Shoulder Subluxation and Instability

What Is Shoulder Subluxation? Causes and Symptoms

Shoulder subluxation is a condition characterized by translation at the glenohumeral joint beyond physiologic limits with some glenohumeral contact maintained. It is considered a type of shoulder instability that is less severe than a glenohumeral dislocation, which is defined as the complete disassociation of the humeral head from the glenoid. Unlike a dislocation that requires a manual closed reduction maneuver or radiographic evidence of complete separation, a subluxation does not necessitate a reduction, and the relationship between the humeral head and glenoid is maintained on radiographic imaging.

Causes of shoulder subluxation can be varied:

• Traumatic events such as athletic actions involving collisions or other impacts can lead to anterior glenohumeral subluxation. A traumatic subluxation is associated with a definitive athletic action that results in a temporary cessation of play. These events can forcefully stretch the stabilizing structures of the shoulder.
• Atraumatic origins can also contribute to subluxation. This may be due to factors such as capsular laxity or altered muscle control of the shoulder complex, or both. Repetitive overhead sports activities can also lead to gradual attenuation of the anteroinferior static restraints, predisposing to anterior shoulder instability, which may manifest as subluxation. Some individuals with multidirectional instability may sublux their shoulders with minimal force or by placing their arms in certain positions. This condition is often associated with generalized ligamentous laxity.
• Underlying anatomical factors such as a relatively shallow glenoid fossa or abnormal size or angulation of the glenoid may increase the risk of instability, potentially leading to subluxation.

Symptoms of shoulder subluxation can include:

• Pain in the shoulder, especially during or after activities. Glenohumeral instability resulting from traumatic anterior glenohumeral subluxation is a common cause of shoulder pain in young athletes.
• A subjective sensation of the shoulder being "loose," "slipping out," or feeling unstable. Patients may report their shoulder "slipping out" or only report pain associated with certain movements.
• Weakness in the affected arm.
• Reduced overhead mobility or difficulty performing certain movements.
• In some cases, an anterior apprehension sign and a symptomatic load shift can be present on physical examination.

It's important to note that unlike a complete dislocation, the diagnosis of a traumatic anterior glenohumeral subluxation can be more elusive and cannot be as objectively documented. A high index of suspicion for shoulder instability is needed when treating young athletes who present with shoulder pain, especially after a traumatic event.

Anatomy of Shoulder Stability

The stability of the glenohumeral joint, which boasts the greatest range of motion in the body, is maintained by a complex interplay of both static and dynamic stabilizers. Instability arises when there is abnormal or symptomatic movement of the humeral head with respect to the glenoid.

Key Structures Contributing to Shoulder Stability:

