Caudal foot placement superior to toe elevation for navicular palmaroproximal-palmarodistal-oblique image quality.

Abstract

BACKGROUND: Palmaroproximal-palmarodistal oblique (PaPr-PaDiO) radiographs are regularly obtained for a full evaluation of the navicular bone (NB). Despite their routine use, different acquisition techniques are described. OBJECTIVES: To determine optimal foot placement and beam angle for obtaining PaPr-PaDiO views. STUDY DESIGN: In vitro experiment. METHODS: A convenience sample of 26 disarticulated forelimbs were placed in six different positions using a leg press to mimic the weight-bearing position. In each position, navicular PaPr-PaDiO images were obtained with eight different beam angles. The resulting 1248 radiographs were graded for their diagnostic quality and the compacta spongiosa demarcation of the NB. RESULTS: Diagnostic quality and compacta-spongiosa demarcation was graded higher for feet positioned caudally and angle between 40&#xb0; and 45&#xb0;. Elevation of the toe significantly decreased the NB palmar border angle (elevated mean: 40.66, SD: 4.46, non-elevated mean: 42.06, SD: 4.70) (P&#xa0;<&#xa0;.01), but seemed to have no obvious positive influence on radiographs. MAIN LIMITATIONS: Using disarticulated legs could only mimic positions but, using a press, weight-bearing positions were replicated as closely as possible. The use of a convenience sample makes the results of the study exploratory only. CONCLUSIONS: Caudal foot placement seems to improve the image quality of the navicular PaPr-PaDiO view. The widely used standard beam angle of 45&#xb0; appears to be the favourable angle for acquisition with a varied range of -5&#xb0;. Elevation of the toe, standard in most commercially available navicular skyline cassette holders, does not influence the obtained image quality.