The term anterior shoulder instability refers to the shoulder in which soft tissue or bone injury results in subluxation of the humeral head or dislocation from the socket. [1] It is an injury to the glenohumeral joint (GHJ) in which the humerus is displaced from its normal position in the center The socket and articular surfaces no longer touch each other.
See also the related pages on shoulder instability, shoulder subluxation and shoulder dislocation.
Clinically Relevant Anatomy
The glenohumeral joint (polyaxial spherical joint) is one of the largest and most complex joints in the human body. It has the greatest range of motion of all joints, but this makes it inherently unstable and has the highest potential for dislocation of all body joints. GHJ is formed in The humeral head fits into the socket and is an irregular oval that is an extension of the scapula, like a ball and socket, although only 25% of the humeral head is in contact with the socket at any one time.
This joint is surrounded by many ligaments and muscles that make it stable. The surrounding capsule can also add some stability by strengthening the coracohumeral and glenohumeral ligaments of the capsule. Other important bones in the shoulder include:
- acromion: bony protrusion on the outside of the scapula
- Clavicle: connects the acromion to the axial bone through the acromioclavicular and distal sternoclavicular joints
- coracoid: the hamate of the scapula
There are several other important structures in the shoulder:
- Rotator Cuff: Collection of 4 muscles originating from the scapula (infraspinatus and teres minor) that stabilize the GHJ and allow a wide range of motion.
- Bursae: There are many bursae associated with the shoulder, with the subacromial bursa being the one most likely to present symptoms of bursitis. It is located between the upper surface of the supraspinatus tendon and between the acromiocoracoid process and the downwardly extending coracoacromial ligament At the attachment of the humeral tendon of the supraspinatus
- Labrum: An annulus of cartilage fibrous that extends upward from the glenoid, providing stability in a deeper cup-like form for the humeral head to fit. [2]

Epidemiology /Etiology
Epidemiology
Anterior shoulder dislocations are more common than posterior dislocations. [3]
Studies have shown that younger patients have a significantly higher incidence of recurrent shoulder dislocations. [4][5] The consequences of initial anterior glenohumeral dislocation in patients over the age of 40 are very different from those in the younger population, mainly because Incidence of rotator cuff tears and related neurovascular injuries. The anterior or posterior support structure of the shoulder may also be disrupted after anterior dislocation. In the younger population, the anterior capsular ligament structure fails most often, while in the older population Patients with pre-existing degenerative weakening of the rotator cuff are more prone to failure of the posterior structure. [4]
Etiology
GHJ is stabilized by dynamic and static structures. [4]
Rotator Cuff Muscles
- Dynamic Stabilizers: Rotator Cuff Muscles Biceps Deltoid Muscles
- Static stabilizers: glenohumeral joint capsule, glenohumeral ligament, negative labral pressure in the joint capsule and bony conformity of the joint. [3][5]
- Labrum: This concave compression mechanism plays an important role in the stability of the glenohumeral joint by keeping the humeral head positioned at the glenoid against translational forces. The concave glenoid surface consists of glenoid shape, glenoid cartilage and labrum. The labrum increases the width and depth of the glenoid. Instability increases with the size of the glenoid defect. [6]
- The glenohumeral ligament: The main function of the superior glenohumeral ligament is to resist the downward translation and external rotation of the humeral head in the adduction arm. The main function of the middle glenohumeral ligament is to resist external rotation from 0° to 90° and provide Frontal stability for moderately abducted shoulders. The inferior glenohumeral ligament consists of two bands, anterior and posterior, and a sac in the middle. The main function of the front strap is to resist front and lower translation. [5] [7]
Excessive external rotation or hyperrotation of the thrower’s shoulder has been reported to be associated with the development of internal impingement syndrome (when the shoulder is maximally externally rotated and the medial articular impingement of the supraspinatus adjacent posterior superior glenoid and labrum). Impingement syndrome is a potential precursor to instability of the anterior shoulder [


Signs and symptoms of front shoulder instability:
- 95% of acute traumatic dislocations.[5]
- Dead arm syndrome indicates pathological anterior instability. It occurs when the arm is in abduction and external rotation. The patient complained of severe pain in the front of the shoulder and tingling in the hand, with sudden arm drooping. This syndrome is often seen with overhead movements such as Volleyball Tennis Swimming and water polo [7]
