Growth-Adjusted Comparison of Angular Change After Radioulnar Fracture Repair with and Without Concurrent Ulnar Ostectomy in Immature Small-Breed Dogs

This retrospective cohort study compared antebrachial angular change following radioulnar diaphyseal fracture repair in immature small-breed dogs treated with or without concurrent ulnar ostectomy (UO). Medical records of small-breed dogs younger than 12 months that underwent plate fixation for radioulnar diaphyseal fractures were reviewed, and dogs were divided into UO and non-UO groups. Joint orientation angles (medial proximal radial angle [MPRA], lateral distal radial angle [LDRA], valgus angle [VA], and sagittal plane angle [SPA]) were measured on the operated limb at surgery and at bone union, and contralateral-limb measurements were used to calculate growth-adjusted net change. Twenty-eight dogs were included (UO, n = 13; non-UO, n = 15), 24 of which had contralateral follow-up. Operated-limb angular change (Δoperated) differed significantly between groups for all four angles (Holm-adjusted p < 0.05); mean changes were larger in magnitude in the non-UO group. These between-group differences persisted in the growth-adjusted analysis (Holm-adjusted p < 0.05). Elbow incongruity did not differ significantly between groups (0/13 vs. 3/15; p = 0.23). Concurrent UO was associated with smaller magnitudes of Δoperated, and this association persisted after growth adjustment. Prospective studies controlling for potential confounding factors are needed to confirm this association.