Nonunions of the proximal humerus can be very debilitating to the patient, as often they present with a considerable amount of pain and varying degrees of functional loss. The rate of nonunion is reported to be approximately 1.1–10 % following closed treatment of proximal humeral fractures [12, 30–32]. A prospective study from Hanson et al. evaluated 124 proximal humerus fractures in an effort to study the outcomes of conservative management. When evaluating bony union they found 93 % of patients achieved a solid union after 1-year follow-up; however only 3 % required surgery for this. The median time to definite union was 14 weeks, and not surprisingly, they found smoking was a significant risk factor for nonunion. Smokers had a 5.5-time increased likelihood of developing a nonunion compared to nonsmokers [12]. Court-Brown and McQueen reported a 1.1 % nonunion rate in their prospective study of 1,027 consecutive proximal humerus fractures, but noted the rate to increase with higher degrees of metaphyseal comminution (8 %) and surgical neck displacement (10 %) [30]. In general, fracture patterns that disrupt the necessary blood supply for healing place patients at higher risk for nonunion and are commonly seen in two-part surgical neck fractures [33, 34]. Greater tuberosity nonunions are rare unless markedly displaced as they usually will heal and hence are more likely to develop a malunion. In addition, systemic diseases may compromise a patient’s ability to heal a fracture, especially those with severe osteopenia, obesity, heavy smokers, nutritional deficiencies and/or metabolic bone diseases. These same systemic factors though, may also lead physicians to avoid surgery in patients with displaced fractures for fear of postoperative complications. Given the potential for significant morbidity associated with surgical management of this problem, nonoperative management is an option, if this is the nondominant arm in an elderly person and pain is not too severe (Fig. 9.2). Because although in theory, more than 1 cm of displacement of the surgical neck fractures deems a surgical neck fracture “displaced,” many surgeons do accept a large degree of displacement in elderly, more sedentary patients, as long as there is some contact between the humeral head and the shaft. As long as these displaced fractures heal, the patient often will maintain some degree of function (although he may be stiff) and have minimal pain. However, if there truly is minimal to no contact between the shaft and the humeral head, surgery should be considered, because a nonunion can be very painful and function can be drastically impacted. If surgical intervention is still not deemed safe, a very detailed conversation about expectations should be had with the patient and family. A painful nonunion could take away the independence of an elderly patient who prior to the injury, was living alone and functioning well (Fig. 9.3).

Upon presentation of a symptomatic nonunion, many patients have substantial dysfunction and are rarely able to perform ADLs. The pain can be severe and is worsened by any attempt to use the extremity. These symptoms are typically not tolerated well in any population. Physical examination typically reveals pain and stiffness, and often the patient is pseudoparalytic. Integrity of the axillary nerve must always be determined. The standard radiographic views are always obtained, including a true anteroposterior (AP) in the plane of the scapula (grashey) an outlet and an axillary view. Often a computed tomography (CT) scan is helpful in judging better the degree and extent of bone loss, which can be substantial. In particular, surgical neck fractures with a varus deformity are higher risk for a nonunion. While there is bone contact between the humeral head and the shaft, this fracture pattern tends to be unstable. The more cortical distal fragment has poorer healing qualities compared to the more cancellous proximal fragment. An already soft, cavitated humeral head becomes more cavitated by motion against the medial cortical bone of the humerus and this further compromises healing potential in this area (Fig. 9.4). A CT or magnetic resonance imaging (MRI) scan will clearly show the cavitation of the humeral head and will often guide the surgical treatment choices. Patients who present with this fracture pattern should be watched closely for the first 3 weeks with serial X-rays. If the humeral head continues to collapse into further varus deformity, the micromotion between the medial humeral head and the calcar can cause a substantial degree of bone loss as described (Fig. 9.5). These are better detected early, when perhaps a standard open reduction and internal fixation (ORIF) can be performed rather than an arthroplasty.

If possible, the surgeon should always try to avoid the development of a nonunion by careful assessment of the fracture pattern, weighing carefully also patient-specific risk factors. Patients should be warned about the risks of smoking and encouraged to quit smoking until fracture consolidation is obtained. The concern is that the treatment of proximal humeral nonunions, as compared with that of acute fractures, poses additional challenges due to bone loss, compromised bone quality, associated malunion, and soft-tissue contractures. The evidence indicates that the results of late arthroplasty placement are inferior to those of acute replacement/fixation for the treatment of proximal humerus fractures [17, 31, 35, 36]. The treating surgeon should also beware the patient with preexisting glenohumeral arthritis, as there is often joint contractures, and thus motion is shifted to the fracture site. Even nondisplaced proximal humerus fractures are higher risk for development of a nonunion, and these fractures should be given careful consideration (Fig. 9.6).

