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Abstract
Abstract
A dislocation of the glenohumeral joint is a non-physiological translation of the humeral head resulting in a complete detachment of the humerus from the glenoid.
Dislocations occur mostly during sports when falling on the outstretched arm or after high impact collisions such as in rugby, American football or ice-hockey. However, dislocations may also happen during seizures or spontaneously.
Men below age 30, who regularly participate in contact sports are at the highest risk of an injury to the shoulder.
Patients suffering from a dislocation experience intense pain and discomfort. Depending on the direction of dislocation, the arm is held in a unique position, which might help with diagnosis. Additionally, radiographs can be performed.
Treatment depends on the age, sex and concomitant injuries sustained from dislocation. The older the patient and less severe the structural damage, the more likely conservative treatment with immobilisation lowers the chance of recurrent dislocations.
General considerations
General considerations
Definition
Definition
A dislocation of the glenohumeral joint is a non-physiological translation of the humeral head resulting in a complete detachment of the humerus from the glenoid.
Aetiology
Aetiology
Usually, dislocation is a result of traumatic events such as falling on the outstretched arm or accidents [1]. For atraumatic dislocations and instability visit glenohumeral instability. The glenohumeral joint may dislocate in 3 different directions: anteriorly, posteriorly and inferiorly.
Mechanisms resulting in dislocation:
Anterior dislocation (Luxatio subcoracoidea, Luxatio anterior)
Falling on the outstretched arm in abducted and externally rotated position [1]
Posterior dislocation (Luxatio posterior)
Direct high-energy collisions with the arm in adducted, flexed and internally rotated position (67%) [2]
Seizure (31%) [2]
Electrocution (2%) [2]
Inferior dislocation (Luxatio axillaris, Luxatio erecta)
Axial compression through arm in fully abducted position [3]
Hyperabduction force to arm in fully abducted position [3]
Epidemiology
Epidemiology
As the anatomy of the shoulder allows for maximal mobility, it is only clear that the glenohumeral joint is the most dislocated joint in the body with 45% of all dislocations [4]. Anterior dislocations are by far the commonest, followed by posterior and inferior dislocations [3, 5]. Most patients are male and range from 15 to 25 years of age (47%) as a second peak is seen in the elderly, where injury mechanisms tend to be low velocity falls [4]. In the majority of cases, injuries are sustained during sporting activities such as American Football, Rugby or Ice-hockey [4]. Therefore, young men participating in contact sports are at the highest risk.
Clinical presentation
Clinical presentation
Following a shoulder dislocation, patients experience severe pain and are unable to move the affected arm normally. Patients also position their arm in a unique way after a luxation of the shoulder in order to relieve pain. In anteriorly dislocated shoulders, the arm is held in abduction and external rotation. Patients with posteriorly dislocated shoulders tend to hold their shoulder in adduction and internal rotation, whereas when suffering from inferiorly dislocated shoulders the arm is abducted to 125° on average (70°-170°) and pronated with the hand resting on the forehead or behind the head [3].
Diagnosis
Diagnosis
History
History
Medical history should always contain the mechanism of injury as well as previous instability events of the affected shoulder. Additional information that might proof useful is level of activity and hand dominance as it is important for athletes of certain sports that involve throwing [6].
Disease specific diagnosis
Disease specific diagnosis
Clinical presentation along with a short examination often suffices to make a diagnosis. In anterior dislocations, a dent below the acromion may be visible as well as palpating an empty socket. Posterior dislocation has similar findings; however, signs might not be as pronounced [2]. Often a fullness of the posterior aspect of the axilla can be seen as well as palpated [2]. A humeral head palpable in the axilla may impress in cases of inferior dislocation [3].
Specific instability tests are of little to no use in the acute setting as patients are in severe pain and discomfort. Imperative on the other hand is peripheral neurovascular testing with special focus on the innervation territory of the axillary nerve, as nerve lesions are common concomitant injury in shoulder disloactions [6].
Radiographic imaging is always indicated for patients with primary dislocation, if the causative force may have caused fractures or other lesions or the examiner is uncertain of the joint position [7]. Radiographs are not needed if the patient is suffering from recurrent dislocations with relatively low force [7].
Differential diagnosis
Differential diagnosis
Clavicula fracture
Rotator cuff injuries
Anteriorely dislocated shoulder in ap-view (left) and Y-view (right)
Treatment
Treatment
Dislocated shoulders are to be reduced as promptly as possible. There are severeal reduction techniques for different displacements of the humeral head, which all involve placing the humeral head in a more favourable position by rotating, flexing, abducting and applying traction to the shoulder [7]. A selection of reduction techniques goes as followed:
Stimson
Hippocrates
Traction-counteraction
Arlt
It is important to note that prior to reduction, proper analgesia and or sedation should be administered. After reduction, peripheral neurovascular status should be reasessed and correct position of the humeral head radiographically confirmed.
