1 Background

Anterior shoulder dislocations are a very common and they are very dramatic, painful and patients present early for management.¹ The published literature on bilateral coracoid fractures with chronic anterior dislocations is sparse. Management of these condition requires good patient and radiological assessment.² These conditions have been commonly seen in patients with epilepsy and only the arm that they fell on is adequately investigated³ Treatment modalities can vary from conservative treatment by closed relocation and immobilization in patients who come within 6 weeks to surgical methods. The options in surgery include glenoid reconstruction, hemiarthroplasty (HA) with bone defect augmentation, capsular repair, total shoulder arthroplasty (TSA), and reverse shoulder arthroplasty (RSA).

We present a case of a young 30-year-old male who presented with a chronically locked anterior dislocation of the left shoulder and recurrent right shoulder dislocation with bilateral non-union of the coracoid.

2 Case presentation

A right-handed dominant 34-year-old male presented with bilateral shoulder pain and reduced range of motion of the left side and recurrent instability of the right shoulder. The mechanism of injury for the left side was due to a fall when he slipped on a wet floor, one year ago. He had a left shoulder dislocation that failed two attempts at reduction and resulted in severe pain and stiffness. He also reported right shoulder dislocation while playing soccer where he slipped and fell on the affected side, 6 months ago. He was able to manually reduce the right shoulder dislocation with two other reported incidences of unprovoked trauma. During his morbid period, he had reduced activities of daily living and analgesic drug dependence. He had no history of seizures, trauma, or electrocution. He also had no history of any comorbidities.

On examination, his Beighton's score was 3. On the left side, there was a loss of contour of shoulder with gross restriction of range of movements. There was significant muscle wasting around the shoulder joint. On the right side, the apprehension test was positive for shoulder dislocation. The neurovascular examination was normal, on both sides.

3 Investigations

Plain radiographs of the left shoulder revealed anteriorly displaced humeral head in the subcoracoid region, indicating an unreduced anterior dislocation. There was a discontinuity along the medial rim of left glenoid. Few bony fragments were seen along inferior glenoid rim in the right shoulder, suggesting loose bodies. There was non visualisation of normal coracoid process in the left shoulder (Fig. 1). the right shoulder was located in the glenoid cavity.

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Fig. 1 Plain Radiograph of the Chest (a) and Anterior and posterior view of right (b) and left (c) shoulder joints, showing dislocation of the left shoulder (a, c). There is a discontinuity seen along the medial rim of left glenoid (c). Few bony fragments (arrow) are seen along inferior glenoid rim in the right shoulder (b). There is non visualisation of normal coracoid process in the left shoulder (c).

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Magnetic Resonance Imaging (MRI) confirmed an unreduced (locked) anterior dislocation of the left shoulder, with a large engaging Hill Sachs lesion, a bony Bankart's lesion with anterior glenoid bone loss, and ununited fracture of the coracoid process, which is displaced anteriorly and lying anterior to humeral head (Fig. 2).

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Fig. 2 Left MRI axial images PD (a) & PDFS (b), FFE sequences (c), and Sagittal T1W (d), PDFS (e) and coronal images (f) reveals antero-inferior dislocated and impacted head of the humerus (arrow) with bony Hill-Sachs defect in its postero-superior aspect. Bony Bankart's lesion is seen with avulsed anterior labrum displaced anteriorly (arrow head). There is also associated fracture of coracoid process (∗), which is displaced anteriorly and lying anterior to humeral head seen in (a).

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The MRI of right shoulder revealed a Hill Sachs defect in its postero-superior aspect, a bony Bankart's lesion (with bone loss of 25%) and an avulsed and displaced anterio-inferior labrum.

There was also a non-ununited fracture from the base of coracoid process, with anterior displacement (Fig. 3).

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Fig. 3 Right MRI axial images PD (a) & PDFS (b), and coronal STIR (c) images reveals mild antero-inferior subluxation of the humeral with bony Hill-Sachs defect in its posterosuperior aspect (arrow). Bony Bankart's lesion is seen with avulsed anterio-inferior labrum displaced anteriorly (arrowhead). Axial T1 (d), FFE (e) and sagittal T1W images (f) show associated comminuted fracture of coracoid process (∗), which is mildly displaced anteriorly with few separated fracture fragments from the base of coracoid process (x).

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The computed tomography (CT) scan of the right shoulder identified a comminuted fracture of coracoid process, with a mild anterior displacement. Hill-Sachs lesion and bony defect in the glenoid were also seen (Fig. 4).

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Fig. 4 CT scan of the right shoulder (a) with sMIP reconstructed images (b) identifies a comminuted fracture of coracoid process (∗), which is mildly displaced anteriorly with few separated fracture fragments from the base of coracoid (x). Hill-Sachs lesion is also appreciated in image (a) (arrow) with bony defect in glenoid (arrowhead).

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4 Treatment

The left side was initially managed with a Latarjet's procedure and an uncemented hemiarthroplasty. The ununited coracoid process with a superior displacement was found. But due to recurrent instability it was converted to a reverse shoulder arthroplasty (Fig. 5). The right side also showed an unreduced humeral head, a non-union of the coracoid process and a bony Bankart's lesion. The right side treated with an open Latarjet's procedure, using the ununited coracoid as a graft, which was fixed with two screws fixation (Fig. 6). This bony glenoid augmentation provided enough stability in external rotation and abduction as confirmed intraoperatively and at postoperative follow ups.

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Fig. 5 Plain radiograph of the right shoulder showing reverse shoulder arthroplasty.

