Case Report

A 20-year-old man with no relevant medical history presented at the emergency department reporting type-VI right AC dislocation, displaced and comminuted open left tibio-fibular shaft fracture (Gustilo IA) and homolateral medial malleolar fracture, multiple rib and vertebral fractures, after being injured in a motorbike accident. The AC dislocation was provoked by highspeed impact against a road pole. All lesions were diagnosed after a total body CT scan, executed on patient arrival at the emergency department, according to hospital protocols for polytraumatized (Figure 1). The patient arrived unconscious, hypotensive with an arrhythmic heart rate. After the early first aid, a low level of haemoglobin was noticed. The clinical scenario suggested a possible hypovolemic shock and therefore a total body CT scan with contrast was immediately requested to rule it out. The CT scan showed active spreading of contrast in arterial phase from the subclavian right artery, a homolateral hematoma (13x10cm) in the subclavian region, suggesting a right axillary-subclavian artery traumatic rupture in addition to type VI right AC dislocation (Figure 2). The patient immediately underwent an endovascular repair of subclavian/axillary artery injury with a covered stent (VIABAHN® 6mmx15cm). After the endovascular repair surgery, the patient underwent orthopaedic surgery. Surgical open reduction of the AC dislocation was performed with open access to AC joint and manual manoeuvres; the joint was stabilized with 3 K wires. No coracoclavicular ligament repair was performed (Figure 3-6). The open shaft tibia fracture and medial malleolar fracture were treated respectively with external fixation (XCaliber® Orthofix) and with cannulated screw. The following days a complete upper right limb paralysis with hypo/anaesthesia of the homolateral axillary region was found. After three weeks electromyography and evoked potentials were performed which demonstrated severe nerve conduction disorder along the somatosensory pathways and axonal injury to the upper trunk of the right brachial plexus. Five weeks after the accident and after clinical and radiographic examination, the three K wires were removed from the right AC joint (Figure 7) to perform brachial plexus MRI which showed involvement of primary trunks. From the radiographic and clinical examination, the dislocation showed signs of healing. However, the paralysis of the upper limb persisted. At 2-year follow-up the patient reported complete upper limb paralysis and no signs of AC secondary dislocations.

Figure 1: 3D reconstruction of total body CT scan executed on patient arrival at emergency department. Detail of right shoulder.

Figure 2: Active spreading of contrast from the right subclavian artery in arterial phase contrast CT scan, suggesting traumatic rupture in addition to type VI right AC dislocation.

Figure 3: Intraoperative fluoroscopy after reduction and K-wires fixation of the AC joint.

Figure 4: Postoperative X-rays.

Figure 5: Postoperative CT scan showing subclavian/axillary artery repair.

Figure 6: Absence of contrast spreading after vascular repair in the postoperative CT scan.

Figure 7: Postoperative X-rays after 5-week removal of K wires.

Discussion

Among the dislocating injuries of the upper limbs, type VI acromioclavicular (AC) joint dislocation is extremely rare and only few case reports are reported in current literature [4]. Type VI AC dislocation can occur with two different patterns: subacromial or subcoracoid [2]. Mechanism of injury consists of extreme abduction and subsequent external rotation of the shoulder with highly intensive load [5]. Traumatic dislocations are often associated to other injuries involving surrounding anatomical structures. In type VI AC dislocations, concomitant clavicular and coracoid fractures, ligamentous ruptures and neurovascular lesions can be observed [8]. The latter represents a surgical emergency if important arterial vessels are damaged. In such cases, a multidisciplinary approach is mandatory. In most of the analysed case-reports, diagnosis of AC dislocation is usually late. As a matter of facts, if not considered in the differential diagnosis and specifically looked for on imaging studies, the lack of specific clinical signs on physical exam combined with other distracting injuries can make it easy to miss, especially in polytrauma patients. In some cases, possible lack of initial local imaging is reported, leading to late diagnosis [9]. For this reason, even though AC joint dislocations are seldom reported, a clinical suspicion during physical exam and radiological assessment is essential to prevent missed or delayed diagnosis of this injury [9]. The commonest reported complication directly caused by late diagnosis is osteolysis of the distal end of clavicle, because of its entrapment under the coracoid process.

