Extended Abstract

Introduction
Posterior shoulder fracture dislocation (PSFD) is a rare injury. The mechanisms causing this injury can be divided into atraumatic and traumatic groups, which are associated with an axial load on the arm in a flexed, adducted, and internally rotated shoulder position. Pathological findings consist of a rupture of the capsulolabral complex and the reverse Hill-Sachs. Sometimes there are fractures of the tuberosities, particularly the lesser tuberosity, fractures of the articular surface of the humeral head, or a comminuted proximal humerus, indicating the complexity of treating this injury.
Relatively normal initial radiography, a relatively normal position of the upper limb (adduction and internal rotation), pain with the slightest movement, and lack of accurate examination are major barriers to early diagnosis of this injury. Early diagnosis and treatment of this injury reduces the probable complications of serious functional disability, avascular necrosis, and arthritis. Numerous treatment options have been posed for this injury, including closed reduction, open reduction, internal fixation, and shoulder joint replacement.
This article reports a case of a closed irreducible posterior shoulder fracture dislocation in a young individual following a seizure after tramadol abuse, which was treated with a deltopectoral approach, open reduction, and internal fixation with a plate.
Case Presentation
A 25-year-old male patient with no history of epilepsy, seizures, or underlying diseases presented to the emergency ward after experiencing a seizure following the misuse of tramadol. After seizure control and resuscitation, physical examination revealed pain and swelling in the right shoulder. The shoulder was in an internally rotated and adducted position, and passive and active external rotation and shoulder elevation were absent. Neurovascular examination of the upper extremity and laboratory tests were normal. After initial radiography, a three-part fracture dislocation of the right shoulder was diagnosed, and a computed tomography (CT) scan was performed for better treatment decision-making. A neurology consultation was carried out for the patient, and sodium valproate (500 mg once at night), clonazepam (2 mg once at night), and diclofenac (50 mg as needed) were prescribed. Two days later, the patient was a candidate for open reduction and internal fixation.
After general anesthesia in a semi-sitting position and a deltopectoral approach with preservation of the cephalic vein, it was entered anteriorly and superiorly via the rotator cuff interval. After evacuating the hematoma and distally pulling the humeral shaft for better visualization of the joint space, the humeral head, which was located behind the glenoid, was reduced into the joint using a Bennett forceps. The valgus and version angles of the humeral head were checked. Subsequently, the greater and lesser tuberosities were sutured together with an Ethibond suture. After reduction, the humerus underwent initial fixation with a 2.0 mm steel pin (which was decided to be retained due to its firm fixation) and the final fixation was then performed with a proximal humeral anatomical plate below the tip of the greater tuberosity and lateral to the bicipital groove. Cancellous screws were placed, and the fixation status was checked with intraoperative radiography (C-arm), which was satisfactory. The patient was taken out of the operating room with a sling and the arm strapped to the chest. Postoperatively, anteroposterior and lateral scapular radiographs were taken, which were satisfactory. The sutures were removed on the 10^th day. The steel pin was removed under local anesthesia on the 4^th week.
Starting the day after surgery, pendular movements of the shoulder and active movements of the elbow and fingers began. In the third week, passive shoulder movements (flexion, extension, and abduction) up to 90° were allowed, and in the 5^th week, full passive and active shoulder movements were allowed. Clinical and radiographic evaluations were performed at weeks 2, 4, 6, as well as at months 3 and 6. Complete healing was observed after 3 months. After 6 months, the patient was satisfied and there was no evidence of avascular necrosis or arthritis of the shoulder joint.
Conclusion
PSFD is a rare injury. Early diagnosis and treatment are crucial in preventing serious complications. Because of multiple traumas and the relatively normal position of the shoulder (internal rotation and adduction), even on anteroposterior radiographs, it often goes undiagnosed and untreated, leading to complications, such as mal:union:, avascular necrosis of the humeral head, arthritis, chronic pain, and disability in performing daily activities. Failure to reduce the humeral head within the first 24-48 hours culminates in avascular necrosis of the humeral head, followed by collapse and arthritis, necessitating shoulder joint replacement.
In this injury, particularly on anteroposterior radiographs of the shoulder, three findings should be taken into account: a) Absence of the Halfmoon sign (due to normal overlap of the humeral head and glenoid), b) presence of the Lightbulb sign (an abnormal sign of the humeral head), and c) presence of the double shadow line sign (head splitting sign).
CT scan, particularly axial and 3-dimensional cuts, is beneficial in better understanding the anatomy of the lesion and making appropriate decisions about the surgical procedure. Magnetic resonance imaging (MRI) is usually not necessary, particularly in young people.
In LPSFD cases, closed reduction is not possible. Various surgical treatment options have been proposed, including open reduction and fixation with pins, external fixation, internal fixation, bone grafting, and shoulder joint displacement. The size and number of fragments, the fracture of the articular cartilage, the length of the metaphysis attached to humeral head, bone density, patient age, comorbidities, and the patient’s demand are crucial in selecting the treatment.
Open reduction and internal fixation with a plate is the preferred treatment in young and active individuals. Shoulder joint displacement is recommended in three- or four-part fractures in elderly and osteoporotic patients, those with non-fixable or large bone defects of the humeral head (more than 50%), fractures of the humeral articular cartilage, and complex chronic cases (more than 3 weeks), as well as avascular necrosis with collapse and arthritis of the shoulder joint. The poor prognosis of arthroplasty in these injuries has resulted in a more conservative approach (fixation).
Several approaches have been proposed for this surgery, with the deltopectoral approach, which allows for increased exposure, being the most common and used in this patient. In cases where the lesser tuberosity or subscapularis tendon is intact, access for reducing the humeral head behind the glenoid or neck of the scapula is very challenging. In these cases, access is through the rotator cuff interval. Although release of the attachment site of any tendon is not usually recommended, the subscapularis tendon is sometimes released to reach the humeral head.
In the anterolateral and trans-deltoid lateral approach, care must be taken to avoid the axillary nerve. The posterior shoulder approach is used particularly in cases where reduction is not possible with an anterior approach, the humeral head is trapped behind the glenoid, and there is a large bone defect, and sometimes bone grafting to the humeral head is required.
Ethical Statement
This study was approved by the Research Ethics Committees of Golestan University of Medical Sciences (IR.GOUMS.REC.1403.024).

Key message: PSFD is a rare and challenging injury. With accurate physical examination and radiography, early diagnosis can be made, and early surgical treatment with open reduction and internal fixation using an anatomical plate is recommended, particularly in young and active individuals.