F1000Research F1000Research 2046-1402 F1000 Research Limited London, UK 10.12688/f1000research.173743.1 Clinical Practice Article Articles CHRONIC POSTERIOR SHOULDER DISLOCATION: A CASE SERIES

[version 1; peer review: awaiting peer review]

 Abdulrazzaq Mohammed Ali Conceptualization Data Curation Formal Analysis Investigation Methodology Writing – Original Draft Preparation Writing – Review & Editing https://orcid.org/0000-0002-5245-7489 a 1 Orthopedic Surgeon, University of Fallujah , College of Medicine, Al-Anbar / Al-Fallujah, 00964, Iraq ali-med@uofallujah.edu.iq

No competing interests were disclosed.

 9 2 2026 2026 15 215 30 1 2026 Copyright: © 2026 Abdulrazzaq Mohammed A 2026 This is an open access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Shoulder dislocation of the posterior variety is a rare condition, representing less than 2% of all dislocation types of the Shoulder Joint. During the acute presentation of posterior shoulder dislocation, the rate of misdiagnosis is high 50%-80% because acute posterior shoulder dislocation is not diagnosed during the initial presentation. The causes of this high rate of misdiagnosis are a lack of clarity regarding the signs of this type of dislocation and inadequate radiological assessment.

A delayed diagnosis can result in painful and stiff shoulders, leading to chronic shoulder dislocation. The resulting decrease in joint motion and loss of many activities, instability, recurrent shoulder dislocation, and delay in diagnosis may result in Osteoarthritis or AVN of the humeral head. The chronicity of posterior shoulder dislocation may necessitate a complex surgical procedure for reduction with an unpredictable rate of success.

The purpose of this case series was to clarify the difficulties in the diagnosis and management of chronic posterior shoulder dislocation by presenting three cases of posterior shoulder dislocation from the Orthopaedic Department at Fallujah Teaching Hospital in Iraq.

 Posterior shoulder dislocation Reverse Hillsach lesion Modified McLaughlin Procedure Deltopectoral approach Lesser Tuberosity Subscapularis muscle The author(s) declared that no grants were involved in supporting this work. Introduction

Shoulder dislocation is a common and frequent presentation in the emergency department. However, posterior shoulder dislocation is rare, accounting for <2% of all cases of shoulder dislocation. 1

The mechanisms of posterior shoulder dislocation are indirect forces that produce marked internal rotation and adduction (occurring during a fit or convulsion, or with an electric shock) or falling on an outstretched hand or on the flexed adducted arm. 2 A direct blow to the front of the shoulder may also be considered as a direct mechanism of posterior shoulder dislocation. 1

Posterior shoulder dislocation is difficult to diagnose initially and is frequently missed because the dependence is mainly on a single A-P view, which is similar to normal as well as the forgetfulness of thinking about this condition during examination of the patients. 3

Radiologically, the anteroposterior (AP) view may show an electrical bulb sign and empty glenoid fossa. 1 A lateral and axillary view is essential (although it is painful for patients), which may show posterior subluxation or dislocation and sometimes a deep indentation on the anterior aspect of the humeral head (Reverse Hillsach lesion). 4 A CT scan is also required to confirm the diagnosis. 1, 2

Posterior shoulder dislocation may be associated with fractures of the lesser tuberosity, posterior part of the glenoid, or the surgical neck. 4 The treatment is closed reduction; if failure occurs, then surgical or open reduction. 1, 2 Posterior shoulder dislocation may be complicated by osteoarthritis, stiffness, instability, or aortic Necrosis. 5

This clinical case series aimed to highlight a rare condition that can be easily missed in acute presentation in the emergency room due to the lack of clinical features and inadequate radiological assessment. Three cases of chronic posterior shoulder dislocation, missed in diagnosis, will be discussed, with an explanation of the methods used to reach the diagnosis and treatment.

 Cases presentation Case 1

A 25 years old male patient presented to a private clinic in Fallujah city on 11/10/2024 with left shoulder pain and limitation of movement for 2 months. The forearm was clasped to his chest with inability to perform external rotation of the forearm. The patient had a history of electrical shock injury prior to his compliant.

On examination, there was loss of shoulder contour with limitation of movement with a positive posterior drawer test. Radiographs showed a light-bulb appearance ( Figure 1). The CT scan showed Reverse Hillsach lesion ( Figure 2).

AP view of shoulder with Light Bulb appearance. CT of shoulder with Reverse Hillsach lesion.

The management plan involved surgical reduction of this dislocation using the Modified McLaughlin Procedure. The patient was admitted to the operative room in Fallujah Teaching Hospital to undergo the surgical procedure using the deltopectoral approach to reduce the dislocation by the open method with transfer of the subscapularis with its lesser tuberosity to the defect (Reverse Hillsach) on the anterior part of the Humeral Head ( Figure 3).

Intraoperative open reduction with fixation of the lesser tubercle with subscapularis muscle to the reverse Hillsach Lesion.

Postoperatively, the patient wore a Gunslinger sling for 4 weeks, followed by exercise. The postoperative radiograph is shown in ( Figure 4).

Post-operative radiograph with screw fixation of the lesser tuberosity to Reverse Hillsach defect. Patient perspective

The patient expressed significant satisfaction with the outcome, noting that he could finally return to his daily activities without the constant pain and severe limitation he had experienced for two months following the injury.

