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Traumatic Subclavian artery pseudoaneurysm secondary to periprosthetic fracture of shoulder arthrodesis

Published onApr 15, 2023
Traumatic Subclavian artery pseudoaneurysm secondary to periprosthetic fracture of shoulder arthrodesis
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Abstract :

Traumatic subclavian artery pseudoaneurysms are rare clinical entities. Initial symptoms may be covert, resulting in delayed diagnosis and severe complications. There have been several case reports on traumatic subclavian pseudoaneurysm, but this may be the first case report involving an arthrodetic shoulder.

In this case report, we discuss an 85-year-old gentleman who presented with a right shoulder pulsatile mass after a couple of traumatic falls onto the arthrodetic shoulder. CT angiogram demonstrated a right subclavian pseudoaneurysm, and the patient was treated with endovascular stenting.

This case highlights the importance of recognizing traumatic subclavian artery pseudoaneurysm is necessary, especially in high-risk patients (with previous arthrodesis/prosthesis.), to reduce morbidity and mortality.

Keywords: pseudoaneurysm, glenohumeral arthrodesis, subclavian pseudoaneurysm, periprosthetic fracture, acute fracture, non-union

False aneurysms arise at the site of arterial damage and are known as pseudoaneurysms. They differ from real aneurysms in that they are not contained inside a layer of the artery wall.

History :

An 85-year-old gentleman with a history of right shoulder arthrodesis presented to A&E after a mechanical fall onto his right shoulder.

On examination, he was tender at the level of his humeral head. Blood pressure and distal pulses were normal. The previous arthrodesis and chronic brachial plexus injury limited movement and sensation. The patient had right shoulder arthrodesis five decades ago for a fracture which resulted in a brachial plexus injury. The patient did not report any acute neurological symptoms.

His past medical history includes Type 2 diabetes, Primary hypertension, chronic heart failure, and peripheral vascular disease.

Physical examinations were otherwise unremarkable.

Findings:

The patient was discharged with a humeral brace, to be followed up at fracture clinics on a monthly basis. A joint decision for conservative management was made due to the osteopenic bone quality and poor soft tissue coverage. It was noted that during his 2nd follow-up, the patient reported a reduction in shoulder function. Serial shoulder radiographs during the follow-up appointments demonstrated non-union of the humeral fracture.

3 months later, the patient presented again to A&E with a second fall onto the right shoulder. On examination, there was a large right shoulder pulsatile mass overlying the anterior aspect of the shoulder. Distal pulses were intact, and there were no acute neurological changes. The patient was hemodynamically stable.

Figure 1

Shoulder radiograph prior to presentation: Shows solitary arthrodetic screw (cannulated cancellous screw).

Figure 2

Initial shoulder radiograph after 1st fall demonstrated a peri-prosthetic fracture of his right shoulder at surgical neck fracture inferior to the arthrodesis level.

Figure 3

Figure 3 & Figure 4 : Follow-up shoulder radiographs at fracture clinic 1 month after the initial fall and 2.5 months after the initial fall. Non-union periprosthetic fracture inferior to the arthrodesis screw. There is an appearance of a soft tissue opacity surrounding the shoulder joint in Figure 4 .

Figure 4

Figure 3 & Figure 4 : Follow-up shoulder radiographs at fracture clinic 1 month after the initial fall and 2.5 months after the initial fall. Non-union periprosthetic fracture inferior to the arthrodesis screw. There is an appearance of a soft tissue opacity surrounding the shoulder joint in Figure 4 .

Figure 5

Shoulder radiograph at time of 2nd fall . There is a further medial displacement of the fractured fragment with non-union. Arthrodesis screw was otherwise still intact with no new periprosthetic fracture/loosening. The overlying soft tissue opacity has increased in size on this current radiograph.

CT angiogram was subsequently performed. Both arterial and delayed phase were performed, demonstrating a large enhancing soft tissue mass lesion replacing the proximal humerus.

Figure 6

Figures 6 & 7 : CT angiogram in the arterial phase & CT Angiogram in venous phase. The subclavian artery traverses posterior to the lesion with some anterior flattening due to mass effect. No apparent neck is evident. However, distal vasculatures demonstrate reduced contrast enhancement. The uniform enhancement and increased attenuation on delayed scan indicate a degree of vascular connection.

Figure 7

Figures 6 & 7 : CT angiogram in the arterial phase & CT Angiogram in venous phase. The subclavian artery traverses posterior to the lesion with some anterior flattening due to mass effect. No apparent neck is evident. However, distal vasculatures demonstrate reduced contrast enhancement. The uniform enhancement and increased attenuation on delayed scan indicate a degree of vascular connection.

CT angiogram showed a homogenous collection at the fracture site without direct communication with the arteries. It was proposed that the pressure from the lump has reduced the attenuation to the artery distally. The learning point from this case was that a homogenous and uniformly enhancing lesion even if it does not show direct communication with arteries in a post-traumatic arthrodesis shoulder is unlikely to be a solid mass/malignancy, and a pseudoaneurysm or hematoma, should be excluded first. It is hypothesized in multiple case reports that the narrow neck of a pseudoaneurysm leads to delayed diagnosis [1][2][3]. It also seems to be the case with our patient.

