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    Acute Coracoid Fracture with Recurrent Traumatic Anterior Glenohumeral Instability

    A police officer who fell on his shoulder during training exercises presents with significant pain, including severe night pain, and difficulty with range of motion. He has a past medical history of 2 arthroscopic procedures on that shoulder for a prior glenohumeral dislocation. What is the best option to manage him this time?

    Authors

    Daniel E. Davis, MD, MS, and Mark D. Lazarus, MD

    Background

    Anterior dislocation of the glenohumeral joint is common and is generally associated with a soft tissue injury of the anterior inferior labrum or the rotator cuff. [1] Bony injuries can also occur in the form of a Hill-Sachs defect of the humeral head or anterior inferior glenoid rim fracture. [2] Large fractures of the glenoid or the greater tuberosity may also occur but are not as frequent. [3] Fracture of the coracoid process with traumatic dislocation is extremely rare.

    There have been 12 reports in the literature of coracoid fracture associated with anterior glenohumeral dislocation. [4-15] In many of these cases, the coracoid fracture was discovered as a pseuodarthrosis after non-operative management of the glenohumeral instability. [4,7,9,12,14]

    More recent studies have discussed operative management with either fixation of the coracoid fracture or transfer to the anterior glenoid; however, these were mostly performed in subacute or chronic cases. [12,13,15] In previous cases, the coracoid fragment was not always large enough to transfer to the anterior-inferior glenoid or surgery was performed after a coracoid pseudoarthrosis was recognized. Recurrent instability after undergoing a Bankart repair with an acute coracoid fracture is a rare event.

    Case Presentation

    A 41-year-old right hand-dominant male who works as a police officer presented with significant left shoulder pain of 1 month’s duration. He was injured during training exercises when he slipped off of a 6-foot wall and landed on his abducted left upper extremity. Since the injury, he has experienced significant pain, including severe night pain, and difficulty with range of motion. He was not sure if he felt his shoulder dislocate and no formal reduction of the shoulder was required after the injury.

    Past history in the injured shoulder is significant as the patient sustained a glenohumeral dislocation that was treated with an arthroscopic Bankart repair at another institution 4 years prior to the current injury. This operation was complicated by postoperative stiffness, necessitating a subsequent arthroscopic capsular release and biceps tenodesis.

    After the second operation, the patient continued to experience symptoms of instability but he was able to perform his work duties. For the month since his most recent injury, however, he has been unable to perform his tasks as a police officer.

    Physical Exam

    • Height: 5 feet, 10 inches; weight: 195 pounds; BMI: 28
    • No gross deformity or ecchymosis of the left shoulder
    • Positive tenderness to palpation over the coracoid process; no tenderness over the acromioclavicular joint, acromion, or greater tuberosity
    • Active and passive forward elevation to 120°, limited by pain
    • Passive external rotation with the arm adducted to 30°, with full strength and resistance to external rotation
    • Internal rotation to the side, pain-limited weakness with resisted internal rotation
    • Positive abdominal compression test

    Imaging

    • Plain radiographs showed a well-reduced glenohumeral joint with no arthritis, as well as a suggestion of irregularity of the coracoid process, although this was not definitely visualized (Figure 1).
    • CT scan showed a shear fracture of the coracoid process distal to the elbow with lateral and inferior displacement (Figure 2), as well as a moderate-sized Hill Sachs defect with a depth of 11 mm (Figure 3). There was minimal anterior glenoid bone loss measuring 5 mm and a glenoid diameter of 31 mm; thus, the lesion was on track (Figure 4).
    • An MRI was obtained and showed an irregularity of the anterior-inferior labrum with evidence of prior repair.

     

    Figure 1. Preoperative AP plain imaging shows that the humerus is well-aligned within the glenoid with a suggestion of a Hill-Sachs defect superiorly. In addition, the inferiorly displaced coracoid fragment can be visualized at the joint line (left). The axillary lateral view again demonstrates the Hill-Sachs defect posteriorly, the tip of the laterally displaced coracoid is viewed at the top of the figure (right).

     

    Figure 2: Axial CT imaging shows the fracture end of the base of the coracoid (top left). The fragment of the distal portion of the coracoid is visualized in a separate slice. It appears that the fracture is distal to the elbow or bend of the coracoid process (top right). The sagittal CT imaging clearly demonstrates the fractures coracoid fragment (bottom).