• Rotator Cuff: The rotator cuff muscles (supraspinatus, infraspinatus, teres minor, and subscapularis) are crucial dynamic stabilizers of the glenohumeral joint. Their primary function is to compress the humeral head against the glenoid cavity, thereby centralizing it during active arm movements and limiting shear stresses. This compressive force enhances joint stability.
  • Each rotator cuff muscle contributes uniquely to shoulder movement and stability:
    • Subscapularis primarily performs internal rotation.
    • Supraspinatus is involved in elevation.
    • Infraspinatus and teres minor are responsible for external rotation.
  • The rotator cuff muscles also work in conjunction with the glenohumeral ligaments to appropriately tension them during motion. Additionally, their contraction may tighten the underlying joint capsule, creating a soft tissue barrier against excessive humeral head translation.
  • Studies using electromyography (EMG) have shown that rotator cuff muscles are active throughout the full range of motion. Their strength, dynamic efficiency, and endurance are vital for providing stability and reducing stress on the capsular ligaments. An imbalance in strength between anterior and posterior rotator cuff muscles can lead to instability.
• Glenohumeral Ligaments: These are thickenings within the joint capsule and serve as important static stabilizers, primarily limiting motion at the extremes of the joint's range. They develop tension to resist passive motion. The anterior glenohumeral joint capsule contains three distinct ligaments:
  • Superior Glenohumeral Ligament (SGHL): Primarily limits anterior and inferior translation of the adducted humerus.
  • Middle Glenohumeral Ligament (MGHL): Primarily limits anterior translation in the lower and middle ranges of abduction (around 40-60 degrees).
  • Inferior Glenohumeral Ligament Complex (IGHLC): This complex has anterior and posterior bands, as well as an axillary pouch. It is the most important ligamentous stabilizer during abduction.
    • The anterior band is the primary restraint to anterior translation when the arm is abducted and externally rotated. It also resists inferior translation in mid-abduction.
    • The posterior band is the primary static restraint to posterior translation with the arm abducted. It also resists inferior translation at 90 degrees of abduction.
    • The IGHLC functions like a sling, with its bands tensioning depending on the arm's position and rotation.
• Glenoid Labrum: This is a fibrocartilaginous rim attached to the periphery of the glenoid fossa. It contributes to static stability by deepening the glenoid concavity (by about 50%), which enhances the articulation with the humeral head. This deepening allows for a suction phenomenon at the joint. The labrum can also act as a "chock block," increasing resistance to glenohumeral translation. Furthermore, it serves as an attachment site for the glenohumeral ligaments anteriorly and the biceps tendon superiorly.
• Joint Capsule: The shoulder joint capsule is a large and relatively loose structure that surrounds the glenohumeral joint, allowing for its extensive range of motion. While lax in mid-ranges of motion, it becomes taut at the extremes, contributing to stability. It is reinforced by the glenohumeral ligaments. The integrity of the capsulolabral complex is crucial for stability. The capsule also plays a role in maintaining negative intra-articular pressure, which contributes to stability.

The stability of the glenohumeral joint is therefore a result of the coordinated function of these static and dynamic stabilizers, with their roles varying depending on the position and movement of the arm.

Causes and Risk Factors

Several factors contribute to shoulder subluxation and multidirectional instability (MDI):

Shoulder Subluxation Causes:

• Trauma: Traumatic anterior glenohumeral subluxation is a common occurrence, particularly in contact sports such as American football, rugby, rodeo, wrestling, judo, lacrosse, gymnastics, and boxing. The mechanism of injury typically involves hyperabduction and external rotation of the arm, often with a force directed from posterior to anterior that displaces the humeral head. Falls on an outstretched arm and sudden wrenching movements can also lead to traumatic instability events.
• Pathoanatomy from Trauma: These traumatic events can result in structural damage to the shoulder joint, including:
  • Bankart lesion: Avulsion or detachment of the anterior inferior aspect of the glenoid labrum and capsular attachments at the glenoid rim. MRI often reveals a high incidence of these lesions in patients with traumatic anterior glenohumeral subluxations.
  • Hill-Sachs lesion: An impaction fracture on the posterolateral aspect of the humeral head caused by the anterior glenoid rim impacting against the posterior humerus.
  • These lesions can contribute to persistent pain and recurrent instability following a subluxation event.
• Repetitive Overhead Motions: Chronic stress from repetitive overhead sports like throwing, volleyball, and tennis can predispose individuals to anterior shoulder instability. The extreme external rotation with the humerus abducted and extended can lead to gradual attenuation (stretching) of the anteroinferior static restraints, resulting in increased glenohumeral translation.
• Age: Younger athletes who experience a traumatic subluxation are at a higher risk for recurrent instability events if not properly diagnosed and treated. The collagen profile of shoulder tissues in younger individuals, being more elastic due to a higher content of type III collagen, may make them more prone to recurrent dislocation or subluxation after an initial stretching injury.

