In Vivo Follow-Up of Spontaneous Repair of Osteochondral Defects in Rabbits Patellar Groove with Quantitative MRI

Piia Kristiina Valonen¹, Hertta Pulkkinen¹, Virpi Tiitu¹, Mikko Lammi¹, Risto Ojala², Miika Nieminen², Ilkka Kiviranta³

T₂-weighted imaging, T₁-mapping, and dGEMRIC were used to follow spontaneous repair of osteochondral defect in rabbits. Lesions (∅ 4 mm, 3 mm in depth) were made into the patellar groove, and MRI was taken 1 week, 2, 4, and 6 months after surgery. Pre-contrast T₁-values shortened significantly for cartilage and bone repair, with cartilage T₁ approaching the value of intact tissue. The dGEMRIC index also showed a decreasing trend. MRI was successfully used to follow the properties of spontaneous repair tissue, but in six months it did not achieve the structure of intact cartilage, shown with MRI and histology.