Medial Humeral Condyle Fracture 

Medial condyle fractures involve a fracture line that extends through and separates the medial metaphysis and epicondyle from the rest of the humerus (see image below). By definition, the fracture line must involve the trochlear articular surface.

Medial condyle fractures must not be confused with medial epicondyle fractures (depicted in the image below) that involve the medial column but are extra-articular. These 2 fracture patterns are separate entities and are treated differently. Both fracture patterns may be difficult to diagnose in young children, especially before the secondary ossification centers have formed.^{[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]}

For patient education resources, see the Breaks, Fractures, and Dislocations Center, as well as Broken Arm and Broken Elbow.

Medial condyle fracture

Fracture of the medial condyle of the humerus is a rare injury. Isolated case reports appear in the literature. Although the medial condyle fracture has been described in the literature since the early 1800s, some controversy exists as to whether these were descriptions of true medial condyle fractures or whether these were really descriptions of more common medial epicondyle fractures. Studies have reported greater numbers of medial condyle fractures in the literature; however, the overall incidence of these fractures remains quite low. Of all elbow fractures in children, medial condyle fractures are reported to account for less than 1%.^{[1, 2, 3, 4, 5, 6, 7, 8, 9, 13, 14]}

In 1964, Milch proposed the first classification system for unicondylar humerus fractures.^[15] The Milch system is based on the location of the fracture line in the distal humeral epiphysis. Milch first described an avulsion fracture due to a transverse valgus force. He then described a classification system for 2 types of fracture caused by longitudinal forces. A Milch type I fracture splits the trochlear groove, leaving the lateral trochlear ridge intact. A Milch type II fracture splits the capitotrochlear sulcus such that the lateral trochlear ridge is part of the fracture fragment (see image below for a depiction of the two types). A type II fracture is inherently unstable and is called a fracture dislocation.^[4] The avulsion and type I fractures can be treated open or closed; however, more complex type II fractures should be treated only with open reduction and internal fixation (ORIF).^[7]

In 1965, Kilfoyle combined his own experience with 5 colleagues to collect a total of 11 examples of medial condyle fracture and separated them into 3 types of injury, as depicted in the image below.^[16] Type I involves a greenstick fracture or crush of the medial condyle metaphysis down to but not including the physis. He also stated that these may actually be incomplete supracondyle or intracondyle fractures. Type 2 involves a fracture through the physeal plate and epiphysis without displacement or rotation. Type 3 is similar to type 2 but with moderate-to-severe displacement and rotation of the fracture fragment.

Medial epicondyle fracture

In 1818, Granger reported the first unequivocal description of a medial epicondyle fracture. Granger described a fracture that resolved rapidly and left little functional deficit. In the early 1900s, several authors recognized that the fracture was often associated with elbow dislocation and that the avulsed fragment could become entrapped within the joint.

In 1950, Smith dispelled many of the complications previously attributed to medial epicondyle fractures. Smith refuted that medial epicondyle fractures were associated with growth disturbance, pain and disability, weak elbow flexion, or ulnar nerve dysfunction and went on to prove his theories in his classic study. He concluded that fractures involving the medial epicondyle were relatively benign and were not associated with significant functional deficit.

Farsetti et al confirmed Smith's conclusions.^[17] Even in 42 patients with isolated fractures of the medial epicondyle with displacement of 5-15 mm, no significant difference was found between those treated with ORIF and those treated nonsurgically. No universally accepted system exists for classification of medial epicondyle fractures.

Injuries to the medial aspect of the distal humerus in young children can range from an avulsion fracture of the medial epicondyle to a much more serious Salter-Harris type IV fracture of the medial condyle, which crosses the physeal plate.^[18] The distinction between these types of fractures is key to the selection of appropriate treatment. This diagnosis may be difficult to ascertain due to the limitations of radiographic visualization of cartilaginous fractures observed with the developing anatomy in this area. Inadequate reduction of the physeal growth plate and the joint surface cartilage in a medial condyle fracture can lead to serious complications.

