A comparison of acetate and digital templating for hip resurfacing

This study sought to determine whether templating for metal-on-metal hip resurfacing is more accurate with digital or acetate methodology. The medical records of 102 consecutive patients who underwent hip resurfacing at our institution were retrospectively reviewed. Records lacking preoperative radiographs that included a magnification-establishing marker were excluded, leaving 78 records for study. Two investigators independently prepared acetate and digital templates of the preoperative radiographs, which had been calibrated to 120% magnification, to predict femoral and acetabular component size. Accuracy was measured by comparing the predicted component sizes to the surgically implanted component sizes. Digital templating was more accurate than acetate templating in predicting hip resurfacing component size when measuring accuracy of templates by the absolute error of predicted component sizes (femoral, P < .001; acetabular, P = .002), and by the prediction of components to +/-1 size difference (femoral, P = .001; acetabular, P = .002). Experience of the templating surgeon did not correlate with templating accuracy for acetate or digital templating. Although acetate templating is often regarded as the "gold standard" in preoperative planning, data from the current study shows that digital technology can be used for accurate preoperative templating prior to hip resurfacing procedures.