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Aims

Ossified ungular cartilages may be associated with foot pain. There are no detailed descriptions of their radiological appearance. Dorsopalmar images are considered best for evaluation of ossification; the usefulness of oblique images has not been assessed. The aims were to describe the radiological appearance of ossified cartilages and to determine the usefulness of oblique images.

Methods

Radiographs of all feet (n = 169, 2005–2012) with ≥ Grade 2 ossification (Dyson et al. 2010) of one/both ungular cartilages were assessed subjectively using a purpose-designed grading system, after a repeatability study in which 10 sets of radiographs were examined 10 times. Detection of abnormalities was compared among conventional and oblique images.

Results

Radiological abnormalities including focal/diffuse increase in trabecular bone opacity, loss of trabecular architecture, and loss of definition between the trabecular bone and the cortices were more frequent in lateral cartilages (72, 59 and 60, respectively) than medial (41, 36 and 33, respectively). Cartilage shape varied in dorsopalmar images, being straight (270), curving axially (19) or abaxially (10). There was modelling of the cortices in 52 lateral (33 mild, 19 moderate) and 23 medial (17 mild, 6 moderate) cartilages. There were separate centres of ossification (SCsO) in 30 lateral and 14 medial cartilages. Fractures were present in 18 medial and 13 lateral cartilages, 20 at the base. Accurately distinguishing between fractures and osseous reaction around junctions between ossification centres was impossible in 8 cartilages. In total SCsO or fractures were seen in 59 dorsopalmar and 81 oblique images. Fracture sites and junctions between ossification centres were consistently best seen in oblique images. Palmar curvature of the cartilages could only be accurately detected in oblique images and was present in 31 cartilages.

Conclusions and practical significance

Lateral cartilages had a greater variation in radiological appearance than medial cartilages. Oblique images can provide information not available from other images.

Ethical animal research

Not required by this Congress: retrospective analysis of archived radiographs. Sources of funding: None. Competing interests: None.