Elbow dislocation can lead to severe pain, pressure and swelling in the elbow, continued anterior displacement of the lower humerus and posterior displacement of the ulnar hawk, forming a posterior dislocation of the elbow joint. Due to the different directions of violence, the ulnar hawk can sometimes be displaced medially or laterally in addition to posteriorly, and in some cases, it can be combined with rostral fracture. The distal humerus is separated from the proximal articular alignment of the radius and ulna. With the distal humerus as the standard point, posterior displacement of the proximal radius and ulna is posterior dislocation, anterior displacement is anterior displacement, and lateral displacement is lateral dislocation. Posterior dislocation of the elbow joint is the most common. Therefore, the clinical examination of severe pain, pressure and swelling of the elbow is based on the following special manifestations of dislocation The elbow is obviously deformed, the elbow fossa is full, the forearm appearance becomes shorter, the ulnar hawk is posteriorly protruding, and the posterior part of the elbow is hollow and depressed. The joint elasticity is fixed at 120 to 140 degrees, with only a tiny passive mobility. The posterior bony marker relationship of the elbow is altered. In normal elbow extension, the three points of the ulnar eminence and the medial and lateral epicondyles of the humerus are in a straight line; in flexion, they are in an isosceles triangle. In dislocation, the above relationship is destroyed, while in supracondylar humerus fracture, the triangular relationship remains normal. 2. Comorbidity of elbow dislocation Posterior dislocation is sometimes combined with ulnar nerve injury and other nerve injuries, ulnar rostral fracture, and anterior dislocation is often accompanied by ulnar hawk fracture, etc. 3.X-ray examination The front and side view of elbow joint can show the type of dislocation, combined fracture, and distinguish it from supracondylar fracture.