Visual lameness assessment in comparison to quantitative gait analysis data in horses

Abstract

BACKGROUND: Quantitative gait analysis offers objective information to support clinical decision-making during lameness workups including advantages in terms of documentation, communication, education, and avoidance of expectation bias. Nevertheless, hardly any data exist comparing outcome of subjective scoring with the output of objective gait analysis systems. OBJECTIVES: To investigate between- and within-veterinarian agreement on primary lame limb and lameness grade, and to determine relationships between subjective lameness grade and quantitative data, focusing on differences between 1) veterinarians, 2) live versus video assessment, 3) baseline assessment versus assessment following diagnostic analgesia. STUDY DESIGN: Clinical observational study. METHODS: Kinematic data were compared to subjective lameness assessment by clinicians with ≥ eight years of orthopaedic experience. Subjective assessments and kinematic data for baseline trot-ups and response to 48 diagnostic analgesia interventions in 23 cases were included. Between and within-veterinarian agreement was investigated using Cohen's Kappa (κ). Asymmetry parameters for kinematic data ('forelimb lame pattern', 'hindlimb lame pattern', 'overall symmetry', 'vector sum head', 'pelvic sum') were determined, and used as outcome variables in mixed models; explanatory variables were subjective lameness grade and its interaction with 1) veterinarian, 2) live or video evaluation and 3) baseline or diagnostic analgesia assessment. RESULTS: Agreement on lame limb between live and video assessment was 'good' between and within veterinarians (median κ=0.64 and κ=0.53). There was a positive correlation between subjective scoring and measured asymmetry. The relationship between lameness grade and objective asymmetry differed slightly between 1) veterinarians (for all combined parameters, p-values between p<0.001 and 0.04), 2) between live and video assessments ('forelimb lame pattern', 'overall symmetry', both p≤0.001), and 3) between baseline and diagnostic analgesia assessment (all combined parameters, between p<0.001 and 0.007). MAIN LIMITATIONS: Limited number of veterinarians (n=4) and cases (n=23), only straight-line soft surface data, different number of subjective assessments live versus from video. CONCLUSIONS: Overall, between- and within-veterinarian agreement on lame limb was 'good', whereas agreement on lameness grade was 'acceptable' to 'poor'. Quantitative data and subjective assessments correlated well, with minor though significant differences in the number of millimetres, equivalent to one lameness grade between veterinarians, and between assessment conditions. Differences between baseline assessment versus assessment following diagnostic analgesia suggest that addition of objective data can be beneficial to reduce expectation bias. The small differences between live and video assessments support the use of high-quality videos for documentation, communication, and education, thus, complementing objective gait analysis data.