Summary
This study was conducted to compare the anatomical tibial plateau angle (TPA) with
that measured by observers from a lateral radiograph of the limb, the hypothesis being
that there would not be any statistically significant differences between the observer
measured TPA and the true anatomical TPA. Twelve pelvic limbs from skeletally mature
greyhound cadavers, without any clinical or radiographic evidence of stifle pathology,
were used in this study. The radiographs were taken of each limb in a lateral position
with the primary beam centered over the tibial eminences and collimated to include
the stifle and tarso-crural joints. For subsequent radiographs, Kirschner wires were
inserted to enable identification of the tibial plateau. The TPA was then measured,
by three observers, from the plain radiographs and by one observer from the marked
radiographs. The mean observer TPA was 24.4° (range 17–30°) and the mean anatomical
TPA was 23.8° (range 15–31°). The mean and median discrepancy between the anatomical
TPA and the observer TPA was negative and very small (− 0.64° and 0°). The magnitude
of the discrepancy between individual measurements made by the observers tended to
overestimate small angles and underestimate the large ones, and this trend is statistically
significant. These results suggest that the measurements made by observers accurately
represent the anatomical slope of the tibial plateau. Therefore, observer TPA is suitable
for the planning and assessment of TPLO procedures. However, as the anatomical TPA
moves away from a median angle (23.25°) the magnitude of error in the measurement
increases.
Keywords
Tibial plateau angle - dog - anatomical
