The bicipital groove lies between the greater and lesser tuberosities and serves as a pathway for the long head of the biceps as it traverses from its intra-articular origin from the superior glenoid-labrum complex into the proximal arm. The pectoralis major inserts on the humeral shaft and displaces it medially. The subscapularis inserts on the lesser tuberosity and causes medial displacement, whereas the supraspinatus and infraspinatus insert on the greater tuberosity and cause superior and posterior displacement. The anatomic neck is at the junction of the head and tuberosities, and the surgical neck is below the greater and lesser tuberosities. The four anatomic components of the proximal part of the humerus are the head ( 1), lesser tuberosity ( 2), greater tuberosity ( 3), and shaft ( 4). Displacement of fracture fragments is due to the pull of muscles attaching to the various bony components. 12įIGURE 9-1 The anatomy of the shoulder is complex, and shoulder function depends on proper alignment and interaction of anatomic structures. 13 The head is inclined approximately 130 degrees with respect to the humeral shaft. 11, 12 The most superior portion of the articular surface of the humeral head averages 8 mm above the greater tuberosity, 11 and humeral version averages 29.8 degrees (range, 10-55 degrees). 10 The articular head is spherical and has a diameter of 37 to 57 mm. Fractures of the proximal humerus occur in predictable patterns based upon the muscular insertions of the pectoralis major, subscapularis, supraspinatus, and infraspinatus ( Fig. The proximal humerus consists of the humeral head, greater tuberosity, lesser tuberosity, and humeral shaft. Proximal humerus fractures alter these complex interactions, resulting in pain, decreased range of motion, and disability. Moderate loads are counteracted by the deltoid and rotator cuff, and larger loads are counterbalanced by capsulolabral structures and bone structure. Loads of increasing severity are initially offset by joint surface anatomy, joint volume, atmospheric pressure, and joint fluid cohesion and adhesion. Stability and function of the glenohumeral joint is provided by an interaction of mechanisms that promote near global range of motion and purposeful function. To appropriately manage proximal humerus fractures, it is crucial to understand the complex anatomy of the shoulder girdle. These injuries tend to be more severe regarding soft tissue compromise and fracture displacement requiring operative intervention. In contradistinction to the elderly, younger patients generally sustain proximal humerus fractures during high-energy situations such as motor vehicle collisions, seizures, or electrical shock. 2, 7 Specific risk factors associated with the development of proximal humerus fractures in the elderly include low bone density, impaired vision and balance, lack of hormone replacement therapy, previous fracture, three or more chronic illnesses, and smoking. 7, 8 A majority of these injuries are nondisplaced or minimally displaced and have a good overall prognosis with nonsurgical management. Nearly three fourths of all proximal humerus fractures occur in patients older than 60 years, and they generally occur as a result of low-energy trauma such as a fall from standing height. 7 In general, proximal humerus fractures occur more in female patients than male patients (3 : 1 ratio), and the overall incidence increases with age. 3 – 6 Nonoperative versus operative management of these injuries depends upon the mechanism of injury, the patient’s physiologic age including activity level, and fracture pattern. Proximal humerus fractures account for nearly 5% of all fractures, 1, 2 and incidence increases secondary to an aging population and associated osteoporosis. With regard to shoulder girdle injuries, proximal humerus fractures remain challenging in both their initial diagnosis and treatment. Nationwide Trends in Management of Proximal Humeral Fractures: An Analysis of 77,966 Cases from 2008 to 2017. McLean A.S., Price N., Graves S., Hatton A., Taylor F.J. Epidemiology of Proximal Humerus Fractures. Iglesias-Rodríguez S., Domínguez-Prado D.M., García-Reza A., Fernández-Fernández D., Pérez-Alfonso E., García-Piñeiro J., Castro-Menéndez M. Trending a Decade of Proximal Humerus Fracture Management in Older Adults. Patel A.H., Wilder J.H., Ofa S.A., Lee O.C., Savoie F.H., O’Brien M.J., Sherman W.F. Epidemiology of Proximal Humeral Fractures: A Detailed Survey of 711 Patients in a Metropolitan Area. Passaretti D., Candela V., Sessa P., Gumina S. The Epidemiology of Proximal Humeral Fractures.
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