- Rotator cuff weakness, especially external rotation and “empty can” abduction are common in athletes with anterior instability. [7]
- Bankart injury is the most common consequence of traumatic anterior shoulder instability. [5]
- Humeral avulsion of the glenohumeral ligament is also a cause of instability in the anterior part of the shoulder. [5]
- During anterior dislocation, the posterolateral aspect of the humeral head contacts the anterior inferior border of the glenoid, often resulting in a Hill Sachs defect. This defect is observed in up to 80% of patients with initial anterior dislocations and 100% of patients with recurrent anterior dislocations unstable. [3][5] If this bony concave surface engages the anterior glenoid at 90° and external rotation to the arm, it is termed a “Joint Hill Sachs lesion” and carries a higher risk of failure after arthroscopic stabilization surgery

Symptoms associated with recurrent anterior instability: [7]
- Glenohumeral joint pain
- Stiff shoulders and difficulty warming up for activities
- Rotator cuff weakness
- A popping or stuck feeling in the shoulder joint
- Pain when back or above shoulder height
- Fear of sleeping with arms overhead during abduction and external rotation
- Nervous system: tingling or burning in the lower arms and hands, or localized numbness of the skin over the deltoid
- Anterior glenohumeral joint line and posterior rotator cuff tenderness
Differential Diagnosis
- Posterior instability
- Frozen shoulder/adhesive capsulitis
- Dead arm syndrome
- Rotator cuff tear
- Subacromial impingement
- Internal impingement
- Biceps tendinopathy
Diagnostic Procedure
Anterior shoulder instability is diagnosed by a comprehensive medical history radiology and three specific tests performed in this order: the fear repositioning and the raid (release) test. These tests are highly specific and highly predictive of traumatic anterior glenohumeral instability. the fourth Testing The Bone Worry Test is similar to the Worry Test, but is used to diagnose instability with a significant bone lesion component. [8]
History[9]
GHJ instability can be classified according to the direction, chronicity, and etiology of the instability. A thorough history and physical examination are essential. Attention should be paid to sport participation and hand dominance at age activity levels and any other joint instability, especially opposite shoulder. If trauma is the cause of symptoms, record information about arm position and trauma strength. If this information is not known, it is useful to find the arm position that reproduces the symptoms.
GHJ instability can be classified according to the direction, chronicity, and etiology of the instability. A thorough history and physical examination are essential. Attention should be paid to sport participation and hand dominance at age activity levels and any other joint instability, especially opposite shoulder. If trauma is the cause of symptoms, record information about arm position and trauma strength. If this information is not known, it is useful to find the arm position that reproduces the symptoms.
Radiology[9]
The initial images taken are usually anterior-posterior (AP) and axillary lateral views. If pain limits the patient’s ability to tolerate a lateral view of the axilla, the Velpeau view can be obtained in a semi-reclined sitting position. Other views that may be useful include: Shoulder AP view Internally rotated West Point view, Didiee view and Stryker notch view.
Hill Sachs lesions are best viewed on an AP radiograph of pronation using the Stryker notch view. The Stryker notch view was obtained with the patient supine with the arm bent forward to 100° and the X-ray centered on the coracoid. apical oblique view The patient is seated and rotated 45° and the beam is directed caudally 45° and can also be used to evaluate posterior humeral head defects. [10]
In the case of bony Bankart lesions, recurrent instability can lead to erosive or abrasive loss of the glenoid rim, resulting in progressive instability. Loss of the glenoid rim in 20% has been shown to result in severe recurrent instability and often requires surgical correction of the bone defect. This defect can be seen on the axillary view and can be suggested by the rupture of the sclerotic line surrounding the glenoid rim on the AP view of the shoulder. If further investigation is required, Didiee and West Point’s views may be considered. Get a Didiee view with the patient Lie prone with the hand on the ipsilateral iliac crest with the X-ray beam at 45° laterally to the floor. The West Point view was obtained in a similar prone position with shoulders abducted 90°, elbows flexed, and arms suspended off the tabletop. X-ray beam is 25° medially, 25° caudal.
