Background: Distal humeral fractures are the most common pediatric elbow fractures. Although frequent, displaced fractures are still challenging in treatment and may lead to unfavorable elbow deformities as long-term complications. Post-surgical evaluation always includes plain radiographs for evaluating alignment and bone union. However, there is currently no evidence supporting the role of follow-up radiographs at different time periods after pin removal.

Objectives: This study aimed to compare the Baumann angle and the Lateral humeral-capitellar angle (LHCA) at pin-removal day, short-time period (1-2 weeks after removal), and long-time period (>12 weeks after removal).

Study design: The study includes an ambidirectional cohort.

Settings: The study was conducted in the Police General Hospital.

Subjects: Pediatric patients (<14 years old) with distal humeral fractures who underwent pinning were included in the study.

Methods: This study was conducted on 137 patients from the radiograph database from 2010 to 2024. Plain radiographs of the elbow in AP and lateral views were used for measuring the Baumann angle and LHCA. The calculation was performed using IBM SPSS Statistics for Windows, Version 16 (Released 2015; IBM Corp., Armonk, New York, United States).

Results: The Baumann angles at the pin-removal day, short-time period, and long-time period were 71.95o ± 3.77 o, 71.92 o ± 3.84 o, and 72.12 o ± 3.76 o, respectively. The LHCA was 51.44 ± 2.29, 51.37 ± 2.47, and 50.92 ± 3.42, respectively. Statistical analysis results show no significant difference in each period for the Baumann angle (p=0.368), but a slightly significant decrease in the LHCA at the long-time period (p=0.01). Subgroup analysis was performed, indicating no difference in the Baumann angle and LHCA among age groups (2-5 years old vs >5 years old). For subgroup analysis of fracture locations, the lateral condylar humerus fracture group had a significant change in the LHCA about 3.25o at a long-time period (p=0.043). However, the angles were all in the normal range.

Conclusions: Follow-up plain radiographs demonstrated that the Baumann angle remained stable across the pin-removal day, short-term, and long-term, regardless of age or fracture location. In contrast, the LHCA showed a significant but small decrease at long-term follow-up, particularly in patients with lateral condylar fractures, suggesting a remodeling tendency specific to this subgroup. These could indicate no role of follow-up radiographs after pin removal.

Sireethorn Chatpermporn graduated with a Doctor of Medicine from Chulalongkorn University, Thailand. She is currently a 4th-year orthopaedic resident at Police General Hospital, Thailand.