle belly which means that it becomes a non-functional muscle tendon unit. […] And so the likelihood of being able to fix that are very slim to none. […] Now youre developing arthritis and now youre developing pain, and the ball and socket are no longer lined, they are arthritic, and the balls actually running up into this acromion and creating arthritis underneath the acromion as well.

• #52 Answers to Your Questions About Rotator Cuff Tears: J. Michael Bennett, MD, PA: Orthopaedic Surgeon

  https://www.orthopedicsportsdoctor.com/blog/answers-to-your-questions-about-rotator-cuff-tears

  When we talk about a full thickness rotator cuff tear, why its in your best interest to really consider getting it fixed early while you can fix it arthroscopically through minimally invasive poke hole incisions through the shoulder. […] Because the only solution for this at this point with the best long-term outcomes is a replacement and its actually called a reverse total shoulder replacement.

• #53

  https://www.orthobullets.com/shoulder-and-elbow/3044/rotator-cuff-arthropathy

  Rotator cuff arthropathy is a specific pattern of shoulder degenerative joint disease that results from a rotator cuff tear leading to abnormal glenohumeral wear and subsequent superior migration of the humeral head. […] Pathophysiology […] cuff tear arthropathy […] mechanical factors […] loss of the concavity due to compression effect […] decreased range of motion and shoulder function […] humeral head migration […] instability with possible recurrent dislocations. […] Rotator cuff arthropathy is characterized by the combination of […] rotator cuff insufficiency […] glenohumeral cartilage destruction […] superior migration of the humeral head […] subchondral osteoporosis […] humeral head collapse. […] crystalline-induced arthropathy […] degradation proteins in the synovium destroy the rotator cuff and cartilage […] end-stage disease leads to calcium phosphate crystal deposits.

• #54 The Radiology Assistant : Shoulder Rotator cuff injury

  https://radiologyassistant.nl/musculoskeletal/shoulder/rotator-cuff-injury

  The rotator cuff plays an important role in the stabilization of the glenohumeral joint during movements of the arm. Rotator cuff tears are the most common cause of shoulder pain and result in loss of strength and loss of stability of the shoulder. […] The etiology of rotator cuff tears can be traumatic, like in a direct trauma to the subscapular muscle and tendon or a more chronic tear of the supraspinatous tendon due to repetitive trauma in overhead sports-activity. This is usually seen in younger people. In older people the cause of rotator cuff tears is degenerative as seen in subacromial impingement or due to hypovascularity in specific parts of the tendons. […] Full thickness tears (FTT) extend from the bursal surface all the way to the articular surface. […] Rotator cuff arthropathy is a pattern of joint degeneration due to loss of stabilizing function by the rotator cuff. The rotator cuff provides a net inferiorly directed force, balanced by a superiorly directed force by the deltoid muscle. In rotator cuff arthropathy the following findings can be seen: massive rotator cuff tear, glenoid erosion, cartilage loss, cysts and osteophyte formation, collapse of humeral head, superior migration of humeral head with femoralization of humeral head and acetabularization of the coraco-acromial arch. […] Signs of irreparability and indication for reverse total shoulder arthroplasty are: static superior migration, narrowed or absent acromiohumeral interval, fatty infiltration 50% of RC muscles.

• #55 Rotator cuff injury – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/rotator-cuff-injury/symptoms-causes/syc-20350225

  Rotator cuff injuries can range in severity from simple inflammation to complete tendon tears. […] Rotator cuff injuries are most often caused by progressive wear and tear of the tendon tissue over time. Repetitive overhead activity or prolonged bouts of heavy lifting can irritate or damage the tendon. The rotator cuff can also be injured in a single incident during falls or accidents. […] Without treatment, rotator cuff problems may lead to permanent loss of motion or weakness of the shoulder joint.

• #56 Rotator Cuff Disease: Practice Essentials, Pathophysiology, The extrinsic hypothesis

  https://emedicine.medscape.com/article/328253-overview

  This theoretical model on the continuum of the cuff degeneration demonstrates the result of many years of overuse, but this process is also the consequence of the phenomenon that happened when human beings first stood erect. That development led to the use of the glenohumeral joint in a biomechanically unusual way (eg, repetitive overhead activities, arm length activities, throwing). The extremely long lever arm of the upper limb leads the short lever arm cuff muscles to produce extremely high forces in order to stabilize the joint, in opposition to the upward pull of the humeral head by the deltoid and preventing the impingement of the cuff, but at the expense of overload and degeneration. […] In summary, the pathophysiology of rotator cuff degeneration may be explained by a combination of extrinsic, intrinsic, and biomechanical factors; however, it is not understood why in some individuals those pathological changes cause pain, but not in some others.

• #57 Rotator Cuff Injury: Pathogenesis, Biomechanics, and Repair

  https://pmc.ncbi.nlm.nih.gov/articles/PMC11580759/

  This is due to extrinsically healing of rotator cuff tendons, instead of the more intrinsic healing, which causes rotator cuff tendons to not undergo the necessary biomechanical remodeling to prevent reinjury leading to a mechanically and functionally inferior healed tendon. […] In this article, we thoroughly discussed the underlying pathophysiology of rotator cuff tears from onset to repair to healing, demonstrating that rotator cuff tendon healing is an intrinsically flawed process, irrespective of the risk factors, occurrence of rotator cuff tears, or surgical treatment. […] Rotator cuff healing can only be successful if rotator cuff tendon repair surgery is augmented with biologics to promote a successful intrinsic healing environment.

• #58 Abstract | Rotator Cuff Injury: Pathogenesis, Biomechanics, and Repair

  https://fortuneonline.org/abstract/rotator-cuff-injury-pathogenesis-biomechanics-and-repair-5402.html

  Rotator cuff tears are one of the most common surgically addressed disorders, as the tears in the tendon can affect anyone regardless of risk factors or activity level. The rotator cuff is responsible for most of the shoulder motion, hence the tendon-bone interface experiences immense stress making it incredibly prone to failure. Rotator cuff tendon tears can either occur due to trauma or natural degeneration of the rotator cuff. […] In this article, we thoroughly discussed the underlying pathophysiology of rotator cuff tears from onset to repair to healing, demonstrating that rotator cuff tendon healing is an intrinsically flawed process, irrespective of the risk factors, occurrence of rotator cuff tears, or surgical treatment. Rotator cuff healing can only be successful if rotator cuff tendon repair surgery is augmented with biologics to promote a successful intrinsic healing environment.

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