Association Between Inertial Sensor-Based Lameness Classification and Musculoskeletal Injury Sites in Horses.

Background: Lameness may result from injuries to different anatomical structures and can manifest during various phases of the stride. Subjective evaluation differentiates between supporting and swinging limb lameness, whereas objective assessment using an inertial sensor system classifies lameness as impact or pushoff, representing asymmetries in the early and late stance phases, respectively. Objective: To determine whether the type of lameness is associated with the site of musculoskeletal injury. Study design: Retrospective case series. Methods: : Lameness in 519 horses was categorized as impact, pushoff, or mixed-type lameness. Diagnoses were recorded, and the relationship between lameness type and injury site was assessed using a chi-square test. Logistic regression was used to determine the effect of lameness type and musculoskeletal injury region (distal limb, proximal limb, distal and proximal limb, spine, and muscle) as well as a specific diagnosis. Results: : Impact lameness was most common in forelimbs, while mixed-type lameness predominated in hindlimbs. The distal limb was the most frequently affected region in both. No statistically significant association was found between lameness type and injury site in either the forelimbs or hindlimbs. Tendons and ligaments were the most frequently injured structures in forelimb impact (25.7%) and hindlimb mixed lameness (21.2%), followed by navicular syndrome (18.9%) and distal tarsal osteoarthritis (11.7%), respectively. Tendon and ligament injuries were significantly more frequent in hindlimbs (p<0.001), whereas navicular syndrome and fetlock joint pain were more common in forelimbs (p<0.001). Main limitations: Small sample sizes for pushoff lameness and proximal limb injuries may have limited statistical power. Conclusion: Objective lameness assessment using an inertial sensor system provides limited value in predicting the anatomical site of musculoskeletal injury. Sensor-based lameness classification should therefore not be solely relied upon to localize the underlying cause of lameness in clinical cases.