Retrospective performance‐indexed analysis of Thoroughbred racehorses undergoing surgical management of proximal sesamoid bone fractures

Background Proximal sesamoid bone fractures (PSBFs) are a leading cause of economic losses. Post‐operative racing prognosis is multi‐factorial; however, recent studies are lacking. Objectives To provide an update on racing outcomes for horses undergoing surgical management of PSBFs, analyse variables affecting performance and compare post‐operative racing performance with pre‐operative data and case‐matched controls. Study Design Retrospective case series. Methods Thoroughbred racehorses that underwent PSBF repair (2008–2022) were included. Data retrieved included fracture type, limb, axiality, treatment, age, sex, suspensory ligament branch (SLB) injury, surgical date, date of racing return, and pre‐ and post‐operative starts and places (1–3), which generated a performance index (PI) and PI per start (PI/S). Chi‐squared assessed the effect of categorical variables (sex, limb, fracture type, axiality, SLB injury and pre‐surgical racing experience) on racing outcome. Wilcoxon signed‐rank test compared pre‐ and post‐operative performance indices. Kruskal–Wallis and Mann–Whitney U tests assessed significance between categorical variables and numerical variables (age, recovery, number of starts (Nstarts), and performance indices). Binary logistical regression performed multivariable analysis. Change in PI and PI/S, and Nstarts were compared between matched controls and cases using Mann–Whitney U tests. Results Overall, 86/168; 51.2% (confidence interval (CI): 43.5%–58.9%) horses raced post‐operatively. Of the 113 horses that raced pre‐operatively, 57 raced post‐operatively (50.4%, CI: 41.8%–59.3%). Forelimb fracture cases (42.3%) were less likely to race post‐operatively compared with hindlimb cases (65.6%, p = 0.003). In univariable analysis, horses that underwent surgical management of mid‐body fractures (15.8%) were less likely to race compared with other fracture types (apical 56.1%, abaxial 60.5% and basal 25%, p = 0.001). Horses undergoing screw‐fixation were less likely to race compared with fragment‐removal (17.4% vs. 56.6%, p = 0.001). Axiality, pre‐operative racing and SLB injury did not affect return‐to‐racing. No significance was observed for post‐operative Nstarts, change in PI, change in PI/S or the return‐to‐racing proportion between cases and controls. Main Limitation The retrospective nature and drop‐out rate limited post‐operative analysis. Conclusion Surgical management of apical and abaxial PSBFs via fragment removal is associated with improved post‐operative outcomes compared with PSBFs necessitating internal fixation. Limb is a significant determining factor for return to racing. Post‐operative racers have good longevity, although reduced PI/S compared with pre‐operative performance.