Multidirectional Instability (MDI):

• Definition: Multidirectional instability involves symptomatic translation of the humeral head beyond the physiologic limits in multiple directions, typically anterior, posterior, and inferior.
• Etiology: The causes of MDI can be varied and are often categorized as congenital, acquired, or posttraumatic.
  • Congenital Factors: Generalized ligamentous laxity or hypermobility is a significant predisposing factor for MDI. This can be associated with connective tissue disorders like Marfan’s syndrome and Ehlers-Danlos syndrome, or simply milder forms of joint hypermobility. A family history of instability or hyperlaxity may also be present. Our previous discussion highlighted that laxity describes the passive motion characteristics of the joint, and some individuals can have increased laxity without instability. However, in MDI, this laxity becomes symptomatic.
  • Acquired Factors: Repetitive stress on the shoulder, particularly in overhead activities, can lead to acquired MDI by gradually stretching the capsular structures. Suboptimal muscle control around the shoulder may also contribute to or be a consequence of acquired instability.
  • Posttraumatic Factors: While MDI is often thought of as atraumatic, a traumatic event, even a minor one, can initiate instability in individuals with underlying generalized laxity. The trauma exacerbates the pre-existing laxity, leading to multidirectional symptoms.
• Pathoanatomy of MDI: MDI is less commonly associated with specific lesions like Bankart tears compared to traumatic unidirectional instability. Instead, it is often characterized by a voluminous and redundant inferior capsular pouch and stretched ligaments. Some studies have shown differences in collagen fibril diameters in skin samples of patients with primary MDI compared to those with unidirectional anterior instability, suggesting a possible underlying connective tissue abnormality.
• Muscle Control: Abnormal muscle control and altered patterns of shoulder muscle activity have been observed in patients with atraumatic instability. Weakness in scapular stabilizing muscles has also been correlated with multidirectional shoulder instability, although it is unclear whether this is a primary cause or a secondary effect. The Stanmore Triangle classification acknowledges the role of abnormal muscle control (muscle patterning) as a primary factor in some cases of shoulder instability (Polar III).

In summary, shoulder subluxations are often caused by trauma, particularly in sports, leading to structural damage. Young athletes and those with repetitive overhead activities are at higher risk. Multidirectional instability, on the other hand, is frequently associated with underlying generalized ligamentous laxity, which can be congenital, acquired through repetitive stress, or exacerbated by trauma. Muscle control and the integrity of the joint capsule also play significant roles in both conditions.

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Why Physiotherapy is Critical

Physiotherapy is critical for managing non-surgical shoulder instability and "loose shoulders" because it focuses on strengthening the dynamic stabilizers of the glenohumeral joint, which include the rotator cuff and scapular muscles, and improving proprioception. Shoulder instability is defined as abnormal or symptomatic motion, usually a translocation of the humeral head with respect to the glenoid, while laxity describes the passive motion characteristics of the joint. Increased laxity doesn't always lead to instability, but a disruption of the static and dynamic restraints can.

