Morphological Association Between Proximal Ulna Dorsal Angulation and Elbow Radiographic Osteoarthritis: A Propensity-Score Matched Case-Control Multicenter Study

This study aimed to compare the Proximal Ulna Dorsal Angulation (PUDA) in patients with primary elbow osteoarthritis (OA) to those with healthy elbows to determine the potential association of the PUDA with elbow osteoarthritis.

This multicenter retrospective radiographic comparative cohort study explored institutional databases between 2011 and 2024. All patients aged over 18 years with primary elbow OA were included in the OA group. Patients with post-traumatic OA and inflammatory arthritis were excluded. The control group consisted of healthy patients with normal elbow radiographs. The PUDA was measured on lateral radiographs using PACS software. OA was graded according to the Broberg and Morrey classification. Propensity score matching was performed at the participant level to reduce confounding by age and sex.

After propensity score matching, 169 elbows were included (61 OA, 108 controls). Mean PUDA was significantly higher in the OA group compared with controls (7.1 ° ± 2.7 ° vs 5.6 ° ± 2.3 °, p < 0.001) corresponding to a mean difference of 1.5 ° (95% CI 0.7-2.3; p < 0.001). A PUDA ≥ 5.7 ° was more frequent in the OA group (69% vs 47%, p < 0.001). No significant difference in age or sex distribution was observed after matching.

Increased proximal ulna dorsal angulation was significantly associated with primary elbow osteoarthritis in an age- and sex-matched population. These observations indicate a potential association between the PUDA angle and elbow OA that warrants confirmation in prospective longitudinal studies.

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