The management of a non-union depends on the quality of the available bone and the type of non-union. Classification of the non-union as atrophic or hypertrophic can help identify the factors that contributed to the failure to heal, and therefore suggest how to treat the cause of the non-union. In atrophic non-unions the etiology is a lack of biologic response to generate a fracture callous, and most commonly, is due to poor blood supply. In contrast, the hypertrophic non-union has all the biology needed to heal the fracture, but inadequate stability to allow for solid union. The treatment of an atrophic nonunion should include attempts at improving the biologic healing capacity of the fracture or joint arthroplasty options. Hypertrophic non-unions require rigid fixation, and often will have adequate bone stock that makes joint replacement less likely.

In cases where there is adequate bone stock in the humeral head and no evidence of arthritic changes, open reduction and internal fixation has historically had variable results. Multiple techniques have been employed, including conventional plate and screw fixation, intramedullary rods and fixed angle devices. The use of intramedullary fixation with a tension band construct originally showed high rates of healing in a small series by Neer [8]. However, all of the patients required reoperation due to stiffness and painful hardware, and subsequent attempts to reproduce the results in the original series by Neer have been met with high rates of failure [9]. Recent series using fixed-angle plate constructs with structural bone grafting using a fibular allograft or iliac crest have demonstrated healing rates of 90–95 % and improved clinical outcome scores [10, 11]. The author’s preferred treatment for non-unions with good bone stock and no evidence of avascular necrosis or arthritis is open reduction and internal fixation with a proximal humeral locking plate with an intramedullary fibular allograft strut (Fig. 23.2a, b).

Non-unions that have severe cavitation of the humeral head, advanced osteoporosis, avascular necrosis or glenohumeral arthritic changes are contraindications to attempted fixation and bone grafting. In these instances joint replacement, consisting of hemiarthroplasty, total shoulder arthroplasty or reverse shoulder arthroplasty, is the preferred treatment. Traditionally hemiarthroplasty has been the most common joint replacement for the treatment of proximal humeral non-unions. Hemiarthroplasty for proximal humeral non-union is a very challenging procedure due to both bone and soft tissue compromise. Multiple studies have demonstrated improvement in pain scores, but limitation in function outcomes with high rates of component malposition and tuberosity malunion, non-union or resorption [12, 13]. Despite improved implant design, fixation techniques and bone grafting, the rates of tuberosity complications are still high. As a result of the difficulties with tuberosity healing, interest has developed in the use of reverse total shoulder arthroplasty for the treatment of proximal humeral nonunions [14]. There are still only small series and limited evidence to support the use of the reverse, and further study is still needed to determine if the results are superior to hemiarthroplasty. The author’s preferred treatment currently is to use hemiarthroplasty for patients who are young or active, or who are not amenable to open reduction and internal fixation techniques. However, in the elderly or lower demand patient, we do use the reverse total shoulder replacement for proximal humeral non-unions (Figs. 23.3a, b and 23.4a, b).

The treatment of proximal humeral malunions depends on multiple factors, including the type of deformity, as well as patient factors, such as bone quality and the presence of associated arthritic changes [15]. Procedures that preserve the native glenohumeral articulation including osteotomy, ostectomy, tuberoplasty or acromioplasty are preferred in the young and active population. Arthroscopic treatment of impingement or contractures that result from proximal humeral malunions has shown good results in small clinical series [16, 17]. A recent study by Ladermann et al. reported improved function and pain scores with good and excellent results in six of nine patients treated with arthroscopic tuberoplasty with detachment, and advancement, and repair of the rotator cuff [16]. In cases of varus malunions with more severe deformity, a valgus osteotomy of the proximal humerus is a treatment option. Benegas et al. demonstrated improvement in pain and functional range of motion with union in 5 of 5 patients treated with a valgus producing osteotomy of the proximal humerus [18]. Due to the small sample sizes and lack of controlled trials, there is no clear superiority of one technique over another, and each surgeon should use clinical judgment to determine the best treatment option for patients with milder deformity and no glenohumeral joint incongruence or arthritis (Fig. 23.5a, b).