Open Reduction and Internal Fixation of Proximal Humerus Fractures



Open Reduction and Internal Fixation of Proximal Humerus Fractures


Mark T. Dillon

Stephen Torres

Mohit Gilotra

David L. Glaser





ANATOMY



  • The osseous anatomy of the proximal humerus consists of the greater tuberosity, the lesser tuberosity, and the articular surface.



    • The subscapularis inserts onto the lesser tuberosity, whereas the supraspinatus, infraspinatus, and teres minor insert onto the greater tuberosity.



  • Knowledge of deforming forces associated with humerus fracture allows the surgeon to better treat proximal humerus fractures by both operative and nonoperative means.



    • In a two-part surgical neck fracture, the pectoralis major pulls the humeral shaft anteromedial.


    • In a two-part greater tuberosity fracture, the pull of the supraspinatus, infraspinatus, and teres minor tendons displaces the greater tuberosity superiorly and/or posteriorly.


    • With a three-part fracture involving the lesser tuberosity, the attachment site of these tendons into the greater tuberosity is intact, and the articular surface of the humeral head rotates externally to face anteriorly.


    • Three-part fractures involving the greater tuberosity result in unopposed subscapularis function, and the humeral articular surface rotates posteriorly.


    • Four-part fractures result in displacement of the shaft and both tuberosities, leaving a free head fragment with little soft tissue attachment.


  • An understanding of the vascular anatomy is crucial to treat fractures of the proximal humerus effectively and to predict potential risk of avascular necrosis.


  • The proximal humerus receives its blood supply from two branches of the axillary artery: the anterior and posterior circumflex humeral arteries.


  • Historically, the main blood supply to the humeral head has been thought to be the anterolateral ascending (arcuate) branch of the anterior circumflex artery10; however, there is new evidence to suggest the primary supply is from the posterior circumflex humeral artery.12


  • The arcuate branch runs just lateral to the tendon of the long head of the biceps in the bicipital groove, enters the humeral head, and becomes interosseous proximally at the transition between the bicipital groove and greater tuberosity and supplies the medial aspect of the humeral head.12


  • The posterior circumflex humeral artery branches from the axillary artery, travels through the quadrangular space with the axillary nerve, winds superolaterally around the posterior aspect of the humerus, and supplies the superior, lateral, and inferior aspects of the humeral head.12



    • The relationship of the arteries to the humerus is important when assessing risk of avascular necrosis as certain fracture patterns put these vessels at increased risk. Fractures with extension into the dorsomedial metaphysis and disruption of the medial calcar have significantly higher rates of ischemia then those that leave these areas intact.11


PATHOGENESIS



  • In older patients, proximal humerus fractures usually result from a ground-level, low-energy fall.


  • In contrast, younger patients sustain proximal humerus fractures as the result of higher energy mechanisms such as an automobile collision or a sports-related injury (eg, extreme sports).


  • The presence of an associated glenohumeral dislocation can also be present and must be determined at the time of initial evaluation.


PATIENT HISTORY AND PHYSICAL FINDINGS



  • History should include the mechanism of injury, social situation, and preexisting shoulder symptoms, which could indicate rotator cuff pathology or arthritis.


  • On presentation, patients with proximal humerus fractures complain of pain in the shoulder that is made worse with attempted movement.


  • Visual inspection can reveal ecchymosis and swelling of the arm and palpation generally elicits diffuse pain.


  • Assessment of the range of motion (ROM) may be difficult due to pain but is important to help determine the stability of the fracture. If the shaft and the proximal portion move as a unit when taken through internal and external rotation, the fracture usually is stable. If however, they do not and crepitus is felt, the fracture is unstable.


  • If there is an associated dislocation, it may be possible to palpate the humeral head as an anterior fullness.


  • A thorough neurovascular examination is performed to determine the presence of associated injuries.


  • Patients younger than 50 years are more prone to nerve injuries. One study demonstrated nerve injury, usually of the axillary nerve, in nearly 40% of patients in this age group who sustained shoulder dislocations or surgical neck fractures.2



    • Major vascular injury is very rare in these fractures; however, a high index of suspicion should be present when evaluating fractures with significant medial displacement. The axillary artery can be injured in these instances and diminished radial and ulnar pulses should alert the surgeon to this possibility.13


IMAGING AND OTHER DIAGNOSTIC STUDIES



  • Initial imaging studies consist of anteroposterior, scapular Y, and axillary views.



    • Additional views also may include internal and external rotation views if the fracture pattern is stable. Internal rotation views help to visualize the lesser tuberosity, whereas external rotation shows the greater tuberosity. West Point axillary view may be useful for fracture of the anterior glenoid rim and a Stryker notch view for a Hill-Sachs lesion.


    • Traction views also may prove helpful if tolerated by the patient.


  • A computed tomography (CT) scan may be helpful if radiographs do not demonstrate the fracture pattern adequately.


  • Studies have shown that the addition of a CT scan improves intraobserver reproducibility only minimally and does not affect interobserver reliability.1


  • However, CT scanning may prove valuable in determining the method of fixation as well as identifying associated injuries such as Hill-Sachs fractures and bony Bankart lesions.


  • Indications for magnetic resonance imaging (MRI) are limited, although it may prove useful if there is any concern regarding soft tissue injuries, including the glenoid labrum and rotator cuff.


DIFFERENTIAL DIAGNOSIS



  • Glenohumeral dislocation


  • Scapula fracture


  • Clavicle fracture


  • Humeral shaft fracture


  • Neurovascular injury


  • Neuropathic arthropathy



NONOPERATIVE MANAGEMENT

Jul 22, 2016 | Posted by in ORTHOPEDIC | Comments Off on Open Reduction and Internal Fixation of Proximal Humerus Fractures

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