Original Editor - Liesbeth De Feyter, Daphné Bertrand, Lisa De Pelsemaeker, Arnaud Jacquet as part of the Vrije Universiteit Brussel Evidence-Based Practice Project Show
Top Contributors - Laura Ritchie, Scott Cornish, Andeela Hafeez, Admin, Leana Louw, Liesbeth De Feyter, Kim Jackson, Fasuba Ayobami, Tony Lowe, Borms Killian, Naomi O'Reilly, Kai A. Sigel and Wanda van Niekerk Definition[edit | edit source]The term anterior shoulder instability refers to a shoulder in which soft tissue or bony insult allows the humeral head to sublux or dislocate from the glenoid fossa.[1] It is an injury to the glenohumeral joint (GHJ) where the humerus is displaced from its normal position in the center of the glenoid fossa and the joint surfaces no longer touch each other. Also see related pages for shoulder instability, shoulder subluxation and shoulder dislocation. Clinically Relevant Anatomy[edit | edit source]The glenohumeral joint (multi-axial spheroidal joint) is one of the largest and most complex joints in the body. It has the greatest range of movement of any joint, but this leaves it inherently unstable and with the highest chance of dislocation of all the body's joints. The GHJ is formed where the humeral head fits into the glenoid fossa, an irregular oval shape, which is an extension of the scapula, like a ball and socket, although only 25% of the humeral head makes contact with the glenoid fossa at any time. This joint is surrounded by numerous ligaments and muscles which give it stability. The surrounding capsule may also add some stability with the coracohumeral and glenohumeral ligaments reinforcing the capsule. Other important bones in the shoulder include:
The shoulder has several other important structures:
Epidemiology /Etiology[edit | edit source]Epidemiology[edit | edit source]
Research suggests that incidence of recurrent
shoulder dislocation is significantly higher in younger patients.[4][5] The consequences of
an initial anterior glenohumeral dislocation in patients over forty years of age are quite different than in the younger population, primarily due to the increased incidence of rotator cuff tears and associated neurovascular injuries. The anterior or posterior supporting structures of the shoulder can also be
disrupted following an anterior dislocation. In the younger population, anterior capsuloligamentous structures most commonly fail, whereas in older patients with pre-existing degenerative weakening of the rotator cuff, the posterior structures are more likely to
fail.[4] Etiology[edit | edit source]The GHJ is stabilised by both dynamic and static structures.[4]
Excessive external rotation or over-rotation of the thrower’s shoulder is purportedly associated with the development of internal impingement syndrome (which occurs when the shoulder is maximally externally rotated and the intra-articular side of the supraspinatus tendon impinges on the adjacent posterior superior glenoid and glenoid labrum). Impingement syndrome is a potential precursor to anterior shoulder instability.[7] Characteristics/Clinical Presentation[edit | edit source]Signs and symptoms for anterior shoulder instability:
Shoulder MRI after dislocation showing Hill-Sachs lesion and labral Bankart's lesion Symptoms related to recurrent anterior instability:[7]
Differential Diagnosis[edit | edit source]
Diagnostic Procedure[edit | edit source]Diagnosis of anterior shoulder instability is through a thorough history, radiology and three specific tests carried out in this order: apprehension, relocation and surprise (release) test. These tests are highly specific and strongly predictive of traumatic anterior glenohumeral instability. A fourth test, the bony apprehension test, is similar to the apprehension test, but is used to diagnose instability with a significant osseous lesion component.[8] History[9][edit | edit source]GHJ instability can be categorised by the direction of instability, the chronicity, and the etiology. A thorough history and physical examination are essential. Age, activity level, sports participation, and hand dominance should be noted, as well instability in any other joints, especially the contralateral shoulder. Where a trauma is the cause of the symptoms, information about the position of the arm and the force of the trauma is noted. If this information is unknown, finding the arm position which reproduces symptoms is useful.
