Proximal ulna angular measurements in elbow dislocations: radiographic insights into simple vs. complex injuries

Elbow dislocations are common injuries, classified as simple or complex based on the presence of fractures. While the stabilizing structures of the elbow have been well-studied, the influence of proximal ulna anatomical variations on the risk and severity of dislocations remains unclear. This study aimed to evaluate proximal ulna dorsal angulation (PUDA), proximal ulnar varus angle, and olecranodiaphyseal angle (ODA) in healthy individuals, patients with simple elbow dislocations, and those with complex elbow dislocations. We hypothesized significant differences in these angles between the groups.

A comparative cross-sectional study was conducted including healthy controls (n = 182), patients with simple elbow dislocations (n = 112), and patients with complex elbow dislocations (n = 52). Standardized anteroposterior and lateral elbow radiographs were obtained to measure PUDA, proximal ulnar varus angle, and ODA. Radiographic measurements were conducted by 2 independent observers to ensure reliability. The study aimed to determine anatomical differences that could influence the likelihood and severity of elbow dislocations.

ODA was significantly lower in patients with complex elbow dislocations compared to both healthy controls and those with simple dislocations. Patients with radial head fractures had significantly lower ODA values than those without fractures. PUDA showed small differences between right and left elbows, but these differences had limited clinical relevance. Lower ODA was independently associated with the development of radial head fractures, indicating its potential as a factor of injury severity.

ODA serves as a significant anatomical marker that can differentiate between simple and complex elbow dislocations and is associated with fracture risk, particularly in complex dislocations. These findings suggest that assessing ODA may aid in evaluating elbow stability and planning treatment strategies for dislocation injuries.