Subsequently, an ultrasound Doppler was made to characterize the lesion further. US Doppler demonstrated a large 9cm collection with turbulent flow. Findings were interpreted as a subclavian aneurysm arising from the subclavian artery with 0.6 cm neck

Figure 8

Doppler showing arterial waveform within the neck of lesion.

Figure 9

Narrow neck of pseudo-aneurysm is demonstrated in this image.

Figure 10

US Doppler of the shoulder demonstrating turbulent flow.

The patient underwent endovascular treatment with a 9x5mm Viabhan stent and post dilated with a 7mm balloon by the Interventional Radiology team.

Retrograde right CFA 5F access upgraded to 9F to facilitate stent. Angiograph confirmed pseudoaneurysm in the right shoulder region being fed by a breach in the continuity of the distal subclavian/proximal axillary artery. The distal position was gained in the brachial artery with stiff Amplatz guide wire, which straightened the vessel. A 5F parallel vertebral catheter was advanced with its tip in the innominate artery, and angiography was performed to delineate the pseduo0aneurysm. A 9mm x5cm Viabhan stent was placed and post-dilated using a 7m m balloon, satisfactorily excluding the pseudo-aneurysm.

Closed with 8F angioseal. No immediate post-op complication was reported.

Figure 11
Figure 12
Figure 13
Figure 14

Figure 11, 12,13 & 14 : Top to bottom, Figure 11 shows faint opacification of the pseudo-aneurysm in the arterial run. In figure 12 the opacification becomes larger but less dense as contrast mixes with the turbulent blood within the pseudo-aneurysm. Figure 13 stent has been placed. Figure 14, the check artery run shows no opacification as it was noted before. Because the neck was too narrow, the stenting was sufficient to exclude this pseudoaneurysm. Works in a similar principle to the flow diverter in the brain.

Discussion:

Glenohumeral arthrodesis is associated with multiple long-term complications such as infection, pain, unacceptable arm position, pseudoarthrosis, and periprosthetic fracture [4][5][6]. Periprosthetic fracture is the 2nd most common postoperative complication in glenohumeral arthrodesis, with studies demonstrating an incidence rate between 13-21% [6] [7].

Old age, female gender, osteoporosis/osteopaenia , rheumatoid arthritis, arthrodesis loosening, and infection [7] [8] are risk factors for periprosthetic fracture as they result in weaker bones that may fracture even from low-impact injury [9].

Neurovascular structures such as the axillary artery, subclavian artery, and brachial plexus are at risk of injury due to their anatomical proximity to the glenohumeral joint.

Subclavian artery pseudoaneurysm is a rare clinical entity secondary to traumatic or iatrogenic causes. The subclavian artery pseudoaneurysm incidence rate ranges between 0.4 to 1.0% [10]. Blunt trauma accounts for less than 5% [11] of traumatic subclavian injuries. The low incidence can be attributed to the protective factor from the musculoskeletal structures overlying the subclavian artery.

The relatively high incidence of bony injuries associated [12] with subclavian artery injury suggests high-impact trauma, such as motor vehicle accidents or falls from height. Binet et al. [13] proposed that vascular injury results from rapid deceleration and shearing forces on the artery. This is less likely in our case due to the absence of high-impact fall. Instead, the vascular injury could have been secondary to fractured fragments.

Literature search demonstrates a few cases [6][14][15][16][17][18][19][20] of traumatic subclavian pseudoaneurysm. However, this may be the first case involving a glenohumeral arthrodesis.

In the early stages of subclavian pseudoaneurysm, clinical findings may be covert. As pseudoaneurysm increases in size, it may present as a pulsatile palpable mass [20] and exerts a mass effect on nearby neurovascular bundles resulting in complications such as thromboembolic episodes, neurological compromise [16], ischemia [21], Horner syndrome [14][18], rupture and possibly death.

Ultrasonography can also be a valuable tool in the initial assessment of vascular injuries. The benefits of ultrasonography over angiography include the absence of ionizing radiation and contrast usage, availability, and cost. As demonstrated in this case, diagnosis can be complicated in the presence of longstanding neurological deficit or absence of overt symptoms. The use of angiography to aid diagnosis has been well documented in the literature [22]. Contrast-enhanced ultrasound also would be an option to characterize the neck of an aneurysm better if the Doppler study was limited [23]. However, fortunately, in our case, we could see the narrow neck of the aneurysm on Doppler itself.

Prompt assessment with ultrasound Doppler and CT angiogram, even without overt clinical findings, should be initiated to avoid severe complications and mortality. Management of subclavian pseudo-aneurysm is also challenging due to the anatomy and associated surgical complications. As it is located posterior-inferiorly to the clavicle, compression is unsuitable. Historically, surgical repair has been the mainstay for managing subclavian pseudoaneurysms. However, it carries high morbidity, e.g., rupture, thromboembolic episodes, iatrogenic neurovascular injury, hemorrhage, infection, and nature of the operation (open thoracotomy).

Current practices such as ultrasound—guided thrombin injection and endovascular repair (stent insertion) have replaced surgical repair as they carry lower morbidity [24]. This case raises clinical awareness of subclavian pseudoaneurysm in an arthrodesis shoulder post-traumatic fall, especially in the presence of a pulsatile swelling.

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