Fetlock Parameters Development on Dorsopalmar Radiographs in the Equine Forelimb

Several reports have discussed possible bony morphological causes of fetlock pathology but without relating them to its morphometry. Radiographic measurement is widely used in constructing numerical databases of bone morphometry. Such measurements would not be reliable unless all factors affecting the radiographs were considered. Therefore, this study aimed to establish a specific dorsopalmar view (DP) for fetlock radiographic measurements, and then to develop reliable and repeatable fetlock parameters that represent fetlock conformation on those DP radiographs. Ten cadaveric forelimbs from ten adult horses were cut at the distal third of the radius and mounted in a normal posture for DP radiography. Specific features on fetlock bones were used as landmarks to identify the DP at zero degrees. Other bony features were selected as landmarks for developing fetlock parameters on these radiographs. Twenty-seven parameters were designed in the form of angles (12) and ratios (15). The repeatability and consistency of each parameter was tested. A specific fetlock DP view was determined at zero degrees based on certain landmarks. All angular and ratio parameters showed high reliability and consistency in their measurements. The established parameters provide an opportunity to test the relationship between fetlock morphometrics and performance, or the likelihood of certain pathologies.