FRACTURE OF DISTAL HUMERUS
In adults, fractures of the distal humerus often require surgical fixation because they are usually caused by a high-energy injury and frequently are comminuted and/or intra-articular in location. Fracture patterns include supracondylar, transcondylar, intercondylar (T or Y), lateral or medial condyle, or epicondyle and isolated capitellar or trochlear fractures. Intra-articular fractures may be difficult to adequately assess on plain radiographs; therefore, CT scans may be needed.
Surgical fixation can be with plates and screws, or screws alone, depending on the particular fracture pattern. Joint replacement has also become an option for distal humerus fractures that may be too comminuted to be stabilized with plates and screws.
Complex Intra-articular Fractures
Comminuted intra-articular fractures of the distal humerus are among the more challenging orthopedic injuries, and their reconstruction requires considerable surgical skill (see Plate 2-21). The major complications include restricted elbow motion and early degenerative joint disease.
Surgical fixation of comminuted intra-articular fractures can be problematic: the distal fragments are small, minimizing the number of available screw sites, and the fragments are primarily cancellous bone, which compromises screw purchase. In addition, the surface of the distal fracture fragments is primarily articular cartilage, which must be protected, and the complex topography of this region can make reconstruction of the normal anatomy difficult.
The structure of the distal humerus is conceptualized as two bony columns diverging from the shaft. The medial column includes the medial pillar of the distal humerus, the medial condyle and epicondyle, and the trochlea. The lateral column includes the lateral pillar of the distal humerus, the lateral epicondyle and condyle, and the capitellum. To approach and fix intra-articular fractures of the distal humerus, an intra-articular osteotomy of the olecranon is usually performed and the olecranon and the aponeurosis of the triceps brachii muscle are reflected proximally, exposing the entire distal humerus (see Plate 2-21). The ulnar nerve is also identified and typically transposed as part of the surgical approach. Internal fixation of the distal humerus first involves reconstructing the articular surface and holding the fragments together with transverse Kirschner wires or lag screws. The articular surface is then reattached to the shaft with plates and screws to provide stability in both the anteroposterior and mediolateral planes. Current techniques utilize bicondylar plating with precontoured plates that match the anatomy of the distal humerus. Bicondylar plating can be performed with the plates at right angles to one another (medial plate and posterolateral plate) or straight across from one another (medial plate and lateral plate). The olecranon is reattached with a precontoured plate to fit the olecranon or a tension band wire (see Plate 2-21). Newer surgical approaches have been developed and are now being utilized that avoid the need for an olecranon osteotomy while still providing enough visualization of the distal humerus from appropriate fixation. This can speed up recovery after surgery and avoids the risk of developing a nonunion at the osteotomy site.
Total elbow arthroplasty has also become an option for comminuted distal humerus fractures. In elderly patients with poor bone quality, such fractures may be unable to be stably fixed with plates and screws. Joint replacement allows early range of motion and function for these otherwise devastating elbow injuries, without requiring bony healing (see Plate 2-22). In younger patients with severely comminuted distal humerus fractures that cannot be reconstructed with plates and screws, elbow hemiarthroplasty is becoming a surgical alternative in select cases. This replacement of only the humeral side of the elbow is a newer option in this patient population that is typically considered too active for a complete elbow replacement.
Early elbow range of motion is important after plating or elbow arthroplasty to avoid stiffness. Protected active and active-assisted exercises (flexion-extension, pronation-supination) are encouraged soon after surgery to maintain range of motion in the elbow joint.
Fractures of Lateral Condyle
Fractures of the lateral condyle can involve the capitellum alone or extend medially to involve the lateral portion of the trochlea (see Plate 2-21). Fractures of the lateral condyle are more common than those of the medial condyle and are usually displaced and require surgical fixation. As with any intra-articular fracture, open reduction and internal fixation is performed to reestablish the articular surface as accurately as possible and to allow early active motion. A plate and screws or screws alone can be used for fixation, depending on the fracture pattern. In fractures of the lateral condyle, both in adults and in children, it is important to preserve all the soft tissue attachments, particularly posterolaterally, to maintain the blood supply to the fragment. With rigid internal fixation, the patient can begin active motion as soon as the soft tissues have healed.
Fractures of Capitellum
Fractures of the capitellum alone are uncommon and may be difficult to diagnose if the fracture fragment is very small. Any effusion within the elbow joint together with displacement of the fat pads on plain radiographs suggests either a capitellar fracture or other nondisplaced fracture near the elbow.
There are four types of capitellar fractures. The type I (Hahn-Steinthal) fracture is a coronal fracture that involves a large part of the osseous portion of the capitellum and is typically treated with open reduction and internal fixation with one or two screws. This method makes early joint motion possible in rehabilitation. These screws often need to be placed on the articular surface in an anterior to posterior direction and, therefore, are headless and countersunk (see Plate 2-23). The type II (Kocher-Lorenz) fracture is a sleeve fracture that involves primarily the articular cartilage with very little underlying bone. The fragment is often too small to be fixed, and treatment includes excision of the fragment. Type II fractures cause few subsequent problems in the elbow joint. Type III fractures are comminuted and also may be difficult to fix, and a type IV fracture is similar to a type I fracture, except that it extends more medially and includes a major portion of the trochlea.
Fractures of Medial Epicondyle
The medial epicondyle is the common origin of several flexor muscles of the hand and wrist. When the medial epicondyle is fractured, the flexor muscles pull the fragment distally. The injury is often accompanied by valgus instability of the elbow if the collateral ligament is affected and by injury to the ulnar nerve. If there is significant valgus instability of the elbow, the epicondyle must be reduced to its anatomic position and secured with a pin or a screw. During the surgical procedure, care must be taken to protect the ulnar nerve from inju y, and ulnar nerve transposition may be necessary.