Radiology[9][edit | edit source]Initial images taken are normally anteroposterior (AP) and axillary lateral views. If pain restricts the patient's ability to tolerate an axillary lateral view, a Velpeau view may be obtained in a semi-reclined, seated position. Further views that may be useful include: AP views with the shoulder internally rotated, a West Point view, a Didiee view, and a Stryker notch view. Hill Sachs lesions are best viewed on AP radiographs in internal rotation and using a Stryker notch view. The Stryker notch view is obtained with the patient in the supine position and the arm forward flexed to 100° with the x-ray centred over the coracoid . An apical oblique view taken with the patient seated and rotated 45° and the beam directed 45° caudally is also useful for evaluating posterior humeral head defects.[10] In cases of bony Bankart lesions, recurrent instability can cause erosive or attritional loss of the glenoid rim causing progressive instability. Loss of 20% of the glenoid rim has been shown to cause significant recurrent instability and usually requires surgical correction of the bony deficiency. This deficiency may be seen on the axillary view and may be suggested by a break in the sclerotic line encircling the glenoid rim on the AP view of the shoulder. If further investigation is needed Didiee and West Point views can be considered. The Didiee view is obtained with the patient prone and the hand is placed on the ipsilateral iliac crest with the x-ray beam directed laterally at 45° to the floor. The West Point view is obtained in a similar prone position, with the shoulder abducted to 90° and the elbow bent with the arm hanging off the table. The x-ray beam is directed 25° medially and 25° caudally. Other imaging modalities such as CT and MRI are useful in clinical situations where the diagnosis is unclear. CT may be useful to demonstrate and quantify bony abnormalities including glenoid bone loss or fractures, glenoid version and humeral head abnormalities. Adding contrast and performing a CT arthrogram of the shoulder can also provide some insight into the status of the labrum, rotator cuff and ligamentous complex. MRI is extremely useful, and the preferred method to evaluate these soft tissues, however, it does not provide as clear a picture of the associated bony injuries. In the acute setting, the hemarthrosis resulting from the dislocation serves as an intra-articular contrast medium. In the more chronic setting, gadolinium-enhanced MRI is a useful modality to investigate for soft tissue pathology such as labral tears and capsular damage.[11] In addition to Bankart lesions, an anterior periostial sleeve avulsion (ALPSA) or a humeral avulsion of glenohumeral ligament (HAGL) can occur with an anterior shoulder dislocation. These are associated with higher recurrence rates and if missed they can lead to higher post-surgical failure rates. HAGL and ALPSA lesions are best seen using MRI and MR arthrogram. Outcome Measures[edit | edit source]
Examination[edit | edit source]Special tests[edit | edit source]Load and shift test[12][13][edit | edit source]This test can be performed with the patient in sitting or in supine. In sitting, the patient’s arm rests on the thigh with the examiner to their side and slightly behind. One hand is used to stabilise the scapula and the other is placed on the shoulder. The thumb is positioned over the posterior humeral head and fingers over the anterior humeral head. The humerus is loaded by pushing the humeral head into a neutral position within the fossa. Whilst maintaining the humeral head in this position, humerus is shifted forwards by applying an anterior force, to asses anterior instability. Some movement is normal, but should not be more than 25% of the humeral head. Instability is classified as follows:
Apprehension, Relocation and anterior release tests[13][14][edit | edit source]The patient is in a supine position, with the shoulder in 90° of abduction and maximal lateral rotation. A positive apprehension test occurs if the patient either looks apprehensive or resists further movement. To differentiate apprehension from other potential conditions, the relocation test is used. Start position is the same as that for the apprehension test, then an anterior-posterior force is applied to the shoulder to relocate the humerus in the fossa. The apprehension will decrease in the case of shoulder instability. The final test is the release test, where the posteriorly directed force applied in the relocation test is removed. The result is considered positive if the patient’s apprehension returns. Anterior drawer test[8][15][edit | edit source]The patient is in a supine position and