• Strengthening Dynamic Stabilizers:
  • The rotator cuff muscles (supraspinatus, infraspinatus, teres minor, subscapularis) are primary dynamic stabilizers that centralize the humeral head on the glenoid. They limit shear stresses by compressing the humeral head against the glenoid. They also work with static ligaments to appropriately tension them during motion. Physiotherapy exercises aim to strengthen all components of the rotator cuff. Studies have shown that maximal contraction of posterior rotator cuff muscles reduces anterior ligamentous strain. Strengthening exercises can compensate for impairment in specific rotator cuff muscles.
  • The scapulothoracic muscles maintain optimal orientation of the scapula, providing a secure platform for glenohumeral articulation. Synchronous scapular rotation and humeral elevation are crucial for maintaining alignment. Scapular strengthening exercises are a key component of physiotherapy. Weak scapular musculature has been correlated with multidirectional and anteroinferior shoulder instability. Exercises target scapular retractors (rhomboids, middle trapezius), protractors (serratus anterior, pectoralis minor), and upward rotators (upper and lower trapezius, lower serratus anterior). Closed chain exercises can encourage recruitment of scapulothoracic muscles.
• Improving Proprioception:
  • Proprioception is the body's awareness of joint position and motion. Mechanoreceptors in the capsuloligamentous structures relay this information to the central nervous system. Joint instability can be associated with a decrease in proprioceptive reflexes, predisposing to reinjury.
  • Physiotherapy aims to retrain proprioceptive mechanisms. Exercises include joint repositioning tasks, proprioceptive neuromuscular facilitation techniques, upper extremity weight-bearing exercises, and plyometric exercises. Studies have shown that proprioception (joint repositioning) is significantly affected by muscular fatigue. Functional exercises that include positions of instability can evoke reflexive muscular activity, protecting against joint instability. Weight-bearing exercises can facilitate joint mechanoreceptors to enhance proprioception. Rhythmic stabilization drills can improve neuromuscular control and enhance the sensitivity of afferent mechanoreceptors.
• Non-operative Management Focus:
  • Non-operative rehabilitation is often the primary approach for various types of shoulder instability, especially multidirectional instability. Burkhead and Rockwood found that an exercise program was effective in managing 80% of patients with atraumatic instability.
  • Physiotherapy programs are individualized based on the type of instability, clinical diagnosis, anatomical structural defects, and abnormal movement patterns. Assessment includes posture, core stability, scapula control, rotator cuff function, and joint laxity.
  • Rehabilitation progresses through phases focusing on pain reduction, restoring range of motion, improving strength and endurance, and enhancing dynamic stability and neuromuscular control. Closed kinetic chain exercises are used early to facilitate co-contraction and proprioception.

In summary, physiotherapy plays a crucial role in the non-surgical management of shoulder instability and loose shoulders by specifically targeting the dynamic stabilizers for strength and endurance, and by improving the proprioceptive awareness and neuromuscular control necessary for functional joint stability. This approach aims to reduce pain, prevent recurrence of instability episodes, and enable patients to return to their desired activities.

Prognosis: Recovery Timeline

The prognosis and recovery timeline for shoulder instability, particularly in the context of conservative rehabilitation and the consideration of surgery, can vary depending on several factors.

A non-operative rehabilitation program for traumatic anterior shoulder instability will vary in length for each individual depending on factors such as the severity of the instability (subluxation versus dislocation), the number of previous dislocations, associated pathologies (like labral tears), the presence of bony lesions, and the patient's desired goals and activity level.

• Achieving functional stability through conservative rehab may take 3–6 months
• For in-season athletes with anterior shoulder instability (including subluxations), a nonoperative management protocol involving immediate rehabilitation without immobilization allowed 90% to return to sport for part or all of their season, although recurrence was common.
• Dickens et al. found that intercollegiate athletes with anterior shoulder instability (including subluxations) who underwent immediate accelerated rehabilitation had 73% return to sport during the season, but with a mean of 2.2 recurrent instability events per athlete per season. There was no significant difference in recurrence between initial subluxation and dislocation in this study.
• Early rehabilitation requires caution in stressing the capsule and avoiding extreme ranges of motion until dynamic stability is restored.
• For atraumatic instability, the rehabilitation focuses on improving proprioception, dynamic stability, and neuromuscular control.

The sources also indicate when surgery might be considered:

• Surgical reconstruction is generally recommended in the presence of structural damage, such as in the Polar I group of the Stanmore Triangle (instability directly related to trauma with structural deficit), and has been shown to prevent recurrence. This can include issues like recurrent dislocations or labral tears.
• According to Gil et al., young athletes with initial subluxation events and demonstrated labral lesions, as well as patients with recurrent instability, are indicated for surgical stabilization.
• The decision to consider surgery may also depend on the presence of glenoid or humeral bone loss.
• For chronic recurrent glenohumeral subluxations, surgical stabilization procedures have been reported with good outcomes. Warren reported on patients with chronic recurrent subluxations who underwent stabilization, noting a high incidence of Bankart and Hill-Sachs lesions.