The age of the patient, the extent of initial injury and displacement, and delay in initial treatment play important roles in the clinical outcome. For medial epicondyle fractures, nonoperative management of fractures displaced up to 15 mm does not appear to be associated with functional deficit unless there is entrapment of the epicondyle fragment in the joint. Entrapment of the epicondyle fragment in the joint can block motion, and therefore, the fragment should be reduced.

Frequency

Fracture of the medial condyle is very rare, especially when compared to frequency of other elbow fractures. In one study, radiographs of 589 elbow fractures in children younger than 16 years were reviewed. The most common fractures were the supracondyle fracture (55%), radial neck fracture (14%), lateral humeral condyle fracture (12%), medial epicondyle fracture (8%), and olecranon fracture (7%).^[19] No cases of medial condyle fracture were reported.^[20]

Fractures of the medial condyle are so rare that they receive little coverage in most popular textbooks and may not be mentioned at all in others. The incidence is described in the literature from less than 1-2% of all elbow injuries in children. Most displaced medial condyle fractures occur when the trochlea is not ossified completely. In some studies, the average age has varied (ie, age 10, 11, 9.5, and 7 years). Although a child of any age can sustain this fracture, it is most common during the developing years (ie, in children aged 7-14 years).

Medial epicondyle fractures are much more common than medial condyle fractures. In a large combined series of 5228 fractures of the distal humerus, medial epicondyle fractures constituted 14.1% of all distal humeral fractures and 11.5% of all fractures occurring around the elbow. Medial epicondyle fractures are 4 times as likely to occur in males, and most cases occur in children aged 9-14 years. Peak incidence is in children aged 11-12 years. The reported incidence of association with elbow dislocation reaches 55% in some series, and the fragment may be incarcerated in the joint in approximately 15-18% of cases.^[21]

Medial condyle fracture

The following 3 possible mechanisms for medial condyle fracture^{[1, 2, 3, 5, 6, 7, 8, 9, 11, 13]} have been described:

• A fall on the palm of an outstretched arm, with the elbow forced into valgus (see image below) Valgus levering force creating fracture.
• A fall on the point of the elbow (apex of the flexed elbow), with the olecranon driving the medial condyle proximally and medially (see image below) Olecranon acting as a wedge and creating a medial condyle fracture.
• An avulsion fracture due to violent contraction of the flexor and pronator muscles that attach to the medial epicondyle, such as that which occurs in arm wrestling (see image below) Medial condyle fracture caused by traction through flexor pronator origin.

Medial epicondyle fracture

Three mechanisms of injury for medial epicondyle fractures^{[22, 23]} have been proposed for an acute injury. All 3 mechanisms result in a partial or complete separation of the apophyseal fragment from the rest of the humerus. The 3 mechanisms are as follows:

• A direct blow on the posterior medial aspect of the epicondyle that may be associated with fragmentation of the avulsed bone
• Pure avulsion injury produced by the flexor muscles of the forearm (see image below) Epicondyle fractures can be caused by traction forces.

  • This avulsion may occur in combination with a valgus stress that locks the elbow in extension. The classic example is the child that falls on the extended arm and hyperextends the wrist and fingers, placing more stress on the forearm flexors. The normal valgus angulation or carrying angle of the elbow tends to accentuate the forces responsible for the avulsion injury. This mechanism can also explain associated injuries, including a radial neck fracture with valgus angulation and greenstick fractures of the olecranon.
  • The second type of avulsion injury may be a pure muscular avulsion secondary to contraction of the forearm flexor musculature with an elbow flexed. This mechanism may be responsible for medial epicondyle fractures associated with arm wrestling and throwing a baseball.
• The final mechanism proposed for medial epicondyle fracture is associated with a dislocation of the elbow, as depicted in the image below. In this mechanism, the ulnar collateral ligament provides an avulsion force that causes the medial epicondyle to fail. Elbow dislocation associated with medial epicondyle fracture. In this lateral view, the fragment is marked with a circle.

