Medial–lateral versus lateral-only pinning fixation in children with displaced supracondylar humeral fractures: a meta-analysis of randomized controlled trials

BACKGROUND: Supracondylar humeral fractures (SCHFs) are frequent in children, and closed reduction with percutaneous pin fixation remains the standard surgical treatment for displaced SCHFs. Two pinning configurations, medial–lateral crossed entry pinning (MLP) and lateral-only entry pinning (LP), are widely used, but which one is superior to another one is still debatable. This meta-analysis aimed to compare the efficacy and safety of both pinning fixation methods. METHODS: Randomized controlled trials (RCTs) were searched on PubMed, EMBASE, Web of Science, Cochrane library and Google Scholar. Relative risk (RR) and mean difference (MD) with corresponding 95% confidence interval (CI) were calculated for radiographical outcomes, functional outcomes and complications. RESULTS: A total of 19 RCTs comprising 1297 Gartland type II and type III fractures were included. MLP had a decreased risk of loss of reduction (RR = 0.70, 95%CI 0.52–0.94, P = 0.018) but a higher risk of iatrogenic ulnar nerve injury (RR = 2.21, 95%CI 1.11–4.41, P = 0.024) than LP. However, no significant difference was observed for incidence of ulnar nerve injury if applying a mini-open technique in MLP group (RR = 1.73, 0.47–6.31, P = 0.407). There were no differences between both groups in loss of carrying angle (MD = − 0.12, 95%CI − 0.39 to 0.16), loss of Baumann angle (MD = 0.08, 95%CI − 0.15 to 0.30), excellent grading of Flynn criteria (RR = 1.06, 95%CI 0.99–1.14, P = 0.102) and pin tract infection (RR = 0.92, 95%CI 0.50–1.70). CONCLUSIONS: MLP is more effective in maintaining fixation, while LP is safer with respect to ulnar nerve injury. MLP with a mini-open technique reduces the risk of ulnar nerve lesion and is an effective and safe choice. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13018-023-03528-8.