Ipsilateral fractures of the acromion and coracoid processes of the scapula

Abstract

A fracture of the acromion and coracoid processes of scapula is rarely seen in the outpatient clinic, due to the acromion's anatomical position and shape, as well as the strong ligaments and muscles that are attached to it. These fractures are caused by either direct or indirect high-energy trauma injuries to the shoulder joint, leading to severe pain and a grossly restricted range of motion. Several acromial classifications were reported, but this type of longitudinal plane fracture of the acromion process in our case is yet to be described in the current literature. We present a rare combination of the coracoid process and unstable acromion bony projection fractures that have not previously been noted for this type of fracture. The closest to this is Kuhn's type III classification. A 51-year-old male presented to our emergency department complaining of the right shoulder pain and difficulty raising his arm following a 2-wheeler accident. The patient was managed by open reduction and internal fixation with 3 cannulated cancellous screws fixation and progressed well with no postoperative complications. He was asymptomatic postoperatively and regained full range of motion after 4 months.

1. Introduction

Combined fractures of the scapula's acromion and coracoid processes after a traumatic shoulder are uncommon in the outpatient clinic, accounting for only a small percentage of all scapula fractures. Less than one-sixth of all scapula fractures involving the acromion process have been explained in the existing literature by different mechanisms of injuries for acromion fractures.¹ High-energy traumas commonly result in fractures of the acromion and coracoid process, which are often seen in associated with other injuries.² Moreover, the fracture occurs primarily in the acromion's longitudinal plane. Elderly people are more likely than younger people to sustain fragility fractures due to low energy trauma.³ The most frequent symptoms among patients who present with a displaced acromial fracture are pain and have a grossly restricted range of motion. For displaced acromial fractures, instead of deciding to choose conservative management or Kirschner wire or tension band fixation straightaway, it should have to weigh against each treatment option. However, there is no universally accepted treatment or fixation method.^1,4 Various classification systems in the literature to explain the type and location of the acromion and coracoid fractures (Ogawa and Kuhn's classifications respectively).^1,4, 5, 6, 7 Radiological findings, particularly 3-dimensional CT scans¹⁰ were the primary criterion for determining whether a surgical intervention was required for this type of fracture.¹¹ Herein, we present a unique case of a 51-year-old male who sustained a displaced acromial fracture of the scapula along with coracoid process fracture, which was successfully treated by open reduction and internal fixation with 3 cannulated cancellous screws fixation. The patient consented that the information of this case would be submitted for publication.

2. Case report

The patient was a 51-year-old male who presented to our emergency department with the right shoulder pain and difficulty in raising his arm. He was hit by a 2-wheeler in an accident and landed directly on his right shoulder. He had no prior history of shoulder trauma. A focused physical examination of the affected shoulder revealed lateral bruising and mild swelling over the acromion process of the scapula, as well as a restricted range of motion. There was no associated injury, and the neurological examination of the affected limb found no abnormalities. The initial plain radiograph of the right shoulder showed an acromion process fracture (Fig. 1). A 3-dimensional CT scan was obtained and demonstrated a displaced fracture of the acromion process and non-displaced fracture of the coracoid process of the scapula (Fig. 2). A MRI was performed to rule out rotator cuff muscle injuries, which revealed intact rotator cuff muscle and myofascial oedema (Fig. 3).

Fig. 1.

X-ray of the right shoulder. (A) Preoperative anteroposterior and lateral views showing displaced fracture of the acromial process. (B) Immediate postoperative anteroposterior and lateral views showing anatomic reduction of the acromion process and the placement of 3 cannulated cancellous screws (size 4 mm).

Fig. 2.

Preoperative CT scan with 3 dimensional reconstructions shows displaced acromion process fracture and non-displaced coracoid process fracture of the scapula.

Fig. 3.

MRI coronal T1, T2, and axial view revealed intact rotator cuff muscle and myofascial oedema along with a displaced fracture of the acromial and non-displaced coracoid processes of the scapula.

Based on clinical and radiological findings, the patient has a displaced acromial fracture along with significant pain and was unable to lift his arm. Therefore, we decided to operate on him the following day in order to restore the anatomic integrity of the shoulder and functional status before the injury. The patient was informed about the surgery, and he agreed to an early surgical intervention.

