11.1 Introduction

Proximal humerus fractures are the third most common fractures in patients older than 65 years, with an approximate unadjusted incidence of 82 per 100,000 person-years, and a nearly 2:1 female to male distribution.1 As incidence of these injuries is expected to significantly increase with the growth in the elderly population segment over the next decades, it follows that the incidence of symptomatic fracture sequelae will increase as well.2,3 While nonoperative management of proximal humerus fractures may yield satisfactory outcomes in older and lower-demand patients with regard to pain and quality of life, functional limitations are typical with degrading results as fracture complexity increases.4,5,6 Symptomatic malunion and nonunion of the proximal humerus remain an especially difficult treatment challenge for even the most experienced shoulder surgeon.

11.2 Classification and Surgical Considerations

As classically described by Neer, the proximal humerus anatomy, as it relates to fractures and treatment, can be divided into four distinct parts: articular segment (head), greater and lesser tuberosities and their rotator cuff components, and the humeral shaft. Displacement of each part by 1 cm or more or angulation of more than 45 degrees is considered significant, regardless of the number of fracture lines.7 The vast majority, up to 85%, of proximal humerus fractures are minimally displaced and can be treated nonsurgically with a brief period of immobilization followed by a progressive rehabilitation program.7 The success of nonsurgical treatment has been reinforced in recent literature, and may similarly be expected for patients with mild fracture malunions or low physical demand.4,5,6 In contrast, patients with proximal humerus nonunion or significant malunion may experience disabling pain and unacceptable functional limitation.8,9,10,11

Beredjiklian et al10 proposed a classification system for osseous fracture sequelae of the proximal humerus based on pattern of anatomic disruption using plain radiographs. Type I malunions included greater and/or lesser tuberosity displacement of greater than 1 cm from anatomic position. Type II malunions were defined by articular incongruity from intraarticular extension of fracture, posttraumatic arthritis, or osteonecrosis with humeral head collapse. Type III malunions were described as greater than 45-degree rotational deformity of the articular segment with respect to the humeral shaft in any plane, clinically resulting in changes in humeral version or varus/valgus alignment.

For preoperative arthroplasty planning, we prefer to use the system described by Boileau et al, which classifies more severe proximal humerus fracture sequelae into two categories and four types with implications for arthroplasty surgical management based on need for tuberosity osteotomy.12,13 Category 1 is defined as impacted intracapsular fracture sequelae with greater tuberosity-diaphysis continuity, and includes Type 1 (humeral head collapse or osteonecrosis) and Type 2 (locked dislocation and fracture-dislocation) patterns. Greater tuberosity osteotomy is rarely indicated or required. In contrast, Category 2 fracture sequelae are defined by disimpacted extracapsular patterns that traditionally require greater tuberosity osteotomy. This category includes surgical neck nonunions (Type 3) and severe tuberosity malunions (Type 4).

Overall, surgical treatment options are essentially dependent on the deformity, and can be divided into humeral head-preserving or humeral head-sacrificing techniques.14 The primary humeral head-preserving surgical options are corrective osteotomy, tuberoplasty, acromioplasty, and soft-tissue release, which are normally reserved for milder abnormalities. Humeral head-sacrificing treatments include hemiarthroplasty, anatomic arthroplasty, and reverse shoulder arthroplasty. Addressing both bony deformity and soft-tissue dysfunction is essential for optimal outcome.10

11.3 Preoperative Evaluation and Planning

As with any other orthopaedic evaluation, a detailed history and physical examination should be performed. The patient’s current level of shoulder function should be thoroughly assessed. Age, activity level, physical demands, and comorbidities (if present) will also help to guide optimal treatment. A thorough neurologic examination should be performed, with special attention paid to any patients with any associated history of nerve injury or dysfunction.