    Figure 3. This axial slice of the CT shows the circle method for measuring the depth of the Hill Sachs (HS) lesion. By finding the deepest portion of the lesion and creating a perfect circle encompassing the humeral head, the depth of the lesion can be measured from the deepest portion to the circumference of the circle, which was found to be 11 mm.

    Figure 4. The sagittal view of the CT is used to estimate anterior glenoid bone loss. A perfect circle is made at the inferior portion of the glenoid. The depth of anterior inferior bone loss is measured from there, 5 mm in this case. The diameter of this circle was also calculated at 31 mm to determine the glenoid tracking, using the glenoid tracking formula: GT = 0.84(D) – d = 0.84(31) – 5 = 21.04. Because GT < HS of 11 mm, the lesion is theoretically on track.

    Diagnosis

    • Recurrent traumatic shoulder instability with associated acute coracoid fracture

    Treatment

    It was not clear from imaging whether the patient had an adequate amount of coracoid bone to transfer to the anterior inferior glenoid. In addition, the size of the Hill-Sachs defect and glenoid lesion were on the borderline of requiring a transfer procedure. Given the history of prior capsular release, there was concern about the possibility of anterior capsular deficiency.

    Therefore, we planned to perform an arthroscopic evaluation to assess glenoid bone loss, engagement of the Hill-Sachs with the defect, and the status of the labrum and anterior capsule. If arthroscopic repair was amenable, it would be performed with coracoid fixation. If repair was not amenable arthroscopically, an open procedure would be performed with possible coracoid transfer if the fragment was large enough to accommodate screw fixation.

    These options were discussed with the patient, including the risks and benefits of alternative procedures, and he agreed to move forward with the surgical plan.

    Procedure

    • The patient was positioned in a beachchair positioner with bony prominences padded.
    • An exam under anesthesia demonstrated a grade III load and shift test in the anterior direction, with complete anteroinferior dislocation on abduction and external rotation.
    • Shoulder arthroscopy commenced with a viewing portal posterior-superior-lateral in the event that arthroscopic labral repair would be performed.
    • A moderate-sized Hill-Sachs defect with degenerative changes of the posterior superior humeral head was noted (Figure 5). There was a large Bankart tear with an estimated 20% loss of the anterior inferior glenoid rim (Figure 6). The decision was made to transition to an open procedure when it was determined that the Hill-Sachs defect was engaging with the anterior-inferior glenoid during abduction and external rotation.

    Figure 5. Intraoperative arthroscopic superior (left) and posterior (right) views of the humerus from the posterolateral portal show the Hill Sachs defect with degenerative changes at the margins.

     

    Figure 6. Arthroscopic images of the anteroinferior (left) and anterior (right) portion of the glenoid show the degenerative nature of the labral tear as well as the anterior inferior glenoid bone loss.

    • A standard deltopectoral approach was performed and the fractured fragment of the coracoid process was dissected from the base, with the musculocutaneous nerve protected distally.
    • The fragment was examined and determined to be large enough to transfer to the anterior glenoid and accommodate 2 screws.
    • The undersurface of the fragment was stripped of soft tissue and lightly decorticated.
    • The anterior inferior glenoid was exposed through a transverse split in the subscapularis muscle and capsule.
    • The surface was prepared by elevating the labrum and anterior inferior glenohumeral ligament, followed by a decortication of the bone. The coracoid fragment was then fixed to the glenoid utilizing 2 3.5-mm cortical lag screws in a standard fashion for a Latarjet coracoid transfer.
    • The labrum and capsule were then repaired to the lateral soft tissue of the coracoid fragment. The wound was irrigated and closed in a standard fashion.

    Postoperative FollowUp

    The patient’s postoperative course was standard for instability surgery and Lataret coracoid transfer.

    • His shoulder was immobilized in an abduction sling for 4 weeks postoperatively to allow for soft tissue and bony healing.
    • A home stretching program began at 4 weeks, followed by formal physical therapy with stretching and strengthening at 8 weeks.
    • At 3 months after surgery, the patient had 160° of forward elevation, 40° of external rotation, and internal rotation to T10. There were no signs of instability or apprehension.
    • At this point, a non-laborer or low-demand patient would generally be released to full activity. Higher-demand workers, such as this patient, perform an additional 6 weeks of physical therapy for work hardening.
    • At 6 months after surgery, the patient was free of painand had a range of motion of 170° forward elevation, 45° external rotation, and internal rotation to T9, with no signs or symptoms of instability.
    • Radiographs confirmed complete healing of the transferred coracoid (Figure 7). The patient was cleared to return to full work duty.

