Racing performance in 75 Thoroughbreds after arthroscopic removal of Osteochondritis dissecans from the lateral femoral trochlear ridge before first race start in Korea (2015-2017).

The lateral trochlear ridge of the stifle joint is highly susceptible to developing Osteochondrosis (OC)/Osteochondritis dissecans (OCD) lesions. This retrospective study evaluated the medical and racing outcomes of 75 Thoroughbreds who underwent arthroscopic OCD removal at the Jeju Stud Farm Equine Hospital from 2015 to 2017. The analysis included medical records, radiographic assessments, and race performance data, comparing 75 horses that underwent surgery with 257 control horses selected as siblings from the same dam. The surgical group had comparable racehorse registration rates (89.3 %) and first race start rates (72.0 %) compared to those of the control group (84.8 % and 74.7 %, respectively). However, horses that underwent surgery had their first race start later (p = 0.000864, p < 0.0001) and participated in fewer total races (p = 0.01708, p < 0.05) than the control group. Despite these differences, there were no significant variations in sales prices, career earnings, race points, or retirement age. Furthermore, neither the size of the OCD lesion nor the timing of the surgery significantly influenced overall racing performance metrics, except for a reduction in career duration for horses operated on at an older age. Sex-based analyses revealed that male horses consistently outperformed females in career duration and earnings. Subgroup analyses revealed significantly poorer outcomes in females treated before 12 months of age and those with large lesions (≥ 40 mm), including fewer starts and earlier retirement. In summary, arthroscopic surgery for stifle OCD in Thoroughbreds before their first race start did not negatively affect overall performance. While lesion size and surgery timing had minimal impact, this study suggests that sex-related factors may more strongly influence post-surgical outcomes.