Glenoid Rim Fractures: Acute Reduction and Fixation

Mohamad Y. Fares

Peter Boufadel

Bryson R. Kemler

Joseph A. Abboud

Glenoid fractures constitute a debilitating injury that can significantly affect the quality of life and functions of the presenting patient. Being the most mobile joint in the human body, the shoulder relies on the small surface area of the glenoid to articulate with the large surface area of the humeral head. Hence, minor insults to the glenoid surface can lead to instability, weakness, immobility, and dysfunction. Management strategies have varied with regard to glenoid fractures. These include conservative treatment for patients with minor nondisplaced fractures and surgical treatment for patients with more severe presentations. Surgical management has evolved from traditional open techniques and can now include arthroscopic techniques for reduction and fixation, depending on the nature and etiology of the presenting fracture. Current reports have shown favorable results for both approaches, and have confirmed the utility of these procedures in the setting of reduction and fixation of glenoid fractures. That being said, knowing the advantages and disadvantages of the different treatment options and the different surgical approaches is pivotal for appropriately deciding on the best therapeutic strategy. This would also be helpful for administering proper patient education that can ensure well-formed expectations and optimal postoperative outcomes.

INTRODUCTION

The glenoid is a pear-shaped bony process that acts as the socket for the glenohumeral joint. Glenoid sizes may vary in the general population, but the average glenoid is about 32 mm in length and 25 mm in width, with around 1° of retroversion from the scapular axis.¹ It is also approximately tilted 15° from the scapular plane, and is supported by a robust bony column termed the glenoid vault.¹^,² It is nourished by different vessels that include the anterior and posterior circumflex vessels, branches from the rotator cuff muscles, and the suprascapular artery. Relative watershed areas are often situated in the anterosuperior portion of the glenoid as well as circumferentially around the rim.¹^,³

Situated at the lateral side of the scapula, the glenoid articulates its small surface area with the significantly larger radius of the humeral head, allowing for the greatest range of motion and mobility in the body.¹ Hence, the glenoid plays a pivotal role in ensuring the joint’s stability and in providing the necessary range of motion required for daily life activities. As such, minute fractures may have significant deleterious effects on the presenting patient and may lead to limitations in function and daily life activities.

Glenoid rim fractures are uncommon but debilitating injuries that often occur due to high-energy trauma such as motor vehicle accidents or instability incidents.¹^,⁴ These fractures are often concurrent with other injuries and can lead to chronic instability, weakness, immobility, and significant loss of function.¹^,⁴ Treatment of such injuries varies according to severity, and no strict algorithms have been established to guide management. Options differ between conservative management for minor fractures that remained anatomically aligned to arthroscopic and open procedures depending on fracture etiology and presentation.¹^,⁴ To gain additional insight into the operative techniques used for repairing such fractures, the aim of this book chapter is to explore the methods used for reducing and fix glenoid rim fractures in orthopedic surgery.

INDICATIONS AND CONTRAINDICATIONS

The majority of scapular fractures can be treated nonoperatively, under close observation and monitoring, with immobilization in a sling for several weeks, followed by early range of motion and progressive strengthening as the fracture heals. However, intra-articular fractures involving the glenoid, if left untreated, can result in severe complications including persistent pain, malunion or nonunion, deformity, instability, weakness, stiffness, and early glenohumeral arthrosis.⁵^, ⁶ ^and ⁷ Given the significance of these fractures, and the fact that the majority occur in young patients at an average age of 35 years,⁸ intra-articular fractures involving the glenoid are highly likely to require surgical treatment.

Surgical indications for glenoid fractures in the literature include glenohumeral instability, involvement of more than 25% of the articular surface, and/or a glenoid surface step-off or gap of more than 4 mm.⁵ Surgical fixation is also indicated for extra-articular (scapular neck) fractures exhibiting significant displacement of the glenoid with a translation of 1 cm or more, a fracture angulation exceeding 40°, or a glenopolar angle measuring less than 20°.⁵ Surgical fixation is indicated to restore the mechanical axis and articular congruity. In addition, patient age and activity level are important factors to consider during the decision-making process for treatment.