     

    Figure 7. These 6-month postoperative radiographs demonstrate the well-healed coracoid fragment and screws in appropriate, stable position on the AP (left) and axillary (right) views.

    Discussion

    Coracoid process fractures are rare, and they are more frequently involved with acromioclavicular pathology than with glenohumeral pathology. [16] Classically, fractures of the coracoid process are described in their relation to the insertion of the coracoclavicular ligments. Fractures that are proximal to the ligaments (Type 1) are typically more unstable and require fixation, whereas fracture distal to the ligamentous insertion (Type 2) may be treated non-operatively. [17] Coracoid process fractures associated with glenohumeral instability, as presented in this case, are rare and have only been described in 12 case reports.

    Early case reports recognized this fracture pattern of the coracoid process after dislocation and described successful treatment with closed reduction and non-operative management. One case presented by Wong-Chung et al [11] noted the coracoid fragment created a block to reduction, thus necessitating open reduction with anatomic fixation of the coracoid fragment.

    In 3 studies, 5 patients presented with a subacute or chronic painful pseudoarthrosis of the coracoid process after an anterior glenohumeral instability event. Garcia-Elias and Salo [4] described this scenario in a patient who was managed non-operatively. They concluded that lateral radiographs should be obtained after dislocation to identify a potential coracoid injury. [4] Saragaglia et al [7] and Allagui et al [9] described 4 cases in which a pseudoarthrosis of the coracoid was recognized in patients with recurrent anterior instability. The patients were successfully treated with a transfer of the fractured coracoid in a Latarjet-type procedure. [7,9]

    Coracoid fracture with traumatic dislocation has also been described with other concomitant fractures of the greater tuberosity and glenoid. In a series of 6 cases, Plachel et al [5] described the “triple fracture dislocation” of the coracoid, greater tuberosity, and glenoid with dislocation and focused on the recognition and anatomic treatment of this fracture pattern. Robinson et al [14] recognized this fracture pattern in 6 of 234 patients who had sustained a traumatic dislocation after a seizure. They noted that in 4 cases, a Latarjet transfer was able to be performed, but in 2 cases, the fracture was too distal on the coracoid and a Eden-Hybbinette procedure was performed instead. [14]

    The most recent case presented by Verma et al [13] in 2016 was similar to our case in that the coracoid fragment was noted on a recurrent traumatic dislocation in a young male. Dissimilar to our case, however, the coracoid fracture was too distal and unable to be transferred to the glenoid. Therefore, stability was gained by performing an Eden-Hybinnette with iliac crest bone graft. [13] Skedros et al [15] presented a similar case in 2014; however, there was delayed presentation with a coracoid non-union. They treated their patient with bone grafting and screw fixation of the coracoid followed by an open capsular shift to manage instability.

    Our case adds a report of a unique fracture dislocation to the literature. In prior reports, it was evident that this rare pattern is not frequently noted acutely and, thus, leads to a painful pseudoarthrosis that is managed after subsequent recurrent instability. As was seen in our case, the use of axillary lateral radiographs, as well as axial imaging with CT or MRI, is extremely helpful in recognizing this pattern. If appropriately recognized acutely, this fracture dislocation pattern can be treated well with an acute transfer of the coracoid to gain stability and to avoid a painful pseudoarthrosis.

    Author Information

    Daniel E. Davis, MD, MS, is an orthopaedic surgeon with The Rothman Institute, Philadelphia, Pennsylvania. He specializes in the treatment of shoulder and elbow conditions. Mark D. Lazarus, MD, is a shoulder and elbow surgeon with The Rothman Institute, Philadelphia, Pennsylvania. He specializes in arthroscopic surgery, minimally invasive surgery, and shoulder replacement.

    Shoulder and Elbow Editor, Rothman Institute Grand Rounds

    Daniel E. Davis, MD, MS

    Disclosures

    The authors have no disclosures relevant to this article.

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