Interventions: Patients will randomly assigned into five groups (active, sham and control) and will followed for fourteen months (two moths pre-operative and twelve months post-operative). All groups will undergo post-operative physical therapy (PT) according to the standard guidelines. In addition, the active groups will be treated with the device and its four biomechanical elements that had been individually calibrated for each patient. The sham group will be treated with the same device; however, the biomechanical elements will have zero perturbation and will be positioned along the central longitudinal line of the shoe-platform. The control group will be treated only according to the standard post-operative protocol.