The most frequent symptom of presentation, apart from swelling and pain in the acute phase, is mechanical block of shoulder. In our report, clinical signs of a hypovolemic shock were essential for differential diagnosis and instrumental exams made possible to highlight the presence of the arterial lesion. Contrast CT scan was the most diriment exam for diagnosis and permitted a sudden vascular surgery repair of the damaged artery, achieved with a stent positioned via endovascular approach. The ability of the emergency department to promptly request appropriate exams was also determinant to achieve a correct early diagnosis. Although in current literature not many cases of type VI AC dislocation are mentioned, many surgical techniques are reported [3,8,1013]. Conservative treatment is never possible for type VIb AC dislocations. It can be taken into consideration only in type VIa, also generally surgically treated in acute setting; conservative treatment is possible in chronic dislocations with no sympthoms, no ROM limitations and no distal clavicle osteolysis [4]. In one reported case the type VIa AC dislocation reduced spontaneously and no further treatment was considered [14]. When conservative treatment was attempted in type VIb dislocations [13,15], the difficulty with which the outer end of the clavicle was reduced suggests that open reduction is a best choice. Even if reduction may be possible in the early stages by closed manoeuvres, traction and hyperabduction of the arm may provoke neurologic injuries. Successful closed reduction of subcoracoid dislocations has never been reported and when taken into consideration, was immediately converted into surgical open treatment. On the other hand, if not treated, traumatic AC dislocation results in recurrent dislocation [16]. The integrity of the coracoclavicular ligaments is the greatest concern, so reduction and fixation of the clavicle is often followed by coracoclavicular ligaments reconstruction to ensure the stability of the acromioclavicular joint [3]. When type VIb AC dislocation is surgically approached, clavicle entrapped under coracoid and posterior to intact conjoint tendon is a common intraoperative finding. Coracoclavicular ligaments (conoid and trapezoid) are always disrupted, but in some cases their integrity is reported, avoiding the need for their reconstruction. AC ligaments, articular capsule and intra articular disk are often also damaged: intra articular disk damage seems to induce future AC joint arthrosis. When AC dislocation is tardively treated, osteolysis of distal clavicle is a common finding, compromising future complete shoulder ROM recovery. Clavicle reduction can occasionally be difficult [13] and when reduction is impossible, osteotomy of the coracoid process is performed to unhook the clavicle. It usually happens when surgery is delayed but it is also practiced when the surgeon is reluctant to apply more force on an already compressed brachial plexus. Distal clavicle entrapment by conjoint tendon is a further common complications to reduction. Surgical techniques usually focus on coracoclavicular ligament augmentation because they proved to be primary stabilizers of the acromioclavicular joint. It is reported the use of temporary coracoclavicular lag screw and AC K-wire, ligament repair and imbrication of the deltotrapezial fascia over the top of the clavicle [5]. Use of two Steinmann pins [12], coracoclavicular screw [13] or tension band wiring [3] to stabilize the dislocation are also reported. AC K-wire fixation is also reported. In three cases, only open reduction was performed and no implant was used; in a different case, stabilization was obtained by suturing deltotrapezial fascia and joint capsule [8,16,17]. As far as timing is concerned, treatment is recommended within 2-3 weeks [18]. Despite this, literature shows that even if diagnosis is delayed, surgical treatment can give a good outcome apart from cases in which distal clavicle osteolysis is already occurred [17]. As a matter of facts, delay in reduction of dislocation can lead to clavicle osteolysis which compromises good functional outcome [9]. During follow-up, osteolysis of clavicular distal end, calcification of the coracoclavicular ligaments and joint capsule, narrowing of the joint surface are mentioned. AC joint arthrosis is also a late complication especially when intra articular disk is ruptured and dislocated. However, despite all these radiological findings, all patients had satisfactory functional results [11]. In our case no ligament reconstruction was performed. Since the patient reported complete upper limb paralysis, no evaluation of functional outcomes was possible. The only purpose of the performed treatment was to restore anatomical continuity of the shoulder girdle and to release the neurovascular structures to avoid further damage. This is an important example of teamwork and co-operation between the emergency department, vascular and orthopaedic surgeons that allows a safe and effective management of the patient. To our knowledge this is the first case of a Type VI AC dislocation associated with traumatic rupture of the axillarysubclavian artery and severe neurological complication managed in our department. Within the limitation of this case report, we believe it is mandatory to exclude neurovascular damages prior to any surgical intervention, as this was crucial in our case.

