Caudal foot placement superior to toe elevation for navicular palmaroproximal-palmarodistal-oblique image quality.
Authors: Peeters Manon W J, Thursby Jasmine J, Watson Hannah E, Berner Dagmar
Journal: Equine veterinary journal
Summary
# Editorial Summary Optimal positioning for palmaroproximal-palmarodistal oblique (PaPr-PaDiO) navicular radiographs remains inconsistent across equine practices despite their routine diagnostic use. Peeters and colleagues evaluated 26 disarticulated forelimbs using a mechanical press to replicate weight-bearing positions, acquiring 1248 radiographs across six foot placements and eight beam angles to assess diagnostic quality and cortical-cancellous bone demarcation of the navicular bone. Caudal foot placement significantly improved image quality and bone margin visualisation, whilst the standard 45° beam angle proved optimal (with acceptable variation of ±5°); notably, toe elevation—a standard feature in most commercial cassette holders—reduced the palmar border angle by approximately 1.4° yet provided no measurable benefit to diagnostic quality. For practitioners, this research suggests that existing navicular radiographic protocols relying on toe elevation may be unnecessarily complex, and that positioning the foot more caudally within the cassette holder could enhance diagnostic yield without additional technical demands or cost implications.
Read the full abstract on PubMed
Practical Takeaways
- •When acquiring navicular PaPr-PaDiO radiographs, position the foot caudally rather than using standard toe-elevated cassette holders to improve image quality
- •Use a 45° beam angle (±5° variation acceptable) as the standard for these projections—this confirms existing practice
- •Stop elevating the toe on navicular skyline cassette holders; this modification doesn't improve image quality and may alter anatomical angles unnecessarily
Key Findings
- •Caudal foot placement produced superior diagnostic quality and compacta-spongiosa demarcation compared to other positions
- •Beam angle between 40° and 45° yielded optimal image quality, with 45° being the standard favourable angle
- •Toe elevation significantly decreased the navicular palmar border angle (elevated mean 40.66° vs non-elevated mean 42.06°, P<0.01) but provided no positive influence on radiographic quality
- •Of 1248 radiographs evaluated from 26 disarticulated forelimbs in 6 positions with 8 beam angles, caudal positioning consistently outperformed other foot placements