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Large image of Figure 1.

Figure 1

Radiographs at time of injury: AP and Lateral. A) AP Right Shoulder, B) AP Left Shoulder, C) Lateral Right Shoulder, D) Lateral Left Shoulder

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Figure 2

Representative CT scans at the time of injury: A) Sagittal, B) Coronal, and C) Axial views of the left humerus, D) Sagittal, E) Coronal, and F) Axial views of the right humerus.

Large image of Figure 3.

Figure 3

Radiographs of the left humerus 1.5 months after the initial injury, preoperative planning for ORIF. A) Y-view, B) AP Neutral, C) Y-view

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Figure 4

Intra-Operative Radiographs of ORIF Left Proximal Humerus.

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Figure 5

Imaging from 3 months postoperative visit ORIF Left Proximal Humerus. Evidence of some collapse humeral head and potential avascular necrosis.

Large image of Figure 6.

Figure 6

Plain-film radiographs of the right shoulder 8 months after the initial injury demonstrating post-traumatic arthritis: A) AP External Rotation, B) AP Internal Rotation, C) 45-45 oblique view

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Figure 7

Preoperative CT scans of the right shoulder, 10 months after initial presentation: A) Sagittal, B) Coronal, and C) Axial view.

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Figure 8

Intra-Operative Radiographs of Right Reverse Total Shoulder Replacement.

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Figure 9

Imaging from follow-up 1 year and 3 months following ORIF Left Proximal Humerus. Evidence of partial collapse humeral head and avascular necrosis.

Large image of Figure 10.

Figure 10

Intra-Operative Radiographs of Left Hardware Removal and Left Reverse Total Shoulder Replacement

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Posterior shoulder dislocations are a rare and often missed cause of shoulder dislocations. They comprise approximately 2-4% of all shoulder dislocations and are associated with concomitant injuries in about 65% of patients1x1Basal, O., Dincer, R., and Turk, B. Locked posterior dislocation of the shoulder: A systematic review. EFORT Open Rev. 2018; 3: 15–23https://doi.org/10.1302/2058-5241.3.160089

Crossref | PubMed | Scopus (13)
| Google ScholarSee all References
,2x2Betz, M.E. and Traub, S.J. Bilateral posterior shoulder dislocations following seizure. Int Emergency Med. 2007; 2https://doi.org/10.1007/s11739-007-0017-y

Crossref | PubMed | Scopus (13)
| Google ScholarSee all References
,7x7Rouleau, D.M. and Herbert-Davies, J. Incidence of Associated Injury in Posterior Shoulder Dislocation. Journal of Orthopaedic Trauma. 2012; 26: 246–251https://doi.org/10.1097/BOT.0b013e3182243909

Crossref | PubMed | Scopus (78)
| Google ScholarSee all References
. On presentation, posterior shoulder dislocations are associated with severe pain and muscle spasms. The arm is usually adducted and in slight internal rotation, with resistance to external rotation and abduction due to pain5x5Ketenci, I.E., Duymus, T.M., Ulusoy, A., Yanik, H.S., Mutlu, S., and Durakbasa, M.O. Bilateral posterior shoulder dislocation after electrical shock: A case report. Annals of Medicine and Surgery. 2015; 4: 417–421https://doi.org/10.1016/j.amsu.2015.10.010 (PMID: 26904192)

Crossref | PubMed | Scopus (6)
| Google ScholarSee all References
. The most common mechanism of posterior shoulder dislocations is from seizures, usually tonic-clonic, and occur in approximately 34-38% of cases4x4Kelly, M.J., Holton, A.E., Cassar-Gheiti, A.J., Hanna, S.A., Quinlan, J.F., and Molony, D.C. The aetiology of posterior glenohumeral dislocations and occurrence of associated injuries: a systematic review. Bone Joint J. 2019; 101-B: 15–21https://doi.org/10.1302/0301-620X.101B1.BJJ-2018-0984.R1

Crossref | PubMed | Scopus (8)
| Google ScholarSee all References
,7x7Rouleau, D.M. and Herbert-Davies, J. Incidence of Associated Injury in Posterior Shoulder Dislocation. Journal of Orthopaedic Trauma. 2012; 26: 246–251https://doi.org/10.1097/BOT.0b013e3182243909

Crossref | PubMed | Scopus (78)
| Google ScholarSee all References
. Other classic mechanisms include electric shock or electrocution, falls, and anterior-directed shoulder trauma such as a fall on an outstretched hand or motor vehicle accident1x1Basal, O., Dincer, R., and Turk, B. Locked posterior dislocation of the shoulder: A systematic review. EFORT Open Rev. 2018; 3: 15–23https://doi.org/10.1302/2058-5241.3.160089