The malunion rate after nonoperative treatment of proximal humerus fractures has been estimated to be 4–20 %, with a recent systematic review showing varus malunion as the most complication of nonoperative treatment [13, 37]. Some degree of malunion is almost inevitable with nonoperative treatment but when symptomatic, malunion is often associated with debilitating pain, limitation of range of motion, loss of function and subsequent significant disability. For the symptomatic patient, operative intervention is often required, but these surgeries prove especially challenging. Multiple factors contribute to the difficulty of malunion surgery, including disruption of the normal anatomy, substantial soft tissue scarring and contracture, especially of the rotator cuff, and osteoporosis. Several studies have clearly shown that the results of arthroplasty for secondary treatment of malunion are inferior to those of primary treatment, especially when a corrective osteotomy is necessary [35, 37–41]. Functional outcomes are lower and complications higher when arthroplasty is performed for the sequelae of proximal humerus fracture malunion [35, 37–44]. Truly, the better goal is to avoid the malunion if possible, as careful and close evaluation of initial fracture patterns and close patient follow-up can reduce the incidence of this devastating and technically challenging complication.

The main three types of malunions described by Beredjiklian et al. include: malposition of the tuberosities, incongruity of the articular surface, and malalignment of the tuberosities and humeral head relative to the shaft [43]. Upward pull of the greater tuberosity can lead to abutment against the acromion, limiting elevation. Posterior displacement can lead to abutment against the glenoid and can limit external rotation. Both positions can lead to a shortened and contracted rotator cuff. Varus or valgus deformities of the humeral head in the frontal plane can change the normal structural relationships within the glenohumeral joint. This can alter joint mechanics, increase contact forces within the joint, and result in areas of greater stress concentrations. Combined, these factors can lead to contractures, stiffness, and even predispose to head collapse [44]. Malunion due to a missed intra-articular fracture can lead to secondary arthritis within the glenohumeral joint.

Malunion is more commonly seen in two-part fractures, as displaced three- and four-part fractures are more likely to undergo early surgery. When a malunion of a three- or four-part does occur, it is often quite severe, with substantial distortion of anatomy, requiring quite complex surgery. In general, 10 mm of displacement is typically recognized as the threshold for acceptable displacement of a greater tuberosity fracture, although less displacement is accepted in more active patients. The deltoid force required for abduction is significantly higher when the greater tuberosity is displaced more than 5 mm and painful impingement and loss of function is less tolerated in the more active population [45]. Malunion between the humeral head and shaft is often tolerated well and can surprising lead to decent functional outcomes, especially in the elderly. If the passive range of motion can be maintained, the joint is congruent and the rotator cuff is intact, these can be tolerated well and function preserved. However, it has been shown that if the malalignment is more than 45° between the humeral shaft and the articular segment, there could be an unacceptable loss of forward elevation and abduction [43, 46–48].

When patients present with a symptomatic malunion, pain and loss of motion are the primary complaints. A careful exam should be performed, with attention to impingement and biceps signs. If passive external rotation is very limited, often there is a bony block to mobility, such as a very posterior greater tuberosity impinging against the glenoid (Fig. 9.7). In the worst-case scenario, the posterior greater tuberosity can impinge on posterior glenoid with external rotation and almost lever the humeral head anteriorly, leading to anterior instability. Further, strength testing can show rotator cuff weakness as the external rotators have been placed in a position that shortens and contracts the muscle tendon unit, leading to decreased strength. Likewise, cuff pathology can develop due to superior displacement of the greater tuberosity attritionally breaking down the superior cuff. Painful biceps pathology may also occur due to malunion of the bicipital groove and can be a substantial pain generator.

The most common errors during diagnosis occur with improper evaluation of the fracture pattern. The AP view will allow determination of the neck-shaft angle and the degree of humeral head varus or valgus. The scapular lateral and AP view allow assessment of the height of the greater tuberosity, and the axillary view is instrumental in evaluating the posterior displacement of the greater tuberosity as well as position of the bicipital groove. A CT scan with three-dimensional (3D) reconstructions is the best option to understand the complex anatomy of the presenting fracture as well as a malunion [39, 49]. For the presenting malunion, this can be helpful in determining if the greater tuberosity is healed to the shaft (more manageable) or if it healed to the posterior humeral head or even posterior glenoid. In these cases it can be virtually impossible to restore normal anatomy because of the severe shortening of the cuff. Tuberosity osteotomy is a formidable undertaking and in general should be avoided at all costs. Even after proper technique, mobilization of the tuberosity and achievement of a successful union is exceptionally challenging [35, 50]. Prosthetic arthroplasty is the primary treatment when there is joint incongruity and secondary arthritic changes are present, preferably without an osteotomy. However, for symptoms due primarily to the malunion of the greater tuberosity, minimally invasive techniques represent a viable treatment option [51, 52].

