Morphological Analysis of Bone Deformities of the Distal Femur in Toy Poodles with Medial Patellar Luxation

Abstract

Objective The aim of this study was to evaluate the bone deformities of the distal femur of Toy Poodles with medial patellar luxation (MPL) using computed tomography. Methods Computed tomography data from 37 stifles of Toy Poodles (16 normal, 10 grade 2 MPL and 11 grade 4 MPL) were analysed. For trochlear morphology, sulcus angle, medial or lateral trochlear inclination and trochlear angle were compared. For condylar morphology, distance between the apex of the medial or lateral trochlear ridge and the most caudal point of the medial or lateral femoral condyle (MC or LC), the length of the cranial/middle (anterior) part (MC(a) or LC(a')) and caudal (posterior) part (MC(p) or LC(p')) of distal femur and medial or lateral condyle width (MCW or LCW) were measured, and the ratios of medial-to-lateral condyles and anterior–posterior parts were compared. Results Sulcus angle was significantly higher, and medial trochlear inclination was significantly lower in grade 4 MPL group than other groups. Lateral trochlear inclination was not significantly different among 3 groups. Trochlear angles at proximal trochlear groove were significantly lower in grade 4 MPL group than other groups. MC/LC, MC(a)/LC(a'), MC(a)/MC(p), and LC(a')/LC(p') were significantly lower in grade 4 MPL group than other groups; however, there were no significant differences in MC(p)/LC(p') and MCW/LCW among three groups. Conclusion Hypoplasia of the cranial and middle rather than caudal compartment of the distal femur was the primary morphological abnormality in Toy Poodles with grade 4 MPL.

Computed tomographic measurements of the femoral trochlea in dogs with and without medial patellar luxation

“…We accept our first hypothesis, as in this study the overall FTGA in dogs without MPL was smaller compared to MPL dogs, similarly to what other authors have recently reported. 8,14,15 Among SB and MLB populations, we discovered a mean FTGA of 128 ± 4.7 in SB and 119 ± 5.6 in MLB with cutoff values of 134 and 128 respectively. These data slightly differ from human literature, which suggests that a normal trochlea has an average sulcus angle of 138 ± 6 , while dysplastic trochleae have a sulcus angle >145 .…”

“…11,12 The benefits of the broad availability of radiographs and ease for performing a skyline view of the femoral trochlea are counteracted by the threedimensional complexity of the trochlea morphology, which changes in proximodistal direction. 7,14,15 Moreover, from the authors' perspective, when performing the skyline radiographic projection, it is difficult to select and analyze one specific point of the trochlear groove. As a result, it would be necessary to perform multiple radiographs with a different degree of stifle flexion, although this will probably increase the sedation time and costs.…”

“…To the authors' knowledge, CT was used in two studies to evaluate the FTGD and trochlear ridge orientation using angular measurements in SB. 14,15 A shallower femoral trochlear groove in MPL dogs compared to dogs without MPL, was observed proportionally to the MPL grade. Both studies were performed in small breed (SB) dogs.…”

“…As a result, little information concerning the trochlear morphology in dogs with and without MPL is available. To the authors' knowledge, CT was used in two studies to evaluate the FTGD and trochlear ridge orientation using angular measurements in SB 14,15 . A shallower femoral trochlear groove in MPL dogs compared to dogs without MPL, was observed proportionally to the MPL grade.…”

Ideal Anchor Points for Patellar Anti-rotational Sutures for Management of Medial Patellar Luxation in Dogs: A Radiographic Survey

“…Limited data are available on femoral condylar morphology, despite morphological studies in medium to large breed dogs, and in small breeds. 23 26 27 28 29 A trend to a more “vertically” oriented trochlea was noted in small breeds with medial patellar luxation. 23 Visually, many of our small breed dogs had “hockey-stick”-shaped distal femora and a relatively large radius to the trochlear arc, resulting in placement of the best-fit centre caudal to the metaphysis.…”