Contraindications to surgical fixation of glenoid fractures include patients who are unable to undergo surgery due to medical health reasons. These also include patients with minimally displaced or angulated extra-articular fractures that can be treated non-operatively, and patients with severely comminuted fractures of the glenoid that lack adequately sized bone fragments, as these may not benefit from surgical fixation as well.

PREOPERATIVE PREPARATION

Arthroscopic Approach

Arthroscopic fixation is typically indicated for anterior and posterior glenoid rim fractures such as bony and reverse bony Bankart lesions, typically found in patients with recurrent anterior or posterior shoulder instability. Preoperative evaluation of the patient involves an appropriate clinical exam and imaging of the glenohumeral joint. As an anterior shoulder dislocation puts the axillary nerve at risk, a complete neurovascular exam is important to obtain preoperatively.⁹

Imaging begins with standard anteroposterior (Grashey) and lateral (scapular Y) radiographs and should include the Stryker notch view to identify the presence of a Hill-Sachs lesion, which may be addressed concurrently with any glenoid or labrum injury.¹⁰^,¹¹ Magnetic resonance imaging (MRI) with or without arthrogram remains the primary modality for evaluating soft-tissue pathology in patients with shoulder instability; however, computed tomography (CT) with 3-dimensional (3D) osseous reconstruction provides superior conceptualization of bony anatomy.¹² Quantification of glenoid bone loss has been identified as a key factor in the surgical decision-making process in these patients,¹³ as Dickens et al revealed that mean glenoid bone loss after first-time dislocation is 6.8% and recurrent dislocation at around 22.8%.¹⁴ Historically, 20% to 25% bone loss has been cited as the threshold to consider a bony augmentation procedure such as a Latarjet; however, a recent study by Shaha et al indicated that in active populations, bone loss >13.5% may lead to unacceptable outcomes without addressing osseous pathology.¹⁵ Given the importance of appropriate glenoid bony assessment, and the observation that an acute fracture of the glenoid rim is observed in up to 1/3 of dislocation events, 3D CT is a recommended addition to the complete evaluation of the unstable shoulder.¹⁶

Arthroscopic fixation of a glenoid rim fracture is performed under general anesthesia either in the lateral decubitus or beach chair position with the arm placed in a movable support.¹⁷^,¹⁸ Lateral decubitus positioning allows for greater distraction of the glenohumeral joint, allowing easier access to the inferior glenoid, whereas beach chair positioning provides optimal rotational control of the shoulder and proponents argue it simplifies the anatomic orientation of the glenoid during repair.¹⁷ The most inferior glenoid anchor is thought to be instrumental in restoring stability and resistance to anterior humeral head translation in Bankart repairs,¹⁹^, ²⁰ ^and ²¹ and studies have consistently shown that when arthroscopic stabilization procedures are performed in the lateral decubitus position, inferior anchors are more commonly utilized.¹⁷^,²²^, ²³ ^and ²⁴ Most surgeons, however, prefer to use the same patient position regardless of the shoulder pathology.²⁵

Open Approach

Open reduction and internal fixation of glenoid fractures is indicated for higher-grade traumatic injuries that involve the glenoid articular surface and often extend into the scapular neck or body. Because of the nature of the mechanism of injury, preoperative evaluation of the polytraumatized patients is often a multidisciplinary effort focused on prioritizing management of life-threatening events such as hemopneumothorax, traumatic brain injury, and spinal trauma.²⁶^, ²⁷^, ²⁸ ^and ²⁹ Associated injuries are as high as 90%,³⁰ and most commonly involve ipsilateral extremity injuries, found in up to 50% of patients,²⁶^,³¹^,³² and brachial plexus palsy, which has an incidence as high as 12.5%.³³ Attention must also be paid to the overlying integument and soft-tissue, as a blow to the superior shoulder may often result in skin abrasion and increase the risk of surgical site infection.