Regarding chronic subluxation rehab, the sources suggest that:

• Patients with chronic recurrent glenohumeral subluxations were part of studies evaluating stabilization procedures.
• The nonoperative rehabilitation principles for instability (restoration of glenohumeral compression stability, scapulohumeral motion synchrony, and proprioceptive mechanisms) are also relevant for those with a history of subluxation.
• The presence of structural damage in chronic subluxation may lead clinicians to consider surgical intervention. However, in the absence of significant bone loss, arthroscopic stabilization alone can be effective for patients with instability who have never experienced a complete dislocation.
• Rehabilitation programs for chronic subluxation would likely follow the same phases as for other types of instability, focusing on addressing any underlying muscle imbalances and restoring motor control.

In conclusion, the recovery timeline for functional stability with conservative rehabilitation for shoulder instability is generally in the range of 3 to 6 months, but can be influenced by the specific characteristics of the injury and the individual. Surgery is often considered for patients with recurrent dislocations, demonstrable structural damage such as labral tears or bony lesions, or persistent instability despite adequate nonoperative management. The rehabilitation for chronic subluxation follows similar principles to other shoulder instability, with surgical options available depending on the presence of structural issues.

Physiotherapy Treatment Plan

A comprehensive physiotherapy treatment plan for shoulder instability involves a biomechanical assessment followed by various exercises and techniques targeting different aspects of shoulder function.

Biomechanical Assessment

A thorough biomechanical assessment is crucial for designing an individualized rehabilitation program. This assessment should include an evaluation of:

• Scapular kinematics: Assessing how the scapula moves is important, as scapulothoracic motion asymmetry is common in patients with shoulder instability. Observing isolated scapula control by asking the patient to elevate, depress, retract, protract, and rotate the scapula can provide insights into scapular movement.
• Rotator cuff strength: Assessing the strength of the rotator cuff muscles (subscapularis, supraspinatus, infraspinatus, and teres minor) in various positions, including both inner and outer ranges, is essential. Specific tests like the Belly-off test and infraspinatus scapular retraction test can be used, but it's also important to assess function throughout the full range of motion. Weakness in the rotator cuff muscles should be identified and targeted in the rehabilitation.
• Joint laxity: Clinical history and physical examination, including motion, strength, and stability assessments, help identify objective signs of instability. Tests like the anterior apprehension test, relocation maneuver, load-shift testing, Jobe relocation test, and sulcus sign assessment are used to evaluate glenohumeral joint laxity and potential instability. Gagey’s Hyperabduction test can be used to evaluate the laxity of the inferior glenohumeral ligaments.
• Posture and core stability: Assessing posture and core stability is also important as they can influence shoulder stability. Increased resting tone in muscles like upper trapezius, pectoralis major, and latissimus dorsi may indicate abnormal motor recruitment patterns.
• Neurological and pain status: These should also be evaluated as part of the overall assessment.

Strengthening Exercises

The sources emphasize the importance of strengthening exercises for both the rotator cuff and scapular stabilizers to improve dynamic stability.

• Rotator Cuff Strengthening:
  • External rotation with bands (Theraband): This is frequently recommended, often performed with the arm at the side (0° abduction) and at 90° of abduction. Side-lying external rotation with or without dumbbells is also mentioned. Resisted external rotation at the limit of movement can test isometric strength in the inner range.
  • Prone Y/T/W raises: These exercises target various scapular and posterior shoulder muscles, including the rotator cuff. Prone horizontal abduction with external rotation is specifically recommended for activating middle and lower trapezius. Prone rowing into external rotation on a stability ball is also suggested.
  • Internal rotation with bands (Theraband): Similar to external rotation, this is performed with the arm at the side and at 90° of abduction. Resisted internal rotation can test the anterior rotator cuff.
  • Other exercises: Exercises like "Full Can" (scaption with external rotation), abduction to 90 degrees with light weight, and prone rowing also contribute to rotator cuff strengthening. Infraspinatus and teres minor strengthening in higher degrees of abduction can reduce anterior glenohumeral ligamentous strain.
  • Isometric exercises: Early in rehabilitation, isometric exercises for the rotator cuff muscles are often initiated with the arm adducted.
• Scapular Stabilizer Strengthening:
  • Wall slides: These help in scapular control and are often recommended.
  • Scapular push-ups (push-ups with a plus): These exercises focus on serratus anterior activation and can be progressed on stable and unstable surfaces.
  • Prone exercises: Prone rowing, prone extension, and prone horizontal abduction are effective for strengthening scapular retractors and other scapular muscles. Lower trapezius exercises like table press-downs with scapular retraction are also suggested.
  • Serratus wall slides and dynamic hug: These specifically target serratus anterior strengthening.
  • Scapular retraction exercises: Emphasizing rhomboids and the middle fibers of the trapezius is recommended, especially for atraumatic multidirectional instability.

