Radiography, computed tomography and magnetic resonance imaging at 0.5 Tesla of mechanically inducedosteoarthritis in rabbit knees

Abstract

In the present experimental study we assessed induced osteoarthritis data in rabbits, compared three diagnostic methods, i.e., radiography (XR), computed tomography (CT) and magnetic resonance imaging (MRI), and correlated the imaging findings with those obtained by macroscopic evaluation. Ten young female rabbits of the Norfolk breed were used. Seven rabbits had the right knee immobilized in extension for a period of 12 weeks (immobilized group), and three others did not have a limb immobilized and were maintained under the same conditions (control group). Alterations observed by XR, CT and MRI after the period of immobilization were osteophytes, osteochondral lesions, increase and decrease of joint space, all of them present both in the immobilized and non-immobilized contralateral limbs. However, a significantly higher score was obtained for the immobilized limbs (XT: P = 0.016, CT: P = 0.031, MRI: P = 0.0156). All imaging methods were able to detect osteoarthritis changes after the 12 weeks of immobilization. Macroscopic evaluation identified increased thickening of joint capsule, proliferative and connective tissue in the femoropatellar joint, and irregularities of articular cartilage, especially in immobilized knees. The differences among XR, CT and MRI were not statistically significant for the immobilized knees. However, MRI using a 0.5 Tesla scanner was statistically different from CT and XR for the non-immobilized contralateral knees. We conclude that the three methods detected osteoarthritis lesions in rabbit knees, but MRI was less sensitive than XR and CT in detecting lesions compatible with initial osteoarthritis. Since none of the techniques revealed all the lesions, it is important to use all methods to establish an accurate diagnosis. Correspondence

Experimental osteoarthritis in rabbits: lesion progression

“…For both methods of diagnostic imaging the evaluation parameters were: presence and size of osteophytes (grade 0 = absent, 1 = small degree, grade 2 = moderate, grade 3 = severe) and subchondral sclerosis (grade 0 = absent, grade 1 =mild, 2 = moderate degree, grade 3 = severe) according to Torelli et al (2004) with modifications. Through the sum of these two parameters, a partial score was assigned to each compartment evaluated and total joint score was obtained by the sum of the parts of each compartment, the joint being scored from 0 to 30, both the RX and CT. At the end of the respective periods and imaging studies, animals were euthanized by intramuscular injection of 50mg/kg ketamine sodium 10% and after 10 minutes, anesthetized with intravenous overdose of sodium thiopental (Thiopentax ® ).…”

“…It is in many situations, more than one diagnostic method, is used to determine the presence and progression (Stickle & Hathcock 1993, Torelli et al 2004). The present study aims to evaluate the evolution of lesions associated with different stages of OA by radiography, computed tomography, macroscopic and histopathologic evaluation, linking these different diagnostic methods, as well as provide information that will help to decide the best timepoint to approach therapy considering the increasing trend of secondary lesions in rabbits with experimental OA.…”

Reprodução experimental da doença articular degenerativa, pelo método cirúrgico associado à terapia condroprotetora, em ratos

“…Os resultados aqui apresentados não diferiram dos encontrados por Mcerlain et al (2008), exceto a calcificação do tendão patelar. Torelli et al (2004) desenvolveram um estudo que induziu a OA em coelhos, por imobilização do membro pélvico, durante 12 semanas. Os animais foram avaliados por exames de raio-x, microtomografia e ressonância magnética, em períodos diferentes.…”

“…A técnica utilizada nos exames foi de 100MA, 67 Kv e 8 Mas. Todos os animais selecionados para o estudo possuíam lesões com escore 0 segundo Torelli et al (2004).…”

“…As tomografias foram avaliadas sob o mesmo critério da avaliação radiográfica, no modelo de Torelli et al (2004). O corte da avaliação foi de 0,76µm na secção oblíqua, o qual se permite visualizar a peça em 360° nos planos horizontal e vertical.…”