Distal humeral fractures are relatively rare and complex injuries. With appropriate preoperative planning and execution of surgical technique, good outcomes may be obtained in most patients. Patients should be counseled regarding loss of motion in these injuries, and elderly, osteoporotic patients with extensive comminution should be considered for total elbow arthroplasty as an alternative to open reduction and internal fixation.
Distal humerus fractures are relatively uncommon orthopedic injuries, representing less than 7% of adult fractures, and approximately 30% of fractures about the elbow.
Most intra-articular distal humerus fractures require operative fixation for an anatomic reduction and to allow for early motion to optimize outcome.
There are multiple approaches to the elbow joint including triceps-sparing, triceps-splitting, triceps-reflecting, and olecranon osteotoy.
Total elbow arthroplasty is an option for management of these fractures in elderly osteoporotic patients.
The elbow joint is composed of three bones (radius, ulna, and humerus) and comprises the ulnohumeral, radiocapitellar, and proximal radioulnar joints. The ulnohumeral joint is a hinge that allows for flexion and extension of the elbow. The axis of rotation of this joint is in slight external rotation (3°–9°) and valgus (4°–8°) from the humeral shaft. The semilunar notch of the ulna engages with the trochlea and this close articulation gives bony stability. The trochlea itself is contained between the lateral and medial columns of the elbow, and it is covered with articular cartilage over 300° of its surface. The medial and lateral columns diverge from the humeral shaft: the lateral column at approximately 20° and the medial column at approximately 45°. The distal articular surface is also angulated anterior to the shaft of the humerus, with approximately 30° to 40° anterior angulation of the capitellum and 25° anterior angulation of the trochlea.
Ligamentous Anatomy and Articular Surface
The medial epicondyle is the distal extent of the medial column. The medial collateral ligament and flexor/pronator musculature originate from this area of the distal humerus. Similarly, on the lateral column, the lateral collateral ligament and extensor musculature originate on the lateral epicondyle. On the lateral column, the articular surface of the distal humerus is the capitellum, which articulates with the radius, to form the radiocapitellar joint. Proximal to the trochlear and capitellar articular surfaces are two concave zones, the olecranon fossa posteriorly and the coronoid fossa anteriorly, which engage the olecranon and coronoid, respectively, during extremes of elbow extension and flexion.
The blood supply to the elbow is made up primarily of branches of the brachial artery, located anteriorly at the elbow joint. The ulnar and radial collateral branches form an anastomosis with the radial and ulnar recurrent arteries around the joint itself, and these arteries are supplemented by branches from the profunda brachii artery posteriorly. The capitellum receives most of its blood supply posteriorly, which becomes relevant with coronal shear injuries, where posterior stripping should be avoided.
The radial, ulnar, and median nerves all cross the elbow joint; however, only the radial and ulnar nerves are typically visualized with fixation of distal humerus fractures via a posterior approach. The ulnar nerve arises from the brachial plexus and travels down the arm in the anterior muscular compartment. The nerve then dives into the posterior compartment at the Arcade of Struthers, approximately 8 cm proximal to the medial epicondyle. It can easily be found closely approximated behind the medial epicondyle, and then it continues through the cubital tunnel and between the two heads of the flexor carpi ulnaris.
The radial nerve leaves the brachial plexus in the posterior compartment of the arm and travels in a distal, lateral path, crossing the humerus approximately 21 cm proximal to the medial and 14 cm proximal to the lateral epicondyle, respectively. The radial nerve lies in the spiral groove of the humerus, closely approximated to bone. Distally it passes through the lateral intramuscular septum approximately 10 cm proximal to the elbow joint.
There are multiple classification schemes for distal humerus fractures, ranging from descriptive to anatomic. The Arbeitsgemeinschaft für Osteosynthesefragen (AO)/OTA (Orthopaedic Trauma Association) classification is widely used and divides the fractures into types A (extra-articular), B (partial articular), and C (complete articular). In the United Kingdom, 38.7% were found to be type A, 24.1% type B, and 37.2% type C. These types are then subdivided based on extent of comminution and fracture complexity. Another commonly used classification system is that of Jupiter and Mehne, which is a descriptive scheme based on the shape of the fracture pattern and its similarity to Roman and Greek alphabet letters.
Capitellar fractures are a specific type of distal humerus fracture with their own classification scheme. In these fractures, a type 1 fracture is a complete capitellar fracture that does not extend into the trochlea; a type 2 fracture consists of an osteochondral fragment that may not have much bony involvement. A type 3 fracture is a comminuted capitellar fracture, and a type 4 fracture is a capitellar fracture that also includes some or all of the trochlea. In this case, a double arc is seen on the lateral radiograph ( Fig. 1 ).
