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.
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 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.
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.  After a 2-week period in which the elbow was immobilized at 120º of flexion, extension was gradually increased. Better outcomes were observed in elderly patients, with ulnohumeral motion averaging 116º 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. 
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. 
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) on the basis of 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.  In the early 1960s, with the formation of the Swiss Arbeitsgemeinschaft für Osteosynthesefragen (AO)-Association for the Study of Internal Fixation (ASIF) group, formal techniques to achieve anatomic reduction with stable fixation began to evolve. Consequently, open reduction and internal fixation (ORIF) of displaced distal humerus fractures has become the standard of care for most patients. Even today, the operative technique continues to evolve.
For patient education resources, see the Breaks, Fractures, and Dislocations Center, as well as Broken Arm and Broken Elbow.
The difficulty in treating complex distal humerus fractures lies in the unique and specific anatomy of the distal humerus, which 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 three different articulations, as follows:
Proximal radioulnar joint
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.
Most distal humerus fractures can be classified into one of the following two etiologic groups:
Those resulting from a high-energy mechanism, such as a motor vehicle accident (MVA)
Those resulting from a low-energy injury, such as a fall while walking
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 after high-energy injury, these fractures can lead to significant functional impairment. Distal humerus fractures most commonly involve both 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.
Loss of terminal extension is frequently observed after distal humerus fracture. Chronic exertional pain can be observed in as many as 25% of patients who have suffered such injury.
Henley and other authors reported good to excellent results in 92% of treated patients at 1.5-year follow-up.  Other studies reported similar numbers, with a range of 60-90% and good-to-excellent results.
Wang et al reported that most poor results tend to occur with complex group C3 fractures and are related to associated injuries and complications.  In their study of 20 patients, 4 complications occurred: 1 nonunion, 1 malunion, 1 deep infection, and 1 brachial artery laceration.
McKee et al studied functional outcome following surgical treatment for displaced intra-articular distal humerus fractures.  After 37 months of follow-up, they found a mean flexion contracture of 25° and an arc of motion of 108°. Significant decreases in mean muscle strength were found in both elbow flexion and extension (75% of normal).
Regarding surgical exposure for distal humerus fractures, a nonunion rate of up to 40% has been reported from chevron osteotomy outcomes, though some authors contend that poor technique is often the source of the complications. Contributory factors include lack of interdigitation of the osteotomy site, malposition of the intramedullary fixation screw, infection, and broken implants.
Bashyal et al reviewed the incidence of infection and other complications in 622 children with supracondylar distal humerus fractures who underwent closed reduction and percutaneous pin fixation. The most common complication was pin migration necessitating return to the operating room for pin removal in 11 patients. A total of six patients (1%) developed infections. One patient had a malunion; four underwent repeat reduction and pinning; and three developed compartment syndromes. The authors concluded that closed reduction with percutaneous pinning has a low complication rate, with a very low rate of infection, and they noted that preoperative antibiotics had little effect on the infection rate. 
Mighell et al retrospectively reviewed 18 patients who underwent open reduction and internal fixation with headless compression screws for large coronal shear fractures of the distal humerus without posterior comminution. Seventeen of the patients had good-to-excellent results on the basis of the Broberg-Morrey scale. Three patients developed avascular necrosis, and five developed arthrosis. No reoperations were necessary.