Radiocapitellar Alignment in Suspected Pediatric Monteggia Lesions: Narrative Review and Imaging Interpretation Framework

Pediatric Monteggia fracture-dislocations may be overlooked when ulnar injury is incomplete or plastically deformed and radiocapitellar malalignment is subtle. Radiographic interpretation is further complicated by incomplete ossification, non-standard projection, and the limitations of applying a single alignment line across all ages and imaging scenarios. This narrative review synthesizes clinically relevant evidence on radiocapitellar alignment assessment in suspected pediatric Monteggia lesions and proposes an imaging interpretation framework for radiographs and problem-solving imaging. The review integrates developmental anatomy, radiographic adequacy, radiocapitellar line behavior, forearm-based P-line assessment, lateral humeral line assessment, ulnar bow sign, and targeted second-line imaging with ultrasound, MRI, and arthrography. The framework emphasizes three practical steps: first determining whether the available images are adequate for line-based assessment; then selecting the line or sign according to age, ossification stage, projection, and available landmarks; and finally reporting discordant or limited studies as equivocal rather than forcing a binary normal/abnormal interpretation. We also summarize diagnostic error considerations, structured reporting elements, and future directions for AI-assisted measurement and uncertainty-aware interpretation. The proposed framework is intended to support consistent radiologic reasoning and communication among emergency physicians, radiologists, and pediatric orthopedic surgeons. It is not a validated diagnostic rule, and prospective observer-performance studies are needed before implementation as a clinical pathway.