Evaluation of hydroxyapatite-coated Schanz screws used in the Heidelberg External Fixation System (HEFS)

The use of monolateral external fixation systems for the correction of limb length and/or axial anomalies involves the implantation of Schanz screws i n the long bones for periods of weeks or months. The loosening rate, which increases with duration of implantation, is a problem. In animal experiment s/superior fixation and a reduced infection rate have been reported for hyd roxyapatite-coated screws in comparison with conventional screws. We report on the clinical application of 59 hydroxyapatite-coated Schanz screws in 1 5 external fixation mountings. The performance of the screws was evaluated by clinical and radiological criteria. Infection was seen in 15 screws, nec essitating the early removal of 6 of them. In patients with a second fixati on system/the infection rate was lower, with infection developing in only 1 of 12 screws.