The Role of Magnetic Resonance Imaging in Evaluating Post-Operative ACL Reconstruction Healing and Graft Mechanical Properties: A New Criterion for Return to Play?

Disruption of the anterior cruciate ligament (ACL) is a common injury. In active patients, it is routinely treated with ACL reconstruction surgery. Following reconstruction, one of the critical decisions that must be made is the optimal timing of return to sport. While a many of biomechanical, biological, and functional criteria have been proposed to determine return to play, these methods are limited at best. As criteria for return to play are multifactorial, there is a growing need for non-invasive technologies, such as magnetic resonance imaging (MRI), to objectively track graft healing, to better assess the graft itself. Measuring the changes in strength of the healing ligament has been shown to be a reliable means of objectively documenting graft healing in pre-clinical studies. While the initial studies of MR-based modeling of ACL graft healing are promising, this technology is still in its infancy and requires optimization. The goals of this review are: 1) to outline the shortcomings of current return to play criteria, 2) to highlight the ability of MRI to determine the status of ACL graft healing, and 3) to discuss the future of imaging technology to determine return to play and its potential role in the clinical evaluation of patients.