Indications for nonoperative management
Most distal humerus fractures are treated operatively. On rare occasions, surgeons may elect to treat a distal humerus fracture nonoperatively, which is often related to the patient’s overall physiologic status. Indications for nonoperative management include
Patients who cannot tolerate surgery or those who may not benefit from surgery
Patients who have neurologic impairment of the limb or overall neurologic impairment.
Patients with severe osteopenia or bone deficiency
Patients with soft tissue problems such as local infection or skin loss
Patients with minimally displaced fractures
It is important to note that the risk of stiffness with cast immobilization is high, and this should be weighed against the risks of surgery. Significantly displaced and unstable fractures may be difficult to manage nonoperatively, as they can develop symptomatic nonunions or can cause early problems with pressure areas on the skin, particularly in elderly patients with poor soft tissue quality. As such, fractures distal to the olecranon fossa or coronal shear injuries of the trochlea and capitellum are easier to manage nonoperatively than unstable supracondylar fractures. Careful and vigilant follow-up must be performed if nonoperative management is chosen.
Indications for surgical management
Any intra-articular fracture of the distal humerus should be considered for surgical management. In rare cases with articular displacement less than 2 mm, these fractures may be managed nonoperatively, as discussed previously, but most of these injuries benefit from open reduction and internal fixation. In addition, associated injuries such as open fractures, concomitant radius and ulna fractures, and neurovascular injuries should point the surgeon toward operative management. Displaced extra-articular (AO/OTA type A) fractures may also be considered for operative management, as controlling reduction of the distal segment in a cast or splint can be difficult and can lead to elbow stiffness. In low-demand patients with osteopenia and very comminuted distal humerus fractures, total elbow arthroplasty is a viable alternative to open reduction and internal fixation. Patients with significant soft tissue defects or contamination can be considered for external fixation as a temporizing measure, although this scenario is uncommon.
Preoperative examination and planning
In all cases, patients should be completely evaluated for other injuries in addition to the distal humerus fracture. In addition, a complete examination of the upper extremity should be performed, including inspection for open wounds or skin at risk, as well as a neurologic examination including the median, radial, and ulnar nerves, and their more distal branches such as the anterior and posterior interosseous nerves and the cutaneous branches. Almost 25% of patients have preoperative ulnar nerve symptoms in type C distal humerus fractures. Evaluation of radial and ulnar pulses is performed and may be compared with the contralateral arm if any abnormalities are detected.
In addition to elbow and forearm films, anteroposterior (AP) and lateral radiographs of the entire humerus up to the shoulder to evaluate for any proximal extension are obtained. AP and lateral traction radiographs of the elbow are extremely helpful for further delineating the fragments and for preoperative planning. Although computed tomography (CT) scans are sometimes used to evaluate elbow injuries, these views are often not orthogonal to the fracture and may or may not be useful for evaluation of the distal humeral fragments. They are particularly useful in examination of other areas of elbow injury such as the radial head, and they may help further delineate coronal shear injuries of the distal humerus. Three-dimensional reconstructions may be particularly useful in this regard. It is important to note that many patients with distal humeral fractures have other injuries about the elbow, and the surgeon should always search for these to avoid missed diagnoses.
The patient is positioned either prone or lateral with the shoulder abducted and the elbow flexed to 90° over a radiolucent arm holder. The arm is sterilely prepared and draped up to the axilla. The authors do not routinely use a tourniquet, but a sterile tourniquet should be available in case it becomes necessary during the procedure.
Multiple approaches to the distal humerus have been described. A universal posterior midline skin incision is used, with variations in the deep approach through or around the triceps musculature ( Fig. 2 ). The incision should have full-thickness fascio-cutaneous flaps to avoid devascularization of the skin and seroma formation. The incision should be curved over the lateral aspect of the olecranon to facilitate coverage of the hardware at closure and to avoid cutting directly through the olecranon bursa, which may increase hematoma formation.
In cases of minimal articular comminution or extra-articular fracture, a triceps-sparing or triceps-splitting approach may be used. In these approaches, the olecranon is left intact, which decreases ability to visualize the articular surface extensively. These approaches are not recommended for fractures with multiple articular fragments. Since the ulnar nerve is closely approximated to the medial epicondyle, with any approach to the distal humerus it should be identified and dissected to avoid injury. Proximally, the nerve is released along its entirety, including the distal medial intermuscular septum and Osborne ligament to avoid any stretch or tension during the remainder of the surgical procedure. It is also released distally through the extent of the cubital tunnel down to the fascia of the flexor carpi ulnaris to its first motor branch.
The triceps-sparing approach described by Alonso-Llames is the most commonly used approach. It allows for elevation of the medial and lateral sides of the triceps off the medial and lateral intermuscular septa, respectively. The anconeus is also elevated with the lateral portion of the triceps. The triceps-sparing approach is an excellent option for total elbow arthroplasty, as the olecranon remains intact, and patients can start immediate elbow range of motion without restrictions. This approach can be converted to an olecranon osteotomy if necessary during the procedure ( Fig. 3 ).