Other imaging modalities, such as CT and MRI, are useful in clinical situations where the diagnosis is unclear. CT can be used to visualize and quantify bone abnormalities, including glenoid bone loss or fractured glenoid deformities and humeral head abnormalities. Add contrast and perform CT Shoulder arthrography can also provide some insight into the status of the labrum-rotator cuff and ligamentous complex. MRI is very useful and the method of choice for evaluating these soft tissues, but it does not provide a clear picture of the associated bone damage. in acute Hemoarthrosis caused by dislocation is used as an intra-articular contrast agent. In more chronic conditions, gadolinium-enhanced MRI is a useful modality to study soft tissue pathology, such as labral tears and capsular damage. [11]
In addition to Bankart injury, anterior shoulder dislocation can also occur with anterior periosteal cuff avulsion (ALPSA) or humeral avulsion of the glenohumeral ligament (HAGL). These are associated with higher recurrence rates, and missing them can lead to higher postoperative failure rates. HAGL and ALPSA lesions are best visualized using MRI and MR arthrography.
Outcome Measures
- Arm Shoulder and Hand Disability (DASH)
- Visual Analogue Scale (VAS
Examination
Special tests
Load and shift test[12][13]
The test can be performed with the patient sitting or supine. When seated, the patient’s arm is resting on the thigh with the examiner on their side and slightly back. Use one hand to stabilize the shoulder blade and place the other hand on the shoulder. thumb is located The back of the humeral head and the fingers are on the front of the humeral head. Load the humerus by pushing the humeral head into a neutral position within the socket. While holding the humeral head in this position, the humerus is moved forward by applying a forward force to the donkey unstable. Some movement is normal, but should not exceed 25% of the humeral head.
Instability is classified as follows:
- Grade 1: Shift between 25% and 50%
- Grade 2: Displacement of more than 50% and spontaneous reset upon cessation of exertion
- Grade 3: More than 50% of displacements do not spontaneously reduce and remain dislocated. The combination of relaxation and symptom recurrence determines a positive or negative result.
Apprehension, Relocation and anterior release tests[13][14]
The patient is in the supine position with 90° of shoulder abduction and maximum lateral rotation. A positive fear test occurs if the patient appears worried or refuses to move further. To distinguish fear from other potential situations, the relocation test is used. The starting position is the same as for the stretch test, then an anterior-posterior force is applied to the shoulder to reposition the humerus in the cranial fossa. With shoulder instability, fear is reduced. The final test is the release test, where the backward orientation Remove the force applied in the repositioning test. If the patient’s apprehension recurred, the results were considered positive.
Anterior drawer test[8][15]
The patient is in a supine position with the affected shoulder at the edge of the table. The patient’s arm should be relaxed. Place the arm in a mid-range abduction position, bend forward and rotate laterally. A steady hand rests on the shoulder blade so that the fingers Secure the scapula with the thumb at the spine of the scapula and coracoid. The patient’s arm is pulled forward to apply a sliding force to the glenohumeral joint. If you hear a click during movement, it may be a labrum tear or a joint that is loose enough to allow The humeral head slides over the edge of the labrum.
Medical Management
Analgesics can be used to reduce pain [16] and place the patient in a comfortable position while maintaining cervical immobilization if necessary. Place a pillow between the patient’s arms and torso to further increase comfort.
Physiotherapy Management
Conservative rehabilitation programs need to be tailored to the patient based on the type and degree of current shoulder instability and the level of functional recovery desired. A rehabilitation program can include a combination of any of the following: Strengthening exercises Dynamic stabilization Training Neuromuscular training Proprioceptive training Strengthen the scapular muscles and gradually return to the desired activity.
Rehabilitation factors
Seven key factors should be considered when designing a rehabilitation program:
- Pathological onset: Pathological shoulder instability may result from acute traumatic events or chronic recurrent instability. The goals of rehabilitation programs can vary widely depending on the occurrence and mechanism of the injury. After traumatic subluxation or dislocation, patients usually Presents with marked soft tissue trauma pain and anxiety. Rehabilitation for first-time trauma patients will be based on the patient’s symptoms, focusing on early control of range of motion to reduce muscle spasms and protection and pain relief.
Conversely, patients with nontraumatic instability often have a history of repetitive injuries and symptomatic complaints. Rehabilitation for this patient should focus on early proprioceptive training, dynamic stabilization training, neuromuscular control, scapular muscle training, and Due to the unique features of excessive capsular relaxation and capsular redundancy in such patients, muscle strengthening exercises can enhance dynamic stability. - Degree of instability: The second factor is the degree of instability present in the patient and its impact on their functioning.
