THE PATELLA THICKNESS TO FEMORAL TROCHLEA DEPTH RATIO THE AS A CHOICE PREDICTOR OFTHE PATELLAR LUXATION SURGICAL TREATMENT IN DOGS

Abstract

Patellar luxation (PL) is a surgical pathology of the knee joint, the lack of timely correction of which can lead to the development of comorbid arthropathies associated with joint instability. There are several PL correction surgical methods, the most widely used of which is the transposition of tibial tuberosity combined with trochleoplasty. However, trochleoplasty requires dissection of the joint capsule, which increases surgical trauma, is associated with damage to articular cartilage, because of which the recovery period is prolonged, and the number of postoperative complications increases. Therefore, it is essential that the surgeon determines whether this surgical trauma is necessary. The aim of our study was to determine the value of the P-STOF index (Patella— Sulcus trochleae ossis femoris) in dogs, in which it is necessary to perform trochleoplasty. During the study, 15 cadavers of dogs weighing up to 12 kg were used (mean weight ±SD: 4.7±3.7 kg). The knee joint area radiography in tangential and mediolateral projections was performed on 30 unpaired pelvic limbs of cadavers of dogs to the depth of the femoral trochlear groove (Sulcus trochleae ossis femoris — STOF) and the craniocaudal thickness of the patella. After that, the joints were opened, and measurements were carried out using an electronic caliper. It was found that reliable results are obtained by measuring the depth of STOF by radiographs in the tangential projection and by measuring the craniocaudal thickness of the patella by radiographs in the mediolateral projection. The mean patella thickness to femoral trochlea depth ratio in dogs without knee arthropathies was 3.1±0.2 (the standard error of the mean is indicated) (95% CI 2.7–3.5) and 4.0±0.3 (95% CI 3.4–4.5) in dogs with identified knee arthropathies. Therefore, when the P-STOFF index value is more than 3.4, trochleoplasty is recommended, since this value represents the lower limit of the confidence interval in dogs with arthropathies.