The patient was in the supine position and general anesthesia was used for induction. Antibiotic prophylaxis is administered intravenously prior to incision, and the shoulder was draped in a meticulous sterile manner. The incision was passed over the scapula spine and extended up to the acromion. After retraction of the fascia and soft tissue, the fracture site was exposed and cleaned. The intraoperative findings showed a displaced acromion process fracture. The fracture was initially reduced and then stabilized by three cannulated cancellous screws (size 4 mm) in a direction perpendicular to the fracture line (Fig. 4A and B). Finally, the stability of fracture was confirmed under C-arm fluoroscopy (Fig. 4C), and the incision was closed in layers. The patient wore an arm sling after surgery and active shoulder motion was allowed at the end of the fourth week. At 4 months postoperatively, the patient has no longer experienced pain in the injured shoulder, and conventional radiographs revealed the fracture had healed completely. The patient had no functional deficits after 6 months of follow-up.

Fig. 4.

Intra-operative images. (A & B) The fracture was initially reduced into its normal alignment and held with a bone clamp before being stabilized by 3 cannulated cancellous screws (size 4 mm) in a direction perpendicular to the fracture line. (C) Intra-operative C-arm fluoroscopy showing 3 cannulated screws.

3. Discussion

Acromion plays an important role in stabilizing the shoulder articulations and maintaining its integrity due to the anatomical position and bony projection shape of the acromion, along with the sturdy ligaments and muscles that attach to it. Fractures of the acromion are unusual (8% – 16% of scapular fractures and 1% of all skeleton fractures).⁵ They often result in high-energy injuries and involve simultaneous fractures of the ipsilateral glenoid, neck, and body of the scapula.¹ The combination of displaced acromial fracture and non-displaced coracoid fracture is unusual, but present in our case. Our patient's fracture mainly occurs in the longitudinal plane of the acromion process, which is extremely uncommon, with only this type of fracture described in the English literature to our knowledge. Although existing acromion fracture classifications emphasize the fracture's anatomic location or shape instead of a fracture description in terms of longitudinal, transverse, or mixed orientation, this continues to be useful in presenting the fracture.

Kuhn et al.⁶ developed the most widely used classification for fractures of the acromion process, which are as follows: Type I fractures are minimally displaced. Type IA fractures are avulsion fractures and heal rapidly. Type IB fractures result from direct trauma to the extremity and are minimally displaced. Type II fractures are displaced laterally, superiorly, or anteriorly and do not reduce the subacromial space. Type III fractures reduce the subacromial space.⁶ The acromion process fracture in our case report resembles a Type III fracture, according to this classification.⁶ However, to the best of our knowledge, this type of displaced acromion process fracture was not mentioned in the current literature. As a result of low energy trauma, elderly people are more likely than younger people to sustain fragility fractures. However, our patient reported high energy trauma.³ There is no generally accepted treatment algorithm or method of fixation for acromial fractures.^1,4 However, using 2 cannulated screws was sufficient and gave a reliable fixation method instead of Kirschner wire or tension band fixation without postoperative complications, and some authors reported a 94% healing rate.⁸ Coracoid fractures frequently occur in conjunction with other scapula or shoulder girdle injuries.^1,9 The surgical indications for acromial fractures are determined by angular abnormality and displacement.¹¹ In our case, cannulated screws were sufficient to provide a reliable fixation on displaced acromial fracture, and we opted for conservative treatment for the non-displaced coracoid process fracture, which also worked well as the fracture healed completely. Our article advances the scarcity of literature on this uncommon injury conjunction of ipsilateral fractures of the displaced acromion process and the non-displaced coracoid process of the scapula, as well as the successful management by open reduction and internal fixation with 3 cannulated cancellous screws.

In conclusion, displaced fractures of the acromial process along with fracture of the coracoid processes of the scapula are uncommon and rarely seen in everyday clinics. Our case was caused by a two-wheeler accident and resembled type III Kuhn's classification of an acromion process fracture. However, this rare fracture does not fall under Ogawa's classification, and the patient was immediately recommended to undergo surgery due to subacromial space encroachment. Three cannulated cancellous screws were fixed in a direction perpendicular to the fracture line, which was sufficient and gave reliable fixation. The patient had no pain in the injured shoulder 6 months postoperatively, and radiographs revealed that the fracture had healed completely.

Funding

None declared.

Ethical statement

This study was approved by the local ethics committee. Informed consent was obtained from the patient.

Declaration of competing interest

No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.

Author contributions

Yusuf Omar Qalib - formal analysis, writing- original draft, writing-review, and editing. Srinivasa Reddy Medagam - investigation and editing. Sunil Dachepalli - review, editing and supervision.