the affected shoulder over the edge of the table. The patient’s arm should be relaxed. Position the arm in a combined midrange abducted position with forward flexion and lateral rotation. The stabilising hand is placed on the scapula so that the fingers and thumb secure the scapula at the spine of the scapula and the coracoid. The patient’s arm is pulled anteriorly to apply a gliding force to the glenohumeral joint. If an audible click is heard during the movement, the glenoid labrum may be torn, or the joint may be sufficiently lax to allow the humeral head to glide over the glenoid labrum rim. Medical Management[edit | edit source]Analgesics can be used to decrease pain[16] with the patient in a position of comfort while maintaining cervical spine immobilisation where necessary. A pillow is placed between the patient's arm and torso to further increase comfort. Physiotherapy Management[edit | edit source]A conservative rehabilitation program needs to be
patient specific, based on the type and degree of shoulder instability present and the desired level of return to function. A rehabilitation programme can consist of a combination of any of the following: Strengthening exercises, dynamic stabilisation drills, neuromuscular training, proprioception drills, scapular muscle strengthening and a graded return to the desired activities. Rehabilitation factors[edit | edit source]Seven key factors should be considered when designing a rehabilitation program:
Rehabilitation guidelines[edit | edit source]Patients may be classified into two common forms of shoulder instability, traumatic and atraumatic. There are specific guidelines to consider in individualising the rehabilitation of each patient. Traumatic Shoulder Instability[17][18][edit | edit source]The program will vary in length for each individual depending on the seven rehabilitation factors.[edit | edit source]Phase I: Acute motion phase[edit | edit source]Goals:
During the early rehabilitation program, caution must be applied in placing the capsule under stress until dynamic joint stability is restored. It is important to refrain from pushing into external rotation or horizontal abduction with anterior instability. Phase II: Intermediate phase[edit | edit source]Criteria to Progress to Phase II:
Goals:
Phase III: Advanced strengthening phase[edit | edit source]Criteria to Progress to Phase III:
Goals:
Phase IV: Return to activity phase[edit | edit source]Criteria to Progress to Phase IV:
Goals:
Follow up[edit | edit source]
Atraumatic Instability[17][18][edit | edit source]This multi-phased program is designed to allow the patient/athlete to return to their previous functional level as quickly and safely as possible. Each phase will vary in length for each individual depending upon the severity of injury, ROM and strength deficits, and the required activity demands of the patient. Phase I: Acute phase[edit | edit source]Goals:
Exercises:
Phase II: Intermediate phase[edit | edit source]Criteria to Progress to Phase II:
Goals:
Exercises:
Phase III: Advanced strengthening phase[edit | edit source]Criteria to Progress to Phase III:
Goals:
Exercises:
Phase IV - Return to activity phase[edit | edit source]Goals:
Exercises:
Criteria to Progress to Phase IV:
Clinical Bottom Line[edit | edit source]
References:[edit | edit source]
What criterion is used to determine whether the AP axial clavicle has been correctly positioned?What criterion is used to determine whether the AP axial clavicle has been correctly positioned? The lateral half of the clavicle is shown above the scapula. Most of the clavicle is projected above the ribs and scapula, with the medial end overlapping the first or second rib.
Which of the following are valid evaluation criteria for a lateral projection of the forearm?Which of the following is (are) valid criteria for a lateral projection of the forearm? The coronoid process and radial head should be superimposed. The radial tuberosity should face anteriorly. To accurately position a lateral forearm, the elbow must form a 90° angle with the humeral epicondyles superimposed.
Which of the following is used to obtain a lateral projection of the upper humerus on patients who are unable to abduct their arm quizlet?The transthoracic lateral projection is used to evaluate the glenohumeral joint and upper humerus when the patient is unable to abduct the arm (as in dislocation).
What are the angle and direction of the central ray for the PA axial projection of the clavicle?Central ray: The central ray should be directed to the scapulohumeral joint perpendicular to the image receptor. For an AP Axial, a cephalic angle of 35 degrees.
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