Forearm crisscross injury is rare. Due to the special mechanism, less than 10 cases have been reported worldwide; all cases involved adult patients.[1, 2] To date, this special injury has not been reported in children; its pathogenesis, treatment, and prognosis remain unclear. Leung et al.[2] first reported the definition of crisscross injury and diagnostic criteria in 2002. A currently recognized crisscross injury refers to simultaneous upper and lower radioulnar joint dislocation with intact interstitial membrane, accompanied by fractures of the radial head and the ulnar styloid process, but not accompanied by ipsilateral ulnar and radial shaft fractures. Lateral orand anteroposterior radiographic findings of the forearm revealed radioulnar crisscross. According to Leung’s study, crisscross injuries can be classified into two types: type I refers to forward radial and ulnar head dislocations; type II refers to posterior dislocation of the radial and ulnar heads. The former is due to forearm overpronation, while the latter is caused by supination (with the intact interosseous membrane serving as a fulcrum that participates in the mechanism of the forearm crisscross injury).[3] Our patient’s imaging data showed that the ulna and radius were crisscrossed in the anterior and lateral X-ray images. Although we did not perform magnetic resonance imaging to prove that the interosseous membrane of the forearm was intact, but the patient's forearm was not swollen. When the anatomical structure of the distal ulna and radius recovered, the superior radioulnar joint was automatically restored without any additional intervention. These results indirectly proved that the interosseous membrane was intact. In our case, strictly speaking, only the superior radioulnar joint was dislocated. The distal radius epiphysis was fractured and some distal joints are still connected to the ulna; hence, the inferior radioulnar joint does not comprise a true dislocation. Since the ligament strength in children is greater than that of the epiphyseal plate, epiphyseal injury occurs in the distal radius without inferior radioulnar separation. We believe that this is a special manifestation of crisscross injury in children.
In this diagnosis of crisscross injury in adults, simultaneous dislocation of the superior and inferior radioulnar joints did not combine ipsilateral ulnar and radial shaft fractures were comprising universally accepted diagnostic criteria. Current reports include no description of fractures other than the radioulnar joint dislocation.[2, 4, 5] During adolescence, tendons, ligaments, and joint capsules are two to five times stronger than epiphyses plates.[6] Therefore, when radioulnar joint dislocations occur in children, their forearms are extremely pronated or supinated, injuries to the epiphyseal plate” are possible because the tendons, ligaments, and joint capsules are stronger than the epiphyseal plates. In our case, the patient's forearm was extremely externally rotated and the shearing force of the epiphysis and ligament of the distal radius increased. Epiphyseal fracture occurred due to the different strengths of the epiphyses and ligaments. The child’s single ulna was unable to support the weight of the body and fracture. Our case was different from that reported in the existing literature, possibly due to the strength between children's different from of bones and ligaments than that of adults. Our patient’s imaging performance is fully consistent with the diagnosis of a type I crisscross injury, ignoring the impact of distal radial epiphyseal fractures and considering the palm and ulna as a whole.
Cases of crisscross injuries reported in the existing literature have been successfully treated with closed reduction, manipulation, plaster, or external fixation. Patients had no complications of joint instability or pain. In a patient reported by Potter et al., closed reduction failed multiple times due to deformities of the radial head, and scar reduction was ultimately successful.[4] In our case, multiple manual reductions failed and the patient had an open epiphyseal fracture. Therefore, epiphyseal fractures must be properly treated as early as possible, and focusing on anatomical reduction; otherwise, late deformities can easily occur due to premature epiphyseal closure. We performed intramedullary fixation to treat the fracture, reducing the patient’s traumatic stress, while achieving anatomical reduction. The patient fully recovered and returned to his normal life, 3 months postoperatively.
In this study, we report a case of forearm crisscross injury in children for the first time and analyze the mechanism and differences from adults. Minimally invasive surgery with intramedullary fixation for a forearm crisscross fracture achieved good results. This case provides a reference for future diagnosis and treatment of similar patients.