Abstract

OBJECTIVES:

To compare centered versus distal tibial plateau leveling osteotomy (TPLO) position on cranial tibial subluxation, postoperative tibial plateau angle (TPA), and tibial long axis shift (TLAS).

STUDY DESIGN:

In vitro biomechanical evaluation.

ANIMALS:

Six pairs of canine cadaveric hind limbs.

METHODS:

One limb of each pair was randomly assigned to the distal (TPLO-D) or centered (TPLO-C) osteotomy group. Cranial tibial subluxation (CTS) under load was quantified sequentially under 3 conditions: intact, after cranial cruciate ligament transection, and after TPLO; a corrected CTS value was also calculated. Postoperative TPA and TLAS were measured. Comparisons were made using 1-way repeated measures ANOVA with a Tukey's multiple comparison post hoc test for CTS, and a Wilcoxon's sign rank test for TPA and TLAS. Significance was set at P<.05.

RESULTS:

TPLO-C had a significantly lower mean CTS than TPLO-D (P<.01). Corrected CTS was also significantly lower in TPLO-C than in TPLO-D (P<.001). Postoperative TPA and TLAS were less in TPLO-C than in TPLO-D (P=.0312).

CONCLUSION:

Our results confirm that distal centering of the TPLO leads to craniodistal translation of the tibial plateau, TLAS, and a postoperative TPA that is greater than expected. This geometric effect has the biomechanical effect expected of inadequate tibial plateau leveling, namely incomplete neutralization of cranial tibial thrust.

CLINICAL RELEVANCE:

The centered osteotomy position is geometrically more precise, and biomechanically more effective than the distal position.