RADIOGRAPHIC EVALUATION OF COXOFEMORAL JOINT LAXITY IN DOGS PART II: COMPARISON OF STRESS - RADIOGRAPHIC POSITIONING TECHNIQUES IN DOGS WITH HIP DYSPLASIA

Abstract

Two stress-radiographic positioning techniques for evaluation of coxofemoral joint laxity in dogs with hip dysplasia were compared with the standard technique. Forty, healthy, large breed dogs were divided into two groups of 20 dogs. Group 1 had normal hips. Group 2 were dogs with mild to moderate grade of hip dysplasia according to the Orthopedic Foundation for Animals (OFA) standard. Dogs were anesthetized and placed in
dorsal recumbency before 3 radiographic techniques, standard hip-extended, 60O and 90O stress techniques, were taken. For the 60O stress technique, hind legs were extended in parallel to each other at 60O to the table top and femoral heads were manually pushed craniodorsally during exposure. For the 90O stress technique, femurs were positioned perpendicular to the table top; stifles were 90O flexed and adducted and femoral heads were manually pushed in a craniodorsal direction during exposure. Subluxation index (SI) and dorsolateral subluxation score (DLS score) of coxofemoral joints were assessed from radiographs. The SI of normal dogs from standard, 60O,
and 90O stress techniques were 0.15, 0.20, and 0.23, and of dysplastic dogs were 0.34, 0.40, and 0.41, respectively. The degrees of subluxation assessed from the two stress technique radiographs were significantly greater (p < 0.05) than those shown on the standard technique radiographs in both groups of dogs. DLS scores of normal
dogs from standard, 60O and 90O stress techniques were 65.1%, 64.3%, and 61.0%, and of dysplastic dogs were 55.4%, 53.6%, and 47.6%, respectively. Mean of DLS scores assessed from the 90O radiographs was significantly lower (p < 0.05) than those assessed from radiographs of other two techniques in both groups of dogs. The
findings suggested that the 90O stress technique is more efficient than the standard and 60O stress techniques for radiographic evaluation of coxofemoral joint laxity in dogs with mild hip dysplasia and early detection of hip dysplasia in dogs that show no clinical signs.