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.