A radiographic study on correlation between Distraction Index with various stifle joint parameters in Canine Hip Dysplasia

Canine hip dysplasia (CHD) is a common orthopaedic condition in dogs, marked by increased joint laxity. This leads to a change in force distribution on the hip joint during growth, affecting limb alignment. Anatomical deformities like coxa valga or varus and genu valgum or varum increase the risk of medial patellar luxation and other stifle affections. In the present study, the angular alterations in the femur and tibia were compared and their correlation with the severity of CHD was evaluated. Statistical analysis of the data obtained from radiographic evaluation revealed that proximal femoral angular alterations showed no significant variation and correlation with distraction index (DI), except Norberg angle, while distal femoral angular alterations (femoral varus angle and quadriceps angle) were significant with severity of CHD, exhibiting a strong positive correlation with DI. Advancing CHD worsens the distal femur varus deformity, affecting the quadriceps extension mechanism and increasing susceptibility to stifle affections. Proximal tibia angles (tibial plateau angle, proximal tibial axis angle, and mechanical medial proximal tibial angle) had a statistically significant positive correlation with DI. Thus it can be inferred that dogs with CHD may develop anatomical alterations in distal femur and proximal tibia, potentially predisposing them to patella luxation and cranial cruciate ligament rupture.