Non-operative aftertreatment strategies in dislocations without concomitant injuries:
Anterior dislocation
Treatment strategies for anterior dislocation are heavily discussed in literature. Immobilisation in a sling is recommended for comfort for 1 to 3 weeks, with younger patients (<30) requiring the longest immobilisation time [6]. There is however no significant evidence that immobilisation decreases the chances of recurrent dislocations [6]. Some studies also suggest to immobilise the shoulder in external rotation, although majority of research disclaims a significant benefit [6].
Posterior dislocation
The shoulder is placed in a brace in external rotation and abduction for 2 weeks [2].
Inferior dislocation
The shoulder is immobilised with a sling for 2-3 weeks [3].
As the topic of initial surgery vs. conservative treatment is heavily discussed in literature, no final recommendation can be made. However, trends point towards surgical treatment if chances of a second dislocation are high [6]. Therefore, it is of utmost importance to evaluate a risk profile for each patient depending on age, sex and concomitant injuries and inform the patient about chances of chronic instability[6]. More about risk profiles under prognosis and progressive course of disease.
Concomitant injuries in first-time dislocation are [2, 3, 4]:
Bankart lesion
Hill-Sachs lesion
Reverse Hill-Sachs lesion
Rotator cuff tears
SLAP lesion
Humerus fracture
Scapular fracture
Neurological injuries
Vascular injuries
Prognosis and progressive course of disease
Prognosis and progressive course of disease
It has been reported that patients below the age of 30 at first-time anterior dislocation have a recurrence rate of 47%-89% [6]. With increasing age, chances of a second dislocation decrease until at the age of 40 or above chances of a second dislocation are 10%-22% [6]. Chances of developing chronic instability and recurrent dislocations or also high in patients with significant bone defects of the glenoid (>20% of the glenoid length, Bankart-lesion) or humeral head (>5/8 of humeral head radius, Hill-Sachs-lesion) [6].
Patients, who suffered from posterior dislocation have a 18% risk of developing recurrent instability [2]. Three risk factors, including age <40 at first dislocation, a reverse Hill-Sachs lesion of >1.5cm^3 and dislocation during seizure, have been identified [5].
After inferior dislocation, instability has been reported at 11% after an average of 2.7 years [3]. Some authors claim that in contrast to other directions of dislocations, stiffness occurs at a much higher rate than instability [3].
References
References
Provencher, Matthew T., Kaare S. Midtgaard, Brett D. Owens, and John M. Tokish. 2021. "Diagnosis And Management Of Traumatic Anterior Shoulder Instability". Journal Of The American Academy Of Orthopaedic Surgeons 29 (2): e51-e61. doi:10.5435/jaaos-d-20-00202.
Rouleau, Dominique M., Jonah Hebert-Davies, and C. Michael Robinson. 2014. "Acute Traumatic Posterior Shoulder Dislocation". Journal Of The American Academy Of Orthopaedic Surgeons 22 (3): 145-152. doi:10.5435/jaaos-22-03-145.
Nambiar, Mithun, David Owen, Peter Moore, Ashley Carr, and Malcolm Thomas. 2017. "Traumatic Inferior Shoulder Dislocation: A Review Of Management And Outcome". European Journal Of Trauma And Emergency Surgery 44 (1): 45-51. doi:10.1007/s00068-017-0854-y.
Smith, G.C.S., T.J.S. Chesser, I.N. Packham, and M.A.A. Crowther. 2013. "First Time Traumatic Anterior Shoulder Dislocation: A Review Of Current Management". Injury 44 (4): 406-408. doi:10.1016/j.injury.2013.01.001.
Robinson, C. Michael, Matthew Seah, and M. Adeel Akhtar. 2011. "The Epidemiology, Risk Of Recurrence, And Functional Outcome After An Acute Traumatic Posterior Dislocation Of The Shoulder". Journal Of Bone And Joint Surgery 93 (17): 1605-1613. doi:10.2106/jbjs.j.00973.
Kane, Patrick, Shawn M. Bifano, Christopher C. Dodson, and Kevin B. Freedman. 2015. "Approach To The Treatment Of Primary Anterior Shoulder Dislocation: A Review". The Physician And Sportsmedicine 43 (1): 54-64. doi:10.1080/00913847.2015.1001713.
Hendey, Gregory W. 2016. "Managing Anterior Shoulder Dislocation". Annals Of Emergency Medicine 67 (1): 76-80. doi:10.1016/j.annemergmed.2015.07.496.
Franklin, Corinna C., and Jennifer M. Weiss. 2019. "The Natural History Of Pediatric And Adolescent Shoulder Dislocation". Journal Of Pediatric Orthopaedics 39 (Supplement 1): S50-S52. doi:10.1097/bpo.0000000000001374.
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