The fixation strength of hydroxyapatite-coated Schanz screws and standard stainless steel Schanz screws in lower extremity lengthening : a comparison based on a new torque value index: the fixation index. Placzek, R Ruffer, M Deuretzbacher, Georg Heijens, E Meiss, A L 2006 - Forschungsinformationssystem des UKE