Schulterinfo.ch - Sternoclavicular SC Joint - Dislocation
Schulterinfo.ch
Abstract
Sternoclavicular dislocation is a non-physiological translation of the proximal clavicula often associated with high impact collisions, which results in pain and/or other symptoms.
Dislocation of the sternoclavicular joint is most often a result of high impact trauma such as: traffic accidents, rugby, American football, and other high collision sports. Dislocation without prior trauma occurs in patients with collagen deficiency disorders or anatomical anomalies of the sternoclavicular joint. Further, this also occurs very often with ageing and usually affects the dominant side, with women being somewhat more affected than men.
Patients suffering from SCJD can roughly be divided into two groups. Anteriorly dislocated SC joints cause a painful lump lateral of the sternum, whereas posteriorly dislocated SC joints tend to cause pain in the medial region of the clavicula. Additionally, dislocated SCJs in posterior direction might pose an acute emergency as they can compress the mediastinum and lead to dyspnoea, dysphagia and vascular- and neurological deficits.
Supplementary to clinical examination and ultrasound, x-ray imaging is used to make a diagnosis.
Most commonly, SCJDs are treated conservatively by closed reduction with subsequent immobilisation of the arm in a sling. If reduction manoeuvre does not proof successful, surgical reduction might be necessary.
Sternoclavicular joint dislocation (SCJD) is a partial or complete ligamentous lesion with disruption of the proximal clavicula from the sternum with pain or loss of function.
Dislocation of the sternoclavicular joint (SCJ) can be either traumatic or atraumatic [1] and in >80% of the cases traumatic dislocation is a result of motor vehicle accidents (MVA) and athletic injuries [2, 3]. Even though the articulation surface of the SCJ is comparably small, the strong ligamentous supporting structure compensates for it, making the SCJ an inherently stable joint [2]. Mechanisms of injury therefore tend to involve relatively high degree of force. Sudden impacts on the lateral aspect of the shoulder (indirect compressing force), such as seen in MVA, or a direct blow to the sternoclavicular joint may be the reason for dislocation [2-4].
- Traumatic (High-energy collisions)
- Motor vehicle accidents
- Sports
- Rugby
- American football
- Etc.
- Atraumatic
- Collagen deficiency disorders
- Clavicular deformity
- Abnormal muscle patterning
- Benign subluxation
- Condition after inflammation in the joint
Additionally, SCJD can be categorised by the direction of dislocation:
- Anterior dislocation
- Posterior dislocation
- Superior dislocation
- Inferior dislocation
Anterior dislocation is 1.5 - 9 times more likely to occur than posterior dislocation [4, 5]. These numbers can be explained by the anatomy and biomechanics of the SCJ as the anterior part of the sternoclavicular joint capsule is the weakest and injuries are most often due to lateral compressive force to the shoulder, therefore resulting in a rupture of the anterior capsule [6]. Superior and inferior dislocation are clinically irrelevant and present themselves so rarely that they are not discussed hereinafter. Although rare, posterior dislocation of the sternoclavicular joint might pose a potential life-threatening danger, since underlying mediastinal structures might be compressed in the process [1-6].
SCJD accounts for 3% of all dislocations around the shoulder and is therefore a rather rare injury [1]. As the medial end of the clavicule is the last epiphyseal plate to ossify at the age of 23-25, patients below that age are more likely to fracture the medial physeal plate of the clavicula, resulting in a pseudodislocation instead of suffering from a true dislocation [1-3, 5].
Patients with an anteriorly dislocated SCJ present with a painful lump lateral to the sternum whereas patients suffering from a posterior dislocation complain about even more intense medial clavicular pain and might feature a medial end of the clavicula, which is less prominent compared to the contralateral side [1, 6]. Both pain and deformity are usually aggravated in supine position [2]. Additional symptoms in posteriorly dislocated SC joints are not a rare occurrence. About 33% of patients report dyspnoea or dysphagia and roughly 15% suffer from symptoms of vascular compression [4].
