Computed tomographic evaluation of femoral and tibial conformation in English Staffordshire Bull Terriers with and without congenital medial patellar luxation.
OBJECTIVE
To compare hindlimb conformation of English Staffordshire Bull Terriers with and without medial patellar luxation using computed tomography.


METHODS
Hindlimb computed tomography (CT) was performed on six English Staffordshire Bull Terriers with grade II or III medial patellar luxation, and six without medial patellar luxation. Inclination angle, femoral condyle trochanteric angle, anteversion angle (AA), distal anteversion angle (DAA), proximal anteversion angle (PAA), femoral varus angle (FVA), tibial valgus angle (TVA), and tibial torsion angle (TTA) were measured. Student's T-test was conducted to compare normal limbs to limbs with medial patellar luxation, all limbs of dogs with medial patellar luxation to limbs of the control group, and medial patellar luxation affected limbs (normal limbs of unilaterally affected dogs excluded) to the control group. P-values less than 0.05 were considered significant.


RESULTS
Two dogs with medial patellar luxation were only affected unilaterally. Limbs of English Staffordshire Bull Terriers with medial patellar luxation had significantly diminished AA and DAA, in addition to decreased TVA. These differences were similar regardless of how the unaffected limbs from affected dogs were treated in our analysis.


CONCLUSIONS
Medial patellar luxation in this population of English Staffordshire Bull Terriers was characterized by a decrease in femoral anteversion, external rotation of the femoral diaphysis, and decreased tibial valgus. These findings may help inform clinical decision making when performing osteotomy for treatment of medial patellar luxation in this breed.
Mark Newman, College of Veterinary Medicine, Murdoch University, Murdoch, WA 6150, Australia, E-mail: M.Newman@murdoch.edu.au.
Mark
M
Newman
Katja
K
Voss
D000818:Animals; D001947:Breeding; D002417:Cattle; D004283:Dog Diseases / Q000000981:diagnostic imaging*; D004285:Dogs; D005269:Femur / Q000000981:diagnostic imaging; D010027:Osteotomy; D031222:Patellar Dislocation / Q000000981:diagnostic imaging / Q000662:veterinary*; D013977:Tibia / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed / Q000662:veterinary*
Musculoskeletal imaging; computed tomography; femoral conformation; orthopaedic disorders; patella luxation; tibial conformation