The Ortolani sign (OS) is very helpful for early detection of hip joint laxity in puppies. However adult patients with hip dysplasia (HD) have frequently negative OS (OS-). The purpose of this study is to relate its presence or absence to existing coxofemoral pathology.
During the period from 2002 to 2004, 160 Estrela Mountain Dogs were admitted to HV-UTAD, to evaluate HD. The population included 110 females and 50 males, older than 1 year, mean 2.5+/-1.6 years old and mean weight 40+/-7.5 Kg. Physical and radiographic studies were performed under deep sedation, assessed by the absence of response to a very firm toe pinch. In sedation protocol we intravenously administered medetomidine (0.02 mg/kg), butorphanol (0.10 mg/kg) and atropine sulphate (0.02 mg/kg). A positive OS (OS+) consisted of a palpable "clunk" when a subluxated hip was reduced by abduction, with the dog positioned in lateral recumbence. Each dog was radiographed in the standard ventrodorsal view (SVV), according to the guidelines of the Fédération Cynologique Internationale (FCI). All hips were assessed individually and classified according to the FCI criteria (grade A, B, C, D and E). A total of 320 hips were evaluated: grade A 76, all had OS-; grade B 58, 13 of these (22%) had OS+ and 45 (78%) OS-; grade C 86, 46 of these (53%) had OS+ and 40 (47%) OS-; grade D 48, 30 of these (61%) had OS+ and 18 (39%) OS-; grade E 52, 15 of these (29%) had OS+ and 37 (71%) OS-. In Chi-squared test (Yates-corrected in 2-by-2 tables), the differences of OS in dysplastic hips (C, D and E), were significant (p<0.01). The OS+, but not the HD (p>0.9), is also more frequent (p<0.001), in dogs younger than 2 years old. No significant results were observed, in OS or HD, between sexes (p>0.5 and p>0.9, respectively), in right and left hip affection (p>0.9 and p>0.4, respectively) or between dogs above or under the median weight (p>0.9 and p>0.6, respectively).
The SVV has some limitations in detecting transitional or mild hip laxity. The OS is helpful, especially to detect the early stages of HD in young dogs. Old dogs with severe HD have OS- frequently. The chronic pathologic changes: in dorsal acetabular rim, fiber-bone deposition in central acetabulum, thickened fibrotic joint capsule, proliferation of osteophytes, limited range-of-motion, fixed hip luxation or teres ligament pathology block the palpable "clunk".