Proprioceptive Training

Proprioceptive training is crucial for improving joint position sense and neuromuscular control.

• Closed-chain exercises: These are highly recommended as they facilitate co-contraction of the rotator cuff and deltoid muscles, enhancing joint stability and stimulating proprioception.
  • Quadruped holds on unstable surfaces: This is an example of a closed-chain exercise that challenges proprioception and stability.
  • Weight shifting: Weight shifting against a wall or onto a table promotes cocontraction.
  • Hand-on-the-wall stabilization drills: These are performed in the plane of the scapula.
  • Push-ups on unstable surfaces: Progressing push-ups to a ball or unstable surface further challenges stability and proprioception.
  • Plank exercises: Plank positions (prone on elbows) can enhance cocontraction at the shoulder joint and improve core stability, and can be progressed to unstable surfaces.
• Rhythmic stabilization drills: These manual techniques performed by a therapist facilitate muscular cocontractions around the glenohumeral joint in various positions.
• Joint repositioning tasks: These exercises retrain proprioceptive mechanisms.
• Proprioceptive neuromuscular facilitation (PNF) techniques: These can be used to retrain proprioception and neuromuscular control.
• Perturbation training: Applying postural and positional disturbances to train the patient to stabilize the humeral head is beneficial.

Manual Therapy

Manual therapy can play a role in managing shoulder instability, although specific techniques and their applications may vary.

• Glenohumeral joint mobilizations:  The importance of restoring full and symmetric capsular mobility is a criterion for progressing in rehabilitation. Joint mobilizations are a common technique used by physiotherapists to address joint restrictions and improve range of motion, which could be relevant in some cases of shoulder instability. VandenBerghe et al. mention joint mobilization in a posterolateral direction to improve posterior capsular mobility, particularly in the context of acquired instability in throwers.
• Soft tissue release for tight pecs: Palpation for increased resting tone in pectoralis major is mentioned as a potential indicator of abnormal motor recruitment patterns. Soft tissue release techniques might be used to address muscle tightness that could contribute to altered shoulder mechanics.

It is important to note that the specific exercises and techniques used in a physiotherapy treatment plan will be tailored to the individual patient's presentation, the type of instability, findings from the biomechanical assessment, and their progress throughout rehabilitation. The progression through different phases of rehabilitation (acute, intermediate, advanced) will also dictate the types and intensity of exercises.

Prevention Strategies

Several strategies can help prevent shoulder subluxation, particularly in overhead athletes:

