Topographical and depth-dependent glycosaminoglycan concentration in canine medial tibial cartilage 3 weeks after anterior cruciate ligament transection surgery—a microscopic imaging study

Abstract

Background: Medical imaging has become an invaluable tool to diagnose damage to cartilage. Depletion of glycosaminoglycans (GAG) has been shown to be one of the early signs of cartilage degradation. In order to investigate the topographical changes in GAG concentration caused by the anterior cruciate ligament transection (ACLT) surgery in a canine model, microscopic magnetic resonance imaging (µMRI) and microscopic computed tomography (µCT) were used to measure the GAG concentration with correlation from a biochemical assay, inductively coupled plasma optical emission spectroscopy (ICP-OES), to understand where the topographical and depth-dependent changes in the GAG concentration occur.Methods: This study used eight knee joints from four canines, which were examined 3 weeks after ACLT surgery. From right (n=3) and left (n=1) medial tibias of the ACLT and the contralateral side, two ex vivo specimens from each of four locations (interior, central, exterior and posterior) were imaged before and after equilibration in contrast agents. The cartilage blocks imaged using µMRI were approximately 3 mm × 5 mm and were imaged before and after eight hours submersion in a gadolinium (Gd) contrast agent with an in-plane pixel resolution of 17.6 µm 2 and an image slice thickness of 1 mm. The cartilage blocks imaged using µCT were approximately 2 mm × 1 mm and were imaged before and after 24 hours submersed in ioxaglate with an isotropic voxel resolution of 13.4 µm 3 . ICP-OES was used to quantify the bulk GAG at each topographical location.Results: The pre-contrast µMRI and µCT results did not demonstrate significant differences in GAG between the ACLT and contralateral cartilage at all topographical locations. The post-contrast µMRI and µCT results demonstrated topographically similar significant differences in GAG concentrations between the ACLT and contralateral tibia. Using µMRI, the GAG concentrations (mg/mL) were measured for the ACLT and contralateral respectively, the exterior (54.0±3.

Reduction of osteoarthritis severity in the temporomandibular joint of rabbits treated with chondroitin sulfate and glucosamine

“…Previous studies have reported complete loss of extracellular matrix GAGs both in articular cartilage with severe OA [52,53] and in degenerative or displaced articular discs [54]. However, in the present study, there was a significant increase in GAGs in the articular discs of OG vs CG rabbits, when analyzing the 2 time points together.…”

Image interpolation improves the zonal analysis of cartilage T2 relaxation in MRI

“…Given our extensive experience with similar canine cartilage at microscopic resolutions (2,21,28,34), the multidisciplinary properties of this type of cartilage are well understood. Our study of canine tibial cartilage at 200 µm per pixel by macro-MRI has approximately the same length scale in comparison to the clinical MRI of a thicker human tibial cartilage at a fraction of millimeters per pixel using a whole-body MRI scanner, both resolving about three pixels across the thickness of cartilage based on the clinical settings implemented.…”

Detection of early osteoarthritis in canine knee joints 3 weeks post ACL transection by microscopic MRI and biomechanical measurement

“…At these locations, the OA cartilages were consistently much softer than the contralateral cartilage The GAG values were obtained by inductively coupled plasma optical emission spectrometry, which have been reported earlier. 24 The numbers in boldface indicate the significant statistical differences between the OA and contralateral cartilage (p < 0.05).…”

“…[18][19][20][21] The degradation occurs topographically over the articular cartilage; the medial tibia cartilage is one of the prominent locations for the onset of OA. 15,[22][23][24] In this study, microscopic MRI (mMRI) T 2 relaxation was used to investigate the early topographic changes in the medial tibiae of canines merely 3 weeks after ACL transection, which initiated OA progression. In addition, the mMRI measurements were correlated with the compressive modulus measured by indentation stressrelaxation experiments.…”