The rate at which the rehabilitation program progresses will vary depending on how unstable and persistent the symptoms are. For example, patients with mild subluxation and muscle protection may initially tolerate strengthening exercises and neuromuscular control training better than patients with mild subluxation and muscle protection. Lots of muscle protection. - Dislocation frequency: The most common conservative treatment for primary traumatic dislocations is immobilization with slings and early controlled passive range of motion exercises, especially for first dislocations. Chronic subluxation seen in nontraumatic unstable shoulders may be Treatment is more aggressive due to lack of acute tissue damage and less muscle protection and inflammation. Rotator cuff and scapula strengthening activities should be initiated when performing ROM exercises. Take care to avoid overstretching the joint capsule Through active ROM activity. The goal is to enhance strength proprioceptive dynamic stability and neuromuscular control, particularly at specific motor points or directions that cause instability complaints.
- Direction of instability: Anterior instability is the most common type of traumatic instability clinically, in which the humeral head is forced to extreme abduction and external rotation or horizontal abduction, and the labral complex and capsule may separate from the glenoid rim .
- Concomitant pathology: Other soft tissues that may be affected and the premorbid state of the soft tissues need to be considered. These accompanying injuries may significantly slow down the rehabilitation program to preserve the healing tissue.
- Neuromuscular Control: A sixth factor to consider is the patient’s level of neuromuscular control, especially at the motor end.
- Activity level: The final factor to consider in conservative rehabilitation of an unstable shoulder is arm dominance and the patient’s desired level of activity. If the patient frequently engages in overhead or physical activity, such as tennis, volleyball or throwing, then The rehabilitation program should include dynamic stabilization exercises for movement, neuromuscular control exercises, and plyometric exercises in the overhead position, once complete pain-free ROM and adequate strength have been achieved. Functional needs involving patients below the shoulder Activities will follow a progressive exercise program to restore full ROM and strength.
Rehabilitation guidelines
Patients can be classified into two common forms of traumatic and nontraumatic shoulder instability. In individualizing each patient’s recovery process, specific guidelines need to be considered.
Traumatic Shoulder Instability[17][18]
The length of the program will vary for each individual based on the seven recovery factors.
Phase I: Acute motion phase
Goals:
- Protect healing capsular structures
- Re-establish pain-free range of motion
- Reduce painful inflammation and muscle spasms
- Delays muscle atrophy/builds voluntary muscle activity
- Re-establish dynamic stability
- Improve proprioception
Exercises:
- Range of motion: Rope and Pulley Active Assist ROM (F IR ER)
- Strengthening/Proprioception: Isometric (Flexion-Abduction Extension IR ER, arm on one side)
- Rhythm stabilization: ER/IR/F/E Scapular plane center of gravity transfer (standing with hands on table) proprioceptive training exercises (active joint regeneration: F/IR/ER
Phase II: Intermediate phase
Criteria to Progress to Phase II:
- Almost full to full passive ROM (ER may still be limited)
- Minimal pain or tenderness
- Good MMT for IR ER flexion and abduction
- Baseline proprioception and dynamic stability
Goals:
- Regain and improve muscular strength
- Normalise arthrokinematics
- Enhance proprioception and kinesthesia
- Enhance dynamic stabilisation
- Improves neuromuscular control of the shoulder complex
Exercises
- Perform ROM activities with 90° abduction to tolerance (painless)
- Initiate isotonic strengthening
- Emphasize ER and Scapula Strengthening: Abduction to 90° Side Lying ER to 45° Push Up to Table Biceps Curl Triceps Push Down Prone Row
- Improves neuromuscular control of the shoulder complex: PNF wall stabilization uses the ball to statically maintain a push-up position on the ball.