• Avoid excessive stretching of the anterior and inferior glenohumeral structures: In overhead athletes with symptomatic internal impingement, excessive anterior shoulder laxity is often an underlying cause. Therefore, aggressive stretching of the anterior and inferior capsule should be avoided as it may increase anterior translation and instability.
• Strengthen the posterior rotator cuff: Many sources emphasize the importance of strengthening the posterior rotator cuff muscles (infraspinatus and teres minor) to improve dynamic stability and balance the forces around the glenohumeral joint. Weakness in posterior shoulder muscles can lead to a temporary loss of stability due to a force couple imbalance with the anterior rotator cuff. Specific exercises include external rotation with bands, side-lying external rotation, and prone horizontal abduction with external rotation.
• Modify throwing mechanics: Maintaining proper throwing mechanics throughout any return-to-throwing program is critical to lessen the chance of re-injury. Using the Crow-Hop method, which involves a hop and a skip before the throw, can help simulate the throwing act and emphasize proper body mechanics. The velocity of the throw should be determined by the distance, and the ball should only have enough momentum to travel the designed distance, focusing on proper mechanics over force.
• Scapular stabilization exercises: A stable scapula provides a foundation for glenohumeral joint function. Strengthening the scapular retractors (rhomboids, middle fibers of trapezius), protractors (serratus anterior, pectoralis minor), and upward rotators (upper and lower fibers of trapezius, lower serratus anterior) is recommended. Exercises like wall slides, scapular push-ups (with a plus), prone rowing, and serratus wall slides can be beneficial. Addressing scapular muscle imbalances, such as dominance of the upper trapezius over middle and lower trapezius and serratus anterior, is important, especially in overhead athletes.
• Core stability: Poor core stability can compromise stability at the glenohumeral joint (GHJ). Therefore, incorporating core strengthening exercises is important for overall shoulder stability.
• Proprioceptive and neuromuscular control training: Exercises that enhance proprioception and neuromuscular control, such as closed-chain exercises (e.g., weight shifts, push-ups on stable and unstable surfaces), rhythmic stabilization drills, and perturbation training, can help the shoulder react to and control movements, potentially preventing subluxation.
• Gradual return to activity: For athletes returning to sport, a gradual and progressive increase in functional demands on the shoulder through an interval sport program is crucial to minimize the risk of re-injury. This program should be individualized based on the athlete's injury, skill level, and goals, and should only progress if the athlete is pain-free at each step.
• Maintain adequate range of motion (ROM): In overhead throwers, maintaining a balanced glenohumeral ROM, particularly internal rotation (IR) and total rotational motion (TRM), within specific limits compared to the non-throwing arm is important. Stretching programs targeting the posterior shoulder can help maintain or improve IR ROM.
• Address glenohumeral internal rotation deficit (GIRD): A GIRD of 12° or more compared to the contralateral shoulder and side-to-side TRM differences greater than 5° may predispose throwers to injury. Stretching exercises, including the sleeper stretch and cross-body stretch, can be used to address posterior shoulder tightness contributing to GIRD.
• Consider shoulder bracing: For patients returning to contact sports, a shoulder-stability brace may be required for the initiation of the return to sport.

By implementing these prevention strategies, particularly focusing on balanced muscle strength, proper mechanics, and controlled progression of activities, the risk of shoulder subluxation can be reduced, especially in the demanding context of overhead sports.

FAQs

• "Do shoulder braces help?" Shoulder braces may be used in specific situations. For instance, in a study of in-season athletes with anterior shoulder instability who underwent nonoperative management, nonoverhead athletes returned to sport wearing a Duke Wyre brace, while overhead athletes wore a Sully brace. Additionally, athletes returning to contact sports after surgical stabilization for shoulder instability might be required to wear a shoulder-stability brace when initiating their return to sport. For patients with congenitally unstable shoulders, bracing of the glenohumeral joint might also be necessary upon returning to sporting activities to provide immobilization or controlled range of motion and protect against further injury.
• "Can yoga worsen instability?" The glenohumeral joint has a large range of motion, making it susceptible to instability, especially during extremes in ranges of motion. Certain activities, such as throwing, volleyball, and tennis, which require extreme external rotation with the arm abducted and extended, have been cited as predisposing factors to anterior shoulder instability due to repetitive glenohumeral capsular overload. Since some yoga poses can involve a significant range of motion and may place stress on the shoulder joint, it is plausible that certain poses could potentially aggravate or worsen existing shoulder instability. However, without specific information in the sources about yoga, this remains an inference based on the general principles of shoulder instability and biomechanics discussed in the provided materials. It would be advisable to consult with a healthcare professional or a yoga instructor experienced in working with individuals with shoulder instability for specific guidance.

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