Background: Distal splint bone fractures, common in racing Standardbreds and Thoroughbreds, are often complicated by secondary suspensory ligament branch (SLB) desmitis. These combined injuries are known to impair post-operative performance, but contemporary data on prognosis is limited. Objective: To evaluate the post-operative performance of horses following distal splint bone fracture ostectomy with concurrent SLB desmitis. Study Design: Retrospective cohort study Methods: Clinical, demographic, and racing data were retrospectively analyzed. Horses with a splint bone fracture and concurrent SLB desmitis underwent standing ostectomy and were followed for 24 months. Kaplan-Meier survival analysis assessed the time to return to racing. Pre- and post-operative performance was compared within the surgery group and against age-, sex-, and breed-matched controls using mixed-effects models. The effects of SLB lesion grade and adjunctive platelet-rich plasma (PRP) therapy were also analyzed. Results: Eleven horses (mean age 9 ± 1.6 years) with fractures of the distal 1/3 of the splint bone and concurrent SLB desmitis were included. The mean time to return to racing was 8.5 months (95% CI: 7.5–9.5). 64% (7/11) of horses raced at least three times post-operatively. Surgery group horses raced significantly more than controls over 24 months (mean difference: 2.2 ± 0.4; p < 0.0001). No difference was found between pre- and post-operative performance within the surgery group (p > 0.05). Horses with grade 1 SLB lesions raced more than those with grade 2 or 3 lesions (p < 0.0001) and controls (p = 0.0008). Age and PRP treatment had no significant effect. Main limitations: Relatively small surgery population size (n = 11) and lack of conservatively treated group for comparison Conclusion: Distal splint bone ostectomy with concurrent SLB desmitis had a favorable prognosis in cases of less severe SLB lesions.