Gait initiation in patients with plantar heel pain: a matched case-control study

Introduction: Plantar Heel Pain (PHP) is a common foot disorder treated by health care professionals. Patients with PHP usually describe pain in the first steps in the morning which are relieved after the first half hour, pain at the plantar aspect of the heel bone, tenderness to palpation, and functional impairment to perform daily activities. Although patients with PHP commonly describe pain during gait initiation, there is a lack of knowledge in the literature regarding the analysis of the ground reaction forces during this task. Objective: The aim of this study was to compare the ground reaction forces during gait initiation in patients with PHP and sex- and age-matched controls. Methods: This is a single-blinded, matched case-control study conducted with 10 patients with plantar heel pain [mean (SD): age 49 (11) years; 6 (60%) female] and 10 matched controls. The study was approved by the Research Ethics Committee of the Augusto Motta University Centre and was conducted in accordance with the Declaration of Helsinki for research in humans. All included participants signed the written Informed Consent Form before the experimental procedures. Gait initiation was assessed using a force platform. The magnitude of the vertical ground reaction forces was computed for the support and swing feet, both normalised to the body mass. The total step duration (in seconds) and the rate of force development (in N/s) were calculated for both conditions. Participants were compared by the Mann-Whitney U-test. Results: Patients with plantar heel pain had statistically significant higher values than the controls of the peak force of the swing foot at peak 1 (patient median=98.7%, control median=17.4%; Z=-3.175, p=<0.001), peak 2 (patient median=101.2%, control median=17.6%; Z=-3.099, p=<0.001), and of the support foot at peak 1 (patient median=61.0%, control median=11.5%; Z=-3.553, p=<0.001). Additionally, the rate of force development was statistically significantly higher in patients with PHP than controls (Z=-3.704, p=0.001), whereas support phase duration was not significantly different between groups (Z=-0.719, p=0.496). Conclusion: Patients with PHP exerted higher ground reaction forces during gait initiation compared to controls. Keywords: Plantar Heel Pain, Gait, Ankle, Lower Extremity, Musculoskeletal Pain.