Race Performance Following Arthroscopic Surgery for Femoropatellar and Tarsocrural Osteochondrosis in Juvenile Thoroughbreds.

Overview

• This study examined how arthroscopic surgery for osteochondrosis (OC) in specific joints of juvenile Thoroughbreds impacts their subsequent racing performance.
• The research compared treated horses to matched control horses to determine if surgery affected race outcomes like starts, wins, and earnings.

Background and Purpose

• Osteochondrosis (OC) is a developmental joint disease common in young horses that can impair joint function and potentially affect athletic performance.
• The femoropatellar (FP) joint in the stifle and the tarsocrural (TC) joint in the hock are common sites for OC lesions in Thoroughbreds.
• The preferred treatment for juvenile horses with OC causing clinical issues is arthroscopic surgery to remove diseased cartilage and treat lesion areas.
• The study aimed to objectively evaluate whether Thoroughbred yearlings treated with arthroscopic surgery for OC in FP or TC joints could compete successfully in racing relative to matched untreated peers.

Study Design and Methods

• Type: Retrospective cohort study including horses less than 2 years old treated between 2010 and 2022.
• Groups:
  • Cases: 49 horses having arthroscopic surgery for OC in FP (27 horses) or TC (22 horses) joints.
  • Controls: For each case, two age- and sex-matched horses from the same stud farm without OC surgery.
• Diagnostic imaging: Lesions were identified and graded using preoperative radiographs.
• Assessments:
  • Primary outcomes included number of race starts, wins, places (2nd), podiums (top 3 finishes), prize money earned, and career duration.
  • Performance data analyzed across 2nd, 3rd, and ≥4-year-old racing seasons.
  • Additional analysis compared unilateral versus bilateral lesion cases for differences in performance.
• Statistical analysis:
  • Used parametric (Student’s t-test, ANOVA) or nonparametric tests (Mann–Whitney U, Kruskal–Wallis), chosen based on data distribution.
  • Compared outcomes between cases and controls and between unilateral and bilateral lesions.

Key Findings

• Lesion Characteristics:
  • In FP group, the lateral trochlear ridge of the femur was the most commonly affected site; 14 horses had bilateral lesions; two had lesions in other joints.
  • In TC group, the distal intermediate ridge of the tibia was mainly involved; 5 horses had bilateral lesions; one had lesions in another joint.
• Racing Performance Comparison:
  • No significant difference was detected between surgically treated horses and their matched controls for any performance measure, including number of starts, wins, places, podiums, prize money across all age categories, or total career duration (p > 0.05).
  • Whether lesions were unilateral or bilateral did not affect performance outcomes significantly within either group (p > 0.05).

Interpretation and Conclusion

• Arthroscopic surgery for OC in the FP or TC joints of juvenile Thoroughbreds appears to allow horses to achieve comparable race performance to unaffected peers.
• Successful racing careers post-surgery suggest that early surgical intervention effectively mitigates OC-associated joint pathology without limiting athletic potential.
• The equivalence in performance between unilateral and bilateral lesion cases indicates that even more extensive OC involvement, when treated timely and properly, does not necessarily impair later racing ability.
• These findings support the clinical practice of arthroscopic surgery for OC lesions in young Thoroughbreds and provide reassurance regarding expected long-term athletic outcomes.