Vertical position of the patella in the stifle joint of clinically normal large-breed dogs

Abstract

The L:P proved to be a repeatable measurement of vertical patellar position, which is independent of stifle angles from 75 degrees to 148 degrees. This measurement could be used as a quantitative method for diagnosing patella alta and patella baja in large-breed dogs.

Use of the modified Insall Salvati method for determination of vertical patellar position in dogs with and without cranial cruciate ligament rupture considering the morphology of the cranio-proximal tibia

“…The point of insertion of the patellar ligament is associated with a small indentation on the tibial tubercle which can be used as a landmark to measure the patellar ligament in dogs (Johnson et al 2006;Mostafa et al 2008). Johnson et al (2002) were assuming that the tibial insertion is constant, although from clinical observations, there is variability of the cranio-proximal part of the tibia, and the insertion point of the patellar ligament is not at a constant height on the tibial tubercle. Our measurement (1.75-3.0) of the modified IS index shows higher values compared to 1.45-2.17 and 1.77-2.29 obtained in the studies of Johnson et al (2006) and Mostafa et al (2008), respectively.…”

“…If we measured the length of patellar ligament on its caudal aspect as Johnson et al (2006) did, we might have got a lower IS ratio value. Values for modified IS ratio were previously reported to be independent of the stifle angle (Johnson et al 2002). We choose the 90° angle based on Mostafa et al (2008) because at this angle the modified IS ratio was at its maximal value.…”

Comparison of reliability of five patellar position indices at various stifle joint angles in pelvic limbs obtained from cadavers of red foxes (Vulpes vulpes)

“…Whereas the knee joint in humans has only a partially engaged patella at the required angle of measurement, the patella of dogs is substantially or completely engaged with the trochlea at the selected angles of measurement. 9 In addition to indices, stifle joint angle was determined from the radiographs (radiographic stifle joint angle). The center of a circle centered over the femoral condyles served as the vertex of the angle, and the arms of the angle passed through the centers of circles centered over the femoral head and tibiotarsal joint.…”

“…Significant interlimb differences in patellar position index values have been reported in humans. 15 No differences in mean interlimb index values were identified in a study 9 of clinically normal large-breed dogs. Comparisons of various patellar position indices would ideally be performed in a population of animals that are uniform in size and comparable in size to small-breed dogs that are typically affected with medial patellar luxation.…”

“…11 The insertion of the caudal border of the patellar ligament on the tibia is identified as a small notch in both humans 11 and dogs. 9 Drawbacks to this technique have been described in the literature of human and veterinary subjects and include variations in nonarticular patellar length, 12 enthesophytosis of the distal patellar pole, 6,7 masking of the caudal aspect of the patellar ligament by effusion, 7 masking of the tibial notch by minor axial rotation of the tibia, 13 and insertion of the caudal border of the patellar ligament proximal to the tibial notch. 13 Additionally, because this index relies solely on measurements of the patella and patellar ligament, surgical correction for patella alta does not change the index.…”