A case-matched controlled retrospective performance indexed analysis of Thoroughbred racehorses that underwent surgical repair of proximal phalanx and third meta-carpal/tarsal condylar fractures.

Background: Standing fracture repair has become established as an acceptable technique with a good long-term prognosis. However, no study has compared racing outcomes with case-matched controls.

Objectives: To compare racing outcomes between a large dataset of horses undergoing standing fracture repair against case-matched controls.

Study design: Retrospective case-matched controlled comparative study.

Methods: Thoroughbred racehorses undergoing standing repair of distal limb fracture(s) over 10 years (2012-2022) at five hospital centres across North America and Europe were included. Data retrieved included age, sex, fracture type, pre- and post-operative racing status, days elapsed between repair and first start, and number of starts and places (1-3), which were used to generate a performance index (PI) and a performance index per start (PI/S). Two case-matched controls were assigned and used for post-operative comparison of racing performance.

Results: 185/265; 69.8% (confidence interval (CI): 63.9%-75.4%) of horses raced post-surgery. No significant difference in the proportion of cases and case-matched controls (260/342; 76% (CI: 71.3%-80.4%)) that returned to racing was observed. No significant difference in post-operative performance indicators (N starts, PI, PI/S) between cases ((9, inter-quartile-range (IQR): 14) (7, IQR: 14) (0.64, IQR: 1)) respectively, and case-matched controls ((9, IQR: 17) (5, IQR: 14.8) (0.6, IQR: 0.66)) respectively, was observed. Fracture type, limb, sex, or pre-operative racing experience did not affect the proportion of horses returning to racing.

Main limitation: The retrospective nature of this study may lead to the omission of data for analysis.

Conclusion: Horses undergoing standing internal fixation of select proximal phalanx and third metacarpal/tarsal condylar fractures have a good prognosis for return to racing and comparable performance with case-matched controls. Horses that undergo standing fracture repair have good longevity, outweighing surgical costs and loss of training.