Distal Humerus Fractures ?>

Distal Humerus Fractures

Distal Humerus Fractures

Introduction

The elbow joint coordinates movements of the upper extremity, facilitating the execution of activities of daily living in areas such as hygiene, dressing, and cooking. When the distal humerus is injured, elbow joint function can be impaired. The goal of open reduction and internal fixation is restoration of normal anatomy. Distal humerus fractures continue to provide challenging reconstructive problems for the orthopedic surgeon.

For excellent patient education resources, visit eMedicine’s Breaks, Fractures, and Dislocations Center. Also, see eMedicine’s patient education articles Broken Arm and Broken Elbow.

History of the Procedure

Many physicians once believed that optimal recovery for complex distal humerus fractures could be achieved through conservative treatment. In 1937, Eastwood described the “bag of bones” technique, which involved compressive manipulation of the distal fragments with collar-and-cuff support and the elbow in flexion.1 After a 2-week period in which the elbow was immobilized at 120 º of flexion, extension was gradually increased. Better outcomes were observed in elderly patients, with ulnohumeral motion averaging 116 º after 2.5 years of follow-up. However, Evans observed that despite the functional range of motion, the final outcome often was a weak and unstable elbow.2

Regarding operative treatment, Watson-Jones commented that even with a perfect anatomic reduction, “the resulting joint movement is always less satisfactory than after less accurate reduction obtainable with external means.” As late as 1969, Riseborough and Radin warned of the limitations of operative intervention for distal humerus fractures.3

Numerous advocates of conservative treatment have described less extensive operative techniques for these fractures. In 1943, Watson-Jones recommended closed treatment or a limited open reduction with Kirschner wires (K-wires) based on poor outcomes with intra-articular involvement. Percutaneous pinning of transcolumnar and supracondylar fractures in elderly, relatively inactive patients continues to be a viable treatment option.

Lambotte, in the first decade of the 20th century, was one of the first to describe operative techniques for stable osteosynthesis of the distal humerus.4 In the early 1960s, with the formation of the Swiss Arbeitsgemeinschaft f ü r Osteosynthesefragen – Association for the Study of Internal Fixation (AO-ASIF) group, formal techniques to achieve anatomic reduction with stable fixation began to evolve. Consequently, open reduction and internal fixation of displaced distal humerus fractures has become the standard of care for most patients. Even today, the operative technique continues to evolve.
Problem

Much of the difficulty encountered in treating distal humerus fractures lies in the complex anatomy of the elbow joint. The highly constrained nature of the elbow joint causes it to absorb energy following direct trauma. Consequently, articular comminution may occur. The distal humerus has a narrow supracondylar isthmus with a sparsity of adequate subchondral metaphyseal supporting bone, especially within the olecranon fossa. The osteopenia observed in elderly patients adds to the complexity. Hastings and Engles have described a “spill over effect,” in which inadequate restoration of a singularly injured joint can lead to abnormal wear and degenerative changes in an adjacent articulation. This effect can apply to the elbow.
Frequency

The incidence of fractures of the elbow joint is small compared to that of fractures of other bones. Elbow joint fractures have been estimated to make up 4.3% of all fractures. Typically occurring following high-energy injury, these fractures can lead to significant functional impairment. Distal humerus fractures most commonly involve both the medial and lateral columns. Single condylar fractures make up approximately 5% of distal humerus fractures. Epicondylar and coronal shear fractures of the articular surface are less commonly observed. In the pediatric population, 80% of all elbow fractures occur in the supracondylar region. The injury typically occurs in young boys aged 5-10 years.
Etiology

Most distal humerus fractures can be classified into 2 etiologic groups: those resulting from a high-energy mechanism, such as a motor vehicle accident (MVA), and those resulting from a low-energy injury, such as a fall while walking.
Presentation

A thorough patient history must be taken in the initial evaluation of these patients. Medical history, surgical history (especially pertaining to the injured extremity), medication use, nonmedication drug use, occupation, and smoking history should be ascertained. In an elderly patient, the reason for the fall must be investigated.

The mechanism of injury also can help to identify other associated bony or ligamentous injuries. Questions regarding the speed of the MVA or the height from which a fall occurred and the position of the arm at impact should be asked.

Understanding the premorbid condition of the patient’s injured extremity also is important, as is ascertaining any preexisting limitations, such as degenerative or traumatic arthritis, instability, stiffness, or neurologic abnormalities (acute or chronic), that may affect treatment.

With high-energy injuries, associated injuries to the head, chest, abdomen, spine, or pelvis must be excluded. Standard screening radiographs, including radiographs of the pelvis, spine, and chest, are obtained.

Physical examination of the patient should include examination of the injured extremity and a thorough primary and secondary survey to determine if any associated injuries are present. A complete examination of the neurovascular status of the extremity should be conducted. An accurate assessment should be made of the sensory and motor contributions of the median (including the anterior interosseous), ulnar, and radial (including the posterior interosseous) nerves, as well as the medial and lateral antebrachial cutaneous nerves. The brachial artery and median nerves lie anterior to the elbow joint and are at risk for disruption. The distal pulses should be palpated and the capillary refills should be assessed, with comparisons made to the contralateral upper extremity. If questions regarding vascular status arise, duplex Doppler studies or angiography should be performed.