Crossref | PubMed | Scopus (13)
| Google ScholarSee all References
,2x2Betz, M.E. and Traub, S.J. Bilateral posterior shoulder dislocations following seizure. Int Emergency Med. 2007; 2https://doi.org/10.1007/s11739-007-0017-y

Crossref | PubMed | Scopus (13)
| Google ScholarSee all References
,4x4Kelly, M.J., Holton, A.E., Cassar-Gheiti, A.J., Hanna, S.A., Quinlan, J.F., and Molony, D.C. The aetiology of posterior glenohumeral dislocations and occurrence of associated injuries: a systematic review. Bone Joint J. 2019; 101-B: 15–21https://doi.org/10.1302/0301-620X.101B1.BJJ-2018-0984.R1

Crossref | PubMed | Scopus (8)
| Google ScholarSee all References
,5x5Ketenci, I.E., Duymus, T.M., Ulusoy, A., Yanik, H.S., Mutlu, S., and Durakbasa, M.O. Bilateral posterior shoulder dislocation after electrical shock: A case report. Annals of Medicine and Surgery. 2015; 4: 417–421https://doi.org/10.1016/j.amsu.2015.10.010 (PMID: 26904192)

Crossref | PubMed | Scopus (6)
| Google ScholarSee all References
. Associated injuries include fractures, with posterior fracture dislocations making up less than 1% of all fracture dislocations, rotator cuff tears and reverse Hill-Sachs injury1x1Basal, O., Dincer, R., and Turk, B. Locked posterior dislocation of the shoulder: A systematic review. EFORT Open Rev. 2018; 3: 15–23https://doi.org/10.1302/2058-5241.3.160089

Crossref | PubMed | Scopus (13)
| Google ScholarSee all References
,7x7Rouleau, D.M. and Herbert-Davies, J. Incidence of Associated Injury in Posterior Shoulder Dislocation. Journal of Orthopaedic Trauma. 2012; 26: 246–251https://doi.org/10.1097/BOT.0b013e3182243909

Crossref | PubMed | Scopus (78)
| Google ScholarSee all References
. Treatment includes closed or open reduction, with additional soft tissue or bony procedures, and patients with delayed treatment for persistent instability may require arthroplasty8x8Rouleau, D.M., Hebert-Davies, J., and Robinson, C.M. Acute traumatic posterior shoulder dislocation. J Am Acad Orthop Surg. 2014; 22: 145–152https://doi.org/10.5435/JAAOS-22-03-145

Crossref | PubMed | Scopus (43)
| Google ScholarSee all References
.

Reported here is a case of bilateral posterior shoulder fracture-dislocations resulting from a seizure due to hyponatremia in a patient with psychogenic polydipsia. The patient was fully informed and gave written consent to submit the details of this case for publication in a peer-reviewed journal.

Case Report

The patient is a 50-year-old male who presented to the emergency department for bilateral shoulder pain after sustaining a seizure due to hyponatremia, as his sodium level was 112 mmol/L (normal range for this institution is 136-145 mmol/L). The patient had a medical history significant for psychogenic polydipsia and bipolar 1 disorder. Initial examination demonstrated mild deformity of both shoulders, mild swelling, absence of ecchymosis and intact skin. The patient was unable to raise his arms, and his range of motion was very limited due to pain. He was able to actively flex and extend his bilateral elbows, wrists and hands, and he was neurovascularly intact. Imaging demonstrated bilateral posterior shoulder two-part fracture-dislocations extending through the head and neck junctions bilaterally, with greater displacement on the left compared to the right (Figure 1). CT Scans obtained that day demonstrated comminuted fractures of the left proximal humerus extending from the medial proximal metaphysis to the articular surface superiorly with moderate override, with the majority of the articular surface rotated and dislocated posteriorly (Figure 2A-C) and posterior dislocation of the right shoulder with comminuted fractures of the anatomic and surgical neck extending to the articular surface (Figure 2D-F). The patient underwent closed reduction of his bilateral shoulder dislocations one day after the injury, and surgery was delayed due to severe hyponatremia.

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Figure 1

Radiographs at time of injury: AP and Lateral. A) AP Right Shoulder, B) AP Left Shoulder, C) Lateral Right Shoulder, D) Lateral Left Shoulder

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Figure 2

Representative CT scans at the time of injury: A) Sagittal, B) Coronal, and C) Axial views of the left humerus, D) Sagittal, E) Coronal, and F) Axial views of the right humerus.