Simple radiographic evaluation, including the classic Neer trauma series of orthogonal views (anteroposterior, scapular “Y,” and axillary), is typically insufficient for evaluation of significant proximal humerus fracture sequelae. Computed tomography (CT) is utilized to better identify the deformity and any bone loss. In addition, CT provides information on glenoid bone stock and rotator cuff fatty infiltration and atrophy. We routinely obtain CT scans as part of the preoperative work-up with sagittal and coronal reconstructions. We will additionally obtain a CT arthrogram if there is significant concern for rotator cuff pathology. Use of three-dimensional CT has been advocated, but we do not routinely use it.15,16,17 Magnetic resonance imaging (MRI) may also be used in preoperative planning for further evaluation of the soft-tissue structures, including the rotator cuff, as well as osteonecrosis; however, we do not routinely obtain MRI as part of our preoperative evaluation.

11.4 Indications for Reverse Shoulder Arthroplasty

Initially described by Neer, fracture sequelae of the proximal humerus can represent some of the most difficult reconstructions in shoulder surgery due to complex patterns of bone loss and deformity.18 Milder malunions of the greater tuberosity and surgical neck may be managed with some combination of arthroscopic or open decompression, capsular release, debridement, and tuberoplasty, while more significant malunions with congruent articular surfaces have been treated successfully with tuberosity or surgical neck osteotomy.10,14,19 Treatment of nonunions of the surgical neck of the proximal humerus with open reduction and internal fixation with or without intramedullary bone grafting has been reported in the literature, and is a reasonable option in younger patients without significant bone loss or joint destruction and biology otherwise conducive to fracture healing.20,21,22,23,24

More complex fracture sequelae with joint incongruity include osteonecrosis with humeral head collapse, severe tuberosity malunion, nonunion of the surgical neck with or without significant bone loss, and chronic locked dislocation and fracture dislocations. These patients may have severe functional impairments and pain, and surgical management is technically challenging due to distorted anatomy as well as capsular contracture, deltoid adhesions, rotator cuff tears, and other soft-tissue abnormalities. Prior to the introduction of reverse shoulder arthroplasty, hemiarthroplasty and conventional arthroplasty have been utilized to treat these sequelae with inconsistent results.8,9,10,12,18,25,26,27 While reported results are variable, one consistent finding is suboptimal outcomes with greater tuberosity osteotomy.

Surgical neck nonunions and severe tuberosity malunion present an especially difficult challenge, as an osteotomy has historically been required for implantation of conventional shoulder arthroplasty. As the indications for reverse shoulder arthroplasty have expanded, multiple authors have recently advocated use of this prosthesis to treat proximal humerus fracture sequelae where greater tuberosity osteotomy would otherwise be required.13,17,28,29,30,31,32,33,34 Early results are promising, but patients should be informed of typically inferior results compared to reverse shoulder arthroplasty for cuff tear arthropathy.35,36

Our primary indications for reverse shoulder arthroplasty in the management of fracture sequelae of the proximal humerus are therefore type 3 (surgical neck nonunion) and type 4 (severe tuberosity malunion) sequelae to avoid the potential morbidity of greater tuberosity osteotomy (► Fig. 11.1 and ► Fig. 11.2). We additionally use the reverse shoulder arthroplasty in type 2 (locked dislocation and fracture-dislocation) sequelae due to significant soft-tissue dysfunction and instability; however, we prefer to treat type 1 (humeral head collapse and osteonecrosis) sequelae with anatomic shoulder arthroplasty.

The contraindications for reverse shoulder arthroplasty for proximal humerus fracture sequelae are similar to those for reverse shoulder arthroplasty in acute fractures as well as conventional shoulder arthroplasty. Active infection is an absolute contraindication, and poor overall health is a relative contraindication. There is no absolute minimum age for reverse shoulder arthroplasty, although glenohumeral joint sparing treatment options should be considered for younger patients if appropriate. As with any surgery, arthroplasty should be approached with caution if the patient is unable to participate in a rehabilitation program to facilitate an optimal outcome. Deltoid insufficiency resulting from permanent axillary nerve palsy is a contraindication specific to reverse shoulder arthroplasty.