Phase III: Advanced strengthening phase
Criteria to Progress to Phase III:
- Full non-painful range of motion
- No palpable tenderness
- Ongoing Progress in Resistance Exercise
- Normal muscle dynamic stability and neuromuscular control
- Improve strength/power/endurance
- Improve neuromuscular control
- Enhance dynamic stabilisations
- Prepare patient/athlete for activity
Exercises:
- Continued Isotonic Strengthening (Progressive Resistance): Full ROM Strengthening Bench Press in Restricted ROM Supine and Incline Chest Press
- Emphasise PNF
- Advanced Neuromuscular Control Training: Ball Flip on Table Pushups, Rhythmic Steady Manual Scapular Neuromuscular Control Training Initiating Perturbation Activity
- Endurance training: timed exercises (30-60 seconds) to increase the number of repetitions for multiple bouts throughout the day
- Start Plyometrics: 2 Hands (chest pass throw side-by-side overhead football) and progress to 1 Hand (dribble 90/90 baseball throw)
Phase IV: Return to activity phase
Criteria to Progress to Phase IV:
- Full ROM
- No pain or palpable tenderness
- Satisfactory isokinetic test
- Satisfactory clinical exam
Goals:
- Maintain optimal strength/strength/stamina levels
- Gradually increase activity level to prepare patient/athlete for full return to activity/sports
Exercises:
- Continue all exercises as in phase III
- Do isotonic strengthening exercises
- Resume normal lifting program
- Initiate interval sport program
Follow up
- Isokinetic test (ER/IR/Abd/Add)
- Progress interval program
- Maintenance of exercise program
Atraumatic Instability[17][18]
This multi-phase program is designed to allow the patient/athlete to return to the previous level of function as quickly and safely as possible. The length of each phase will vary for each individual based on the severity of the injury ROM and strength deficit and the activity needs required patient.
Phase I: Acute phase
Goals:
- Decrease pain/inflammation
- Re-establish functional range of motion
- Establish voluntary muscular activation
- Re-establish muscular balance
- Improve proprioception
- Decrease pain and inflammation
- Treatment modality (i.e. ice electrotherapy)
- NSAIDs
- Gentle joint mobility for pain neuromodulation (Class I and II)
exercises:
- Avoid activity and exercise in extreme cases of ROM
- ROM exercises: Pendulum, rope and pulley
- Strengthening Exercise: Isometric Flexion Abduction Extension
- Proprioception
- Active joint reposition drills for ER/IR
Phase II: Intermediate phase
Criteria to Progress to Phase II:
- Full functional ROM
- Minimal pain or tenderness
- “Good” MMT
Goals:
- Normalize the joint kinematics of the shoulder complex
- Restore and improve muscle strength of the glenohumeral and scapularis muscles
- Improves neuromuscular control of the shoulder complex
- Enhance proprioception and kinesthesia
Exercises:
- Initiate isotonic reinforcement: IR/ER (lateral dumbbell) abduction to 90°
- Start eccentric exercise at 0° abduction IR/ER
- Improving Neuromuscular Control of the Shoulder Complex: Rhythm Stabilization Exercises PNF Weight Transfer Handball Wall Stabilization Exercises in the Medial Medial and Lateral ROM Proprioceptive Scapulothoracic/Glenoid Muscular Systems.
Phase III: Advanced strengthening phase
criteria to Progress to Phase III:
- Full pain-free ROM
- No pain or tenderness
- Ongoing Progress in Resistance Exercise
- Good to normal muscle strength
Goals:
- Enhance dynamic stabilisation
- Improve strength/endurance
- Improve neuromuscular control
- Prepare patient for activity
Exercises:
- Continue isotonic strengthening
- Continue eccentric strengthening
- Emphasis on PNF practice and rhythmic steady hold
- Continue neuromuscular control training: rhythmic steady push-ups progress to unstable surface medicine ball rocker
- Planning Scapular Neuromuscular Control Training: Sidelyng Manual Training
- Emphasis on endurance training: timed workouts (30-60 seconds) to increase reps
Phase IV - Return to activity phase
Goals:
- Maintain optimal strength/strength/stamina levels
- Gradually increase activity level to prepare patient/athlete for full return to activity/sports
Exercises:
- Continue all exercises as in phase III
- Initiate interval sport program
- Patient education
Criteria to Progress to Phase IV:
- Full ROM
- No pain or palpable tenderness
- Satisfactory isokinetic test
- Satisfactory clinical exam
Clinical Bottom Line
- Shoulder instability may have traumatic or nontraumatic causes.
- Anterior shoulder instability is an injury to the shoulder joint where the upper arm is displaced from its normal position in the glenoid and the articular surfaces no longer touch each other.
