Abstract: OBJECTIVE: Supracondylar humeral fractures are the most common type of elbow fractures in children. Closed reduction fixation is the preferred treatment for displaced supracondylar humeral fractures. However, there is still disagreement over the choice of the right technology. Therefore, the purpose of this meta-analysis was to evaluate the efficacy of unilateral and bilateral cross-pinning in children with supracondylar humeral fractures, and to provide a reference for clinical treatment. 
METHODS: A comprehensive search of relevant randomized controlled trials published from inception to January 6, 2023 was conducted on PubMed, Embase, Web of Science, and the Cochrane Library to compare the difference between two types of intralateral cross fixation and lateral fixation in children with supracondylar humeral fractures. The main outcome measures were imaging results (Baumann angle loss and carrying angle loss), elbow function results, and common complications (iatrogenic ulnar nerve injury and needle tract infection). 
RESULTS: (1) A total of 18 studies were included. (2) There was no statistical difference in the imaging results of Baumann angle loss (P=0.47) and carrying angle loss (P=0.47) between the two groups. The proportion of excellent children with joint function recovery score was 70.7% and 74.9% in the lateral fixation group and medial-lateral cross fixation group, with no statistical difference (P=0.12). There was also no statistically significant difference in the incidence of needle tract infection between the two groups (P=0.9), but the risk of iatrogenic ulnar nerve injury was higher in the medial-lateral cross fixation group (P=0.02). (3) However, there was no significant difference in the frequency of ulnar nerve injury in the intralateral cross fixation group when combined exploration with mini-open approach was performed compared with lateral fixation alone (P=0.2). (4) In the Gartland type III subgroup, there were no significant differences in joint functional recovery scores (P=0.13), ulnar nerve injury (P=0.13), and needle tract infection (P=0.61). 
CONCLUSION: The meta-analysis reveals that compared with the lateral fixation technique, the medial-lateral cross fixation method is more likely to cause iatrogenic nerve injury in the forearm, but it also increases the stability of the structure. However, the small incision method combined with the medial-lateral cross fixation seems to reduce the risk of nerve injury in patients. Thus, the therapy of children with displaced supracondylar humeral fractures involves medial-lateral crossing pinning fixation using a mini-open approach as a reliable and secure method.

Key words: supracondylar humeral fractures, lateral fixation, medial-lateral cross fixation, surgical fixation, ulnar nerve injury, meta-analysis, orthopedic implants