Comparison of Insall-Salvati Index and Its Modification in Normal Dogs from Four Different Body Weight Groups.

OBJECTIVE: The objectives of this study were to record the values of Insall-Salvati (IS) index and its modification in dogs classified into four different body weight groups and to determine whether these index values were influenced by sex. STUDY DESIGN: Bilateral mediolateral radiographs of 86 dogs were obtained. The dogs were classified into four different body weight groups: small, medium, large and giant. The patellar length (PL), caudal and cranial patellar ligament lengths (LLca and LLcr), stifle angle and superimposition of the femoral condyles were measured on the radiographs. The IS index and its modification (LLcr:PL) were calculated by dividing LLca or LLcr by the PL respectively. Spearman's correlation test and analysis of variance were used for statistical analyses. RESULTS: The sex of the dog and the presence of enthesophytes at the apex of the patella were two influential factors for the IS and LLcr:PL values. The mean IS values were 1.60 ± 0.28 in small dogs, 1.73 ± 0.27 in medium dogs, 1.82 ± 0.21 in large dogs and 1.97 ± 0.13 in giant dogs. The mean LLcr:PL for the same groups were 2.05 ± 0.23, 2.13 ± 0.19, 2.23 ± 0.21 and 2.27 ± 0.16 respectively. CONCLUSION: The reference intervals for the IS index were 1.04 to 2.16 in the small dogs, 1.19 to 2.27 in the medium dogs, 1.40 to 2.24 in the large dogs and 1.71 to 2.23 in the giant dogs. The reference intervals for the LLcr:PL index were 1.59 to 2.51 in the small dogs, 1.75 to 2.51 in the medium dogs, 1.81 to 2.65 in the large dogs and 1.95 to 2.59 in the giant dogs. Dogs with values exceeding these reference intervals have patella alta and those with values below these intervals have patella baja.

Effects of Tibial Rotational-guided Growth on the Geometries of Tibial Plateaus and Menisci in Rabbits.

BACKGROUND: There are studies on the use of oblique plate over epiphyses for rotational deformities but the effects of this method on bone are not yet known. The purpose of this study was to determine the effect and rebound effect of rotational-guided growth on the geometries of the tibial plateaus and menisci in a rabbit model of tibial axial rotation. METHODS: Thirty male rabbits were 6 weeks old when medial and lateral plates were applied to the proximal tibias of the left side. After 4 weeks, 15 rabbits were euthanized (group 1), and the plates from the tibias of the remaining 15 rabbits (group 2) were removed. The rabbits in group 2 were euthanized 4 weeks later. RESULTS: In the rabbits of group 1, the most striking differences were a decrease in the lateral tibial slope (from 28.3 to 10.8 degrees) and decrease in the ratio of the lateral plateau covered by the meniscus (from 71.9% to 61.3%). After removing the plates (group 2), the observed values of the rebound effects were 25.9 and 29.8 degrees for the lateral tibial slope, and 76.5% and 77.2% for the ratio of the lateral plateau covered by the meniscus. However, the meniscal geometries continued to change. CONCLUSIONS: The rotational-guided growth provided by using plates caused a change in the tibial plateau geometry, and the rebound effect, except in the meniscal geometry, was observed after removing the plates in the growing period of the rabbits. Rotational-guided growth for the restoration of tibial axial rotation deformities may be suggested after determining the clinical effects of the increasing meniscal variables. LEVEL OF EVIDENCE: Clinical relevance: the rotational-guided growth needs close follow-up because of possible changes in anatomy of the bone.

Comparison of goniometric measurements of the stifle joint in seven breeds of normal dogs.

OBJECTIVE: To compare the goniometric measurements of the stifle joint in seven dog breeds, and to determine the relationship among goniometric measurements, age, body weight, tibial plateau angle, crus and thigh circumferences, and widths of quadriceps, hamstring, and gastrocnemius muscles in healthy dogs. METHODS: We used a total of 126 dogs from seven different breeds, and recorded the angle of the stifle joint at standing, extension, and flexion together with the range of motion (ROM). The circumferences of the thigh and crus were also measured. Mediolateral radiographic projections of the tibia and the femur were obtained from the dogs, and the tibial plateau angles, as well as the widths of quadriceps, hamstring, and gastrocnemius muscles, were measured from these images. RESULTS: Neither the sex of the dog nor the differences in the side measured affected the goniometric measurements of the stifle joint. The standing, extension, flexion, and ROM angles were different among the breeds. The standard deviations of the standing and extension angles were small relative to their means, but the standard deviations of the flexion angle were large relative to their means in all breeds. Body weight and muscular measurements were the most influential factors on the stifle flexion angle and ROM. CLINICAL SIGNIFICANCE: Breed differences, body weights, and muscle mass should be taken into consideration during assessment of the stifle function using goniometric measurements.