 Case 2

A 52 years old female patient presented to a private clinic in Fallujah city on 8/3/2025, with left shoulder pain and limitation of movement for 3 months. Her symptoms occurred after an episode of convulsions.

On examination, there was loss of external rotation movement of the shoulder. The X-rays showed a light-bulb appearance ( Figure 5). The CT scan: shows Reverse Hillsach lesion ( Figure 6).

AP view of shoulder with Light Bulb appearance. CT-scan of shoulder with Reverse Hillsach lesion.

The management plan involved surgical reduction of this dislocation using the Modified McLaughlin procedure. The patient was admitted to the operative room at Fallujah Teaching Hospital to undergo the surgical procedure using the deltopectoral approach to reduce the dislocation by the open method with transfer of the subscapularis with its lesser tuberosity to the defect (Reverse Hillsach) on the anterior part of the Humeral Head with Bone Graft ( Figure 7).

Intraoperative open reduction with fixation of the lesser Tuberosity with the subscapularis and bone grafting to the reverse Hillsach Lesion.

Postoperatively, the patient wore a Gunslinger sling for one month followed by exercise. The postoperative radiograph is shown in ( Figure 8).

Post-operative radiology with secured fixation using one screw of the lesser tuberosity to the Reverse Hillsach lesion. Patient perspective

The patient reported a high level of satisfaction after the surgery, specifically highlighting the restoration of her shoulder’s external rotation, which allowed her to regain independence in her personal care.

 Case 3

An 18 years old male patient presented to a private clinic in Fallujah city on 12/7/2025, with right shoulder pain and limitation of movement for 2 months. He had a history of falling, was admitted to the emergency department, and was told that he had a shoulder dislocation (there was no radiological document for his first dislocation). The patient underwent closed reduction (as he said), and later on, the patient still complained of limitation of movement of the right shoulder with severe pain and was admitted to a private clinic seeking relief.

The patient was sent for X-rays that showed a light-bulb appearance ( Figure 9). The CT scan showed the impaction of the Humeral Head in the glenoid fossa with an internally rotated Humeral Head that locks the head in situ (inside the glenoid fossa) without exiting the humeral head outside the glenoid socket ( Figure 10).

AP view of shoulder with Light Bulb appearance. CT-scan of the shoulder with locking of the Humeral head inside the glenoid.

The management plan was discussed with the patient and his family, which was to try closed reduction under general anesthesia (although the rate of success is very low because of the chronicity of the case). If closed reduction fails, we proceed to open reduction.

Under General Anesthesia, closed reduction successfully reduced the head with external rotation of the Humeral Head with a snap. Examination of shoulder joint movement under anesthesia revealed a full range of movements ( Figure 11).

Full range of movement of shoulder joint under general anesthesia.

Subsequently, the patient wore an arm sling for two weeks, followed by exercise. MRI was performed to exclude ligament injuries.

 Patient perspective

The patient and his family were very pleased with the immediate improvement following the closed reduction under anesthesia. He noted that the relief from the ‘locking’ sensation in his shoulder was a major turning point in his recovery.

 Discussion

Posterior Shoulder dislocation includes acute (time less than 6 weeks), chronic (>6 weeks), and recurrent dislocations. Its etiology is either direct (high-energy trauma) or indirect (epilepsy or electrical injury).

The usual presentation is that the arm claspes to the chest, posterior bulge of the shoulder, hollow anterior shoulder with a projecting coracoid, limitation of movement, and inability to perform external rotation of the shoulder.

Radiology included AP, lateral, and axillary views. Computed tomography (CT) scans are required in doubtful cases. Radiological signs included a light bulb appearance, empty glenoid sign (anteroposterior, AP view), or indentation of the anterior part of the humeral head (in Lateral or Axillary view).

Treatment is a trial of closed reduction under anesthesia; if it fails, open reduction is required, and the stability of the joint is performed after reduction.

 Conclusion

Posterior shoulder dislocation is difficult to diagnose because of the rarity of cases, shortage of clinical signs, and inadequate radiological assessment. Therefore, clinical suspicion aids in the diagnosis.

Early diagnosis leads to early management, which decreases the risk of complications. Converting the condition to chronic dislocation worsens complications and leads to osteochondral lesions and joint destruction.

 Consent

Written informed consent was obtained from the patients, permitting the publication of these case reports and their images.

 Data availability

The data associated with this study are available on Zenodo at: https://doi.org/10.5281/zenodo.18144826. 6 Licensed under CC0 1.0 Universal.

 References Apley AG Solomon L Warwick D : Apley’s System of Orthopaedics and Fractures. Boca Raton: CRC Press; 10th ed. 2018. Azar FM Beaty JH Canale ST : Campbell’s Operative Orthopaedics. Philadelphia: Elsevier; 14th ed. 2021. Court-Brown CM Heckman JD McQueen MM : Rockwood and Green’s Fractures in Adults. Philadelphia: Wolters Kluwer; 9th ed. 2019. Miller MD Thompson SR Hart JA : Miller’s Review of Orthopaedics. 8th ed. Philadelphia: Elsevier;2019. Kowalsky MS Levine WN : Traumatic posterior glenohumeral dislocation: classification, pathoanatomy, diagnosis, and treatment. Orthop. Clin. North Am. 2008;39(4):519–33. viii. 18803981 10.1016/j.ocl.2008.08.003 Mohammed A : Dataset title. Zenodo. 2026. 10.5281/zenodo.18144826