| disease | Humerus External Condyle Fracture |
It is relatively common in children's elbow fractures. It is actually a separation of the external hip bone epiphysis. Its incidence is second only to humerus supracondylar fractures and is an intra-articular fracture. According to statistics from the Pediatric Orthopedics Department of Beijing Jishuitan Hospital, from 1970 to 1980, there were 9,427 cases of elbow injuries in children, among which 629 cases were humerus external condyle fractures, accounting for 6.7% of the total. The male-to-female ratio was 3.3:1, with the left side more affected than the right. The youngest age of onset was 1 year, and the oldest age recorded was 14 years. The peak incidence occurred between ages 4 and 8, accounting for 54% of the total cases. A large portion of the fracture fragment consists of cartilage. The younger the patient, the more cartilage is present. On X-rays, only the ossification center of the humerus external condyle epiphysis and the metaphyseal fracture fragment are visible, while the cartilage does not appear. In reality, the fracture fragment is quite large, almost equivalent to half of the distal humerus epiphysis. Therefore, in clinical practice, the size of the fracture fragment must be fully estimated. Improper management of this type of fracture often leads to various deformities and complications, resulting in elbow joint dysfunction.
bubble_chart Pathogenesis
The cause of injury is essentially the same as that of humerus supracondylar fracture. It is mostly caused by indirect composite forces. When a child falls with the palm of the hand on the ground, the forearm is often in a pronated position, and the elbow joint is slightly flexed. Most of the force is transmitted along the radius to the radial head, which then impacts the humerus external condyle, resulting in a fracture. At the same time, it is often combined with factors such as elbow valgus stress and extensor muscle traction, leading to the fracture. The fracture line runs obliquely downward and inward from the upper part of the external condyle to the radial side of the trochlea. The bone fragment often includes the radial metaphyseal fragment, the capitulum epiphysis of the humerus, and the radial part of the trochlea. Depending on the direction of the force, forearm rotation, and adduction traction, different types of fractures can occur.
Generally, it is divided into 3 types. Beijing Jishuitan Hospital classifies it into 4 types based on pathological changes.Type I: Non-displaced fracture. The bone membrane is not torn, and a fracture line can be seen on the X-ray in the metaphysis.
Type II: Lateral displacement type. The bone fragment is displaced laterally, anteriorly, or posteriorly. In grade I displacement, the bone membrane is partially torn, while in grade III displacement, it is completely torn. After reduction, the bone fragment is unstable and may displace again during fixation.
Type III: Rotational displacement type. The fracture fragment is displaced laterally, anteriorly, or posteriorly, with rotational displacement. Due to the complete rupture of the local extensor membrane and bone membrane, combined with the traction of the forearm extensor muscles, the longitudinal axis of the fracture fragment can rotate outward by 90° to 180°. It may also rotate forward or backward to varying degrees on the transverse axis. The humeroulnar joint remains unchanged.
Type IV: Fracture-dislocation type. The fracture fragment may exhibit lateral displacement and rotational displacement, while the elbow joint may dislocate radially, ulnarly, or posteriorly. The joint capsule and collateral ligaments are torn, and the soft tissue injury in the elbow is severe.
This type of fracture is not uncommon. Hardacre reported 46 cases of displaced fractures, with 9 cases (approximately 20%) complicated by elbow dislocation. Due to the severe soft tissue injury in the elbow, treatment is more difficult than for the other three types, and the prognosis is also worse. Therefore, Beijing Jishuitan Hospital classifies this type of fracture as the fracture-dislocation type to emphasize its significance.
Swelling on the lateral side, gradually spreading, may involve the entire joint. Fracture-dislocation type exhibits the most severe swelling. Ecchymosis appears on the lateral side of the elbow and gradually spreads to the wrist. Blisters may develop on the skin 2–3 days after the injury. There is obvious tenderness on the lateral side of the elbow, and tenderness may even occur around the lower end of the humerus. In displaced fractures, bone crepitus and movable bone fragments may be palpated. Cubitus valgus deformity may occur, with widening of the elbow and alteration of the three-point relationship at the posterior elbow. Loss of elbow joint mobility is observed. Pain worsens during passive movement, while rotational function is generally not restricted.
Radiographs show that the fracture line of the humeral capitulum often exceeds half of the ossification nucleus or does not pass through the capitellar ossification nucleus but instead traverses the cartilage between the humeral capitulum and the trochlear groove, with a fracture line present at the metaphysis. The fracture fragment may displace laterally. In fracture-dislocation type radiographs, the anteroposterior view shows the fracture fragment along with the ulna and radius displacing radially or ulnarly, while the lateral view shows posterior displacement, and occasionally anterior displacement may be seen. Humerus external condyle fractures present in various forms on radiographs, and even within the same fracture type, their manifestations often differ.
bubble_chart Treatment Measures
This fracture is an intra-articular fracture. It is also an epiphyseal fracture, with the fracture line passing through the growth plate. The quality of reduction directly affects the integrity of the joint and the size of bone bridge formation at the growth plate, as well as the degree of deformity. Therefore, regardless of the method used, anatomical reduction or near-anatomical reduction must be achieved to avoid severe sequelae. The treatment methods for each type of fracture are as follows.
2. Lateral displacement type: Closed reduction should be performed. Extend the elbow in a varus position to widen the lateral gap, supinate the forearm, and extend the wrist to relax the extensor muscles. Use the thumb to push the fracture fragment. If the fragment is displaced posterolaterally, the thumb should push it anteromedially to achieve reduction. If X-ray confirms successful reduction, a long-arm posterior plaster splint or splintage can be used for 4–6 weeks. The immobilization position (elbow extension or flexion and forearm supination) depends on post-reduction stability.
This type of fracture is unstable. If closed reduction fails or the fragment re-displaces and cannot be reduced, open reduction with two Kirschner wires for internal fixation should be performed.
3. Rotational displacement type and fracture-dislocation type: Closed reduction is attempted. Based on X-ray findings, identify the orientation of the fracture fragment. Position the elbow in varus and the forearm in supination. Use fingers to first correct the rotational displacement of the fragment, then push it back into the joint for reduction. If accompanied by lateral or posterior elbow dislocation, reduce it simultaneously. Alternatively, push the fragment posteriorly first, correct the rotation, and then push it back into the joint for reduction. The immobilization method and duration are the same as for the lateral displacement type.
If closed reduction is unsuccessful, open reduction should be performed to correct the rotational displacement of the fracture fragment. Preserve as much soft tissue attached to the fragment as possible to avoid avascular necrosis. Fix with two Kirschner wires, and postoperatively, immobilize with a plaster splint for 4–6 weeks. Remove the wires and external fixation afterward and begin elbow mobilization.
4. Old fracture: Surgery is generally not recommended. For fractures within 3 months with significant displacement and nonunion, Beijing Jishuitan Hospital performs open reduction and internal fixation. As long as intraoperative reduction is satisfactory and internal fixation is stable, combined with active postoperative functional exercises, most patients can still achieve good outcomes. Even if the elbow is stiff preoperatively, partial functional improvement can still be achieved after surgery.
5. Complications
(1) Cubitus valgus deformity: Injury to the lateral epiphyseal growth plate of the distal humerus can lead to premature closure, causing uneven development of the distal humerus and resulting in cubitus valgus with a fishtail deformity of the distal humerus. For significant valgus, corrective osteotomy can be performed.
(2) Ulnar neuritis or palsy: Due to traction from cubitus valgus deformity or impingement of the ulnar nerve by the olecranon, ulnar neuritis may develop. Once identified, the ulnar nerve should be transposed anteriorly as early as possible to prevent palsy.
