Congenital dislocation of the radial head I. Overview Congenital dislocation of the radial head is a rare deformity. It is common unilaterally and accounts for 40% bilaterally. About half of the cases are unilateral deformities. This disease generally manifests as autosomal dominant inheritance. Diagnosis (a) Clinical manifestations Pathologic changes and clinical manifestations vary depending on the age of the patient and the type of radial head dislocation. This deformity is often not easy to detect at birth, and the diagnosis is often made after examination of minor trauma to the elbow in childhood. Congenital dislocation of the radial head is often associated with ulnar bending, and the direction of the curvature of the bend varies depending on the type of dislocation. In anterior dislocation of the radial head, the curvature of the ulna is forward, and there is a sense of mechanical obstruction when the elbow joint is flexed, and the elbow socket is palpable to the radial head. In posterior dislocation of the radial head, the curvature of the ulna bends dorsally, the elbow joint cannot be fully straightened, and the protruding radial head can be touched at the back of the elbow. In lateral dislocation of the radial head, the curvature of the ulna is curved to the lateral side. This type seldom affects the flexion and extension of the elbow, but the forearm rotation forward and backward activities are limited. (B) X-ray manifestation In the above three types of radial head dislocation, the long axis of the radial stem does not pass through the center of the humeral tuberosity. In congenital radial head dislocation, the humeral tuberosity is obviously underdeveloped, and the radial head is mostly oval. (C) Differential diagnosis Congenital radial head dislocation should be differentiated from traumatic dislocation, radial neck fracture, Monteggia fracture, and pulled elbow. Ulnar flexion is not a specific sign of congenital radial head dislocation and can also occur in old traumatic dislocations that have not been reset. Traumatic radial head dislocation is often accompanied by a history of trauma and ossification within the soft tissues surrounding the radial head, often suggesting traumatic dislocation. In both congenital and traumatic radial head dislocation, there is growth of the radial stem. Third, the treatment of newborns and infants once the diagnosis, need to try to close the reset. When the radial head is reset with posterior dislocation, the elbow should be straightened with the forearm rotated back; when the radial head is dislocated anteriorly, the elbow should be flexed. After reset, the long arm should be immobilized in a tubular cast for 4 to 6 weeks. In case of unsuccessful closed repositioning, the radius should be cut and repositioned. In children over 3 years old, if the radius is too long, radial shortening should be performed before cut and repositioning. Prognosis: In older children, due to overgrowth of the radial head, it is difficult to reset by manipulation, and even cut and reset is difficult to be successful until adolescence, if there are still symptoms, radial head resection is needed.