Evaluation of the Tibial Plateau–Patella Angle (TPPA) in Dogs.

Simple Summary: The proximodistal patellar position in canine pathologies, including patella luxation, cruciate ligament rupture, and osteoarthrosis, is not fully understood, while this topic is much better understood in human medicine. Various methods are used to confirm the proximodistal patellar position, but they all require calculations and are infrequently used in everyday practice. In a two-step study with three observers, we investigated, for the first time in veterinary medicine, the applicability of a new, simple method derived from human medicine called the tibial plateau–patella angle (TPPA). This method is independent of the knee angle and magnification, does not require any calculations, and consists of just two lines. This study started with cadavers at different stifle angles. Subsequently, we used 100 X-rays at the optimal stifle angle based on these findings. In both study phases, our results revealed strong agreement among observers. The TPPA varied with the stifle angle but remained consistent across the different weight groups. We concluded that the TPPA is directly dependent on the stifle angulation and tends to be lower with a higher stifle extension angle. It could be difficult for some observers to establish the exact caudal border of the tibial plateau while measuring the TPPA. While the TPPA method shows promise, further evaluation, including breed-specific and pathological considerations, is necessary. Estimating a dog's patellar position involves various methods, which categorize it as norma, alta (high), or baja (low). However, they require various calculations. We aimed to evaluate the clinical applicability of a new method, the tibial plateau–patella angle (TPPA). This could aid in planning patella luxation surgery, estimating the patella position after TPLO and various osteotomies. We conducted a two-step study: first, on 15 stifles without pathologies from nine canine cadavers, and second, using 100 patient X-rays from the archive. Three stifle angle positions (45 ± 5°, 90 ± 5°, and 135 ± 5°) and three weight groups (S, M, and L) were evaluated in the first part of this study. Based on these results, the second part of this study was conducted using 100 pathology-free radiographs at the optimal stifle angle (90 ± 5°) from the archive. All radiographs were measured by three observers with varying levels of experience. Our results indicate that the stifle angle significantly impacted the TPPA, whereby lower values were detected with higher stifle angles, which remained consistent within the weight groups. High inter- and intra-observer agreement was achieved. The physiological TPPA values ranged from 26.7° to 48.8°, remaining consistent within the various weight groups. Observer 3 in Group S exhibited a 20% (insignificant) deviation, possibly due to challenges in determining the caudal point of the tibial plateau. In contrast with humans, TPPA values in dogs are negatively correlated with stifle angles, independent of weight. Our reliable and reproducible protocol suggests the potential benefits of training on small-breed dogs stifles. [ABSTRACT FROM AUTHOR]