Temporary position measurements in bone

ABSTRACT In order to analyze X-ray markers for potential use in biodegradable implants or radio-stereogrammatic analysis (RSA), we combined iopro-mide contrast fluid with biodegradable calcium phos-phate cement. The radio-opacity of 10 × 10 mm markers containing different iodine concentrations (0, 120, 240, 360 and 720 mg per gram cement) was compared to an aluminium wedge of increasing (1–10 mm) thickness. The addition of iopromide increased the radio-opacity in a dose-dependent manner, which was comparable to 9-mm aluminium at concentrations of 240–720 mg/g. Radiographs of markers placed in explanted rabbit and in human femora were made to investigate the clinical accuracy for position determination. Markers of 1 × 1 mm (120 mg/g) were clearly discernable in all femora, and could be used to adequately measure distances of 5–45 mm (accuracy 0.10–2.19 mm). These markers might be embedded in biodegradable implants or used as temporary markers in the bone to analyze postopera-tive position on radiographs.