Tibial tuberosity conformation as a risk factor for cranial cruciate ligament rupture in the dog.

The influence of the tibial tuberosity conformation on cranial cruciate ligament (CrCl) rupture was evaluated and the size of the tibial tuberosity of healthy dogs (group H) was compared with dogs with CrCl rupture (group R) and dogs treated by tibial tuberosity advancement (TTA) (group T). The medio-lateral radiographs of 219 stifle joints were evaluated. Relative tibial tuberosity width (rTTW), proximal tibial tuberosity angle (PTTA), tibial plateau angle (TPA), tibial width (TW) and tibial plateau length (TPL) were measured on each radiograph. Body weight (BW) was measured and relative body weight (rBW) was calculated. The data from group H was compared with that of group R and group T. Group H had significantly larger rTTW, lower BW, lower rBW and smaller PTTA than group R. A comparison of groups H and T showed that dogs from group H were significantly younger, had a lower BW, a lower rBW, a greater PTTA and a smaller rTTW. In each of the comparisons, the TPA and the TW/TPL were not significantly different. The conformation of the canine tibial tuberosity has a significant influence on CrCl rupture. We hypothesized that the smaller the tibial tuberosity width, the larger the cranial tibial thrust, which results in more rapid CrCL degeneration, thus leading to rupture in a younger population of dogs. The rTTW could be a helpful measurement for breeding selection. Only dogs with a rTTW of more than 0.90 should be used for breeding.