| disease | Fracture of the Lateral Humeral Condyle |
It is relatively common in pediatric elbow fractures. It is actually a separation of the lateral epicondylar epiphysis. Its incidence is second only to supracondylar fractures of the humerus 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 pediatric elbow injuries, among which 629 cases were lateral condylar fractures of the humerus, 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 was 14 years. The peak incidence occurred between 4 and 8 years of age, accounting for 54% of the total cases. A significant portion of the fracture fragment consists of cartilage. The younger the patient, the more cartilage is present. On X-ray, only the ossification center of the lateral condylar 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 humeral epiphysis. Therefore, the size of the fracture fragment must be fully estimated clinically. Improper management of this type of fracture often leads to various deformities and complications, resulting in impaired elbow joint function.
bubble_chart Etiology
The cause of injury is essentially the same as that of a humerus supracondylar fracture. It is mostly caused by indirect composite forces. When a child falls and lands on their palm, the forearm is often in a pronated position with the elbow 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. Additionally, factors such as elbow valgus stress and extensor muscle traction often contribute to the fracture. The fracture line runs obliquely from the upper part of the external condyle downward and inward to the radial side of the trochlea. The bone fragment often includes the radial metaphyseal bone piece, 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 the X-ray shows a fracture line 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 shift again during fixation.
Type III: Rotational displacement type. The fracture fragment is displaced laterally, anteriorly, or posteriorly and also undergoes 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, of which 9 cases (about 20%) were combined with 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 a fracture-dislocation type to emphasize its significance.
Swelling on the lateral side, gradually spreading, may involve the entire joint. The swelling is most severe in fracture-dislocation type. Ecchymosis appears on the lateral side of the elbow and gradually spreads, potentially reaching the wrist. Blisters may appear 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, alteration of the three-point relationship at the posterior elbow, and loss of elbow joint movement. Pain worsens during passive movement, while rotational function is generally unaffected.
Radiographs show that the fracture line of the humeral capitulum often exceeds half of the ossification center or does not pass through the ossification center of the capitulum but instead traverses the cartilage of the groove between the capitulum and the trochlea, with a fracture line present at the metaphysis. The fracture fragment may displace laterally. In fracture-dislocation type radiographs, the anteroposterior view shows that the fracture fragment, along with the ulna and radius, may displace radially or ulnarly, while the lateral view shows possible posterior displacement, and occasionally anterior displacement. Humerus external condyle fractures exhibit diverse manifestations on radiographs, and even within the same fracture type, the presentations often vary.
bubble_chart Treatment Measures
The size of the bone bridge formation and the degree of deformity occurrence. Therefore, regardless of the method employed, anatomical reduction or approximate anatomical reduction should 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 applied for 4–6 weeks. The immobilization duration and position (elbow extension or flexion and forearm supination) depend 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 internal fixation using two Kirschner wires should be performed.
3. Rotational displacement type and fracture-dislocation type: Closed reduction is adopted. Based on the X-ray, 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, simultaneous reduction is required. 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 fails, open reduction should be performed to correct the rotational displacement of the fracture fragment. Preserve the soft tissue attached to the fragment as much 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, then begin elbow joint mobilization.
4. Old fractures: Surgery is generally not recommended. For fractures within 3 months with significant displacement and nonunion, Beijing Jishuitan Hospital adopts 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 joint is stiff preoperatively, partial functional improvement can still be obtained postoperatively.
- Cubitus valgus: Deformity caused by injury to the lateral epiphyseal cartilage plate of the distal humerus after trauma, which may lead to premature closure. This results in uneven development of the distal humerus, causing cubitus valgus and a fishtail-like deformity of the distal humerus. For severe cases, osteotomy may be performed for correction.
- Ulnar neuritis or paralysis: Due to traction from cubitus valgus deformity or impingement of the ulnar nerve by the olecranon, ulnar neuritis may occur. Once detected, the ulnar nerve should be transposed early to prevent paralysis.
