The most frequent three-part anterior fracture-dislocation is an anterior dislocation of the humeral head with two rimes affecting the greater tuberosity and the surgical neck. In such cases, the lesser tuberosity remains attached to the head. This is a positive sign in terms of clinical outcome because vascularization is intact. The Laing artery should be respected during the surgical approach because it carries the blood supply to the humeral head. In three-part fracture-dislocations, the humeral neck is usually broken, and the two tuberosities are fractured and displaced. We use a deltopectoralis approach and identify the biceps as a landmark to reduce the head into the glenoid fossa. Sometimes we performed a bicep tenotomy and tenodesis and use ORIF to stabilize the fragments. In the more difficult case of a glenoid fracture that requires synthesis, we split the subscapularis muscle and perform a vertical capsulotomy, after which we reduce the glenoid fragment and stabilize it with cannulated screws.

Three-part posterior fracture-dislocations are characterized by rimes involving the surgical neck and the lesser tuberosity. Fragments are identified with CT scanning, and surgery is planned. A deltopectoralis approach is generally used. The rime between the lesser tuberosity and the intertubercular groove is opened to locate the posteriorly dislocated humeral head and reduce it into the glenoid fossa. The decision to reconstruct the fracture or replace it with a prosthesis depends on the patient’s age, bone quality, comminution of fragments, and soft tissue lesions.

Four-part fracture-dislocations are very complex lesions whose treatment is still debated [4, 5, 7, 8, 18, 22, 23]. The common denominator of this type of lesion is humeral head ischemia because of disruption of the blood supply [24, 25]. Various studies report a high percent of humeral head osteonecrosis [2, 3, 5, 8, 11, 13, 26]. Based on this observation, we replace the head with a humeral prosthesis, particularly in middle-aged and in elderly subjects, and use ORIF only in very young patients.

Recently, Hertel et al. [23] reported that the length of the dorsomedial extension and the integrity of the medial hinge can predict fracture-induced humeral head ischemia. However, although their study was an advance in the field of classification-surgical indications, it does not address the issue of whether osteosynthesis or prosthesis should be performed.

The implant of a prosthesis for a four-part anterior or posterior fracture-dislocation differs slightly from the implant of a standard four-part fracture. The level of difficulty depends on the expulsion zone of the humeral head. In some cases, it is positioned anteriorly near the glenoid rime; in others, the head is ejected outside the subscapularis muscle and must be sought below the plexus and vascular fascia. In rare cases, it lies on the chest wall, and even more rarely, it is displaced intrathoracically [27]. One should always assess for glenoid damage, which can consist in labrum and capsule injury, subscapularis muscle lesion, and even a bony Bankart fracture . In the latter case, osteosynthesis is necessary. In case of a posterior head dislocation, we have to consider the possibility of capsule avulsion from the posterior edge of glenoid and secondary posterior instability also after surgery.

Internal fixation of the humeral head in a four-part fracture-dislocation is difficult mainly because the fragments are unstable and the points of contact of fracture lines are difficult to identify; the same applies in case of humeral replacement.

The gold standard treatment for four-part fractures and fracture-dislocations is the implant of a humeral prosthesis . However, there is now a trend toward humeral reconstruction in patients between 50 and 65 years old [4, 22, 28], whereas in patients older than 65 years the question is whether to implant an anatomic or a reverse prosthesis. We recently proposed a classification to guide this treatment decision [26]. This revisited Neer classification of four-part fractures [3] was prompted by the observation that previous classifications, from Codman [33] to Neer [3] and more recently Hertel et al. [23], do not correlate the traumatic lesion with surgical indications, namely, osteosynthesis versus prosthesis implant. Our classification is based on the study of “missing” fifth fragment, namely, the humeral calcar (Fig. 15.2a, b), which was not considered in previous classifications. To study the calcar , we delimit the calcar area on the medial column using four planes. These planes intersection at well-defined points. The calcar lies between two axial parallel planes denoted as “alpha” and “beta” (see Fig. 15.2a) that cross the anatomic and surgical neck, respectively. A third plane denoted as “gamma” intersects these planes orthogonally on the medial border of the lesser tuberosity. The fourth and last plane denoted as “delta” is coronal oblique and passes central to the humeral calcar, thereby dividing it into two parts: anterior and posterior. Thus, we can define the involvement of the calcar in the fracture, particularly on the CT scan, and determine the relationship between its fracture and cephalic cup with the other three fragments (i.e., the lesser and greater tuberosities and the surgical neck). This enables us to forecast the difficulties in case of reconstruction and the most appropriate technique to use.

This process resulted in six main fracture types divided into 16 subgroups (see Fig. 15.3). Fracture-dislocations are types V and VI. Type V is characterized by anterior displacement of the humeral head, which may be outside the articulation due to a tear in the capsule and outside the subscapularis muscle or outside the capsule but retained on the subscapularis muscle. Type V is divided into four subtypes. Subtype VA is extra-subscapular; the calcar is fractured on the beta plane, the entire tuberosity complex is fractured, and the greater tuberosity is displaced, whereas the lesser tuberosity can remain linked to the periosteum. Subtype VB is extracapsular with a fracture of the calcar on the alpha plane and with tuberosities displaced and often multifragmented. Subtype VC is intrasubscapular with a fracture in the beta plane. Type VD is intrasubscapular with a fracture on the alpha and beta planes and head splitting. Type VI fractures are characterized by posterior displacement of the head and are divided into VIA, which is an avulsion fracture of the lesser and greater tuberosities, and VIB, which is characterized by head splitting with the upper part of the head linked or not to the greater tuberosity.

To test our classification , we examined all the data (emergency room radiographs, CT scans, Neer classification, surgical technique used, type and results of surgery) related to 173 cases of complex fractures of the proximal third of the humerus. On the X-rays, we evaluated bone parameters in relation to the position of the calcar, humeral head inclination, and the position of the tuberosities. We focused on the morphology of the calcar fracture that serves as a landmark for implantation of the prosthesis at the correct height and retroposition (Table 15.1). If the humeral head is expelled anteriorly, outside the glenoid cavity after a shoulder dislocation, we carry out the bone block technique [29] that enables an anatomic reconstruction and stable fixation.