- Anterior shoulder dislocations are more common than posterior dislocations.
- The recurrence rate after primary shoulder dislocation is highest in individuals under the age of 20. Anterior instability occurs in 95% of acute traumatic dislocations.
- Anterior shoulder instability was diagnosed by medical history radiology and the following three tests: fear displacement and raid (release) tests, performed separately.
- Rehabilitation should be individual-based and take into account the patient’s pre-morbid state and activity level
References:
- Medscape. Anterior Glenohumeral Instability. Available from: https://emedicine.medscape.com/article/1262004-overview (accessed 29 August 2020).
- ↑ Web MD. Picture of the shoulder. Available from: http://www.webmd.com/pain-management/picture-of-the-shoulder (accessed 29 August 2020).
- ↑ Jump up to:3.0 3.1 3.2 Chen AL, Bosco III JA. Glenohumeral bone loss and anterior instability. Bulletin of the NYU hospital for joint diseases 2006 Dec 22;64(3-4):130-138.
- ↑ Jump up to:4.0 4.1 4.2 Araghi A, Prasarn M, St Clair S, Zuckerman JD. Recurrent anterior glenohumeral instability with onset after forty years of age. Bull Hosp Joint Dis 2005 Jan 1;62:99-101.
- ↑ Jump up to:5.0 5.1 5.2 5.3 5.4 5.5 5.6 Pope EJ, Ward JP, Rokito AS. Anterior shoulder instability – a history of arthroscopic treatment. Bull NYU Hosp Jt Dis 2011;69(1):44-9.
- ↑ Rhee YG, Lim CT. Glenoid defect associated with anterior shoulder instability: results of open Bankart repair. Int Orthop 2007;31(5):629-34.
- ↑ Jump up to:7.0 7.1 7.2 7.3 7.4 Satterwhite YE. Evaluation and management of recurrent anterior shoulder instability. Journal of athletic training 2000 Jul;35(3):273.
- ↑ Jump up to:8.0 8.1 Lo IK, Nonweiler B, Woolfrey M, Litchfield R, Kirkley A. An evaluation of the apprehension, relocation, and surprise tests for anterior shoulder instability. The American Journal of Sports Medicine 2004;32(2):301-7.
- ↑ Jump up to:9.0 9.1 Dumont GD, Russell RD, Robertson WJ. Anterior shoulder instability: a review of pathoanatomy, diagnosis and treatment. Current reviews in musculoskeletal medicine 2011;4(4):200.
- ↑ Pavlov H, Warren RF, Weiss Jr CB, Dines DM. The roentgenographic evaluation of anterior shoulder instability. Clinical Orthopaedics and Related Research 1985;194:153-8.
- ↑ Rokous JR, Feagin JA, Abbott HG. Modified axillary roentgenogram a useful adjunct in the diagnosis of recurrent instability of the shoulder. Clinical Orthopaedics and Related Research 1972;82:84-6.
- ↑ Shultz SJ, Houglum PA, Perrin DH. Examination of musculoskeletal injuries. Human Kinetics; 2005.
- ↑ Jump up to:13.0 13.1 Farber AJ, Castillo R, Clough M, Bahk M, McFarland EG. Clinical assessment of three common tests for traumatic anterior shoulder instability. JBJS 2006;88(7):1467-74.
- ↑ Savoie III FH, O’Brien MJ. Anterior instability in the throwing shoulder. Sports Medicine and Arthroscopy Review 2014;22(2):117-9.
- ↑ Milgrom C, Milgrom Y, Radeva-Petrova D, Jaber S, Beyth S, Finestone AS. The supine apprehension test helps predict the risk of recurrent instability after a first-time anterior shoulder dislocation. Journal of shoulder and elbow surgery 2014;23(12):1838-42.
- ↑ Wilson SR, Price DD. Shoulder Dislocation in Emergency Medicine. Medscape; 2011.
- ↑ Jump up to:17.0 17.1 Wilk KE, Macrina LC, Reinold MM. Non-operative rehabilitation for traumatic and atraumatic glenohumeral instability. North American journal of sports physical therapy 2006;1(1):16.
↑ Jump up to:18.0 18.1 Burkhead Jr WZ, Rockwood Jr CA. Treatment of instability of the shoulder with an exercise program. JBJS 1992;74(6):890-6.