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

PURPOSE: To detect early osteoarthritis (OA) in a canine Pond–Nuki model 3 weeks after anterior cruciate ligament (ACL) transection surgery, both topographically over the medial tibial surface and depth-dependently over the cartilage thickness. METHODS: Four topographical locations on each OA and contralateral medial tibia were imaged individually by magnetic resonance imaging (MRI) at 17.6 μm transverse resolution. The quantitative MRI T(2) relaxation data were correlated with the biomechanical stress-relaxation measurements from adjacent locations. RESULTS: OA cartilage was thinner than the contralateral tissue and had a lower modulus compared to the contralateral cartilage for the exterior, interior, and central medial tibia locations. Depth-dependent and topographical variations were detected in OA cartilage by a number of parameters (compressive modulus, glycosaminoglycan concentration, bulk and zonal thicknesses, T(2) at 0° and 55° specimen orientations in the magnet). T(2) demonstrated significant differences at varying depths between OA and contralateral cartilage. CONCLUSION: ACL transection caused a number of changes in the tibial cartilage at 3 weeks after the surgery. The characteristics of these changes, which are topographic and depth-dependent, likely reflect the complex degradation in this canine model of OA at the early developmental stage.