Fourier analysis of vertical ground reaction forces in dogs with unilateral hind limb lameness caused by degenerative disease of the hip joint and in dogs without lameness.

OBJECTIVE: To evaluate the applicability of Fourier analysis for assessment of ground reaction forces (GRFs) and differentiation between dogs with unilateral hind limb lameness caused by degenerative joint disease of the hip (DJD-H) and dogs without lameness. ANIMALS: 37 dogs with or without unilateral DJD-H. PROCEDURES: Data were obtained from other studies and analyzed retrospectively. Among the 37 dogs, 20 had unilateral DJD-H and 9 (non-Belgian Malinois breeds) had no lameness; another 8 were nonlame Belgian Malinois (radiographically confirmed Fédération Cinologique International classification A [ie, no hip dysplasia or DJD-H]). Gait data acquisition was performed as dogs walked on a treadmill with integrated force platforms. The peak vertical force, mean vertical force, and vertical impulse were compared among the 3 groups. Fourier analysis was performed on the force-time curves for the vertical GRF, and calculated Fourier coefficients were compared within and between groups.
RESULTS: Lameness in the hind limbs with DJD-H was detectable via conventional analysis of the GRF as well as via Fourier analysis. However, subtle gait aberrations in the forelimbs of the dogs with DJD-H were detected solely via Fourier analysis of GRFs and remained undetected via conventional analysis. CONCLUSIONS AND CLINICAL RELEVANCE: Results support the applicability of Fourier analysis for evaluation of force-time curves of GRFs. Fourier analysis can reveal subtle alterations of gait that might otherwise remain inapparent; however, further investigation is necessary before this method can be routinely applied for lameness detection in dogs.