Conclusions

Type VI AC dislocation is a rare shoulder injury, which can be presented with neurovascular damage. Correct identification of injured anatomical structures is fundamental for clinical and surgical management. Vascular repair and subsequent open reduction and fixation with 3 K-wires demonstrated to be a successful and effective technique.

Conflicts of interest: The authors certify that there is no conflict of interest with any financial organization regarding the material discussed in the manuscript.

Funding: The authors report no involvement in the research by the sponsor that could have influenced the outcome of this work.

Authors’ contributions: All authors contributed equally to the manuscript and read and approved the final version of the manuscript.

References

1. Patterson, William R (1967) Inferior Dislocation of the Distal End of the Clavicle, The Journal of Bone & Joint Surgery: September 49: 11841186.
2. Gerber, C; Rockwood, C A Jr (1987) Subcoracoid dislocation of the lateral end of the clavicle. A report of three cases., The Journal of Bone & Joint Surgery: Volume 69: 924-927.
3. Davies, EJ, Fagg JA and Stanley D (2014) ‘Subacromial, supracoracoid dislocation of the acromioclavicular joint with ipsilateral clavicle fracture: a case report with review of the literature and classification’, JRSM Open.
4. Juhn MS, Simonian PT (2002) Type VI acromioclavicular separation with middle-third clavicle fracture in an ice hockey player. Clin J Sport Med. 12: 315-317.
5. Grossi EA, Macedo RA (2013) Acromioclavicular dislocation type VI associated with diaphyseal fracture of the clavicle. Rev Bras Ortop. 48: 108-110.
6. Canbora KM, Tu¨ zu¨ ner T, Yanik SH and Go¨ rgec¸ M (2011) Subcoracoid dislocation of the acromioclavicular joint. Acta Orthop Traumatol Turc 45: 463–465
7. Kontakis GM, Katonis PG (1997) Subcoracoid trapping of the proximal fragment of a fractured clavicle. J Trauma. 43: 144-145.
8. Torrens C, Mestre C, Pérez P, Marin M (1998) Subcoracoid dislocation of the distal end of the clavicle. A case report. Clin Orthop Relat Res. 348: 121-123.
9. Balai E, Sabharwal S, Griffiths D, Reilly P (2020) A type VI acromioclavicular joint injury: subcoracoid dislocation in a patient with polytrauma. Ann R Coll Surg Engl, 102: e1-e3.
10. Schwarz N, Kuderna H (1988) Inferior acromioclavicular separation. Report of an unusual case. Clin Orthop Relat Res. 234:28-30.
11. Kapicioglu M, Cetin H, Bilsel K (2019) Late diagnosis of subcoracoid type 6 AC dislocation: A case report. SICOT J. 5: 37.
12. Emami, Mohammad J, Ali H, Zahra B and Arash K (2010) “Subcoracoid dislocation of the lateral end of the clavicle: Mechanism of injury.” Injury Extra 41: 58-61.
13. Wisniewski, T (2003) Inferior Subcoracoid AcromioclavicularDislocation. Eur J Trauma 29: 156–160.
14. Cresswell TR (1998) Spontaneous reduction of an inferior acromioclavicular joint dislocation. Injury. 29: 567-568.
15. McPHEE, I. B. F.R.A.C.S (1980) Inferior Dislocation of the Outer End of the Clavicle, The Journal of Trauma: Injury, Infection, and Critical Care: August 20: 709-710.
16. Sage J (1982) Recurrent inferior dislocation of the clavicle at the acromioclavicular joint. A case report. Am J Sports Med. 10: 145-146.
17. Neumann JA, Boyle MJ, Reay KD, Lee J, Coleman B, Dalgleish AJ (2014) Subcoracoid dislocation of the distal clavicle: A case report with eight-year follow-up. Inj Extra 45: 58-61.
18. Tauber M, Koller H, Hitzl W, Resch H (2010) Dynamic radiologic evaluation of horizontal instability in acute acromioclavicular joint dislocations. Am J Sports Med. 38: 1188-1195.