Lateromedial and oblique radiographs detect most fetlock pathologies as effectively as a full series in horses

Radiographic protocols for the metacarpo-/tarsophalangeal joint during pre-purchase examinations (PPE) vary internationally, but their impact on pathology detection remains unclear. Optimising imaging protocols is essential to balance diagnostic accuracy with workflow efficiency and radiation exposure.

To evaluate the effect of different radiographic view combinations on fetlock pathology detection and observer agreement in a PPE context; hypothesising that detection rates vary with view selection.

Retrospective observational study.

Two observers reviewed fetlock radiographic series using four view combinations: lateromedial (LM) alone, LM and dorsopalmar/plantar (LM/DP), LM and oblique projections (LM/OB), and the full series (FULL). McNemar's chi-squared test assessed detection differences; Cohen's kappa evaluated intra- and inter-observer agreement, and diagnostic parameters were calculated for reduced views relative to the full series.

A total of 673 fetlock series were reviewed. The LM/OB combination showed no significant difference in detecting most pathologies compared to the full series. Observer agreement was generally highest with the full series. Intra-observer agreement was highest for LM/OB, except for subchondral bone changes in the proximal phalanx, where LM/DP performed better; though overall agreement was low. Lateromedial projections reliably detected fragmentation, sesamoid fractures, and osseous cyst-like lesions. Oblique views were superior for sesamoid bone changes.

Retrospective design, selection bias, and lack of gold standard confirmation.

While LM/OB offers a practical compromise in many PPE scenarios, certain pathologies, particularly subchondral bone changes, may require additional views. A tailored approach based on age, discipline, and clinical risk may optimise diagnostic yield.