Approximately 1.5 months post-initial injury and presentation, the patient was able to undergo initial surgical intervention with open reduction and internal fixation (ORIF) of the left humerus. Plain-film radiographs were repeated for accurate operative planning and demonstrated a fracture pattern consistent with the initial CT scans (Figure 3). The left proximal humerus fracture was treated first in order to preserve the native glenohumeral joint (Figure 4). Due to the fracture pattern on the right side, we did not believe that the native glenohumeral joint could be preserved, so arthroplasty was delayed until recovery from the ORIF.

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Figure 3

Radiographs of the left humerus 1.5 months after the initial injury, preoperative planning for ORIF. A) Y-view, B) AP Neutral, C) Y-view

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Figure 4

Intra-Operative Radiographs of ORIF Left Proximal Humerus.

At the patient’s three-month follow-up appointment, partial collapse of the left humeral head was noted on x-ray, indicating possible avascular necrosis (AVN) (Figure 5). The patient continued to struggle to maintain his sodium within normal limits due to his psychogenic polydipsia, and thus he was unable to undergo surgery on his right proximal humerus until exactly one year after initial injury and presentation. During his preoperative evaluation, his range of motion in flexion was 110 degrees and in external rotation was 20 degrees (Table 1). Due to the patient’s accompanying rotator cuff tear and post-traumatic arthritis (Figure 6 and Figure 7), he underwent a right reverse total shoulder arthroplasty (Figure 8). At his follow-up visit 2.5 months after his right rTSA, his range of motion in flexion was 150 degrees, his external rotation was 15 degrees, his ASES score was 85, and his visual analog scale (VAS) score was 0 (Table 1).

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Figure 5

Imaging from 3 months postoperative visit ORIF Left Proximal Humerus. Evidence of some collapse humeral head and potential avascular necrosis.

Table 1Patient-reported outcomes and functional range of motion measurements pre- and post-reverse total shoulder arthroplasty
Pre-operative MeasurementsPost-operative Measurements
LeftROM – Flexion110°160°
ROM – External Rotation20°25°
ASES85
VAS1
RightROM – Flexion100°150°
ROM – External Rotation20°15°
ASES85
VAS0
View Table in HTML
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Figure 6

Plain-film radiographs of the right shoulder 8 months after the initial injury demonstrating post-traumatic arthritis: A) AP External Rotation, B) AP Internal Rotation, C) 45-45 oblique view

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Figure 7

Preoperative CT scans of the right shoulder, 10 months after initial presentation: A) Sagittal, B) Coronal, and C) Axial view.

 Opens large image

Figure 8

Intra-Operative Radiographs of Right Reverse Total Shoulder Replacement.

At a subsequent follow-up appointment for the left shoulder, 16 months post-injury, the patient presented with worsening left-shoulder pain. On plain radiographs, AVN of the humeral head was once again noted with further collapse on x-ray, and the patient was recommended to undergo arthroplasty of the left shoulder (Figure 9). At that time, his range of motion in flexion was 100 degrees and in external rotation was 20 degrees (Table 1). 6 weeks later, (18 months post-initial injury and presentation) the patient underwent removal of hardware and conversion to rTSA, due to advancing AVN of the humeral head, torn rotator cuff, scar tissue, and adhesions (Figure 10).

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Figure 9

Imaging from follow-up 1 year and 3 months following ORIF Left Proximal Humerus. Evidence of partial collapse humeral head and avascular necrosis.

 Opens large image

Figure 10

Intra-Operative Radiographs of Left Hardware Removal and Left Reverse Total Shoulder Replacement

At his subsequent follow-up appointments, he reported adequate pain control and denied numbness or tingling in his distal extremities. As of his most recent follow-up visit, 10 months after his left rTSA, he had 4/5 strength in both flexion and external rotation, his range of motion in flexion was 160 degrees and his external rotation was 25 degrees, his ASES score was 85, and his VAS score was 1 (Table 1).

Discussion

This case of bilateral posterior shoulder fracture-dislocations is unique to other case reports in the current literature because it is the result of severe hyponatremia leading to seizure activity in a patient with psychogenic polydipsia. Cases of unilateral or bilateral posterior shoulder dislocations documented in the literature due to seizure activity, have been attributed to causes such as epilepsy, seizure disorders, hypoglycemia, and alcohol withdrawal2x2Betz, M.E. and Traub, S.J. Bilateral posterior shoulder dislocations following seizure. Int Emergency Med. 2007; 2https://doi.org/10.1007/s11739-007-0017-y

Crossref | PubMed | Scopus (13)
| Google ScholarSee all References
,3x3Gosens, T., Poels, P.J., and Rondhuis, J.J. Posterior dislocation fractures of the shoulder in seizure disorders--two case reports and a review of literature. Seizure. 2000; 9: 446–448

