PROXIMAL HUMERUS FRACTURES, ANATOMY, EPIDEMIOLOGY, MECHANISMS OF ACTION, CLASSIFICATION, CLINICAL PRESENTATION, IMAGING PRESENTATION, DIFFERENTIAL DIAGNOSIS, TREATMENT AND COMPLICATIONS

Introduction: Proximal humerus fractures (PHF) make up 5 to 6% of all fractures presented in adults. Approximately 67 to 85% of proximal humerus fractures are managed non-surgically, however with technological advances, improved techniques and increased patient demand, the rate of surgery is increasing. The use of open reduction internal fixation (ORIF) has remained stable, hemiarthroplasty has decreased and reverse shoulder arthroplasty (RSA) has increased. Objective: to detail current information related to proximal humerus fractures description, anatomy, epidemiology, mechanisms of action, classification, clinical presentation, imaging presentation, differential diagnosis, treatment and complications. Methodology: a total of 35 articles were analyzed in this review, including review and original articles, as well as clinical cases, of which 24 bibliographies were used because the other articles were not relevant for this study. The sources of information were PubMed, Google Scholar and Cochrane; the terms used to search for information in Spanish, Portuguese and English were: humerus fractures, Neer, proximal humerus, osteosynthesis and humerus prosthesis. Results: Fractures of the proximal humerus figure between 4 and 5 % of all fractures, 5 and 6 % in some other bibliographies; among those of the humerus they are the most common with 45 %. Fractures of the proximal humerus are more frequent in women, presenting higher rates compared to men, presenting a ratio of 2:1, possibly also due to alterations in bone density. Fractures of the proximal humerus at birth are infrequent, representing a rate of 10.1/100,000 births. Conclusions: Fractures of the proximal humerus account for 4 to 6 % of all fractures; among those of the humerus they are the most common at 45 %. Approximately 85 % of these fractures are non-displaced. Fractures of the proximal humerus have a bimodal distribution. Fractures of the proximal humerus are more frequent in women, presenting higher rates compared to men, presenting a ratio of 2:1. The most common mechanism of injury is the fall on the upper limb in extension at the same height. It is of utmost importance to know the correct anatomy in order to have a better impact on the quality of treatment. Affected individuals classically come with the upper limb held to the thorax with the contralateral hand and showing swelling, pain on palpation, pain during mobility and sometimes crepitus. A good examination should be performed for possible neurovascular involvement. All patients suspected of having a proximal humerus fracture should have radiographic imaging. There are several classifications, however the most widely used is the Neer classification. It is important to make a correct differential diagnosis. The main goal of treatment is to relieve pain and restore function. There are various types of treatment that will depend on the type of fracture and the patients clinical condition. Among the most common complications are neurovascular injury, thoracic injury, myositis ossificans, pseudarthrosis, shoulder stiffness and osteonecrosis. KEY WORDS: humerus, fractures, osteosynthesis, trauma.