Fracture of the medial epicondyle of the humerus is the most common type of elbow injury, frequently seen in adolescents, accounting for approximately 10% of elbow joint fractures. It ranks third among elbow injuries, following supracondylar fractures of the humerus and fractures of the lateral condyle of the humerus.

bubble_chart Pathogenesis

When falling with the elbow joint in an extended position and supporting the ground with the hand, the upper limb is in an abducted position. The valgus stress causes the elbow joint to valgus, while the forearm flexor muscles contract violently, avulsing the medial epicondyle. The medial epicondyle is an epiphysis that closes relatively late, and before closure, the epiphyseal line itself is a potential weak point. Therefore, it can lead to epiphyseal separation, being pulled downward and forward, with rotational displacement. At the same time, the medial space of the elbow joint is temporarily stretched open, or a posterolateral dislocation of the elbow joint occurs. The avulsed medial epicondyle (epiphysis) becomes trapped within the joint. Based on the severity of the injury, it can be classified into four degrees.

Ⅰ° injury: Only a fracture or epiphyseal separation with minimal displacement.

Ⅱ° injury: The bone fragment is displaced downward and rotated forward, reaching the level of the joint.

Ⅲ° injury: The fractured fragment is trapped within the joint, accompanied by a semi-dislocation of the elbow joint.

Ⅳ° injury: Posterior dislocation or posterolateral dislocation of the elbow joint, with the bone fragment trapped within the joint.

bubble_chart Clinical Manifestations

Pain, especially localized swelling and tenderness on the inner side of the elbow, with the disappearance of the normal contour of the medial epicondyle. Limited elbow joint movement, weakness in forearm pronation, wrist flexion, and finger flexion. In cases combined with elbow dislocation, the shape of the elbow joint is significantly altered, and functional impairment is more pronounced, often accompanied by symptoms of ulnar nerve injury.

bubble_chart Diagnosis

X-ray films can provide a definitive diagnosis.

Attention should be paid to whether there are other associated injuries, such as fractures of the radial head, neck, or ulna olecranon.

For type I and II fractures, reduction can be achieved by flexing the elbow and wrist, pronating the forearm, and using fingers to push the medial epicondyle backward and upward. Immobilize with a long-arm gypsum splint or brace for 3 weeks. For type III fractures, reduction should be performed as early as possible. With the elbow extended, the wrist dorsiflexed, fingers straightened, and the forearm supinated, the elbow is maximally abducted to utilize the tension of the flexor muscles to pull the bone fragment out of the elbow joint, then treat it as a type II fracture. For type IV fractures, the elbow dislocation should be reduced while maintaining tension in the flexor muscles to avoid trapping the medial epicondyle within the joint after reduction. Once the medial epicondyle is pulled out of the joint, treat it as a type II fracture.

For cases where manual reduction fails, those with ulnar nerve symptoms, combined with other fractures, or old injuries, open reduction and internal fixation surgery should be performed. Crossed fixation with two Kirschner wires is most suitable. If the ulnar nerve shows significant twisting or crushing, anterior transposition of the ulnar nerve should be performed simultaneously.

bubble_chart Differentiation

The medial epicondyle of the humerus appears around 6 to 10 years of age and typically closes around 18 years old. However, in some cases, it may remain unclosed, and differentiation from a fracture should be noted.