The elbow dislocation of trans-olecranon fracture is a rare type of injury. It is often caused by high-energy violence or low-energy injury in elderly patients with osteoporosis. In the semi-flexion of the elbow, the violent axial impact of the distal humerus on the trochlear notch of the proximal ulna leads to olecranon fractures or complex concomitant fractures of the proximal ulna, including the trochlear notch of the olecranon. After the injury, the alignment relationship between the humeroulnar and humeroradial joint was destroyed, the anterior joint capsule was torn, and the elbow joint and forearm were dislocated. Coronary fractures often accompany it. However, it always maintains stability of the upper radioulnar joint and is less associated with ligament injury, and the annular ligament is usually left intact. The change of humeroulnar joint position was mainly due to the destruction of bone structure at the trochlear notch of the olecranon rather than ligament injury. The fracture of bone structure has many forms, such as simple non-comminuted transverse fracture, oblique fracture, complex comminuted fracture of trochlear notch, etc.

The elbow dislocation of trans-olecranon fracture is not common in clinical practice. The purpose of this retrospective study is to investigate the pathological characteristics and treatment strategies of this injury.

The author selected 23 patients with elbow dislocations of trans-olecranon fractures from July 2013 to July 2021 and retrospectively analyzed their medical records and imaging data. Among them are 17 males and 6 females with an average age of 39 (21-65) . There were 10 cases of left elbow joint involvement and 13 cases of right. Ten patients had simple transverse or oblique olecranon trochlear notch fractures (Mayo type IIIA) , 13 patients had complex comminuted olecranon trochlear notch fractures (Mayo type IIIB) , of which 4 had fracture fragments extending towards the proximal end of the ulna. Twelve combined coronal process fractures were classified according to Regan Morrey type II. We restored the olecranon's anatomical length and the proximal ulna's anatomical curvature through the posterior median surgical approach of the elbow joint. All patients were treated with 3.5 mm proximal ulna anatomical plates for rigid internal fixation of olecranon fractures. For 4 patients with severe comminuted proximal ulnar fractures, 1 or 2 small plates with a diameter of 2.7 mm were used to fix the comminuted fracture on the medial or lateral front of the ulna. After reducing the coronal process fracture, we set it with screws of a proximal ulnar plate or used countersunk compression hollow screws and anchor nails and repaired the anterior elbow joint capsule.

23 patients were followed up for 1-8 years, with a mean follow-up period of 2.55 years. All patients’ fractures achieved bone healing after 3 to 6 months, with an average time of 4.5 months. All patients had good anatomical relationships at the elbow, with complications such as traumatic arthritis in 3 cases, ectopic ossification in 3 cases, and nerve injury in 1 case. After the corresponding treatment, they recovered well. All patients did not experience internal fixation failure, infection, etc. The long-term functional follow-up of the elbow joint was good, with an average range of flexion and extension motion of 107.8 degrees and an average range of elbow rotation motion of 102.5 degrees at the last follow-up. The average VAS score at the final postoperative follow-up was 0.8 points. The average DASH score is 37.6 points. The MEPS score is 91.7 points.

The elbow dislocation of trans-olecranon fracture is a common type of complex fracture dislocation of the elbow in clinical practice. The author emphasizes the importance of anatomical repair of the olecranon and trochlear notch, rigid internal fixation with plates, and early functional exercise as diagnostic and treatment strategies, which can restore the rotation, flexion, and extension function of the elbow, reduce the incidence of elbow instability after olecranon fracture and dislocation surgery, and improve the clinical efficacy of patients' elbow joints.