In Silico Morphometric Analysis of the Tibia Following Four Virtual Proximal Levelling Osteotomies for the Treatment...

(1) To describe and compare the morphometric changes of the tibia following four virtual proximal tibial osteotomies for treatment of canine cranial cruciate ligament deficiency and (2) to determine how these changes are affected by the initial tibial plateau angle (TPA).

A total of 30 mediolateral radiographic views of canine stifle were selected. A dedicated radiographic digital planning software was used to virtually perform four osteotomy techniques for each case: tibia plateau levelling osteotomy (TPLO), cranial closing wedge osteotomy (CCWO), modified cranial closing wedge osteotomy (mCCWO), and centre of rotation of angulation-based levelling osteotomy (CBLO). Changes in tibial length, anatomical-mechanical axis angle (AMA angle), proximal tibial angulation, and patellar ligament insertion point were measured and compared.

All the parameters evaluated were significantly affected by the osteotomy technique and the initial TPA. Mean ± SD of tibial length pre-simulation was 174.2 ± 23.6 mm, and the largest significant reduction was observed after mCCWO (169.6 ± 23.3 mm) (P < 0.001). Mean ± SD of AMA angle pre-simulation was 3.1 ± 1.4 degrees and a significant reduction was observed after CCWO (1.1 ± 0.16 degrees) (P = 0.0782), but there was no significant difference among treatments. Mean ± SD of the distal tibia axis/proximal tibial axis (DTA/PTA) angle pre-simulation was 4.5 ± 2.8 degrees, and the biggest significant reduction was seen with CBLO (-10.94 ± 0.65) (P < 0.0001). The cranial and distal shift of the patellar ligament insertion point was significant after CCWO (P = 0.0004, P < 0.0001 respectively), mCCWO (P = 0.0001, P < 0.0001 respectively), and CBLO (P = 0.03, P = 0.0006 respectively) osteotomy techniques.

Proximal tibial osteotomy techniques cause morphometric changes of the tibia, and a steeper TPA exacerbates these changes. TPLO caused the fewest morphometric changes. Further investigations are warranted to understand the clinical implications on the biomechanics of the stifle.