Malunion of a proximal humerus fracture at times is anticipated if the patient was a poor surgical candidate. In these cases, if function is adequate and pain tolerable, the patient likely can avoid surgical intervention. However, many times development of a malunion is due to failure to appreciate the extent of displacement, lack of adequate radiographs, or lack of adequate follow-up radiographs to detect displacement of initially nondisplaced fractures. Overzealous or premature rehabilitation and range of motion of an initially nondisplaced fracture can also lead to malunion. Soft tissue interposition such as the long head of the biceps could also be a factor contributing to the malunion. In general, though, it is preventable with proper initial evaluation and follow-up as proper initial treatment has the best chance of achieving a successful outcome.

Posttraumatic stiffness, especially after a minimally displaced fracture pattern and not actually loss of motion due to a malunion, is an avoidable complication. Of course, the lower demand the patient, the better tolerated the complication. However, as expected, it is not well tolerated in the young active patient. The most important factor is avoidance of prolonged immobilization, which has been shown to be of no value [10]. Functional recovery has been shown to be much better when a structured physical therapy program starts early [25, 53]. Especially in those with a stable fracture pattern, early protected mobilization is imperative and pendulums, hand, wrist and elbow motion can be started as soon as comfort allows. Passive mobilization of the shoulder can occur when the fracture is “sticky” and moves as a unit, typically by 3 weeks post injury. However, one should be sure that the loss of motion is not due to some other reason, such as missed greater tuberosity fracture blocking motion, and careful attention should be given to proper radiographs to assure this.

When a greater tuberosity fracture occurs, especially if isolated, the fragments are often small and comminuted and can deemed as unimportant to examiners who do not realize that these fragments contain the attachment of the rotator cuff. They can also be misinterpreted as calcium deposits (Fig. 9.8) [54]. Even if the fragment is not displaced, when small enough, joint fluid can intercede between the fragment and the cuff footprint and lead to nonunion and eventual resorption of the fragment. One should hold a high index of suspicion for these patients, especially if radiographs appear unchanged yet the patient continues to complain of pain and symptoms similar to rotator cuff pathology. MRI can be helpful in detecting these fragments initially or later showing the eventual cuff pathology so proper treatment can occur (often at this point, a formal cuff repair) (Fig. 9.9). Further, even if it is not small, the greater tuberosity fracture can be missed if the proper X-rays are not obtained. At times, the greater tuberosity can be pulled out of sight on the AP view. A critical eye can evaluate the AP film and notice that the greater tuberosity is not present, and then pick it up on an axillary and scapular lateral view. If it is missed, this can lead to a painful malunion as described above (Fig. 9.10).

Posttraumatic glenohumeral arthritis is most often related to missed intra-articular pathology, such as a humeral head split that subsequently healed in a malunited position. As above, it can also occur after a two-part malunion in which the joint contact forces are altered by a more varus positioned humeral head and arthrosis ensues (Fig. 9.11). Arthritic change typically takes much longer to progress, and patient symptoms may present many months to years down the road from the initial injury. At times, it presents subsequent to the actual traumatic impact itself. Except in the cases of joint incongruity and malunion, it truly is not preventable, and this should be explained to the patient initially as a possible long-term consequence of the initial fracture.

As well stated by Murray et al., in their paper on proximal humerus fractures, “complications may occur as an inevitable consequence of the original injury, or as a result of errors in treatment” [11, 46]. Unfortunately, more often than not, “errors in treatment” are the more prevalent reasons for operative complications. One must remember that at times, operative treatment of proximal humerus fractures is not any better than nonoperative treatment. There truly is not a consensus on best practices for treatment of proximal humerus fractures [55, 56]. Thus, one must take into account all patient factors and medical comorbidities when considering surgery. For instance, if a patient may not be able to participate in postoperative physical therapy, then operative management may be unwise. If the surgeon chooses to intervene surgically it should be because substantial enough improvement is expected that the risks of surgery are worthwhile, and risks should be minimized. Nonetheless, certain fracture patterns do require surgery, and unfortunately, complications and poor outcomes can occur even when surgery was well indicated.