The Geometry of the Proximal Femoral Medullary Canal in German Shepherd and Kangal Dogs

Abstract

The proximal femur has morphological variability that is related to its functional and biomechanical properties. Therefore, researchers have long been interested in these variations especially associated with the femoral implant design and implantation in total hip arthroplasty. The positions of the femoral head and the geometrical variations in the medullary canal are evaluated in particular to understand the proximal femoral morphology. The position of head or neck of the dog has already been studied in detail. There are incomplete data to evaluate variations in the geometry of the medullary canal of proximal femur in dog. Proximal femoral morphology of the medullary canal has been evaluated only at the coronal plane in dog studies using plain radiography. The morphometric data on the sagittal plane are also need to innovations in femoral implants. The purpose of this study is to indicate the detailed geometric data about proximal femoral canal of dog using three-dimensional morphometric methods to provide a database for the orthopedic studies. The effect of the breed with different pelvic limb conformation was also studied in this study. The cleaned femora from 16 German shepherd and 16 Kangal dogs were used. The three-dimensional images were reconstructed from the computed tomographic images. The femoral length, the anteversion angle and neck angles, the isthmus position and the widths on medio-lateral and cranio-caudal directions of the cross-sections of proximal femur were measured. The cortico-medullary indices, the isthmus position index and the canal flare indices were also calculated to detailed investigation of medullary canal of the proximal femur. According to our study results, it must be considered in stem design that the level of the isthmus might change in response to different conformations of the dog breeds, whilst the flare indices are similar in the dogs. The flare of the medullary canal was firstly evaluated with the cranio-caudal diameters on the three-dimensional images in this study. The cortico-medullary index shows some variation between the dog breeds across the levels and the directions of the cross-sections of the proximal femur. Nowadays, three-dimensional images can be acquired and morphometric measurements can be done easily by tomography in a lot of veterinary clinics. The data from three-dimensional morphometric analysis may contribute to the optimization of the design and preoperative selection of femoral implants by surgeons.

Keywords

• Medullary canal
• Femur
• Geometry
• Dog