In both cases, paraesthesia and/or weakened pulses or signs of venous congestion of the upper limb may be present as well as an adducted arm in form of a relieving posture to minimise movement in the shoulder girdle [6].
Patients will usually describe a traumatic event, related to an accident or sports, feeling a pop at the moment of impact followed by pain and swelling [1]. Often SCJD is not diagnosed immediately, which is why patients might present themselves days or weeks after the initial trauma.
If no specific trauma can be recalled, the examiner should ask about family history, other signs of collagen disorders or muscle deformity.
There are visible signs, which the examiner should pay special attention to in diagnosing SCJD such as a bony lump in anterior dislocation or indentation and hematoma in posterior dislocation [2]. These signs may however not be as distinct since swelling might mask the clinical assessment [2]. A thorough neurovascular status should be assessed as well due to the vicinity of the brachial plexus, of which the ulnar nerve is affected the most [3].
In order to accurately diagnose SCJD, imaging is needed. Initially, an x-ray is performed in AP as well as serendipity view to rule out any trauma to the clavicula [1]. However, obtaining a 3D overview a computerised tomography (CT) is the best modality [1]. The examiner is able to assess the SCJ position and compression of mediastinal structures as well as medial clavicular fractures, which are difficult to see on radiographs due to overlap . A case with CT imaging can be found on Radiopedia.
- Clavicular fracture
- Chest wall injury
- Septic SCJ
- Pneumothorax
- Bronchospasm
Note: SCJD is a rare condition. SCJD should be considered if other differential diagnoses have proven false or circumstances indicate the presence of a SCJD.
Subluxation without rupture of the ligamentous apparatus of the sternoclavicular joint can always be treated conservatively [1]. Patients are instructed to immobilize the affected shoulder with a sling and it is recommended to avoid taking part in contact sports up to six weeks with gradual increase of exercise afterwards [1].
Complete anterior dislocation is initially treated by closed reduction [2]. Patients are asked to lay supine on the examination table with the arm in 90° abduction. Under traction, posterior force is applied to the medial clavicula, resulting in a relocation of the SCJ. The affected arm is immobilized in a sling up to six weeks to reduce the chance of re-dislocation [1]. If symptoms persist with pain or instability, patients can be evaluated for operative treatment. However, since risks often outweigh the patient’s symptoms, close attention to evaluating should be paid.
Complete posterior dislocation may pose an acute emergency. Immediate closed reductions should be performed as soon as possible by a medical professional with a thoracic surgeon on stand-by [7]. The manoeuvre is similar to the anterior dislocation, but instead of applying posterior force, the clavicula is grabbed and pulled anteriorly. In a different manoeuvre the affected arm is placed in a “cross-body-adduction-position”, which serves as the traction and posteriorly directed force is applied to the lateral parts of the shoulder with the clavicula acting as leverage [6]. If reduction has proven successful in CT-scans, the arm is placed in a sling up to six weeks to immobilize the affected shoulder. If closed reduction, on the other hand, does not proof fruitful or patients’ symptoms persist, surgical intervention is required [7]. It should be noted that there are high risks of undergoing operative treatment for posterior SCJD. That is why a cardiovascular surgeon needs to be on stand-by or readily available [1]. There are many different ways to re-stabilize the sternoclavicular joint, each method having it’s use for different kinds of underlying structural damage. After successful surgery, the arm is placed in a sling for six weeks. Return to contact sports is usually possible after intense rehabilitation for six months [1].
Prognosis and progressive course of disease
In most cases, anteriorly dislocated SC joints are unstable after closed reduction [2]. However, patients generally do tolerate symptoms well. In contrast, posteriorly dislocated SC joints tend to be stable after performing closed reduction [2]. A meta-analysis has further shown that full pain-free ROM without redislocation was reported at 92% after closed reduction of posterior dislocation [5].
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