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

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.

Functional Anatomy of the Craniomedial and Caudolateral Bundles of the Cranial Cruciate Ligament in Beagle Dogs.

OBJECTIVE: The aim of this study was to investigate detailed functional anatomy of the craniomedial bundle (CrMB) and caudolateral bundle (CdLB) of cranial cruciate ligament (CrCL) for application of intra-articular anatomical reconstruction in dogs. MATERIALS AND METHODS: Twelve stifle joint of 12 Beagle cadavers were used. Anatomical characteristics of femoral attachment regions of the CrCL were determined. Then, the location and area of the footprints of the CrMB and CdLB were objectively measured. Each bundle was equally divided into four fibre bundles, and changes in the fibre arrangement were recorded during stifle range of motion. Additionally, the tension of each fibre bundle at various stifle joint angles was objectively measured. RESULTS: The attachment region of the CrCL clearly differed from that reported in humans. The centre of the CdLB attachment site was located craniodistal to that of the CrMB on the femur and slightly caudal to that of the CrMB on the tibia. The area of the CrMB on the femoral and tibial attachment sites was larger than that of the CdLB. During stifle range of motion, each divided fibre bundle in the CrMB and CdLB was twisted intricately. The tension of the CrMB was higher than that of CdLB. The central part of the CrMB was always tense during stifle range of motion. CLINICAL SIGNIFICANCE: These results may contribute to the application of anatomical reconstruction surgery for CrCL deficient stifle in dogs.

Epidemiologic study of dogs with the displacement or deformity of the medial and lateral fabellae in Japan.

The prevalences of displacement and deformity of the medial and lateral fabellae in dogs were investigated. This was a retrospective epidemiologic study. Radiographs of canine stifle joints (1022 limbs, 534 dogs) were obtained. The images were taken at the Nihon University Animal Medical Center and three private animal hospitals from January 2003 to July 2012. The position and morphology of the medial or lateral fabella were evaluated on the radiographs. The prevalence of displacement of the medial and lateral fabellae was 1.7% and 0.3%, respectively. The prevalence of deformity of the medial and lateral fabellae was 6.9% and 4.6%, respectively. Aplasia or hypoplasia of the fabella was detected more frequently in the medial fabella. On the other hand, a bipartite or multipartite fabella was observed more frequently in the lateral fabella. Nearly all cases of displacement or deformity of the fabella occurred in dogs weighing less than 10 kg. Abnormalities of the fabella were observed in the medial and lateral fabella. We found that abnormal fabellae were closely associated with medial patellar luxation and to a lesser extent with cranial cruciate ligament rupture. No clinical signs were associated with an abnormality of the fabella, with the exception of two dogs with traumatic avulsion of the lateral head of the gastrocnemius muscle.

Evaluation of bone deformities of the femur, tibia, and patella in Toy Poodles with medial patellar luxation using computed tomography.

OBJECTIVES: To evaluate morphological parameters of the femur, tibia, and patella in Toy Poodles with medial patellar luxation (MPL) using three-dimensional (3D) computed tomography (CT) and to compare these parameters between radiography and CT. METHODS: Thirty-five hindlimbs of Toy Poodles were divided into normal and grade 2 and 4 MPL groups. The anatomical and mechanical lateral proximal femoral angle, anatomical and mechanical lateral distal femoral angle (aLDFA, mLDFA), femoral varus angle (FVA), inclination of the femoral head angle, procurvation angle, anteversion angle (AA), frontal angle of the femoral neck, mechanical medial proximal or distal tibial angle, mechanical cranial proximal or distal tibial angle, tibial plateau angle, tibial torsion angle (TTA), Z angle, relative tibial tuberosity width, ratio of the medial distance of tibial tuberosity to the proximal tibial width (MDTT/PTW), patella size, and the patellar ligament length: patellar length (L:P) ratio were evaluated on radiography and 3D CT. RESULTS: The aLDFA, mLDFA, FVA, and TTA were significantly larger and the AA, MDTT/PTW, and patella were significantly smaller in the grade 4 MPL group. There were significant differences in many parameters between imaging tools, and CT was considered less susceptible to potential artefacts and rotational deformities. CLINICAL SIGNIFICANCE: Toy Poodles with grade 4 MPL had significant femoral varus deformity, medial displacement of the tibial tuberosity, internal torsion of the proximal tibia, and hypoplasia of the patella.