Abstract
Objective This article aimed to determine and compare the angular values of the pelvic limb
in normal and medial patellar luxation (MPL) stifles in Chihuahuas using radiography
and computed tomographic (CT) scan, to identify the relationship between pelvic limb
angles and severity of MPL. In addition, radiographic and CT images were compared
to determine the more suitable method of limb deformity assessment.
Methods Sixty hindlimbs of Chihuahuas were divided into normal and grade 1, 2, 3 and 4 MPL
groups. The pelvic limb angles in frontal and sagittal planes were evaluated on radiography
and CT scan. Femoral and tibial torsion angles (FTA and TTA) were evaluated only by
CT scan. All angles were compared among normal and MPL stifles and between radiography
and CT scan.
Results Based on the CT scan, the mechanical lateral distal femoral angle (mLDFA), anatomical
caudal proximal femoral angle (aCdPFA), and TTA were related to the severity of MPL.
The mLDFA and TTA were significantly increased (p < 0.05) in grade 4 MPL, while the aCdPFA was significantly decreased in grade 2,
3 and 4 MPL groups. There were significant differences of many angles between radiography
and CT scan.
Clinical Significance The angles related to MPL in Chihuahuas are aLDFA, mLDFA, aCdPFA and TTA. Radiography
had some limitations for evaluating pelvic limb angles. The caudocranial radiograph
is recommended for the assessment of the distal femoral angles, while the craniocaudal
radiograph is for the tibial angles.
Keywords Chihuahua - medial patellar luxation - pelvic limb deformity - computed tomography
- radiography
