The most common cause of cubitus varus is humerus supracondylar fracture, accounting for about 80%. Other causes include complete distal humerus epiphyseal separation, medial condylar injury, poor reduction of medial condylar fractures, and old elbow dislocation.

bubble_chart Pathogenesis

1. Humerus supracondylar fracture: This is the most common cause, accounting for about 80% of all cubitus varus cases. Some reports indicate that the incidence of cubitus varus complicating humerus supracondylar fractures can reach 30–57%. Most scholars believe the cause is due to medial tilting of the distal fracture fragment. Studies have shown that poor reduction after fracture, medial bone compression and impaction, separation of the lateral fracture end, and internal rotation and torsion of the distal fracture are the main reasons for medial tilting of the distal fracture fragment.

2. Complete distal humeral epiphyseal separation and medial condylar epiphyseal injury: This injury is prone to premature epiphyseal closure or ischemic necrosis of the medial humeral condyle, causing slow or halted growth of the medial condyle, leading to cubitus varus.

3. Poor reduction of medial humeral condylar fracture.

4. Old elbow dislocation.

bubble_chart Clinical Manifestations

The valgus angle in the extended elbow position significantly increases, reaching 15° to 35°, with changes in the elbow's posterior triangle joint and widening of the distance between the lateral condyle and the olecranon. Generally, elbow joint movement remains normal, but there is varying degrees of muscle weakness. The degree of cubitus varus can be measured from X-ray images.

The purpose of treatment is to improve function and correct deformities.

I. Surgical Indications:

1. Cases causing functional impairment or weakening of elbow flexion strength.

2. Cases with elbow joint pain that has not yet developed into traumatic arthritis.

3. Cases with cubitus varus greater than 20° where the deformity has stabilized (1-2 years after injury).

4. Cases of cubitus varus complicated by tardy ulnar neuritis.

II. Surgical Methods:

Supracondylar wedge osteotomy of the humerus and supracondylar "V" osteotomy of the humerus, with the former being more commonly used. The surgery must correct not only the varus but also the internal rotation and hyperextension.