In the developing elbow, fracture through the medial condyle involves part of the cartilaginous or partially ossified trochlea and the ossified medial epicondyle. With the insertion of the common flexor tendon of the forearm and the medial collateral ligament on the medial epicondyle, the fracture fragment tends to rotate around the axis of the epicondyle and can present at various degrees of rotation. Complete rotation puts the fracture surface facing the anterior and medial side of the elbow, with the medial epicondyle pulled distally and the articular surface facing posteriorly and laterally.

In addition, the surrounding soft tissues can be torn, and there may be damage to the articular surface of the ulna. Damage to the articular capsule or medial collateral ligament of the elbow may be present. The ulnar nerve and the vasculature surrounding the elbow joint are also at risk. The blood supply to the epiphysis enters with the attachment of the medial collateral ligament and the common flexor tendon. Separation of these structures at the time of injury or at surgery may lead to avascular necrosis.

The medial epicondyle fragment is usually displaced distally, although at least 2 cases of displacement of the fragment proximally have been reported (see images below). The fracture line usually involves only the apophysis; however, occasionally a fragment of metaphyseal bone is found attached to the avulsed fragment. If the fragment is incarcerated within the joint, the fragment may become adherent to the coronoid process of the ulna. When the fragment is incarcerated within the joint, the universal finding is a thick fascial band that binds the ulnar nerve to the underlying muscle. This thick fascial band is responsible for ulnar nerve dysfunction, either acutely or as a late finding. Other elbow fractures may be associated with medial epicondyle fractures, and care must be taken to recognize the full extent of the injury. Associated injuries include radial neck fractures, olecranon fractures, and coronoid process fractures.

Medial condyle fracture

The patient usually presents with a recent history of a significant fall on an outstretched hand or directly on the apex of the flexed elbow. The elbow may be severely painful following this injury. Swelling, deformity, and loss of function of the elbow may be present. Palpable crepitus may be present over the medial condyle. Elbow motion may be decreased due to swelling and pain. The patient often holds the elbow fixed at approximately 90° of flexion. The patient may present with medial dislocation of the forearm, referred to as a fracture dislocation.

Distal neurovascular changes may occur, especially in the ulnar nerve distribution. Other injuries may be present that are easier to detect, such as elbow dislocation or fracture of the radial head or olecranon, which may distract the physician from making the diagnosis of medial condyle fracture. A high index of suspicion for this type of injury concurrent with other elbow injuries can ensure timely diagnosis and treatment.^{[1, 2, 3, 5, 6, 7, 8, 9, 11, 13]}

Medial epicondyle fracture

The presentation of a patient with a medial epicondyle fracture does not differ significantly from that of a patient with a medial condyle fracture, as described above. A through physical examination should include a valgus stress test to assess for instability of the anterior oblique band of the ulnar collateral ligament (see images below). The test is performed with the patient supine and the arm abducted 90º. The shoulder and arm are externally rotated 90º, with the elbow flexed at least 15º to unlock the olecranon. Valgus stress is then placed through the elbow to assess for ligamentous instability.^{[22, 23]}

Medial condyle fracture

Salter-Harris type IV injuries with 2 mm or more of displacement usually require ORIF. A displaced medial condyle fragment or instability of the fragment with closed reduction is an indication for open reduction with rigid internal fixation. Accurate apposition of the fracture surfaces is important to reduce the risk of growth plate disturbance and to prevent loss of motion due to articular incongruence. Nondisplaced fractures can be treated without surgery.