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Fig. 6 Plain radiograph of the left shoulder showing reconstructed anterior glenoid deficiency with the coracoid graft and fixation with two screws and an anchor to repair the capsule-labral complex.

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5 Discussion

Bilateral anterior shoulder dislocation is not a commonly encountered phenomenon. Dunlop et al. found that 11% of patients who presented with bilateral involvement came for treatment more than 3 weeks.² Patients who presented with chronic (more than 3 weeks) bilateral anterior shoulder dislocations was mostly due to epilepsy,³ and 47% of these cases were associated with a bony lesion with involvement of either the greater tuberosity (78%) or proximal humerus (22%).³

The coracoid fractures associated with shoulder dislocations are rare,^4,5 but an exact incidence of it is not known. There are postulated theories on the mechanism of coracoid fracture in anterior dislocation. One is an avulsion due to violent rapid contraction of the conjoined tendon and the pectoralis minor. This occurs in patients with subglenoid dislocations.^7,8 The other theory is a direct high impact on the coracoid process by the dislocated humeral head. Saragaglia et al. thought that this perhaps occurs when patients have a more proximal displacement of the humeral head or have a longer and laterally pointing coracoid.⁹ Ogawa et al. however did not agree to this theory.¹⁰ We believe that in our case a combination of these both mechanisms were responsible.

Special radiographic views (e.g. lateral axillary) are usually difficult in acute traumatic shoulder due to pain and hence the coracoid fractures can be missed.¹¹ Garth et al.proposed an apical oblique projection view that has minimal manipulation and discomfort.

Another view that can be used is the Lamy's sagittal view.¹² The gold standard imaging modality is a Computed Tomography (CT) scan with 3D reconstruction.¹³ This is helpful in both diagnosis and preoperative planning.

MRI is used to evaluate the additional injuries, specifically labral and rotator cuff tears. Cross-sectional imaging is necessary to guide manipulation or surgery as cross sectional imaging can provide additional information about presence of osseous or soft tissue lesions including engaging Hill Sachs’ defect (obstructing fracture fragment from the glenoid or humeral head) or intraarticular biceps dislocation.¹⁴

Standard MR imaging of the shoulder is acquired in three planes. The oblique coronal plane, Oblique sagittal images and other standard shoulder pulse sequences include fast spinecho proton density/T2 weighted with and without fat saturation, thus evaluating the joint in three plane. T1 sequence to evaluate the bone marrow is also obtained as part of the protocol.

Conventional MR images provides excellent soft tissue evaluation along with bone information. Periartcular edema/haemorrhage, location and severity of bone injury seen on MRI also helps in elucidating the mechanism of injury. Evaluation of labro-ligamnetous injury is depicted beautifully by the MRI with detailed evaluation of glenohumeral ligaments, articular cartilage and additional fractures of coracoid/acromion.^14,15

Saragaglia et al.,¹⁰ have classified these coracoid fractures into three types: type 1, involve fracture of the base with acromioclavicular dislocations, type 2 injuries have fracture of the horizontal part with anterior shoulder instability, and in type 3, there is a fracture-avulsion of the coracoid tip. The Type 2 fractures are associated with shoulder dislocations and usually have un displaced coracoid fractures.^4,6,9,16 Our case had a type 2 fractures on both the sides.

The management of the chronic dislocations is variable. Closed reduction after 6 weeks is not recommended. This can risk humeral head iatrogenic fracture and neurovascular damage. The reduction is also made difficult by the fibrous tissue around the glenoid fossa.¹² Albeit the risk, a case of 7 weeks old bilateral closed reduction has been documented with good outcomes by Mynter et al.¹⁷ The cases with chronic dislocations present with pain, loss in range of motion, and deformity, like left shoulder of our case. The management can range from reconstruction of the glenoid effects, resection arthroplasty to replacement arthroplasty.

The glenoid reconstruction is required in significant glenoid bone loss (>20%) and the choice of glenoid reconstruction can vary depending on the size of the coracoid process fragment. If the fragment is large with intact cortex, Latarjet's procedure is indicated.⁴ For a smaller fragment of the coracoid tip, Boytchev's procedure is used, which involves rerouting the conjoined tendons of the coracobrachialis posteriorly to the subscapularis muscle and reattached to the coracoid process.¹⁸ The location of the coracoid process fracture can also determine the stabilization method that can be used.¹⁹ Coracoid horizontal segment (coracoid elbow) can be managed by the Latarjet's procedure, whereas, Eden-Hybinette procedure is used for the coracoid tip fracture, by transposition of the iliac bone block.

Chamseddine et al. reported an osteotomy of the lesser tuberosity for chronic posterior shoulder dislocation. This has also been seen useful in chronic anterior dislocation with as it allows for preservation of the subscapularis.²⁰

6 Conclusion

This case highlights a rare type of presentation of coracoid fractureswith shoulder dislocations. The coracoid fractures associated with anterior dislocations (Type 2) are usually un displaced and easy to miss. Therefore, proper assessment of patients who present with anterior dislocations should be investigated with greater caution bearing in mind the possibility of associated coracoid fractures.

7 Patient consent

The authors confirm that an informed consent was obtained from the patient for publication of this case report.

Funding

Nil.

Authors’ contribution

JT: Literature Review, Writing, Editing, Final check.

AV: Literature Review, Writing, Editing, Final check.

NG: Writing, Image contribution, Editing, Final check.

RV: Conceptualization, Writing, Editing, Final check.