Does the ulnohumeral angle have a role in the aetiopathogenesis of lateral epicondylitis?

The pathophysiology of lateral epicondylitis (LE) remains not fully elucidated, as it involves a complex interaction of anatomical structures. The primary objective of the research is to identify a potential relationship between LE and the ulnohumeral angle (UHA), which demonstrates the coronal alignment of the elbow. Patients diagnosed with LE between September 1st, 2020, and September 1st, 2023, were retrospectively examined. Demographic information and UHA measurements of patients meeting the inclusion criteria and a control group with similar criteria were collected. Measurements were independently conducted by 2 orthopedists at a 2-week interval and compared. Among 413 patients meeting the inclusion criteria and the control group comprising 420 patients, there were no significant differences in age, gender, and side (P = .447, P = .288, P = .159, respectively). The mean UHA for the LE group was 13.49 ± 4.24, while for the control group, it was 12.82 ± 9.19, showing a significant difference (P = .026). The inter-observer and intraobserver reliability of the angle measurements were both above 0.80. We hypothesize that the increase in UHA in patients with LE reflects an adaptive change secondary to compressive forces acting on the lateral aspect of the elbow. This study is the first to describe the relationship between LE and UHA based on anatomical-biomechanical foundations, suggesting a cause-and-effect relationship. Further studies are warranted to delve deeper into this relationship.