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

Abstract

The aim of this study was to evaluate if the modified Insall Salvati (IS) method can be applied for the canine patient despite differences of proximal tibial morphology, and if such potential differences are also seen in dogs with cranial cruciate ligament rupture. Insall Salvati method is a simple and convenient method for determination of the vertical position of patella, by dividing the length of patella by length of the patellar ligament. The influence of the variable proximal tibial morphology on the modified (IS) index was measured and the value of modified IS index in healthy dogs (n = 25) was compared with dogs with cranial cruciate ligament rupture (n = 26). Medio-lateral radiographs of 102 stifles were evaluated. Patellar ligament length (PLL), patellar length (PL), modified IS ratio and the height of insertion point of patellar ligament on tibial tuberosity were measured. Data of the IS ratio were compared with the value of the height of the insertion point with no significant difference (P= 0.36). There was no significant difference (P= 0.07) in the PLL:PL ratio between dogs affected or unaffected with cranial cruciate ligament rupture. Based on the results of this study we can conclude that the morphology of the cranio-proximal tibia and the height of insertion point of the patellar ligament do not have an influence on the value of the modified IS index both in healthy dogs and in dogs with cranial cruciate ligament rupture.