A radiographic and anatomic study of caudolateral curvilinear osteophytes on the canine femoral neck

Abstract

Caudolateral curvilinear osteophytes (CCOs) are considered to be an important finding for the early detection of canine hip dysplasia. The objective of this study was to determine the association between the radiographic and anatomic appearance of CCOs, and to determine whether CCOs are indicative of osteoarthritis. One hundred canine femurs were used to determine the topographical location of CCOs on the femoral neck, and the anatomic and radiographic presence of CCOs and their association with weight, sex, osteoarthritis, and femoral morphometry. Three angles were calculated to assess femoral conformation. The alpha angle and gamma angle described the angulation of the proximal femur and femoral neck, respectively. The beta angle described the angulation of the distal femur. Anatomic CCO was not detected in four femurs. No radiographic CCO was detected in 35 femurs and osteoarthritis changes were not found in 30 femurs. Statistically significant relationships were observed between anatomic CCO, alpha angle, and gamma angle. Statistically significant associations were observed between radiographic CCO, alpha angle, and gamma angle. The results of this study support an association between radiographic CCO on the femoral neck and osteoarthritis changes in the proximal femur. It can also be concluded that CCOs develop in association with femoral neck angulation, and may therefore be considered as an adaptation to the forces created by body weight that act through the femoral neck.

Features of the Femoral Proximocaudal Joint Capsule Insertion Among Canids

“…Our data set was derived from a large screened group of dry bone specimens that reflected low prevalence of remnant joint capsule insertion enthesophytes. Nonetheless, the data clarify the anatomic association of the capsule insertion and CCO that previously has been inferred, mostly from imaging (Mayhew et al, 2002;Powers et al, 2004;Risler et al, 2009;Kishimoto et al, 2010;Karbe et al, 2012;Miranda et al, 2016;Sarierler and Bellek, 2017) or by occasional visual anatomic assessment (Morgan, 1987;Pyszkova et al, 2017).…”

“…ancient and modern coyote, ancient and modern gray wolf, ancient and modern domestic dog, black-backed jackal, dingo, coyote × domestic dog, red fox, ancient and modern gray fox, arctic fox, swift fox, raccoon dog, and extinct dire wolf (Table 1). Five of these taxa exhibit a frequency of anatomic CCO that is less than would be expected if the underlying population frequency was 91% as observed in modern dogs by Pyszkova et al (2017); these taxa included modern coyote, dingo, modern gray fox, modern arctic fox, and modern swift fox. For these taxa, the species frequency of anatomic CCO thus may be lower than the observed 91% suggested for modern domestic dogs.…”

“…We tested whether the observed frequency of target anatomic features in each taxon was as high as that observed in the domestic dog sample reported recently by Pyszkova et al (2017), using a binomial distribution. Specifically, we estimated the binomial probability (P b ) that given the total number of femora observed in each taxon (n), we would observe at least the number of CCO-affected femora with a population frequency of 91% (from Pyszkova et al, 2017). All estimates were performed in EXCEL 2016.…”

“… P b is the binomial probability of the observed number of femora or less with CCO, given a population frequency of 91% (Pyszkova et al, ).…”

“…Recently, Pyszkova et al () examined 100 femurs from 50 deceased dogs, screening visually for CCO location prior to specimen clearing and taking radiographs following specimen clearing. The authors noted that CCO was observable radiographically in 30% of the dogs, and anatomically in 91% of the dogs.…”