Summary
Objectives: To compare the conformation of the proximal tibia evaluated on a medio- lateral radiograph
between small and large dogs with cranial cruciate ligament disease (CCLD).
Methods: Retrospective clinical study with dogs having radiographic evaluation and CCLD confirmed
at surgery. The first group (n = 52) was comprised of dogs weighing less than 15 kg
and the second group (n = 52) of dogs weighing more than 15 kg. The tibial plateau
angle (TPA), the relative tibial tube-rosity width (rTTW), and the Z angle were measured
on preoperative radiographs with imaging measurement software. Linear mixed models
were used to assess the effect of weight, age, sex, and neutered status on radiographic
measurements and to estimate interobserver variabilities.
Results: The small dog group had a greater TPA (30.1° ± 5.3; p <0.001 with a mean difference
of 4.9° [95% CI: 3.8–6.0]) and Z angle (69.9° ± 5.6; p<0.001 with a mean difference
of 6.1° ([95% CI: 4.9–7.4]) than the large dog group. Sex and neutered status further
influenced the TPA and Z angle val -ues. No significant effect was observed on the
rTTW values. A strong correlation was found between the TPA and the Z angle (r = 0.61,
p <0.001). Variances were not significantly different between observers. Overall the
interobserver variability was low suggesting that agreement was good.
Clinical significance: Small dogs with CCLD have a steeper tibial plateau than large dogs with CCLD. Sex
and neutered status also had an effect on some measured variables. This anatomical
difference could influence the surgical technique, which may affect the outcome. The
good interobserver agreement suggests the observer is unlikely to influence surgical
planning.
Keywords
Canine - cranial cruciate ligament disease - tibial plateau - predisposition