Abstract | Full Text PDF | PubMed | Scopus (29)
| Google ScholarSee all References
. The majority of bilateral shoulder dislocations are posterior, but a rare case of bilateral anterior shoulder dislocation due to hyponatremic seizures was reported9x9Sivananda, P., Sudheer, T., Varun Kumar, P., and Mani Kumar, P. Bilateral Anterior Dislocation of Shoulder with Greater Tuberosity Fracture Due to Hyponatremia: A Rare Presentation. Journal of Evidence based Medicine and Healthcare. 2015; 2: 283–286https://doi.org/10.18410/jebmh/2015/39

Crossref
| Google ScholarSee all References
. The hyponatremic seizures leading to bilateral anterior shoulder dislocation, however, were due to electrolyte deficiency from a diarrheal illness and not a psychologic condition of excess water intake as in this case9x9Sivananda, P., Sudheer, T., Varun Kumar, P., and Mani Kumar, P. Bilateral Anterior Dislocation of Shoulder with Greater Tuberosity Fracture Due to Hyponatremia: A Rare Presentation. Journal of Evidence based Medicine and Healthcare. 2015; 2: 283–286https://doi.org/10.18410/jebmh/2015/39

Crossref
| Google ScholarSee all References
.

Due to the rare incidence of posterior shoulder dislocation, it is often missed on examination and on anterior-posterior (AP) and lateral x-ray imaging3x3Gosens, T., Poels, P.J., and Rondhuis, J.J. Posterior dislocation fractures of the shoulder in seizure disorders--two case reports and a review of literature. Seizure. 2000; 9: 446–448

Abstract | Full Text PDF | PubMed | Scopus (29)
| Google ScholarSee all References
. Posterior shoulder dislocations can be identified on axillary x-rays, but this view can be difficult to obtain in patients due to pain with abduction3x3Gosens, T., Poels, P.J., and Rondhuis, J.J. Posterior dislocation fractures of the shoulder in seizure disorders--two case reports and a review of literature. Seizure. 2000; 9: 446–448

Abstract | Full Text PDF | PubMed | Scopus (29)
| Google ScholarSee all References
. Therefore, CT scans are a helpful tool in diagnosis and management of posterior shoulder dislocations, and were obtained in the patient presented in this case during his initial work-up3x3Gosens, T., Poels, P.J., and Rondhuis, J.J. Posterior dislocation fractures of the shoulder in seizure disorders--two case reports and a review of literature. Seizure. 2000; 9: 446–448

Abstract | Full Text PDF | PubMed | Scopus (29)
| Google ScholarSee all References
. A missed diagnosis of posterior shoulder dislocation can lead to delay in treatment and impaired shoulder function8x8Rouleau, D.M., Hebert-Davies, J., and Robinson, C.M. Acute traumatic posterior shoulder dislocation. J Am Acad Orthop Surg. 2014; 22: 145–152https://doi.org/10.5435/JAAOS-22-03-145

Crossref | PubMed | Scopus (43)
| Google ScholarSee all References
. While in this case the diagnosis was determined upon initial presentation, definitive operative treatment of the fracture-dislocations after closed reduction was delayed due to risks of undergoing surgery with the patient’s severe hyponatremia; surgical management of the left shoulder was delayed 1.5 months from his injury, and surgery on his right shoulder was delayed one year from the date of injury.

Consistent with the majority of cases of posterior shoulder dislocation, this patient sustained associated injuries, including bilateral fractures and rotator cuff tears7x7Rouleau, D.M. and Herbert-Davies, J. Incidence of Associated Injury in Posterior Shoulder Dislocation. Journal of Orthopaedic Trauma. 2012; 26: 246–251https://doi.org/10.1097/BOT.0b013e3182243909

Crossref | PubMed | Scopus (78)
| Google ScholarSee all References
. ORIF is usually necessary after closed reduction for displaced fractures with minimal articular surface involvement10x10Tellisi, N.K., Abusitta, G.R., and Fernandes, R.J. Bilateral posterior fracture dislocation of the shoulders following seizure. Saudi Med J. 2004; 25: 1727–1729

PubMed
| Google ScholarSee all References
. Displaced fractures, fractures involving greater than 40% of the articular surface, and four-part fractures of the proximal humerus are less likely to be successfully treated with ORIF due to the greater likelihood of AVN with these fracture types6x6Ogawa, K., Yoshida, A., and Inokuchi, W. Posterior shoulder dislocation associated with fracture of the humeral anatomic neck: treatment guidelines and long-term outcome. J Trauma. 1999; 46: 318–323

