Ultrasound-guided intra-articular injections of hyaluronic acid (viscosupplementation) in the treatment of symptomatic hip osteoarthritis: Clinic results at 18 month - Brescia, F; Pofi, E; Cardello, P; Meschini, C; Zucchi, S (Ultraschall in der Medizin - European Journal of Ultrasound, 2007)