Medial epicondyle fracture

For nondisplaced or minimally displaced fractures, nonoperative management is the procedure of choice (see images below). More controversy exists with displacement of 5-15 mm. Similar functional results have been reported with operative and nonoperative surgical management. Long-term functional assessment has demonstrated similar results even with radiographic nonunion being apparent on most of the fractures treated nonoperatively. Irreducible incarceration of the medial epicondyle fragment and open fracture are indications for operative management. Excision of the comminuted medial epicondyle fragment has been associated with less optimal results.^[24] Other controversial relative surgical indications include complete ulnar nerve dysfunction after an injury or reduction attempt and valgus instability in high-demand athletes.^{[22, 23, 25]}

The humerus is a bone in the arm. The distal humeral physis, also called the growth plate, is located between the humeral metaphysis proximally and epiphysis distally. The distal humeral epiphysis is bordered proximally by the physeal growth plate and distally by its articular surface with the ulna and radius. The humeral metaphysis is the growing portion of the humerus that lies between the epiphysis and diaphysis (the shaft or central part of a long bone).^{[26, 27]}

The medial condyle of the humerus is the medial column of the distal expansion of the humerus that includes the trochlea, the coronoid fossa, the olecranon fossa, the medial epicondyle, the medial supracondyle ridge, the medial metaphysis, and the groove for the ulnar nerve. Trochlea means pulley. The trochlea is the distal medial articulating end of the humerus, which acts as a pulley for the ulnar trochlear notch to rotate around as the elbow is flexed. The coronoid fossa is the depression on the anterior surface of the medial condyle proximal to the trochlea that accommodates the coronoid process of the ulna. The olecranon fossa is the depression on the posterior surface of the medial condyle proximal to the trochlea, which accommodates the olecranon of the ulna.

The medial epicondyle is a prominent palpable process that projects medially from the trochlea and is the point of origin of the pronator teres and common flexor tendon, which includes the flexor carpi radialis, palmaris longus, flexor carpi ulnaris, and flexor digitorum superficialis.^[28]

The medial supracondyle ridge is a bony ridge that runs proximally on the medial humerus from the medial epicondyle.

The capitellum, a rounded ball of bone adjoining the trochlea laterally, is the distal lateral articulating end of the humerus that articulates with the radial head. The lateral epicondyle is a prominent palpable process that projects laterally from the capitellum and is the point of origin of the common extensor tendon. The lateral supracondyle ridge is a bony ridge that runs proximally on the lateral humerus from the lateral epicondyle. The ulnar nerve, which runs in close proximity to the medial epicondyle, often may be palpated as a rounded cord just posterior to this bony prominence.

The elbow joint is a hinge-type synovial joint formed where the distal end of the humerus articulates with the proximal ends of the radius and ulna. This is a uniaxial joint with movements of flexion and extension. Normal range of motion is from 0° (full extension) to 135° (full flexion). Most functions of the elbow require motion of 30-130°. Consequently, a 30° extension lag has little functional significance. The normal physiologic carrying angle of the elbow in the anatomic position (full supination and extension) is approximately 165-170° (10-15° of valgus angulation).

Flexion is produced by the brachialis (main flexor muscle) and the brachioradialis muscles. In supination, the biceps brachii muscle also flexes this joint; in pronation, the pronator teres assists in flexion. Flexion is limited by the apposition of the anterior surfaces of the forearm and arm, by tension of the posterior arm muscles, and by the collateral ligaments.

Extension is produced by the triceps brachii muscle and is assisted by gravity and the anconeus muscle. Extension is limited by impingement of the olecranon of the ulna on the olecranon fossa of the humerus and by tension of the anterior muscles and collateral ligaments.

At birth, a single cartilaginous cap covers the distal end of the humerus. During development, 4 separate ossification centers form at different times:

• The capitellum is first and begins to ossify when the infant is aged 6-12 months.
• The medial epicondyle is second to form when the child is aged 5-7 years.
• The third center to ossify is the trochlea when the child is aged 7-12 years.
• The last center to ossify is the lateral epicondyle when the child is aged 12-14 years.

Further complicating this pattern of development, the trochlear ossification center is frequently composed of multiple irregularly sized foci that eventually coalesce into a single structure. The trochlear and capitellar ossification centers eventually fuse. The pattern of ossification at these multiple sites is highly variable.

If the patient is unable to tolerate a long surgical procedure due to polytrauma, closed reduction and cast immobilization with 90° of flexion is an option.