Reverse Shoulder Arthroplasty for Proximal Humeral Fractures

Joaquin Sanchez-Sotelo, MD, PhD

Dr. Sanchez-Sotelo or an immediate family member has received royalties from Stryker; is a member of a speakers’ bureau or has made paid presentations on behalf of Acumed, LLC and Stryker; serves as a paid consultant to or is an employee of Exactech, Inc. and Wright Medical Technology, Inc.; has received research or institutional support from Stryker; and serves as a board member, owner, officer, or committee member of the American Academy of Orthopaedic Surgeons and the American Shoulder and Elbow Surgeons.

INTRODUCTION

Reverse shoulder arthroplasty is being performed more and more frequently for the surgical management of proximal humerus fractures.¹^,² Reasons include the unpredictable results provided by internal fixation and hemiarthroplasty,³ better reported outcomes when reverse shoulder arthroplasty has been compared with hemiarthroplasty,⁴^,⁵ as well as increased familiarity with reverse arthroplasty in general. Although reverse arthroplasty for fracture has the potential to compensate to some extent for cuff insufficiency if tuberosity resorption or nonunion were to occur, healing of the greater tuberosity is believed by most to decrease the risk of dislocation and to provide better function through restoration of the function of the infraspinatus and teres minor.⁶ Currently, the various prosthetic designs available result in different degrees of glenoid, humeral, and global lateralization, among other parameters. At present time, the ideal reverse design aspects for fracture applications remains to be determined, but our preference is to combine certain implant features and techniques with the potential to maximize tuberosity healing.

PATIENT SELECTION

Conceptually, shoulder arthroplasty using a reverse prosthesis should be selected for proximal humerus fractures requiring surgical intervention but not amenable to internal fixation or hemiarthroplasty. Unfortunately, decisions regarding when to recommend surgery for a patient with a proximal humerus fracture (and if so which surgical procedure is best) are difficult to agree upon for most orthopedic surgeons.⁷

Indications

Shared decision making for management of proximal humerus fractures should consider (1) fracture pattern and displacement and (2) patient characteristics: What’s the fracture? Who is the patient? We find the Mayo Clinic-FJD classification of particular use to characterize fracture patterns⁸ (Table 1 and Figure 1). Provided patients’ characteristics (age, comorbidities, and expectations) allow, we recommend shoulder arthroplasty for the fracture patterns summarized in Table 2.

TABLE 1 The Mayo Clinic-FJD Classification System for Proximal Humerus Fracture

Surgical Neck (SN)	Isolated (SN)
Surgical Neck (SN)	With fractured tuberosities (SN-GT, SN-LT, SN-GT-LT)
Tuberosity fractures
• Greater tuberosity (GT)	Isolated (GT)
	In the setting of anterior dislocation (GT-DL)
• Lesser tuberosity (LT)	Isolated (LT)
	In the setting of posterior dislocation (LT-DL)
Varus posteromedial (VPM)	Intact tuberosities (VPM)
Varus posteromedial (VPM)	Fractured tuberosities (VPM-GT, VPM-LT, VPM-GT-LT)
Valgus	Intact tuberosities (VL)
Valgus	Fractured tuberosities (VL-GT, VL-LT, VL-GT-LT)
Head fracture or dislocation	Head splitting (HS)
	Head impaction (HI)
	Head dislocation (HD)

Currently, most arthroplasties for proximal humerus fracture are performed using reverse components. Hemiarthroplasty is preferred in two circumstances: (1) head impaction fracture involving more than 40% of the articular surface with intact tuberosities and (2) varus posteromedial or valgus fractures with a single large greater tuberosity fragment. The majority of the fractures treated with replacement do not fit into these two categories and thus receive a reverse shoulder arthroplasty.

FIGURE 1 Radiographic examples of the various categories of the Mayo Clinic-FJD classification system for proximal humerus fracture patterns.

