Proximal humeral fractures account for ca. 5% of all fractures (1) and they are the second most common fractures in the upper limb, following proximal radial fractures, but in patients over 65 years of age, they are the third most common fracture following proximal femoral fractures and proximal radial fractures (2). Palvanen recorded a threefold increase in number of these fractures between 1970 and 2002 (3). The incidence of these fractures is significantly higher in females (proportion of males to females – 3:7), and other risk factors include low quality of the bones and risk of fall (4). 3- and 4-part fractures account for 15% of all fractures (5). It is believed that approximately 70% of 3- and 4-part fractures of the proximal humerus occur in patients over 60 years of age, including 50% in patients over 70 years of age (6).

There are many classification systems of proximal humeral fractures, and the most common are: Neer, AO, Codman-Hertel and an additional Resch system (7-11). Evaluation is made based on X-ray images in 2 projections (AP and Y-gamma) and computerized tomography (usually with 3D reconstruction). According to Neer (7), determining factors in fracture classification include presence of displacement and the number of fragments: group I – undisplaced, group II, III and IV: 2-, 3- and 4-part fractures, respectively; in total, there are 16 types of fractures. This is the most commonly used classification. According to AO, type A includes extra-articular, two-part (unifocal) fractures, type B includes extra-articular, three-part (bifocal) fractures, and type C includes articular fractures. These groups are further divided into the subtypes depending on displacement and degree of crush of the bone fragments, giving 27 types of fractures in total (8). The Resch classification describes the type of displacement and the pathomechanism of the fracture. A key issue is to differentiate whether the fracture belongs to the “impaction” type (unchanged position of the greater tubercle, with rotation of the humeral head and maintained total length of the humerus) or “disruption” type (increased distance between the greater tubercle and the shaft or the head and the shaft). Then, it is necessary to establish whether the fracture is a varus type, a valgus type or a neutral type, depending on the angle within the frontal plane at the image in AP projection. In the scapular plane projection, it is possible to evaluate the flexion, extension or neutral nature of the fracture (11). The unanimity of independent investigators regarding evaluation of the fracture type still remains low, which means that none of the currently used systems is perfect (12-14). According to Resch, the Codman-Hertel system, also referred as the “Lego bricks” system and the additional description of his authorship, is currently the best system for classifying proximal humeral fractures, which also evaluates the condition of the so-called medial hinge, as a support of the humeral head (9-11) and the length of the “metaphyseal” fragment accompanying a detached humeral head (9, 11). Among 200 multifragmentary fractures, 43% constituted fractures of a “varus” type, 31% – fractures of a “valgus” type, and 25% – fractures with the accepted position of the bone fragments (i.e. below 20 degrees of displacement). Among fractures of a “varus” type, 25% constituted fractures of a “disruption” type and 18% constituted an “impaction” type (11). Evaluation of this type of fracture and the degree of displacement of the bone fragments constitutes a base for qualification of the patients for surgical or non-surgical treatment. There are no explicit indications for surgical treatment, but the most controversial are 3- and 4-part fractures, which are the leading subject of this article, because they mainly occur in elderly patients. The most frequently used criterion for evaluation of fractures is Neer’s classification, which defines the following indications for surgical treatment: displacement exceeding 1 cm including the head and the shaft, displacement of the humeral tubercles, and angular position exceeding 45 degrees (7). These criteria will be discussed in the further part of this article.

Proximal humeral fractures are characterized by a few characteristics. The fractures are located in 2 regions comprising the shoulder – the glonohumeral joint, and the subacromial space, which may significantly influence its biomechanics (15, 16). Therefore, a majority of fractures in this area may be treated as articular injuries, so they require “anatomical” reposition – conservative or surgical (compliant with the rules of stabile osteosynthesis of the intra-articular fractures, see below) (8). This process involves an accurate evaluation of the bone fragments, i.e. suitable X-ray diagnostics (RTG, CT). Specific vascularization of this area is also important (9). Due to this fact, proximal humeral fractures may be complicated with necrosis of the humerus, despite the correct treatment. According to Boileau, the risk of necrosis occurrence is different depending on the fracture type:

– 2-part fractures with displacement – < 10%,

– 3-part fractures with displacement – 1-25%,

– 4-part fractures valgus impacted – 25-30%,

– 4-part fractures with displacement – 40-60%,

– 4-part fractures with dislocation – 80-100% (17).

According to Hertel, the most important risk factors of post-traumatic necrosis of the humeral head is the length of the “metaphyseal” fragment accompanying the detached humeral head (“calcar segment” < 8 mm), the break of the medial arch between the shaft and the head of the humerus (“medial hinge disruption” > 2 mm) and type of the fracture in the “LEGO” classification. Most frequently it refers to the fractures including anatomical head fractures, such as:

– isolated two-part fracture of the humeral neck – type 2,

– 3-part fracture with detachment of the head and the greater tubercle, the shaft remains with the lesser tubercle – type 9,

– 3-part fracture with detachment of the head and the lesser tubercle, the shaft remains with the greater tubercle – type 10,

– 3-part fracture with detachment of the head, the greater and the lesser tubercle are attached to each other, but detached from the shaft and the head – type 11,

– 4-part fracture with detachment of the head at the level of the anatomical head – type 12.

According to the same author, the degree of displacement of the bone fragments was less significant, similarly to the presence of the dislocation (9). Despite significant attention that is paid to the vascularization (i.e. vitality) of the humeral head, it should be remembered that necrosis may be well-tolerated by the patients over many years (18). Due to the incidence of these fractures in elderly patients, an important factor is the condition of the bones, with special considerations of the quality of the humeral head, the degree of “crush” of the humeral tubercles and the thickness of the cortical bone in the shaft (it is believed that for standard internal osteosynthesis, a cortical layer of at least 4 mm thick is required) (17, 19).

The next special characteristic of proximal humeral fractures is the key function of the greater tubercle of the humerus. The greater tubercle is the main “indicator” of the correct reposition of the humeral head (or the endoprosthesis head). Correct reposition of the greater tubercle ensures not only the possibility to “support” the humeral head, but also to provide correct vascularization. Moreover, due to anatomical attachments of tendons of the rotator cuff to the greater tuberosity (including two external rotators), its incorrect reposition corresponds to massive damage of the rotator cuff (17, 20).

While making a decision on non-surgical treatment, it is necessary to consider the following factors: