Medial comminution as a risk factor for the stability after lateral-only pin fixation for pediatric supracondylar humerus fracture: an audit

BACKGROUND AND PURPOSE: Closed reduction and lateral-only pin fixation is one of the common treatment methods for displaced supracondylar fracture in children. However, several risk factors related to the stability have been reported. The aim of this study was to evaluate the medial comminution as a potential risk factor related to the stability after appropriate lateral-only pin fixation for Gartland type III supracondylar humerus fracture. METHODS: Sixty-seven patients with type III supracondylar fractures who were under the age of 12 years were included. Immediate postoperative and final Baumann and humerocapitellar angles were measured. Pin separation at fracture site was evaluated to estimate the proper pin placement. Presence of the medial comminution was recorded when two pediatric orthopedic surgeons agreed to the loss of cortical contact at the medial column by the small butterfly fragment or comminuted fracture fragments. Factors including age, sex, body mass index, pin number, pin separation at fracture site, and medial comminution were analyzed. RESULTS: Medial comminution was noted in 20 patients (29.8%). The average pin separation at fracture site was significantly decreased in patients with medial comminution compared to patients without medial comminution (P=0.017). A presence of medial comminution was associated with a 4.151-fold increase in the log odds for the Baumann angle changes of more than average difference between immediate postoperative and final follow-up angle (P=0.020). CONCLUSION: When lateral-only pin fixation is applied for Gartland type III supracondylar humerus fracture in children, the medial comminution may be a risk factor for the stability because of the narrow pin separation at fracture site. We recommend additional medial pin fixation for supracondylar humerus fracture with medial comminution.