Contraindications

The main contraindications for reverse shoulder arthroplasty are summarized in Table 3. In addition to the general contraindications for anesthesia and surgery, reverse should be avoided in the presence of an active infection or when the remaining glenoid bone stock is severely compromised. These last two circumstances are rare, but patients with a concomitant fracture of the proximal humerus and the glenoid, as well as those with preexisting glenoid bone loss secondary to arthritis or old trauma, may not have enough glenoid bone stock to allow implantation of a glenoid component.

A few additional relative contraindications should be considered. Dysfunction of the axillary nerve or brachial plexus creates two potential concerns: deltoid atony may facilitate reverse dislocation in the early postoperative period; in addition, as reverse arthroplasty results in arm lengthening, nerve recovery could potentially be compromised by implantation of a reverse prosthesis. Our preference has been to proceed with reverse arthroplasty in these circumstances. Prior deltoid insufficiency secondary to prior open cuff repair surgery as well as preoperative fractures of the scapular spine or the acromion are rare but could occur secondary to trauma, rheumatoid
arthritis, or cuff tear arthropathy. Our preference is to “ignore” acromial fractures and proceed with reverse arthroplasty when needed. However, we recommend internal fixation of fractures of the scapular spine prior to implantation of a reverse arthroplasty. An associated fracture of the humeral shaft in a patient with a proximal humerus fracture (bifocal fracture) also represents a relative contraindication due to difficulties in implanting the humeral component on a fractured humeral shaft.

TABLE 2 Fractures Considered for Shoulder Arthroplasty

Complex fracture dislocations with
- the dislocated head fractured from the shaft and
- one or both tuberosities fractured
Head splitting fractures
Head impaction fractures involving over 40% of the articular surface
Varus posteromedial fractures with
- One or both tuberosities fractured and
- severe comminution, poor bone quality, advanced age
Valgus fractures with
- One or both tuberosities fractured and
- severe comminution, poor bone quality advanced age, unstable head segment

TABLE 3 Contraindications for Reverse Arthroplasty for Fracture

Absolute
- Contraindications for anesthesia or surgery
- Insufficient glenoid bone stock
- Infection
Relative
- Axillary nerve or brachial plexus injury
- Prior deltoid insufficiency
- Acromion or spine fracture
- Associated humeral shaft fracture

PREOPERATIVE (DIAGNOSTIC) IMAGING

In our practice, good quality radiographs and CT with three-dimensional reconstruction have become the standard of care regarding imaging studies prior to surgical management of all proximal humerus fractures. AP and axillary radiographs allow initial assessment of fracture pattern and displacement to decide whether to recommend nonsurgical or surgical management (Figure 2). When surgery is recommended, CT is obtained and provides a much more detailed depiction of the fracture pattern, and it is particularly helpful to plan the surgical procedure (Figure 3). Particular attention should be paid to the upper medial aspect of the fractured humeral shaft (to determine height of implantation of the humeral component), potential glenoid deformity or bone loss, and the morphology and comminution of the fractured tuberosities. Rarely, a CT angiogram is necessary to identify possible vascular injury in patients with a pale hand, decreased pulses, or an extremely swollen upper extremity.

PROCEDURE

Room Setup/Patient Positioning

Our preference is to perform reverse shoulder arthroplasty for proximal humerus fractures in the beach-chair position and through a deltopectoral approach. We prefer to place the trunk of the patient almost vertical (approximately 70° of trunk flexion in reference to the floor), the so-called “barber-chair” position. A Mayo stand with sterile covers is ideal to assist with arm positioning in different portions of the procedure; in our practice, a Mayo stand is preferred over a mechanical arm holder for this procedure (Figure 4). The surgical technician is best positioned on the side opposite to the operative shoulder. Relative hypertension anesthesia is requested when possible, although it may be risky in older patients with preoperative hypotension, ischemic heart disease, or peripheral vascular disease.

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