Inspection and palpation also should be part of the examination. Open wounds communicating with the joint are common with high-energy injuries. These wounds should initially be treated with antibiotics and tetanus prophylaxis. A povidone-iodine dressing should be placed over the wound to prevent further wound colonization and exposure. The skin should be examined for bruising, ecchymosis, or lacerations, with these findings taken into consideration, especially if operative intervention is to be initiated. Bruising, ecchymosis, or lacerations may represent significant ligamentous damage and resultant instability. A well-padded, well-molded splint with the elbow in slight flexion and neutral rotation provides stability and pain relief until definitive treatment is possible. The splint should be applied with a nonconstrictive dressing. Signs of compartment syndrome of the forearm or upper arm also should be clinically investigated.

Indications

The decision to offer operative intervention for distal humerus fractures is based on many factors, including fracture type, intra-articular involvement, fragment displacement, bone quality, joint stability, and soft-tissue quality and coverage. In addition, individual factors, such as patient age, overall health condition, functional extremity demands, and patient compliance, are all considered. Preoperatively, patients must understand outcome expectations and the importance of rehabilitation.

Conditions in which operative intervention is supported include intra-articular fragment displacement, physeal displacement, supracondylar comminution and displacement, open fractures, floating elbow patterns, neurovascular injury, compartment syndrome, and multiple traumatic injuries.

Primary goals for operative intervention are to restore articular congruity and elbow stability. Another goal is to decrease the possibility of posttraumatic arthritis and elbow stiffness.
Relevant Anatomy

The difficulty in treating complex distal humerus fractures lies in the unique and specific anatomy of the distal humerus that allows it to articulate freely with the radius and ulna. The elbow is a trochoginglymoid joint; it has the capacity to flex and extend within the sagittal plane and also to rotate around a single axis. In fact, the elbow joint consists of 3 different articulations: the radiocapitellar, olecranon-trochlear, and proximal radioulnar joints. Motion within the sagittal plane occurs at the ulnohumeral articulation within the semilunar notch.

The distal humerus resembles a triangle, with the medial and lateral columns making up the sides and the trochlea forming the base (270° arc). The diaphyseal cortical cylindrical shape of the distal humerus splays out into a narrow isthmus to form the medial and lateral triangular columns. These columns are separated by a very thin layer of bone that posteriorly makes up the olecranon fossa and anteriorly composes the coronoid fossa. The lateral column ends distally in the capitellum. The articular surface of the capitellum represents the anterior surface of the inferior lateral column, with a 180° arc. The medial column is entirely nonarticular, with the ulnar nerve lying directly inferior in the cubital tunnel.

Reconstruction of the premorbid anatomy of the trochlea is crucial to restoration of motion and stability. The lateral column lies in approximately 20° of valgus relative to the humeral shaft. The medial column is aligned at a 40° angle to the shaft and ends in the trochlea. The capitellum is angulated 30-40° anteriorly, while the trochlea is angulated 25° anteriorly.

The ulnohumeral articulation is slightly asymmetric. The trochlea is larger in diameter medially than laterally, and this explains the normal carrying angle of the arm as it is extended. The trochlea ends more distally than the capitellum in the coronal plane, leading to a valgus position of the elbow when the arm is fully extended. When the elbow is flexed, the capitellum is projected further anteriorly, resulting in a varus posture. It is important to remember that the distal humeral articular surface is positioned at the normal carrying angle of 11-17° of valgus angulation. Most distal humerus intra-articular fractures split through the trochlear waist, causing comminution and often leading to narrowing of the trochlea after internal fixation. In addition, the condyles are rotated 3-8° internally and positioned in approximately 6° of valgus. Often, the olecranon blocks adequate visualization of the trochlea and olecranon fossa, limiting evaluation of fracture reduction.

In the pediatric population, during the first 6 months, the distal ossification border is distinct and symmetric. The ossification center of the lateral condyle appears in infants around age 1 year. The medial epicondyle appears in children aged 5 years at the medial metaphyseal region. The trochlea ossifies in children aged 9 years. The lateral epicondyle begins to form and fuse with the lateral condyle in children aged 10 years. Before the end of growth, the capitellum, lateral epicondyle, and trochlea fuse to form the epiphysis. However, the medial epicondyle is usually the last to fuse, in adolescents aged 14-17 years.

The blood supply around the elbow is primarily fed by anastomotic vessels from the brachial artery. Most vessels supplying the lateral condyle enter posteriorly and course into the ossific nucleus. They feed into the lateral portion of the trochlea.

Contraindications

Contraindications to operative intervention for distal humerus fractures are patient specific. Factors that should be considered include the patient’s age, overall health condition, functional demands and expectations, and the overlying soft-tissue quality and bone quality. Finally, the surgeon must be able to make an honest evaluation of his or her ability to successfully perform open reduction and internal fixation of the fracture pattern.

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