Severity, distribution and postoperative therapy are not predictors of return to work in western performance horses with stifle chondromalacia.

Objective: (1) To evaluate the ability of western performance horses diagnosed with chondromalacia to return to performance; Specifically, the relationship between the grade of chondromalacia and the horses' ability to resume work; (2) To determine the impact of postoperative therapy on clinical outcomes.

Study design: Retrospective case series.

Animals: Horses (n = 34).

Methods: Records of western performance horses with lameness localized to the stifle that underwent subsequent arthroscopy with chondromalacia as the most significant diagnosis were reviewed. Chondromalacia was surgeon-graded as slight, mild, moderate, or marked. Three evaluated categories of postoperative intra-articular therapy included: (1) bone marrow derived mesenchymal stem cells, (2) equine amniotic allograft product or (3) none. Outcome was defined as returning to previous level of work on a numeric scale (1-10).

Results: Chondromalacia and its degree of severity and focal vs. diffuse distribution identified arthroscopically did not show a significant association (p = .54, .40, respectively) or correlation (p = .18; R-value: 0.27) with the ability to return to athletic performance. The type of postoperative intra-articular therapy did not have any association with the horse returning to athletic work (p = .53).

Conclusion: A statistically significant association between severity, distribution or subsequent postoperative therapy for stifle chondromalacia and the ability to return to work was not observed.

Clinical significance: Compared to previously published reports, this study demonstrated a 74% more favorable prognosis for returning to some level of athletic work despite only 44% of horses returning to their previous level of performance.