Assessment of 3 detorsional planning techniques for distal femoral osteotomy to the distal femoral metaphysis in 3 dog breeds.

Objective: To evaluate the shape of the distal femoral metaphysis in various dog breeds and apply femoral detorsional techniques.

Animals and procedure: Computed tomographic scans of 6 right femurs of dogs from 3 breeds, Chihuahua, border collie, and rottweiler, designated Groups 1, 2, and 3, respectively. On the distal femoral metaphysis axial image, just proximal to the femoral trochlea, femoral craniocaudal and mediolateral diameters were measured and their ratio (R) was calculated. The circumference technique (CiT), cortical arch length method (CAL), and geometric method (GM) were applied to these images to simulate 15° of detorsion. For each technique, the detorsion amount and the resulting detorsion angle (α) were calculated and reported.

Results: Means and standard deviations of R were 0.59 ± 0.10, 0.81 ± 0.05, and 0.87 ± 0.08 for Groups 1, 2, and 3, respectively. In Group 1, due to the femoral flattened shape, the techniques were not reliable. In Groups 2 and 3, the correction was acceptable.

Conclusion and clinical relevance: The distal femoral metaphyseal axial section shape in Group 1 was comparable to an ellipse. Therefore, the tested techniques were not reliable in chondrodystrophic dogs.