bubble_chart Overview

Medial condyle fracture of the humerus, which is more common in children but relatively rare, involves a large portion of the medial epicondyle and trochlea. The injury mechanism, types, and treatment methods are very similar to those of a lateral condyle fracture of the humerus. Therefore, these two injuries form symmetrical "mirror-image" injuries.

bubble_chart Pathogenesis

Indirect external forces are the majority. After falling and landing on the palm, the external force is transmitted along the forearm to the elbow, where the impact between the olecranon articular surface and the trochlea can lead to a fracture. There are also cases where landing with the elbow flexed and accompanied by a varus stress on the distal humerus causes the olecranon to collide with the trochlea, resulting in a fracture. Additionally, a medial humeral hip bone fracture may be an avulsion fracture, similar to a medial epicondyle fracture. As for the specific mechanism of the collision between the olecranon and the trochlea, it could also be due to the rotation of the ulna, where the semilunar notch of the olecranon impacts the medial side of the humerus horizontally. The injury type is similar to that of a lateral humeral condyle fracture. The fracture is classified into grade III.

Grade I fracture: The fracture is non-displaced, with the fracture line running obliquely from above the medial epicondyle downward and outward to the trochlear joint.

Grade II fracture: The fracture line is similar to that of Grade I. The fracture fragment has lateral or Grade I upward displacement but no rotation.

Grade III fracture: The bone fragment exhibits significant rotational displacement. The most common is rotation in the coronal plane, sometimes up to 180 degrees, causing the fracture surface to completely face medially. It can also rotate in the sagittal plane, resulting in the fracture surface facing backward and the trochlear joint facing forward. Occasionally, the ulna may shift inward along with the fracture fragment, leading to elbow joint semi-dislocation.

bubble_chart Treatment Measures

Ⅰ°fracture: Fix with a long-arm posterior Gypsum splint for 4 weeks. An X-ray should be taken for review 1 week after the injury. If there is displacement or rotation of the bone fragment, other measures should be taken. Joint exercises should be performed after the fixation is removed.

Ⅱ°fracture: For cases with insignificant displacement, treat according to the method for Ⅰ°fracture. When the displacement is greater than 3–4 mm, closed reduction should be performed. After pushing the bone fragment laterally to reduce it, fix it with a Gypsum splint. The posterior elbow Gypsum splint should be appropriately widened and carefully molded on the medial side of the elbow. For cases with greater lateral displacement, open reduction and internal fixation should be performed.

Ⅲ°fracture: Open reduction and internal fixation should be performed. Make a medial elbow incision, free the ulnar nerve, and protect it. The fracture surface often faces anteriorly. After clearing the intra-articular hematoma, flip the fracture fragment back into place and fix it by obliquely inserting two thin steel pins from the medial epicondyle outward and upward in a crossed manner. Alternatively, fix it with one cancellous bone screw inserted transversely below the medial epicondyle. For cases fixed with steel pins, immobilize with a Gypsum splint for 4 weeks postoperatively. For cases fixed with screws, external fixation may not be necessary. Joint exercises can begin 1 week later, and functional recovery is very rapid.