MAGNETIC RESONANCE RELAXATION-TIME STUDIES OF FRACTURE REPAIR IN CHICKS: A POTENTIAL METHOD FOR EVALUATION OF FRACTURE HEALING

Abstract

Purpose: To investigate whether magnetic resonance relaxation-time measurements have a role in monitoring fracture healing. Methods: Magnetic resonance relaxation-time measurements were used to assess callus formation in chicks' tibiae and were correlated to the histopathologic and biomechanical changes that occur throughout the process of fracture repair. Results: The effective transverse relaxation time (T2) values recorded during fracture healing process were significantly longer (p = 0.0151) at day 14 (65.5575 ms.), compared with those recorded at days 3 (52.68 ms.) and 7 (55.4313 ms.). The T2 values distributions (a) at day 14 (0.2304) were significantly lower (p = 0.0313) compared with those recorded at days 7 (0.2721) and 10 (0.2742). Using a semiquantitative histologic evaluation, a significant increase in the amount of endosteal new bone (p = 0.048), and periosteal new bone (p = 0.008), associated with a significant decrease in the amount of old bone (p = 0.007) and cartilaginous tissue (p = 0.001) was observed. Analysis of the torque-angle curves demonstrated a low torque and a large angular deformation associated with low stiffness at 3–7 days post-fracture, and a high torque and a small angular deformation associated with high stiffness at 10–14 days post-fracture. Interpretation: Magnetic resonance relaxation-time follows the histopathologic and biomechanical changes occurring during the process of fracture repair and it may have a role as a potential method for objective estimation of fracture repair.