Crossref | PubMed | Scopus (28)
| Google ScholarSee all References
,10x10Tellisi, N.K., Abusitta, G.R., and Fernandes, R.J. Bilateral posterior fracture dislocation of the shoulders following seizure. Saudi Med J. 2004; 25: 1727–1729

PubMed
| Google ScholarSee all References
. Due to the increased displacement of the left proximal humerus fracture, signs of avascular necrosis and humeral head collapse was evident approximately 3 months following ORIF. Arthroplasty is recommended in cases of avascular necrosis, along with in cases of fractures involving greater than 50% of the articular surface and fractures associated with rotator cuff tears10x10Tellisi, N.K., Abusitta, G.R., and Fernandes, R.J. Bilateral posterior fracture dislocation of the shoulders following seizure. Saudi Med J. 2004; 25: 1727–1729

PubMed
| Google ScholarSee all References
. Therefore, this patient originally underwent reverse total shoulder replacement on the right side due to the fracture and associated rotator cuff tear, and subsequently underwent hardware removal and reverse total shoulder replacement on the left due to the patient’s fracture, rotator cuff tear, and development of avascular necrosis.

Conclusion

This rare case of bilateral shoulder fracture-dislocations is unique to the current literature due to its causative mechanism of seizure activity due to hyponatremia from psychogenic polydipsia. The management and treatment course of this patient’s fracture-dislocations were also unusual due to the need to delay surgical intervention because of severe, unmanaged hyponatremia caused by the patient’s excessive water intake. ORIF of the left shoulder was complicated by avascular necrosis, and the patient was treated with bilateral reverse total shoulder replacements.

References

  1. 1Basal, O., Dincer, R., and Turk, B. Locked posterior dislocation of the shoulder: A systematic review. EFORT Open Rev. 2018; 3: 15–23https://doi.org/10.1302/2058-5241.3.160089
  2. 2Betz, M.E. and Traub, S.J. Bilateral posterior shoulder dislocations following seizure. Int Emergency Med. 2007; 2https://doi.org/10.1007/s11739-007-0017-y
  3. 3Gosens, T., Poels, P.J., and Rondhuis, J.J. Posterior dislocation fractures of the shoulder in seizure disorders--two case reports and a review of literature. Seizure. 2000; 9: 446–448
  4. 4Kelly, M.J., Holton, A.E., Cassar-Gheiti, A.J., Hanna, S.A., Quinlan, J.F., and Molony, D.C. The aetiology of posterior glenohumeral dislocations and occurrence of associated injuries: a systematic review. Bone Joint J. 2019; 101-B: 15–21https://doi.org/10.1302/0301-620X.101B1.BJJ-2018-0984.R1
  5. 5Ketenci, I.E., Duymus, T.M., Ulusoy, A., Yanik, H.S., Mutlu, S., and Durakbasa, M.O. Bilateral posterior shoulder dislocation after electrical shock: A case report. (PMID: 26904192)Annals of Medicine and Surgery. 2015; 4: 417–421https://doi.org/10.1016/j.amsu.2015.10.010
  6. 6Ogawa, K., Yoshida, A., and Inokuchi, W. Posterior shoulder dislocation associated with fracture of the humeral anatomic neck: treatment guidelines and long-term outcome. J Trauma. 1999; 46: 318–323
  7. 7Rouleau, D.M. and Herbert-Davies, J. Incidence of Associated Injury in Posterior Shoulder Dislocation. Journal of Orthopaedic Trauma. 2012; 26: 246–251https://doi.org/10.1097/BOT.0b013e3182243909
  8. 8Rouleau, D.M., Hebert-Davies, J., and Robinson, C.M. Acute traumatic posterior shoulder dislocation. J Am Acad Orthop Surg. 2014; 22: 145–152https://doi.org/10.5435/JAAOS-22-03-145
  9. 9Sivananda, P., Sudheer, T., Varun Kumar, P., and Mani Kumar, P. Bilateral Anterior Dislocation of Shoulder with Greater Tuberosity Fracture Due to Hyponatremia: A Rare Presentation. Journal of Evidence based Medicine and Healthcare. 2015; 2: 283–286https://doi.org/10.18410/jebmh/2015/39
  10. 10Tellisi, N.K., Abusitta, G.R., and Fernandes, R.J. Bilateral posterior fracture dislocation of the shoulders following seizure. Saudi Med J. 2004; 25: 1727–1729

Institutional review board approval was not required for this case report.

Disclaimers:

Funding: No funding was disclosed by the authors.

Conflicts of Interest: The authors, their immediate families, and any research foundation with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.

Patient consent: Obtained.

 

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