The Correlation of Canine Patellar Luxation and the Anteversion Angle as Measured Using Magnetic Resonance Images

Abstract

Measurements from magnetic resonance (MR) images can be used to examine the anteversion angle (AT-angle) and its influence on the lateromedial or mediolateral luxating forces on the patella. The AT-angle of the femoral neck was measured with the aid of MR imaging in 45 pelvic limbs without patellar instability, in 33 limbs with patellar luxation and in 6 limbs with rupture of the cranial cruciate ligament. The limbs with medial patellar luxation were divided into three groups based on clinical examination. The mean (range) AT-angle was 7.6 degrees (0 degrees to 24 degrees) in the "normal" group, 8.6 degrees (-10 degrees to 29 degrees) in the group "grade II," and -0.4 degrees in the group "grade III" (-28 degrees to 12 degrees). A mean (range) AT-angle of 4.8 (-4 degrees to 11 degrees) was measured in the pelvic limbs with rupture of the cranial cruciate ligament. Compared to literature that described AT-angles based on radiographs of normal limbs, reduced AT-angles were found in this study due to different lines of measurement of the femoral neck. This study documents that the AT-angle of the femoral neck does not influence patellar instability. This study also demonstrates that MR images can be used to make exact measurements of the canine AT-angle that represent the true anatomy of the femoral neck.

Radiographic and Computed Tomographic Determination of Femoral Varus and Torsion in the Dog

“…In humans, CT and magnetic resonance imaging have become the standard for assessment of both femoral varus and torsion, with multiple techniques described using both modalities 14–19 . In veterinary medicine, the measurement of angle of anteversion and the functional axis of the quadriceps, referred to as quadriceps angle, using magnetic resonance imaging has been reported 9,12 . The use of CT has also been demonstrated to be an effective modality to evaluate dogs with medial patellar luxation both pre‐ and postoperatively 13 .…”

“…6,7 In veterinary medicine, pathologic femoral varus and/or torsion abnormalities have been implicated in the pathogenesis of patellar luxation and canine hip dysplasia. [8][9][10] The magnitude of femoral varus, femoral torsion or both may impact the surgical treatment of both of these syndromes. In the case of patellar luxation, a femoral corrective ostectomy may be required to adequately treat excessive femoral varus.…”

Low‐field Mri and Arthroscopy of Meniscal Lesions in Ten Dogs With Experimentally Induced Cranial Cruciate Ligament Insufficiency

“…In humans, magnetic resonance imaging (MRI) is replacing arthroscopy for evaluation of meniscal injuries as it enables non invasive examination of the entire meniscus, including its tibial surface and the internal structure 18–20 . MRI of the canine stifle joint has been reported in normal dogs, 21,22 clinical patients, 23–30 and in experimental settings 31–39 . However, description of the development and MR appearance of meniscal lesions in the dog is limited.…”

Computation of Femoral Canine Morphometric Parameters in Three‐Dimensional Geometrical Models

“…Computed tomography (CT) and magnetic resonance imaging (MRI) have shown superiority over radiographs in diagnostic evaluation of bone deformities. The inaccuracy due to femoral malposition using CT and MRI has been investigated and statistically quantified .…”

“…The inaccuracy due to femoral malposition using CT and MRI has been investigated and statistically quantified . CT and MRI have been used to assess femoral conformational deformities, detect geometry and joint changes mediated by surgical treatment, as well as quantify and monitor joint disease for early diagnosis of hip dysplasia . Although malpositioning can be effectively reduced using CT and MRI, these techniques allow improvement of femoral orientation and visualization of specific anatomic landmarks since the measurement of femoral angles and axes is still achieved with 2‐dimensional (2D) imaging.…”