The purpose of this study was to assess the effects of an orthosis wearing on the postural capacities of patients undergoing a knee ligamentary surgery. The experimental task was carried out with fourteen patients at the end of their program of rehabilitation. The displacements of the centre of pressure (CP) were recorded during four conditions performed during one-legged stance, alternating the wearing or not of the orthosis as well as the involved leg (sound or operated). The patients were required to maintain a light flexion of the knee and minimising the body motions. Traditional parameters and other issued from fractional Brownian motion modelling were used to assess the postural behaviour. No significant difference was observed, depending on the orthosis was worn or not, nor its interaction with the involved leg. This lack of distinction between the two legs would suggest a complete recovery of proprioceptive capacities of the operated leg after rehabilitation. Our results highlight the uselessness of prophylactic orthosis prescription for a way of life with little soliciting when post-surgery rehabilitation was carried out.