Radiographic evaluation of the fracture should consist of anteroposterior (Grashey) and lateral (scapular Y) orthogonal views of the glenoid. Additionally, CT scan with 3D reconstruction can aid in preoperative planning, as it allows better visualization of fracture displacement and extent. It is also recommended to obtain an anteroposterior view of the opposite shoulder to measure the normal glenopolar angle, as this may be used to compare to the injured side both before and after reconstruction.

SURGICAL TECHNIQUES

Arthroscopic Reduction and Fixation

Examples of arthroscopic procedures for glenoid rim fractures include the use of suture anchors, cannulated screws, or transosseous screws for repairing bony Bankart lesions. For instance, Millett and Braun described the use of an anchor on the articular and deep sides of the fracture fragment, while passing a suture bridge around it.³⁴ They termed this method of fixation a “bony Bankart bridge,” and showed better fragment stability when compared to other techniques.³⁴ Another technique by Porcellini et al described the suture anchors being placed in the subchondral bone of the fracture fragment, and then conducting simple interrupted knots with the suture limb being passed through the capsule.³⁵ Percutaneous cannulated screw fixation with the use of arthroscopic glenoid visualization has also been described in the literature.³⁶ This technique has shown good results with larger fracture fragments, as opposed to small multifragmented fractures that are not amenable to screw fixation.³⁶ Our technique for arthroscopic reduction and fixation of glenoid rim fractures is derivative from Tuman et al.³⁷ This technique is often used for minor glenoid fractures, but has recently been described for Ideberg type V fractures.

The patient is placed in the lateral decubitus position and a standard traction device for lateral shoulder arthroscopy is used. We prefer this position, as it provides more access to inferior sites of the glenoid, which is necessary for glenoid rim fracture cases. The C-arm should be readily accessible for the surgeon should the need for intraoperative fluoroscopic views arise. The patient is then draped and prepped and the procedure commences. A standard posterior portal is created to introduce the arthroscope into the joint. A spinal needle can then be used to introduce an anterior portal within the rotator interval. Depending on the glenoid fracture classification, the rotator interval can be removed or withheld. A diagnostic arthroscopy is conducted, and the surrounding soft-tissue in the joint is examined and evaluated for possible interventions.

The fracture pattern is then assessed for severity and size, and a probe can be used to assess fragment mobility. A Bankart elevator can be used in some instances to mobilize and evaluate the fragment. The fracture fragment, often situated inferiorly to the healthy superior glenoid, may need
manipulation for complete release. A spinal needle can be used again to introduce a posteroinferior portal 2 to 3 cm inferior and distal to the standard viewing portal, which can be helpful during hardware insertion later during the surgery. Once the fracture fragment is appropriately mobilized, a probe can be introduced through the anterior portal to reduce the fracture fragment in the appropriate position. A nonthreaded cannulated screw guidewire can then be passed through this fragment, via the posteroinferior portal, so that it gains access to the fracture site. Caution should be taken to avoid injury to the articular cartilage of the humeral head.

The guidewire is then advanced from the posteroinferior to the anterosuperior direction, toward the superior glenoid cortex. If the provisional reduction is deemed adequate, a second guidewire is placed to prevent fracture mobilization when introducing the screw. The guidewire is used to indicate screw measurement, and a cannulated drill can be used to drill the outer cortex of the reduced fragment. Caution must be taken not to drill too far into the cortex during this step. The screw is placed while the fracture fragment is compressed against the intact superior glenoid, and visual assessment should be conducted to confirm maintenance of reduction. Intraoperative fluoroscopy is then performed to evaluate and assess fracture fixation. If appropriate fixation is confirmed, the guidewires can be removed and incisions be closed before the patient is put in a sling. Intraoperative arthroscopic images during the procedure can be seen in Figure 5-1.³⁷

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